COMBINED EFFECTS OF RADIOACTIVE, CHEMICAL AND ...

COMBINED EFFECTS

OF RADIOACTIVE, CHEMICAL

AND THERMAL RELEASES

TO THE ENVIRONMaHl

PROCEEDINGS OF A SYMPOSIUM STOCKHOLM, 2-5 JUNE 1975

JOINTLY ORGANIZED BY THE IAEA AND NEA (OECD)

COMBINED EFFECTS OF RADIOACTIVE, CHEMICAL AND THERMAL RELEASES

TO THE ENVIRONMENT

PROCEEDINGS SERIES


TO THE ENVIRONMENT

PROCEEDINGS OF A SYMPOSIUM ON THE COMBINED EFFECTS ON THE ENVIRONMENT OF RADIOACTIVE, CHEMICAL AND THERMAL RELEASES

FROM THE NUCLEAR INDUSTRY JOINTLY ORGANIZED BY

THE INTERNATIONAL ATOMIC ENERGY AGENCY AND THE OECD NUCLEAR ENERGY AGENCY

AND HELD IN STOCKHOLM, 2 - 5 JUNE 197 5

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 197 5


TO THE ENVIRONMENT IAEA, VIENNA, 197 5

STl/ PUB/ 404 ISBN 92-0-020275-6

Printed by the IAEA in Austria December 1975

FOREWORD

A considerable increase in the number of nuclear power reactors and irradiated-fuel reprocess-ing plants will be required if the projected development of nuclear power up to the year 2000 is to be realized. The environmental implications of both a greater local concentration of power plants and a more widespread distribution of these throughout the world are being studied.

Since the operation of nuclear facilities results in the controlled release to the environment of small amounts of radioactive effluents, and these facilities and other industrial plants release in addition chemical and thermal effluents, attention must also be given to the study of the combined effects of such releases on environmental ecosystems. A better understanding of these effects is necessary in order to achieve the minimum 'detriment' to environmental quality from nuclear power development.

For many years extensive studies have been carried out on the impact on the environment of radioactive releases from the nuclear industry, particularly as they affect man. More recently, provoked by the forecast rapid development of nuclear power, scientists have also been studying the environmental effects of thermal and chemical releases from the nuclear-industry separately.

The possibility of synergistic and combination effects from interaction of these releases and their significance in respect of man and his environment originally received little attention. However, during the past few years institutes in a number of countries have taken a more active interest in studies on combined effects, considering not only releases to aquatic environments, particularly rivers and lakes, but also releases to the atmosphere.

In order to provide an opportunity for assessing existing knowledge, the Agency, in co-operation with the OECD Nuclear Energy Agency, held a symposium on this subject in Stockholm from 2 to 5 June 1975. The symposium attracted 133 participants, representing 24 countries and nine international organizations. A total of 22 papers from 9 countries and one international organization were presented, and the meeting was concluded with a panel discussion that examined a number of important questions that had arisen concerning the combined effects of releases to the environment from the nuclear and other industries.

The need for such a meeting, and its particular value as a forum for exchange of information in this field, with application to all steam electric power plants and certain other industries, was evinced by the lively discussion generated by the presentation of the papers, and these also emphasized the breadth of interest, involving, as it does, representatives of numerous scientific disciplines.

It is hoped that these Proceedings, which include the full texts of all the papers, the dis-cussions on individual papers and the panel discussion, will prove a useful addition to the library of information on environmental sciences.

EDITORIAL NOTE

The papers and discussions have been edited by the editorial staff of the International Atomic Energy Agency to the extent considered necessary for the reader's assistance. The views expressed and the general style adopted remain, however, the responsibility of the named authors or participants. In addition, the views are not necessarily those of the governments of the nominating Member States or of the nominating organizations.

Where papers have been incorporated into these Proceedings without resetting by the Agency, this has been done with the knowledge of the authors and their government authorities, and their cooperation is gratefully acknowledged. The Proceedings have been printed by composition typing and photo-offset lithography. Within the limitations imposed by this method, every effort has been made to maintain a high editorial standard, in particular to achieve, wherever practicable, consistency of units and symbols and conformity to the standards recommended by competent international bodies.

The use in these Proceedings of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries.

The mention of specific companies or of their products or brand names does not imply any endorsement or recommendation on the part of the IAEA.

Authors are themselves responsible for obtaining the necessary permission to reproduce copyright material from other sources.

CONTENTS

INTRODUCTORY PAPER (Session I)

Interaction mechanisms of radioactive, chemical and thermal releases from the nuclear industry: Methodology for considering co-operative effects (IAEA-SM-197/22) 3 C. Streffer Discussion 11

EFFECTS OF TEMPERATURE ON RADIONUCLIDE UPTAKE (Session II)

Impact of thermal and radioactive effluents on a tropical nearshore ecosystem (IAEA-SM-197/2) 17 B. Pat el, M.C. Balani, Shakunt Pat el, V.K. Panday, S.D. Soman Discussion 34

The effect of temperature on the uptake and retention of 50Co and 6sZn by the common shrimp Crangon crangon (L.) (IAEA-SM-197/10) 35 A. W. van Weers Discussion 48

Influence de la temperature sur la contamination d'especes marines par le fer-59 (IAEA-SM-197/15) 51 A. Fraizier, J. Ancellin Discussion 64

SYNERGISM AND COMBINATION EFFECTS IN AQUATIC SYSTEMS (Session III)

Swedish studies on combination effects of thermal discharges in the aquatic environment: Some aspects of power plant siting policy (IAEA-SM-197/24) 69 U. Grimas, U. Ehlin Discussion 80

Evaluation of the thermal effects of a nuclear power plant (IAEA-SM-197/5) 83 E. loannilli, E. Smedile Discussion 91

Biological effects of simulated discharge plume entrainment at Indian Point Nuclear Power Station, Hudson River estuary, USA (IAEA-SM-197/25) : v ! : 95 G.R. Lanza, G.J. Lauer, T.C. Ginn, Patricia C. Storm, Lois Zubarik Discussion 124

Effect of entrainment in power station cooling systems studied using periphytic communities (IAEA-SM-197/6) 127 E. Smedile, V. Parisi Discussion 142

EFFECTS OF CHEMICAL RELEASES ON RADIONUCLIDE UPTAKE (Session IV)

Techniques de determination rapide des effets de synergie radionuclides — polluants (IAEA-SM-197/16) 145 A. Saas, A. Grauby Discussion 152

Trace element interactions in the estuarine zone of the Anasco River, Puerto Rico (IAEA-SM-197/18) 155 D.A. Wolfe, W.O. Forster, R. McClin, F.G. Lowman Discussion 177

Incidence de la charge polluante des eaux sur le comportement des radionuclides (IAEA-SM-197/14) 179 P. Bovard, A. Grauby, A. Saas, R. Schaeffer Discussion 189

SYNERGISM AND COMBINATION EFFECTS FROM RELEASES TO THE ATMOSPHERE (Session V)

Possible future effects on the population of the Federal Republic of Germany of gaseous radioactive effluents from nuclear facilities (IAEA-SM-197/1) 193 G. Schwarz, H. Bonka, K. Brussermann, D. Brenk Discussion 205

Synergistic effects of atmospheric releases of radioactive gases and S02 in inducing nucleation in the atmosphere (IAEA-SM-197/3) 209 KG. Vohra Discussion 220

Advantages of numerical atmospheric dispersion calculations for estimating dispersal and combination effects of stack releases from the nuclear industry (1AEA-SM-197/20) . . . . 223 H. Schultz, E. Voelz, C.D. Wuneke Discussion 232

Discussion of possible effects due to mixing of radioactive and thermal releases to the atmosphere from nuclear power plants (IAEA-SM-197/28) 233 W. G. Hiibschmann, K. Nester, J. G. Wilhelm Discussion 241

Synergistic effects of airborne emissions from nuclear power plants (IAEA-SM-197/29). . . 243 H. Fuchs, W. Hofmann, H.M. von Euw Discussion 251

OTHER FACTORS IN THE ASSESSMENT OF SYNERGISTIC AND COMBINATION EFFECTS (Sessions VI and VII)

Characteristics of coastal circulation affecting the transport and dispersion of material released from the nuclear industry (IAEA-SM-197/21) 255 J. O. Blanton Discussion 267

A site study of the multiple effects of thermal releases on the aquatic life in an estuarine area (IAEA-SM-197/27) 269 D. Borgese, G. Dinelli, L. Guzzi, E. Smedile Discussion 283

Cost effectiveness of release prevention controls for tritium and krypton-85 (1AEA-SM-197/17) 285 J.J. Cohen Discussion 295

The effect of temperature on the behaviour of marine fishes: A comparison among Atlantic mackerel, Scomber scombrus, bluefish, Pomatomus saltatrix, and tautog, Tautoga onitis (IAEA-SM-197/4) 299 B.L. Olla, A.L. Studholme, A.J. Bejda, C. Samet, A.D. Martin Discussion 307

Cycling of 55Fe and 65Zn in Columbia River carp following reactor shutdown (IAEA-SM-197/19) 309 W.M. Jones, C.D. Jennings, N.H. Cutshall Discussion 318

Efecto de la temperatura de aclimatación sobre la proliferación de precursores eritropoyéticos en Carassius auratus, así como sobre la incorporación de timidina tritiada en tejido hematopoyético e intestinal (IAEA-SM-197/9) 319 M. Nieto García, María José Bengoechea Peré, J. G. Maganto Fernández Discussion 327

Panel discussion on the significance of synergistic and combination effects in the future development of nuclear power programmes, and the need for further studies 331

Chairmen of Sessions, and Secretariat of the Symposium 345 List of Participants 347 Author Index 357

Session I

INTRODUCTORY PAPER

Chairman: R. GRADIN (Sweden)

IAEA-SM-197 /22

INTERACTION MECHANISMS OF RADIOACTIVE, CHEMICAL AND THERMAL RELEASES FROM THE NUCLEAR INDUSTRY

Methodology for considering co-operative effects

C. STREFFER Institut fur Medizinische Strahlenphysik und Strahlenbiologie, Universitats Klinikum, Essen,

Federal Republic of Germany

Abstract INTERACTION MECHANISMS OF RADIOACTIVE, CHEMICAL AND THERMAL RELEASES FROM THE NUCLEAR INDUSTRY: METHODOLOGY FOR CONSIDERING CO-OPERATIVE EFFECTS

A number of chemicals are known which can modi fy radiation effects on ce l l ki l l ing, carcinogenesis and mutagenesis. In this paper data are reported for radiosensitizing agents. In order to discuss the interaction mechanisms of these synergistic e f fec ts , the action of radiation on DNA, on its bio logical functions and on its metabolism are explained briefly. Also it is indicated that part of the radiation ef fects in the DNA can be 'repaired' and that living cells can recover from radiation damage. One group of radiosensitizers interacts with cellular DNA or with the DNP-complex . These reactions change the configurational structure or m e t a -bolism of DNA and DNP. In this connection the action of antibiotics such as act inomycin D, and the action of SH-blocking agents such as iodoacetamide and NEM, as well as the action of alkylating agents, are discussed. A second group of radiosensitizers, especial ly with hypoxic ce l ls , are the electron aff inic chemicals like nitro-compounds, ketones and others. Data are also given on the modi f icat ion of radiation ef fects by changes in temperature. Further, the problem of whether synergistic effects are to be expected arising from the chemicals and radiation originating in the nuclear industry is considered. Data show that repair and recovery processes especially are modi f ied by radiosensitizers. The implications of this fact on sensitization at low radiation doses and at low dose rates, as well as the e f fec t of high LET radiation, are considered. It is of interest that the dose modifying factor of some sensitizers can reach a magnitude of a factor of two to three.

1. INTRODUCTION

After looking through the literature which was available to me and after having tried to get information on this topic f r o m experts in the Federal Republic of Germany, it became clear to me that experimental data on any combined ef fects of chemicals released f r o m the nuclear industry with radiation are very rare , if indeed there are any. However, in a densely populated country like the Federal Republic of Germany it appears question-able whether one can discuss re leases f r o m the nuclear industry in isolation without considering re leases f r o m other industries. When combined ef fects of radiation and chemicals are considered in situations where some of the population are under daily medication and pharmaceuticals are in common use, I think it is justifiable to discuss the topic in a broader sense. It might also be useful, especial ly when considering interaction mechanisms or assessing synergistic e f fects , to include the experience gained in radio -biology generally on the ef fects of ionizing radiation in combination with chemicals or with thermal ef fects .

3

4 STREFFER

2. GENERAL ASPECTS OF PROTECTING AND SENSITIZING AGENTS

It is well-known that the effects of radiation on biological systems can be modified by chemicals such that the damage is reduced, i .e. the chemical is acting as a so - ca l led radioprotector [ 1 , 2 ] . If an agent does not inter-fere with metabolic processes of living cel ls but modif ies the very early radiochemical events, one can generally say that the substance probably acts by means of its electron donating ability. In this connection it is important to mention the sulphydryl containing compounds. These compounds have been found to be effective both with microorganisms as well as with mammalian cells and living mammals.

However, with respect to the topic to be discussed here, the radiosensi -tizing substances — which enhance radiation effects — are certainly of more particular interest. There are a number of substances which are much more effective in biological systems when they are administered in combi -nation with doses of ionizing radiation. Indeed, there are other substances which show no biological effect at all unless given in combination with irradiation. And there are yet other substances which act in an additive fashion. These facts make it clear that radiosensitizing substances can undergo a variety of different detailed interaction mechanisms. However, it is possible to separate the substances into two different c lasses by considering their interaction mechanisms, although this classif ication may be somewhat oversimplif ied: (A) Substances which interact or interfere with metabolic processes and

modify the radiosensitivity of these processes (antibiotics like actinomycin D, bleomycin, tetracyclins; alkylating agents like halogenated hydrocarbons; SH-blocking agents like iodoacetamide, N-ethylmaleimide; substances with hormonal activities);

(B) Substances which interfere and modify the early radiochemical molecular events (nitric oxide, various aromatic keto compounds, nitro compounds, quinones). These chemicals have, in general, an electron affinic structure [3].

3. PRIMARY RADIAT ION-INDUCED LESIONS AND RECOVERY PROCESSES

F o r an understanding of interaction mechanisms, especial ly those of the f irst group of radiosensit izers , it might be useful to discuss brief ly the sites of pr imary lesions which lead to radiation-induced damage in living cel ls . The effects which are mainly relevant to environmental r isks of radiation and which are taken into consideration here are killing of ce l ls , and genetic and somatic ef fects . F r o m the experimental data which are available today, it appears certain that DNA and its metabolism are involved in the development of these radiation ef fects [4]. This has been suggested ever since DNA was speci f ical ly identified as the carr ier of genetic in for -mation; it has been proven for microorganisms , and much experimental evidence also exists f o r proliferating mammalian cel ls [5]. In particular, Alper [ 6] has suggested that, at least for cel l killing, the damage of m e m -branes is a second primary lesion which, together with damage to DNA, is responsible for the biological ef fects . Alper assumes that the cel l m e m -

IAEA-SM-19 7 /22 5

RADIATION DOSE ( rad)

FIG.l Survival rate of irradiated cells as a function of radiation dose.

brane of prokaryotic cel ls and the nuclear membrane of eukaryotic cel ls are involved in this development.

As is well known, the structure of DNA consists of two polynucleotide chains which are coiled to a helical structure. The helix is stabilized by hydrogen bonds between the pyrimidine and purine bases . After irradiation one finds radiochemical damage or elimination of DNA bases, in addition to breaks in one or both polynucleotide chains. The latter lesions lead to so - ca l led single-strand breaks or double-strand breaks [7]. These radiation-induced changes impair the biological functions of the DNA,namely the genome reduplication (DNA biosynthesis) that is necessary f or cel l division and the transcription of the genetic information (RNA biosynthesis) that is necessary for protein biosynthesis. It has been observed that the DNA synthesis is a very radiosensitive p r o c e s s and can be depressed following radiation doses of as little as 25 rad, while the transcription (the DNA-dependent synthesis of m-RNA) is less sensitive [5]. In the case of minor lesions to the DNA, the reduplication of the genome and cel l division may take place but the daughter cel ls may carry mutations.

Investigations during the last 20 years have demonstrated that a part of the radiation-induced lesions in the DNA can be repaired. Most living cel ls , f r o m microorganisms up to mammalian cel ls , possess various repair mechanisms by which base damage and strand breaks can be healed if the

6 STREFFER

complementary polynucleotide strain has still the full genetic information [8]. Experimental studies with bacteria show that the radiosensitivity of the organisms does very much depend on the ef f ic iency of this repair [ 9] and there is good evidence for assuming that a s imilar correlation exists for mammalian cells [10]. These processes may represent a molecular basis f o r the recovery of irradiated cells f r o m sublethal damage, which can be observed when the survival of cells is studied after receiving a fractionated dose of irradiation [ 11]. If the survival rate of irradiated cel ls is plotted on a logarithmic scale against radiation dose one usually obtains a curve with a shoulder in the l ower -dose range and a straight line in the higher-dose range (Fig. 1). The shoulder can be taken as an indication of the existence of r e c o v -ery p rocesses [ 12 ]. It will be shown later that the modification of the radiation damage by chemical substances is often ref lected in changes in this part of the dose -e f fec t curve.

More recent results have shown that such recovery p r o c e s s e s do not only exist with respect to cel l killing but are also observed with radiation-induced genetic and somatic ef fects . The studies of genetic ef fects in mice have demonstrated that the dose rate is a very important factor in deter-mining the number of radiation-induced mutations both for irradiation of spermatogonia and oScytes. In both cases the number of mutations decreases with decreasing dose rate [13, 14]. Analogous results were obtained for ef fects in radiation carcinogenesis [15]. With respect to somatic e f fects , it is of great interest that, at least for Xeroderma pigmentosum, a disease of human skin, the incidence of tumors is apparently higher if the repair systems are inefficient [10]. Thus, this section can be summarized as fol lows: (A) In the development of ef fects of radiation, such as cel l killing, genetic

and somatic changes, primary lesions of the structure and the DNA functions are involved;

(B) A part of these lesions can be repaired and cells can recover f r o m some radiation damage;

(C) The radiosensitivity of cel ls can be modified through the e f f i c iency of these repair and recovery processes . These generalizations are not to be understood as meaning that all three

ef fects (cel l killing, mutagenesis and carcinogenesis) are induced at the same target site or even are due to the same mechanism. However, ionizing radiation causes all three changes, and DNA and its metabolism (including repair processes ) is involved in the mechanistic chain. Therefore substances which interfere with the DNA structure and its metabolism must be seen as candidates f or modifying radiation ef fects . There are a number of sub-stances which bind covalently or non-covalently to DNA [16] and most of these chemicals have been found to act as radiosensit izers [17] . '

4. SENSITIZING EFFECTS OF ACTINOMYCIN D

It is of value to consider some of the groups of radiosensit izers and some typical compounds of these groups in more detail. Substances with antibiotic activities have been studied extensively in this connection. One of these compounds is actinomycin D, which f o rms a non-covalent complex with DNA in such a way as to distort its structure and to inhibit selectively the transcription of DNA for the biosynthesis of m-RNA. This mechanism

IAEA-SM-197 /22 7

depresses protein, synthesis .[ 16]. It has been shown, for several biological systems, that actinomycin D acts as a strong radiosensit izer . Thus, the radiation-induced killing of mammalian cel ls is enhanced when the cel ls are irradiated in the presence of actinomycin D or when the antibiotic is added some minutes after irradiation [18]. Elkind has demonstrated that actinomycin D inhibits the recovery f r o m sublethal damage and thus interferes especial ly with the shoulder of the dose effect curve [18].

A very radiosensitive system is the developing mammalian embryo. Work has been done on the radiosensitivity of the pre-implanted (mouse) embryo by incubation with tritiated water in vitro and the development of the embryo f r o m the 2 - c e l l stage to the blastocyst has been observed. The cultivated blastocysts can be re- implanted and develop to normal mice . At a concentration of 2 00 juCi tritiated water per mill i l itre of incubation medium, no development of blastocysts occurred. At a concentration of 100 juCi/ml about 50% of the embryos developed to blastocysts. When the medium contained l0~4/ug of actinomycin D per mill i l itre together with tritiated water at a concentration of 100 juCi/ml, the effect was the same as f o r 200 iuCi/ml without the antibiotic; actinomycin D given alone had no effect on the development of blastocysts at this concentration. In this con-nection it should be mentioned that it can be important in which chemical f o r m radionuclides like the tritium are present. This will be discussed later.

In another experiment, it was demonstrated that actinomycin D has a strong radiosensitizing effect on the induction of speci f ic enzyme activities like tyrosine aminotransferase [19]. The dose of radiation as well as of the chemical was chosen to be at such a low level that no effect was seen when either was given alone. However, a strong inhibitory effect occurred when the radiation and the antibiotic were combined.

The actinomycin D apparently has two effects: (i) the DNA is more vulnerable to radiation by changes of the DNA configuration; (ii) the repair p r o c e s s e s are inhibited by the substance. The consequence is that the ef fects of ionizing radiation and actinomycin D are not mere ly additive but act in a potentiating way when both are combined. Similar e f fects have been seen for the combination of irradiation and other antibiotics [ 17] and also appear to be typical for other radiosensit izers . These sensitizing actions may be important f or people employed in nuclear faci l it ies who are under medication with antibiotics, especial ly when it is considered that these compounds also have mutagenic ef fects [20]. It is probable that actinomycin D will act synergistically with ionizing radiation also with respect to mutagenesis.

5. SENSITIZING EFFECTS OF SH-BLOCKING AGENTS

A second group of substances which should be mentioned are the s o -called SH-blocking agents like iodoacetamide, N-ethylmaleimide (NEM) and others. These compounds bind covalently to sulphydryl groups and other nucleophilic groups in the cell . Through this mechanism they can change the configuration both of proteins and of nuclear proteins, f o r instance histones. Further the equilibrium

2 R-SH R - S - S - R + 2H+ + 2e"

8 STREFFER

can be disturbed in the living cell , which has consequences for the redox equilibrium [21].

A number of authors have shown that these substances act as radio -sensit izers . Fr i tz -Niggl i [22 ] observed that iodoacetamide increased the number of radiation-induced malformations of mice considerably when the substance was given at a dose which had,without irradiation, no effect at all. Fr i tz -Niggl i assumedthat repair processes are interfered with by iodoacetamide — which leads to radiosensitization. Braun [23] found that the number of pycnotic crypt cel ls increased in the duodenum when the radiation was c o m -bined with SH-blocking agents. Sinclair [ 24] observed that NEM increases the radiosensitivity of mammalian cells to about the same level as is found for cel ls in mitosis . During this phase of the generation cycle the cel ls show no recovery .

6. ALKYLATING AGENTS

Alkylating agents such as the nitrogen mustards can also act as radiosensit izers . These agents are cytotoxic by themselves, can induce malignancies [25] and also show mutagenic e f fects , although these are apparently weak [26]. As a radiosensitizing agent with respect to cel l ki l -ling, these substances generally only show an additive ef fect [ 18]". Nitrogen mustard does apparently not interfere with the recovery f r o m sublethal damage [18]. The alkylating agents also bind covalently to the DNA. Bifunctional substances can make crossl inks between complementary DNA strands. Part of the damage resulting f r o m alkylating agents can be repaired like radiation-induced lesions in the DNA [16]. It is not known whether the substances also increase radiation-induced mutagenesis and carcinogenesis ; however, it seems probable. Compounds like methylhydrazin which act as radiosensit izers in cel l killing may also fall into this group.

7. ELECTRON-AFFINIC AGENTS

As stated ear l ier , there is another group of radiosensit izers which do not interfere with the metabolic p rocesses of cel ls . This group appears to act by virtue of the electron-accepting ability, in a w a y similar to oxygen [3]. These substances, in particular, sensitize hypoxic cel ls . A sensitizing effect of nitro-compounds, quinones and aromatic ketones has been found with anoxic bacteria [ 3]. Chapman et al. [27 ] found that a number of unsatu-rated cyc l i c nitro compounds, f o r example the nitrofurans and nitroimidazoles, sensitize Chinese hamster cel ls . Under anoxic conditions the authors observed a maximum dose modifying factor of 2.8.

8. SENSITIZING EFFECT OF TEMPERATURE CHANGES

The effect of temperature on the development of radiation damage has also been investigated in organisms and cel ls . Holthusen observed that radiation ef fects on Ascar i s eggs were greater when they were kept at higher temperatures after irradiation (see page 2 of Ref. [ 5]). Ktinkel found that the survival time of hibernating Glis glis was longer than of non-hibernating

IAEA-SM-197 /22 9

animals (see pages 3 and 103 of Ref.[ 5]). Ben-Hur et al. [28 ] also studied temperature ef fects on the survival rate of mammalian cells after irradiation. The lowest radiosensitivity was found with these cel ls at 37°C. When the temperature was increased to 39 or 41°C the recovery f r o m sublethal damage was considerably impaired. No recovery was observed when the cel ls were kept at 41°C for two hours after irradiation. In agreement with their data, the temperature effect was found to increase with decreasing dose rate in the range of 3.3 rad /min to 360 rad /min. When the cel ls were incubated at elevated temperatures the repair of single strand breaks in the DNA increased but the repair of a DNA complex was decreased. Temperatures above 41°C after the irradiation caused endonucleolytic- l ike degradation of the DNA [29]. These data are valid f o r mammalian cel ls which usually " l ive" at 37°C. The levels of temperature ef fects may be shifted in other organisms which have other temperature optima under normal physiolog-ical conditions.

9. ARE COMBINED EFFECTS POSSIBLE WITH A NUCLEAR INDUSTRY?

If one looks for sensitizing ef fects of chemicals released f r o m the nuclear industry, the reported data suggest that such combination ef fects are improb -able. However, any biological mechanism that concentrates the radioactive material as well as the possible sensitizing chemical could lead to a situ-ation in which such ef fects have to be considered. Perhaps a possible candidate chemical that might be studied is trichloroethylene, which is released during uranium fuel production and which could act, like other chlorinated hydrocarbons, as a cocarcinogen with ionizing radiation. How-ever, as has been stated ear l ier , re leases f r o m nuclear industry cannot be seen in isolation. When combined ef fects of radiation and chemical substances are assessed, re leases f r o m other industries in the vicinity of nuclear power stations must be considered, as well as the pharmaceuticals which are used by people who are in some way exposed to radiation. Not least, radiobiological data on mammalian cel ls have demonstrated, as was discussed ear l ier , that a temperature increase of only 2°C can have a sensitizing effect on its own. Studies still have to be made as to whether such sensitization also takes place in other organisms and biological systems.

10. EFFECTS DEPENDENT ON LET, RADIATION DOSE AND DOSE RATE

Radiation ef fects due to radionuclides are dependent on the linear energy transfer (LET) of the ionizing radiation, as is observed with ionizing radia-tion f r o m generators. The radiation damage is usually not dependent on the chemical nature of the radioactive material. However, concentrating ef fects in organisms, organs or even in compartments of ce l ls may play a great role . In this connection the chemical nature of the radioactive substance would be important, of course. As has been demonstrated, the same is valid for sensitizing agents like the DNA binding substances, which may be con-centrated in the cel l nucleus and in certain organs such as l iver, for instance. Such effects may be of significance when considering the combined action of radioactive substances and radiosensit izers . There may be an exception to the statement just made, that the chemical nature of the radioactive

10 STREFFER

material does not affect its action as a radiation source , this being tritium. Bond [ 30] has stated that the radiation effect of tritium was the same in cel ls and organisms irrespect ive of whether it was applied as tritiated water or bound in the DNA, for example as tritiated thymidine. However, Streffer and Elias have found that the effect of tritiated thymidine was about 1000 times greater than that of tritiated water when the develop-ment of the pre-implanted mouse embryo was studied [ 31]. It is possible that transmutation-effects have to be considered in this connection. Such a result is certainly not of interest in considering the environmental impact of nuclear power stations. However, tritiated thymidine is very frequently used in biochemical and medical laboratories.

When the mechanisms of various radiosensit izers were discussed, it was pointed out that repair processes and recovery f r o m radiation damage in cel ls were usually impaired by these compounds. Thus repair of DNA synthesis is inhibited by the most pronounced sensit izers [10]. This situation implies that the dose modifying factor can increase with decreasing radiation dose — as has been shown for radiation with a high LET, f o r instance fast neutrons [ 32]. Also decreasing the dose rate may have a similar e f fect , as was shown in connection with thermal ef fects [28].

The dose modifying factor of the substances described is at most 2 to 3, which is of about the same magnitude as for the c lass ical sensitizing sub-stance — oxygen. As with oxygen, the radiosensitizing effect of other substances apparently decreases when the LET of the radiation increases . Berry and Andrews [ 33] found no sensitization by iododeoxyuridine when leukaemia cells were irradiated with fast neutrons. A good radiosensitizing effect of this compound was found with X-irradiation. Halogenated pyrimidine analogues have to be incorporated into the DNA in order to show a sens i -tizing effect [ 34].

11. CONCLUSIONS

(A) Various substances have been proved to enhance the ef fects of ionizing radiation. Chemicals which are re leased f r o m the nuclear industry are probably not effective in this way, but re leases f r o m other industries have to be considered.

(B) The dose modifying factors of these substances, and of temperature lie between two and three under maximal conditions. This factor is an important figure when assessing combined effects .

(C) In almost all cases investigated so far , repair and re covery processes f or radiation damage are impaired by radiosensit izers and by tempera-ture increase.

(D) Therefore the sensitizing effect is usually large at low radiation doses and at low dose rates.

(E) F r o m the data known at present, it appears evident that the modifying ef fects decrease with increasing LET.

R E F E R E N C E S

[ 1 ] BACQ, Z . M . , Chemical Protection Against Ionizing Radiation, Ch. C. Thomas Publ., Springfield (1965). [ 2 ] MELCHING, H. -J . , STREFFER, C . , Adv. Drug Res. 9 (1966) 10. [ 3 ] ADAMS, G.E., Radiation Protection and Sensitization (MOROSON, H.L., QUINTILIANI, M . , Eds) Taylor

and Francis, London (1970) 3.

IA-EA-SM-197/22 11

OKADA, S. , Radiation-Biochemistry, Academic Press, New York, London (1970). STREFFER, C . , Strahlen-Biochemie, Springer-Verlag, Heidelberg (1969). ALPER, Tikrah, "Cell death and its modification: the roles of primary lesions in membranes and DNA", Biophysical Aspects of Radiation Quality - 1971 (Proc. Symp. Lucas Heights, 1971), IAEA, Vienna (1971) 171. SZYBALSKI, W. , Radiat. Res., Suppl. 7_U967) 1 4 7 . HOWARD-FLANDERS, P., BOYCE, R.P., Radiat. Res., Suppl. 6 (1966) 156. HILL, R.F., SIMSON, E., J. Gen. Microbiol. 24 (1961) 1. CLEAVER, H.E., Adv. Radiat. Biology (LETT, J.T. , ADLER, H., ZELLE.M., Eds) Academic Press, New York, London (1974) 1. ELKIND, M.M., SUTTON, H., Radiat. Res. 13 (1960) 556. ELKIND, M.M. , WHITMORE, G.F., The Radiobiology of Cultured Mammalian Cells, Gordon and Breach, New York (1967). SEARLE, A.G. , et al . , Mutat. Res. 6 (1968), 427. RUSSELL, W.L., "The genetic effects of radiation", 4th Int. Conf. Peaceful Uses of Atomic Energy (Proc. Conf. Geneva, 1971) 13, UN, New York and IAEA, Vienna (1972) 4 8 7 , 5 0 1 . UPTON, A .C . , Natl. CancerTnst. Monogr. 14 (1964) 221. WARING, M.J., FEBS Symp. 21 (1970) 143. MOROSON, H.L., QUINTILIANI, M. , Eds, Radiation Protection and Sensitization, Taylor and Francis, London (1970). ELKIND, M.M., SAKOM0TO, K. , Radiation Protection and Sensitization (MOROSON, H.L., QUINTILIANI, M. , Eds) Taylor and Francis, London (1970) 195. STREFFER, C . , SCHAFFERUS, S., Int. J. Radiat. Biol. 20 (1971) 301. EHLING, U., personal communication. STREFFER, C. , "Some aspects of radioprotection by cysteamine and of cysteine metabolism after irradi-ating m i c e " , Radiation Damage and Sulphydryl Compounds (Proc. Panel Vienna, 1968), IAEA, Vienna (1969) 177. FRITZ-NIGGLI, H., Radiation Protection and Sensitization (MOROSON, H.L., QUINTILIANI, M. , Eds) Taylor and Francis, London (1970) 311. BRA UN, H., Radiation Protection and Sensitization (MOROSON, H.L., QUINTILIANI, M. , Eds) Taylor and Francis, London (1970) 389. SINCLAIR, W.K., Abstr. 5th Int. Congr. Radiat. Res. (1974) 164. SCHMAHL, D., Entstehung, Wachstum und Chemotherapie maligner Tumoren, Editio Cantor, Aulen-dorf i. Wiirtt. (1970). RUSSELL, W.L., Molecular and Cellular Repair Processes (BEERS, R.F., HERRIOTT, R.M., TILGHMAN, R.C., Eds) John Hopkins Univ. Press, Baltimore (1972) 239. CHAPMAN, J.D., et al . , Cancer Chemother. Rep. Part 1 , 58 (1974) 559. BEN-HUR, E., ELKIND, M.M. , BRONK, B.V., Radiat. Res. 58 (1974) 38. BEN-HUR, E., ELKIND, M.M. , Abstr. 5th Int. Congr. Radiat. Res. (1974) 6. BOND, V.P., "Evaluation of potential hazards from tritiated water", Environmental Aspects of Nuclear Power Stations (Proc. Symp. New York, 1970, BECK, E.R.A., Ed.), IAEA, Vienna (1971) 287. STREFFER, C. , ELIAS, St., unpublished data. BEWLEY, D.K., Neutrons in Radiobiology, Oak Ridge National Laboratory, USAEC Rep. CONF - 691106, (1969) 244. BERRY, R.J., ANDREWS, J.R., Radiat. Res. 16 (1962) 82. STREFFER, C . , SCHWEIGER, K. , Strahlentherapie 143 (1972) 244.

D I S C U S S I O N

W.G. RUBSCHMANN: You have told us about the biological e f fects of tritium in different chemical f o rms . I am very interested in experiments of this kind, since they may have a bearing on the assessment of the radiological effect of tritium. This nuclide is re leased in the nuclear industry in the f o r m of tritiated water. In assessing the radiological ef fect we normally consider only the energy re leased by radioactive decay. Do you think this is still relevant, or should allowance be made in the dose effect assessment for other e f fects , such as change in chemical behaviour due to radioactive decay?

12 STREFFER

C. STREFFER: I am aware of the fact that tritium is released in the f o r m of tritiated water f r o m nuclear power stations. But there are many laboratories working with tritiated thymidine, some of which may be released. As I said, there are reports in the literature that the effect of tritium is not dependent on the chemical f o r m in which it is used. However, our data show that tritiated thymidine exerts a greater influence than tritiated water in the development of the pre-implanted mouse embryo. Other investigators have shown that tritiated thymidine is more influential than tritiated uridine, which is incorporated into RNA instead of DNA. We have yet to establish the extent to which transmutation phenomena contribute to these different ef fects .

J.J. COHEN: Since there is essentially no tritiated thymidine in nature, I don't real ly see how the results of exposure to this substance can be relevant to the problem of the environmental e f fects of tritium released f r o m the nuclear industry.

C. STREFFER: I agree that tritiated thymidine has no spec i f i c relevance to the environmental impact of nuclear power stations, but at the same time, the many laboratories working with this substance in a veriety of f ields re lease it into waste water systems, usually in the larger cities, where it might well constitute a hazard.

R.J. KIRCHMANN: With regard to the chemical f o r m of tritium in the environment, I fee l that we should not consider just tritium gas and tritiated water. After all, we can observe the incorporation of tritium f r o m water into organic molecules in living beings. When taken up in that way and transferred by food chains, it may then be present in macromolecules of biological interest.

Furthermore , I think we should also consider tritium re leases in the organic f o rm, especial ly f r o m laboratories producing labelled molecules . Some of the compounds released in that manner are precursors that may be incorporated at the biological macromolecule level.

C. STREFFER: It may indeed be necessary to re-evaluate the biological e f fects induced by tritium. At the same t ime, I don't want to place undue emphasis on the hazards of tritium.

K. HUBEL: Most of your examples relate to high concentrations and doses. How should one extrapolate to the lower concentrations and doses that may be expected in the actual environment?

C. STREFFER: The basic concentrations were not high in all instances. In the case of the antibiotics we used amounts comparable with those employed in medicine. The extrapolation of radiation dose is carr ied out assuming a linear relationship, since results are intended to be used in assessing radio -logical r isk as a whole.

I agree that this is something of a problem, as r e covery p r o c e s s e s are not examined under the given conditions. It is , however, the approach taken by the ICRP, and both f or statistical reasons and f r o m the standpoint of safety we have certainly no other choice in the matter for the time being.

P. KAYSER: Do you consider that the radiosensitizing effect of certain antibiotics and other drugs gives us grounds to reconsider radiation r isk evaluation, for example, in X - r a y diagnostics, in as much as the patients have often been given antibiotics and the doses applied to the organs are often high, f o r instance, 10-50 rad? It might be added, furthermore , that such doses are not medical ly justified, and simply result f r o m the inef f i -c iency of the radiological technique applied.

IAEA-SM-197 /22 13

C. STREFFER: Yes, if the radiation dose is as high as you mention in X - r a y diagnostics — which I don't think happensVvery frequently — and antibiotic treatment has been given, then the combined ef fects should certainly be considered. In view of the fact that antibiotics may act as mutagens, i r r a -diation of the gonads would involve greater r isk under those c ircumstances .

F. HEISE: You mentioned a number of substances that increase the damaging ef fects of ionizing radiation. Are there any substances known so far which improve repair mechanisms in ce l ls?

C. STREFFER: I do not know of any substances which by themselves improve repair mechanisms. There are substances, however, which protect biological systems, and also repair p ro cesses , against ionizing radiation. The resulting radiation damage is less when such substances, for example SH-compounds or biogenic amines, are applied in conjunction with irradiation.

K.G. VOHRA: Could you say something about the mechanism by which radiation ef fects are increased by antibiotics?

C. STREFFER: We real ly don't know the exact mechanism involved in the case of the ionizing radiation itself . Antibiotics like actinomycin D may act in two ways in conjunction with irradiation: either the number of pr imary lesions in the target, e.g. DNA, is increased by structural changes, or else the repair and r e c o v e r y processes are impaired.

S. HARTWIG'-j I should just like to comment that, since there is still some doubt as to the ef fects of very low doses of ionizing radiation, it has been planned, in the Federal Republic of Germany, to circulate to persons who are occupationally exposed to radiation, such as radiologists , a question-naire with a view to amassing information on the subject.

I am wondering, however, what value the information will have in the case of persons who are undergoing some sort of medical treatment. The effect of the medication may be greater than that of the radiation.

C. STREFFER: Yes, that might be the case. I think, therefore , that such studies should be geared to people who are employed in nuclear power plants, or who are working with ionizing radiation, although the situation may be more complicated in such cases.

Session II

EFFECTS OF TEMPERATURE ON RADIONUCLIDE UPTAKE

Chairman: R.J. KIRCHMANN (Belgium)

IAEA-SM-197 /22

IMPACT OF THERMAL AND RADIOACTIVE EFFLUENTS ON A TROPICAL NEARSHORE ECOSYSTEM

B. PATEL, M.C. BALANI, SHAKUNT PATEL, V.K. PANDAY, S.D. SOMAN Health Physics Division, Bhabha Atomic Research Centre, Trombay, Bombay India

Presented by K. G. VOHRA

Abstract

IMPACT OF THERMAL AND RADIOACTIVE EFFLUENTS ON A TROPICAL NEARSHORE ECOSYSTEM. The paper reviews and discusses the effects of heated effluents on the bioaccumulation of radionuclides

and possible thermal potentiation of the chromium e f fec t on three species of lamellibranchs, the blood c lam Anadara granosa, the venerid c lam Katelysia opima and the oyster Crassostrea gryphoides. The impact of thermal discharges on the uptake of caes ium, cobalt , iodine and zinc radionuclides was studied exposing bivalve populations in a 1 km long discharge canal of a BWR nuclear power station on the west coast of India. The e f fec t of temperature on feeding rates, since feeding ultimately leads to bioaccumulation of nuclides, of blood c lam A. granosa was studied under laboratory conditions. The filtration rates were temperature dependent over the range 21 to 31°C. The thermal potentiation of the chromium ef fect on the rate of filtration is discussed in light of this metal 's toxic e f fec t .

1. INTRODUCTION

Of the var ious known (control lable) environmental parameters , temperature i s a 'master f a c to r ' that profoundly inf luences the rates of b i o -chemica l and phys io log ica l p r o c e s s e s including survival of larval and adult f o r m s , growth, reproduct ion, migrat ion and structure of the marine e c o -sys tem, espec ia l ly of the benthic communit ies . The evaluation of thermal impacts on these o rgan i sms has been general ly der ived through the laboratory exper iments with the temperature of the culture medium being the pr inc ipal var iable [ 1 - 3 ] . The extent to which the information thus gained could be uti l ized to predict and understand thermal s t r e s s under natural environmental conditions is rather l imited. This is because , under f ie ld conditions, the temperature variat ions are frequently sinusoidal , and the e f f e c t s observed are not only due to thermal impacts alone but a lso due to the combined e f f e c t s of other known and unknown abiotic environmental var iab les [4] .

In continuation of our ear l i e r studies on the rad ioeco l ogy of marine e c o s y s t e m s [ 5 - 7 ] , the present communicat ion d i s c u s s e s the poss ib le e f f e c t s of elevated temperatures on the bioaccumulat ion of a few f i s s i o n - and c o r r o s i o n - p r o d u c t radionucl ides under f ie ld conditions and the poss ib le synerg is t i c e f f e c t s of the chemica ls on certain lamel l ibranchs ; the a r k - s h e l l b lood c lam Anadara granosa (Linn), the oyster C r a s s o s t r e a gryphoides Schlotheim, and the vener id c lam Katelysia opima.

17

18 PATEL et al.

FIG.l . Marine environs off Tarapur atomic power station. Inset: Intake and discharge system showing sites <D 30-35°C; ® 29-31°C; and 3> 27 -29°C, where experimental animals were exposed.

2. TOPOGRAPHY

The thermal impact studies on the local ecosystem assumed significance with the commissioning of a 400 MW(e) BWR nuclear power station on the west coast of India. The plant effluent, containing waste heat, is discharged directly through the secondary coolant (sea water) into the nearshore environ-ment [ 5]. The wastes comprise mainly f i ss ion - and corros ion-product nuclides, namely caesium-134, -137, iodine-131, strontium-89, -90 , cobalt-58, -60 and, to a l e s ser extent, manganese-54, z inc-65, chromium-51 and iron-59, as well as processed chemicals . The latter include chlorine injected at the intake to prevent entry and settlement of fouling organisms and accumulation

IAEA-SM-197 /22 19

of organic matter, potassium dichromate used as a corros ion inhibitor, and sulphuric acid and sodium hydroxide used in the regeneration of ion exchange resins.

The effluent is released through two discharge canals, each about 1 km long, 14 m wide and 4 m deep, on either side of the intake canal (F ig . l ) . These are operated in turn to achieve rapid dispersion and also to minimize possible recirculation of warm effluents by taking advantage of semidiurnal tidal currents. After filtration and monitoring the waste, at slightly alkaline pH-values (9-11) , is re leased into canals transporting approximately 29X10 3

l i tres per second. The temperature drop within the 1 km course of the canals is f r o m 5 to 7°C, f r o m the outfall to the ambient level at the seaward end.

3. FIELD EXPERIMENTS

Since no benthic communities which could be easily col lected f r o m the various thermal plume regions are sustained in the canal, f o r the study of the thermal ef fects populations of oyster Crassostreâ gryphoides and venerid clam Katelysia opima f r o m the oysterbeds 5 km south of power station and ark-shel l Anadara granosa f r o m Bombay harbour (100 km south [7]) were transferred into the south discharge canal. The experimental populations, about 500 animals of the same size and age group, were exposed at three stations, 35, 2 50 and 600 m off the outfall, each station representating a different thermal plume region. At the f i rst , second and third stations temperatures varied f r o m 30 to 35°C, 29 to 31°C and 27 to 29°C, respectively. Each species was maintained in a seperate nylon-net bag of a mesh size depending on the size of the animals, which varied f r o m 2 to 5 cm in length. The bags were exposed in such a way that the experimental animals could easily settle over the water sediment interface. Exposure at beyond 600 m distance f r o m the outfall was avoided since, at high tide, the waters rushing into the canal may dilute the radioactivity concentration considerably towards the seaward end, thus bringing in one more variable. Up to 600 m the rad io -activity concentration, especial ly that of caesium-137, in the canal water was practical ly the same irrespect ive of the tidal conditions (Table I). The temperature, however, varied over the range 5 - 7°C above ambient during the experimental period, when one reactor was operating at about 190 MW(e).

At speci f ic time intervals, the surface temperature along the course of the canal was measured. A two tc f ive - l i t re water sample was col lected

TABLE I. CONCENTRATION OF CAESIUM-137 IN THE SOUTH DISCHARGE CANAL OF TARAPUR NUCLEAR POWER STATION DURING VARIOUS TIDAL PHASES

Distance from the outfall , Caesium-137 (pCi /1) / ^ Low tide , . - j (m) High tide Low tide

35 28.6 33.8 46.0

250 29.8 36.0 44.6

550 31.2 32.5 43 .8

1000 36.0 - 44.0

20 PATEL et al.

to understand the distribution and variation of radioactivity with time, especial ly of caesium nuclides, which formed the major source of contami-nation (70-75%). Caesium nuclides were scavenged through the addition of ammonium phosphomolybdate [7]. A sample comprising 30 to 35 exper i -mental animals was also withdrawn f r o m the three exposure stations and washed thoroughly. The sample was next dissected, soft t issues pooled and dried at 110°C in a hot air oven. The dry matter was homogenized and packed in a plastic counting vial. The gamma activity was measured with a well-type Nal(Tl), 3.5 in X 3.5 in dia., scintillation crystal coupled to a 512 channel pulse-height analyser. The counting time was adjusted, lying between 40 and 800 minutes, depending upon the radioactivity in the sample, to obtain counts at a 95% confidence level. The gamma spectra were further analysed with the help of a computer using a least -squares technique. The total activity due to various nuclides was finally converted to data in p i c o -curies per gram of dry tissue after decay correct ion.

4. LABORATORY EXPERIMENTS

To elucidate the ef fects of temperature on the bioaccumulation of radio -nuclides under f ield conditions and the possible synergistic effect due to chromium contained in the effluent as K 2Cr 20 7 (~l000 kg/a) , the impact of elevated temperatures on the 'rate of filtration' (c i l iary propulsion of water) in A. granosa was studied under laboratory conditions.

The blood clams A. granosa were col lected f r o m Trombay arkbeds [7 , 8], washed free of extraneous matter and maintained under laboratory conditions (24-26°C). After 24 - 48 h of acclimation five experimental animals, each weighing between 40 and 50 g, in 2000 ml f i l tered sea water, were introduced into thermostatically controlled (±0.1°C) glass aquaria at temperatures between 20 and 44°C. The temperature in each tank was gradually increased, reaching the desired range within about 2 hours. To simulate semidiurnal tidal e f fects , the experimental animals were kept dry for 4 -5 h daily at the appropriate temperature. After 24-48 h acclimation at various temperatures, the sea water was replaced by pre -warmed 200 ml (400 ml /animal) sea water containing neutral red (pH 6.8-8.0) at a concentration of 0.001%. After a lapse of 40-60 minutes an aliquot of about 5 ml f r o m each experimental aquarium was siphoned off , acidified and its absorption coeff icient measured at 530 nm using a Beckman DU spectrophotometer. The filtration rate was measured over a period of 3 to 4 hours. The rate of filtration was obtained using the following equation:

(V)C t = (V)C0 ( l -E f ) 1

where (V)C0 is the initial concentration of neutral red in V the total initial volume of sea water, (V)C t the concentration after a lapse of time t, f the fraction of the initial volume V which the animal f i ltered per unit t ime, and E the e f f i c iency of the dye retained by the animal. To obtain the filtration rate fV, we have assumed that the dye retention e f f i c iency of the animal was 100% or E = 1, which reduces the equation to:

(V)C t = (V)C0 ( l - f ) 1

IAEA-SM-197 /22 21

The possible thermal potentiation of the chromium effect was studied following accl imation of about five experimental animals in about ~ 2 000 ml of water containing 2.0 ppm Cr as K2Cr207 between 22 and 36°C f o r 24 to 48 hours. The filtration rate was measured prior to and after exposure to chromium'. No chromium was, however, introduced while measuring the filtration rates. Similarly the filtration rate was also measured after 48 and 96 hours of exposure at various chromium concentrations between 0.01 and 5.00 ppm at 26°C.

F o r the chemical analyses, the tissue samples, 5 g and dried at 110°C, were digested in 1:1 mixture of HNOs and HC104 till a c lear solution was obtained. Chromium was complexed with ammonium pyrolidine dithiocarba-mate at pH 3 and extracted into methyl isobutyl ketone. The organic layer was aspirated into the f lame of an atomic absorption spectrophotometer. Other elements, nickel, cobalt, iron, manganese, copper and zinc, were analysed by aspirating the aqueous solutions directly.

E N E R G Y ( M e V )

FIG.2. Gamma spectra of ark-shell Anadara granosa. and oyster Crassostrea gryphoides on exposure in the discharge canal: (A) ark-shell prior to exposure and (B) after 94 days of exposure at 27 -29°C showing a c c u m u -lation o f 1 3 1 1 , 1 3 7 C s , 5 8 Co and 60Co; (C) Oyster showing, in addition, accumulation o f 6 5 Z n after 38 days.

TABLE II. EFFECT OF TEMPERATURE ON THE ACCUMULATION OF 131I, 137Cs AND 5 8 '6 0Co BY BLOOD CLAM Anadara granosa POPULATION, AND 137Cs IN THE DISCHARGE CANAL

Days after translocation

Cs-137 in canal water

(pCi /1 )

131 I

30 137

Cs

-35°C 58

Co 60„ Co

29-31°C 131, 137 5 8 _ 60

I Cs Co Co

( p C i / g dry tissue of A. granosa)

131 I

27

137Cs

-29 °C 58 _ Co Co

5 30.0 21.2 9.8 3.9 13.5 8.9 8.7 2.8 11.3 9.9 9 .2 3.7 10.9

10 31.7 13.5 6.3 2.4 18.3 12.4 5.5 2.6 22.3 9.2 5 .8 2.4 . 17.7

15 23.4 9.5 5.7 2.8 14.5 - - - - 6.8 3.7 1.7 16.3

19 - - - - - - - - - 10.9 4 .4 1.8 19.9

30 30.4 53.7 14.3 4.9 19.2 45 .0 15.0 3.5 17.3 12.7 9.8 8.2 23.6

43 71.5 - - - - - - - - 36.0 13.6 5.6 37.7

46 • 67.6 18.1 24.5 4.4 28.0 36.6 26.0 8.9 98.1 - - - -

64 61.0 - - - - - - - - 25.5 20.8 7.3 111.4

94 28.6 - - - - - - - - 15.7 9.1 5.7 151.2

IAEA-SM-197 /22 23

5. RESULTS AND DISCUSSION 5.1. Bioaccumulation of radionuclides under f ield conditions

The analysis of gamma spectra of populations of three spec ies of lamellibranchs A. granosa, C. gryphoides and K. opima on transfer f r o m their natural habitat to the contaminated environment showed photopeaks at energies of 0.36, 0.66, 0.82, and 1.17 and 1.33 MeV. These were identified after chemical separations and/or decay as being due to iodine-131, caesium-137, cobalt-58 and cobalt-60, respect ively (Fig.2). The oyster population showed, in addition, a photopeak at 1.11 MeV which was identified as being due to z inc-65. This is evident f r o m Fig.2, which records the gamma spectra of oyster C. gryphoides 38 days after being translocated and of blood clam A. granosa pr ior to and after 94 days of transfer to the dis -charge canal. The distribution of each nuclide expressed as p icocuries per gram of dry tissue, in the three species are recorded in Tables II-IV. It will be seen f r o m the accumulation pattern that, in general, the concentration of each nuclide varied f r o m species to species . Thus both K. opima and A. granosa showed preferential uptake of cobalt-60, the maximum concen-trations reached being 80 and 100 pCi /g , respect ively , after 46 days of exposure. Both the spec ies , however, showed discrimination against z inc-65. Oysters on the other hand, speci f ical ly picked up z inc-65, the concentration of which varied f r o m 4 to 19 pCi /g , whereas the maximum cobalt-60 con-centration, 60 pCi /g , was reached only after 59 days of exposure (Table IV). The bioaccumulation of caesium-137 and iodine-131 varied f r o m 4 to 33 pCi /g and 3 to 71 pCi /g , respect ively (Tables II-IV). The maximum concentration of caesium-137 was in c lam K. opipia (33 pCi /g ) and of iodine-131 in oyster C. gryphoides (71.5 pCi /g ) . It is interesting to note that caesium and iodine radionuclides were the major sources in the effluent, their contributions being 70-75% and 15-20%, respectively, whereas the cobalt radionuclides formed just 2% of the fraction. The bioaccumulation, however, of both caesium and iodine radionuclides was significantly lower than that of cobalt. This suggests that all three species showed partial discrimination against iodine and caesium and speci f ic i ty for cobalt.

Figure 3 re cords the build up of cobalt-60 in the soft t issues of A. granosa and IC opima with time and the radioactivity concentrations in the canal water expressed in terms of caesium-137 activity. Since cobalt radionuclides were below the detection limit even in 20 litre samples, caesium activity was, therefore , measured to express levels of radioactivity in the canal. It will be seen f r o m the uptake curves that, following an increase in the discharge rate, which is evident f r o m the concentration of caesium-137 in the canal, there was a sharp increase in the bioaccumulation of cobalt-60 by both the clam species . However, there was no significant decline in the concentration curve of cobalt-60 in A. granosa following decline in the effluent after 7 5 days of exposure. This suggests slow biological l o s s - ra te constants for the nuclide under environmental conditions. A s imilar trend could not be followed in c lam K. opima since after 46 days of exposure the experimental populations were lost during desilting operations. It is evident f r o m this ser ies of experiments that, in general, the bioaccumulation of cobalt radionuclides in all the three species was dependent upon the nuclide concentration in the medium. The bioaccumulation pattern of caesium and iodine nuclides, especial ly in the blood clam and oyster, did not show a s imilar relationship with concentration in the environment (Tables III-IV).

TABLE III. E F F E C T OF TEMPERATURE ON THE ACCUMULATION OF131I, 137Cs, 58>60Co IN VENERID CLAM Katelysia opima ON EXPOSURE IN THE DISCHARGE CANAL

30 -35°C 29 -31°C 27 -29 °C Days after

translocation 131j 1 3 7Cs 5 8 Co 60Co >31 j 137Cs 5 8 C o 60Co

( p C i / g dry K. opima tissues)

131 j 137Cs 58 Co 60Co

0 * 0.7 - 1.5 - 0.7 - 1.5 - 0.7 - 1.5

5 6.2 6.2 4.3 28.2 - - 7.8 5.3 4 .9 19.9

10 3.9 3.1 2.2 16.7 - - 3.2 2.5 1.6 16.2

15 - - - - - - 3.6 2.4 - 14.3

25 35.7 19.8 15.4 41.6 15.1 19.1 14.1 37.5 12.4 16.6 9.7 27.5

38 - - - - - - 19.4 20.0 12.9 41.8

46 14.9 33.1 14.2 80.5 11.1 28.5 12.4 104.3 9.0 31.5 8.4 80.1

Concentration in population prior to transplant.

TABLE IV. EFFECT OF TEMPERATURE ON THE ACCUMULATION OF 1311, 137cs,58,60co and 65Zn IN OYSTER Crassostrea gryphoides ON EXPOSURE IN THE DISCHARGE CANAL

30-35°C n 27-29°C

Day after translocation

131J 137 Cs 58Co 60Co 65Zn 13IJ 137Cs 58Co Co 68 Zn

p C i / g dry Crassostrea gryphoides tissue

0.4 1.0 - 1.8 - 0.4 1.0 - 1.8 -

5 23.4 6.4 4.5 58.0 18.6 24.7 4.6 7.3 44 .8 -

15 11.2 4 .8 3.5 24.3 4.3 - - - - -

38 71.5 17.5 12.0 43.3 13.0 31.7 15.7 9.0 33.6 6.0

59 - - - - - 10.5 28.7 8.0 59.6 7.0

* Radioactivity in population prior to transplant.

26 PATEL et al.

DAYS

FIG.3. Uptake of 60 Co at 27-29°C by Anadara granosa (©) and Katelysia o p i m a ( A ) , a n d variation in the canal water ( • ) .

However, caesium-137 accumulation by clam K. opima was to a certain extent dependent upon the caesium concentration in the canal (Table III). No such pattern in z inc -65 uptake was observed, though the oysters speci f ical ly concentrated the nuclide.

Patel et al. [7] , studying the radioecology of coastal waters receiving waste f r o m nuclear fuel reprocess ing faci l i t ies , found that an A. granosa population under environmental conditions showed partial discrimination against caesium-137 and preferential uptake of ruthenium-106 and cer ium-144, though caesium was the major source of contamination and was significantly absorbed on the suspended sedimentary particles; the other two nuclides were below the detection limit in the ambient water. Similarly, the opisthobranch gastropod Aplysia benedicti (sea hare) f r o m Tarapur waters was also found by Patel et al. [ 5 ] to show discrimination against both iodine and caesium radionuclides, though these were present in signif i -cant amounts in seaweeds and algal spec ies , on which the population was found to feed exclusively. The concentration of z inc-65 by the oyster popu-lation is expected since the genus, in general, has been found to be an excellent indicator of zinc contamination [6, 9 - 1 1 ] . Thus the differential bioaccumulation of radionuclides observed in the three species of bivalves is not surprising since the f i lter feeding mol luscs , in general, are known to feed selectively [7 , 12].

5.2. Thermal effect on bioaccumulation

Tables II-IV show the concentrations of iodine, caesium and cobalt radionuclides in the three bivalve species on exposure to various thermal plume regions in which the temperatures varied f r o m 27 to 35°C, while the ambient temperature was 22-24°C during the experimental period. The concentration, especial ly of caesium-137, however, remained practical ly the same throughout the course of the discharge canal, as is seen f r o m Table I. The slight increase in radioactivity in the region of confluence could well be due to mixing and recirculation with previous contaminated water. The accumulation of cobalt and caesium radionuclides by A. granosa after 5, 10 and 30 days of exposure was not significantly affected by the temperature (Fig.4, Table II); the concentration of these nuclides varied between 5 and 25 pCi /g with time. However, the accumulation of iodine-131

I A E A - S M - 1 9 7 / 2 27

10

8 z o

20 2 5 3 0 3 5 4 0 4 5

TEMPERATURE (°C)

FIG.4. Effect of temperature on the rate of filtration expressed in m l / m i n per animal (each of ~40 -50 g gross weight) by ark-shell Anadara granosa (©) under laboratory conditions, and on uptake of cobal t -60 ( p C i / g dry) after 5 ( O ) , 10 ( A ) and 30 (V) days of exposure in the discharge canal.

was to a certain extent temperature dependent, especial ly after 30 days of exposure, when it increased f r o m 12.7 to 53.7 pCi /g with a temperature change f r o m 27 to 35°C. In the clam K. opima, after 2 5 days of exposure, cobalt accumulation, in general, increased f r o m 27 to 41.6 pCi /g with increase in temperature (Table III). The thermal dependence of the b ioac -cumulation pattern, however, was not maintained on further exposure (46 days); the concentration by then was practical ly the same (80 pCi /g , Table III) both at the highest and the lowest ranges of temperatures. A s i m i -larly variable pattern was also evident in the uptake of cobalt, zinc, iodine and caesium nuclides by oyster C. gryphoides (Table IV). Unfortunately the experiments could not be continued further since the experimentals were lost during de silting operations.

5.3. Effect of temperature on filtration rates under laboratory conditions

To elucidate the possible and spec i f i c ro le of temperature, if any, on the bioaccumulation, the effect of temperature on the feeding/f i l tration rates by blood c lam A. granosa was measured under laboratory conditions.

The study of the 'filtration rate ' was adopted, since in the benthic c i l iary feeders , it is the basic physiological p r o c e s s which is controlled and modi -f ied by the abiotic variables in the environment. The amount of radioactivity accumulated by lamell ibranchs under laboratory conditions in general is found to be a function of f i ltering rates [12], the modifications of which may ref lect upon and explain the subsequent changes in the bioaccumulation pattern and the possible consequent toxic e f fects . However, we do recognize that under field conditions the filtration rates may be modif ied by the combined ef fects of other abiotic and biotic variables. Further it is not necessar i ly true that all the suspension f i l tered is ingested; this is because feeding generally takes place in the presence of mucus, the secret ion of which is stimulated by the amount of indigestible debris present in the water [13].

28 PATEL et al.

Figure 4 re cords the average rates of filtration expressed as mil l i l i tres of neutral red suspension c leared per minute by an animal weighing about 40-50 g at various temperatures between 20 and 44°C after 24-48 hours of acclimation at the chosen temperatures. The filtration rates were measured over 3 -4 hours or till the dye suspension was almost cleared. The filtration rates increased with increasing temperature f r o m 21 to 30°C, at which exper i -mental animals remained open and extremely active, and movements of mantle folds and foot were evident. With further r ise in temperature the rates declined slightly eventually remaining more or l ess constant between the range 31 and 35°C, at which active/optimum filtration occurred . However, the rates of filtration per individual experimental batch at temperatures exceeding 32.5°C fluctuated significantly (15-20%). At yet higher tempera -tures (exceeding 35°C), though the animals were open and the foot movement was evident, the rate fe l l sharply, this being accompanied by bleeding. Sub-sequently this led to a state when the animal failed to respond to stimuli (moribund). At still higher temperatures (42-44°C), hardly any activity of mantle folds and foot was evident; most of the time foot remained contracted and trapped between the valves, resulting in a filtration rate that was pract i -cally zero (Fig.4). The experimental animal at such high temperatures survived only f or 4 -6 hours. In general, active feeding is observed only within a certain range of temperature (28-32°C) in lamell ibranchs [13-17] . Thus, it is interesting to note f r o m the slope in Fig.4 that the range of temperature over which active feeding in A. granosa was observed was r e l a -tively wide, amounting to about 8-10°C. At the lower range of temperatures at which filtration could be measured, the dependence on temperature was very great, the rate (Qio) being increased by a factor of approximately 6 to 7 f o r every 10°C r ise in temperature over the range 21 to 31 °C.

It could be concluded for this ser ies of experiments that there is no definite and significant effect of temperature in the range 27-35°C on the bioaccumulation, especial ly of caesium and cobalt nuclides under tropical f ield conditions. The thermal dependence of iodine uptake could perhaps be explained in terms of its significantly short eco logical half - l i fe .

The effect of temperature on the uptake and loss of various radionuclides by benthic communities under laboratory and simulated conditions are well documented [18-28] . In general, an increase in temperature, within the range over which optimum physiological rates are recorded, results in increased uptake and turnover of radionuclides. Thus Duke et al. [23] and Wolfe and Coburn [25 ] reported that the uptake of z inc-65 by Crassostrea virginica, Mercenaria mercenaria and Aquipecten irradians and of caesium-137 by Rangia cuneata was temperature dependent within the range 5 to 2 5°C. However, Skauen [28] failed to observe thermal dependence of z inc-65 uptake by oysters . Similarly Fowler and Benayoun [27] also found that cadmium-109 accumulation by Mytilus galloprovincialis was not affected by temperature between 8 and 22°C.

5.4. Effect of chromium on filtration rates

The possible effect of chromium in hexavalent f o r m (potassium dichro-mate) on filtration rate is shown in Fig.5, in terms of per cent increase or decrease in the rate in relation to that of the control. After 48 hours exposure at chromium concentrations varying between 0.01 and 5.0 ppm at 26°C, the rates were to a certain extent modified. The filtration was

IAEA-SM-197/22 29

0.01 0 0 5 01 0 5 10 2 0 5 0

ppm CHROMIUM CONCENTRAT ION

FIG.5. Effect of chromium on the rate of filtration, after 48 and 96 hours of exposure at 26°C, in Anadara granosa expressed in terms of percentage increase or decrease in relation to that of the control. Inset: thermal potentiation of the chromium effect (2 ppm chromium) on the rate of filtration after 24 h exposure.

decreased — in other words the experimental animals were depressed at concentrations between 0.01 and 0.05 ppm chromium. The filtration was increased (stimulated) between 0.1 (+ 163%) and 0.5 ppm and once again depressed at yet higher concentrations, between 1.0 and 5.0 ppm. After 96 hours of acclimation a general depressing effect was evident at practically all the concentrations. However, experimental animals exposed at 0.01 and 0.5 ppm levels c leared the dye suspension at practically the same rate as controls. This behaviour to a certain extent could be explained in terms of inherent physiological states of the experimental animals and partly due to some detoxification of the chromium solution that could have occurred due to the activity of the animals themselves. Further, in general, detoxification appeared to be inversely related to the observed ef fects at shorter exposure, as was evident f r o m the curves shown in Fig.5. At the highest concentration (5.0 ppm), bleeding occurred during the acclimation period between 48 and 96 hours, subsequently leading to the rate being depressed significantly ( - 96%), which was evident f r o m the complete cessation of filtration activity.

Considering the inherent physiological dif ference in the experimental animals due to laboratory conditions, the per cent increase or decrease in

TABLE V. DISTRIBUTION RANGE OF TRACE METALS IN SOFT TISSUES OF LAMELLIBRANCHS, A. granosa, PL opima and _C_. gryphoides AND IN CANAL WATER Average concentrations of 1 0 - 1 5 batches, each comprising 4 - 5 experimental animals are given in parenthesis

Cr Ni C o Fe Mn Cu Zn Species

(ppm, dry wei ght basis)

A . granosa 1 . 0 - 2 . 5 (2 .1)

4 . 0 - 2 0 . 0 (6 .6)

1 3 . 0 - 4 0 . 0 (21.0)

700 - 1 5 0 0 (1150)

14.0 - 4 0 . 0 (28.0)

2 . 0 - 1 6 . 0 (6 .5)

35.0 - 85.0 (65.0)

K. op ima 2 . 0 - 5 . 0 (3 .1)

4 . 0 - 5 0 . 0 (16.4)

1 0 . 0 - 2 5 . 0 (14.7)

700 - 1 3 0 0 (910)

15.0 - 4 0 . 0 (18.8)

3 . 0 - 1 6 . 0 (6 .0)

40 .0 - 80.0 (62.0)

C. gryphoides 3 . 0 - 6 . 0 (3 .7)

5 . 0 - 1 5 . 0 (9.5)

4 . 0 - 1 6 . 0 (10.0)

300 - 750 (500)

5 . 0 - 2 5 . 0 (10.5)

2 3 0 - 620 (390)

200 - 500 (352)

Water <0.005 0.001 0.0002 0.017 0.008 0.025 0.057

IAEA-SM-197 /22 31

filtration rates up to 15%, which is within variations occurr ing in normal laboratory experiments, cannot be considered significant. There fore , the effect observed beyond this limit could only be considered as a depressing or a stimulating effect.

5.5. Thermal potentiation of chromium effect

The possible thermal potentiation (activation) of the chromium effect on rates of filtration by Anadara granosa is shown in an inset to Fig.5. The term potentiation is used in the sense of a possible ' synergist ic e f fect ' , a term generally used to suggest a more than additive ef fect caused by two factors acting in the same direction.

It will be evident f r o m Fig.5 that, in general, the effect of 2 ppm of chromium after 24 hours acclimation at various temperatures was a depres -sing one and as such it increased with temperature f r o m 21 to 28°C. With further r ise in temperature (30-35°C), the experimentals bled during the acc l i -mation period. At yet higher temperatures 36-40°C the filtration rates could not be measured since the animals bled considerably and subsequently became moribund. The filtration rate curve between 30 and 35°C, though the exper i -mental animals had b l e d , s h o w e d slight reduction in injury; in reality increased bleeding should be considered as further decrease in the metabolic rate.

The endogenous chromium concentration in soft t issues of experimentals between 21 and 28°C was 24-30 ppm (dry weight basis) ; it increased with temperature in the range 30-35°C, being 100-180 ppm. Thus temperatures up to 35°C increased the ingestion of chromium, thereby potentiating the depressing effect of the metal. The concentration fel l sharply between 36 and 40°C to 40-50 ppm. This then c learly suggests that bleeding at 30-35°C was caused by the large amount of chromium (100-180 ppm) that had entered the system, whereas between 36 and 40°C it was predominently due to temperature, as discussed earl ier . It will be seen f r o m the data that chromium at 2 ppm or a temperature of 30-35°C when administered as inde-pendent treatments did not cause any bleeding, while the two treatments given simultaneously did. This effect therefore , could be considered as thermochemical ly synergistic in nature.

5.6. Distribution of trace metals

Table V re co rds the average concentrations of a few trace metals, chromium, nickel, cobalt, iron, manganese, copper and zinc, expressed as ppm dry weight, in soft t issues of three species of bivalves and in water. No significant ef fect of temperature on the distribution patterns of these elements was evident. Further, the concentration remained practical ly the same over the period of exposure. Chromium concentration varied f r o m 2 to 5 ppm, cobalt f r o m 10 to 21 ppm, and nickel f r o m 6 to 16 ppm. Zinc and copper concentrations were a maximum (352-396 ppm) in the oyster, whereas iron accumulation was a maximum in blood c lams.

It is interesting to note that, though chromium as the dichromate is contained in the effluent (~1000 kg/a) , no significant accumulation in any of the species was observed. This is not surprising since the chromium concentration was ~0.005 ppm, which may not adversely affect the metabolic rates (as discussed earl ier) .

32 PATEL et al.

Some of the chromium compounds are reported to cause cancerous growths and skin ulcers on marine f ishes [29]. The lethal concentration varied f r o m spec ies to spec ies in the range 18-200 ppm, depending upon the valency state. Jones [ 30] however, found that chromium and nickel at 1 ppm were injurious to stickleback Gasterosteus aculeatus.

Earl ier Raymount [ 31, 32], studying the chromium effect on polychaete worm Nereis sp. also observed that the element in hexavalent f o r m at 1 ppm level was toxic. However, the toxic ef fect in terms of mortality was apparent only after three weeks of exposure. It would be surprising if this concen-tration did not affect some physiological rates after even 1 to 2 days but, since the mortality cr iteria only was considered as a measure toxicity, it is not surprising that mortality occurred after 21 days. In the present ser ies of experiments we were looking for some immediate modification in physio-logical rates that could be detected within a relatively short duration of exposure (2 to 4 days), since during prolonged exposure (3-4 weeks) under laboratory conditions, starvation may also enhance the effect. The results of experiments with blood c lam Anadara granosa show thermal potentiation of the chromium effect up to 35°C, which was evidence of thermo-chemical synergism. Further, the species was found to be extremely sensitive to chromium concentrations as low as 1 to 2 ppm even on 24 to 48 hour exposure. This suggests that chromium concentrations exceeding 1 ppm reduced the c lam's ability to survive thermal shock.

It could be concluded f r o m these studies that: (i) the benthic species like A. granosa, which has erythrocytic haemoglobin [7 , 8] would be a good exper i -mental species to detect metal toxicity which could be measured in terms of bleeding; (ii) the release of waste heat in a tropical nearshore environ-ment may not affect the metabolic rates of benthic poikilotherms adversely as long as the increase is such that the ambient temperature remains in the range of 27 to 35°C, within which physiological rates can be adjusted by some homeostatic mechanism. However, the upper limits of this range may affect the physiology of reproduction, including the maturation of gonads and larval development, as well as shoreward migration of some species .

A C K N O W L E D G E M E N T

Our thanks are due to Dr. A.K. Ganguly, Director of the Chemical Group; Dr. B.K. Gaur, Mr. P.K. Zutshi and Mr. T. Subbaratnam for many helpful suggestions, and to Mrs. A. Sant for technical help.

R E F E R E N C E S

[ 1 ] KINNE, O . , The effects of temperature and salinity on marine and brackish water animals, 1. Temperature, Oceanogr. Mar. Biol. Ann. Rev. (BARNES, H. , Ed.), George Allen and Unwin, London, 1 (1963) 301-40.

[ 2 ] NAYLOR, E., Effects of heated effluents upon marine and estuarine organisms, Adv. Mar. Biol. , (RUSSELL, F.S., Ed.), 3 (1965) 63-103.

[ 3 ] HEDGPETH, J.W., GONOR, J.J., Aspects of the potential e f f e c t of thermal alteration on marine and estuarine benthos, Biological Aspects of Thermal Pollution (KRENKEL, P.A. , PARKER, F.L., Eds), Vander-bilt University Press, Nashville (1969) 80-118.

[ 4 ] PATEL, B., "Field-laboratory comparabil ity in rad ioeco logy" , Reference Methods in Marine Radioecology (Proc. Panel Monaco , 1974) , IAEA, Vienna (1975, in press).

[ 5 ] PATEL, B., VAIANJU, P.G., MULAY, C .D . , BALANI, M . C . , PATEL, S. , "Radioecology of certain molluscs in Indian coastal waters, Radioactive Contamination of the Marine Environment (Proc. Symp. Seattle, 1972) , IAEA, Vienna (1973) 307 -30 .

[6] [ 7 ]

[8]

[ 9 ]

:io]

:n]

;i,2]

13]

; i 4 ]

: i 5 ]

16]

17]

18]

19]

20]

21]

22]

23]

24]

25]

26]

27]

28]

29]

30]

31]

32]

IAEA-SM-197 /22 33

PATEL, B., GANGULY, A . K . , Occurrence of 75Se and 113Sn in oysters. Health Phys. 24 (1973) 559-62 . PATEL, B., MULAY, C .D . , GANGULY, A . K . , Radioecology of Bombay harbour - A~~tidal estuary, Estuarine Coastal Mar. Sci . 3 (1975) 13-42 . PATEL, B., PATEL, S . , Blood clams material for physiological and b iochemica l studies, J. Mar. Biol. Ass. India 14 (1972) 555-63 . SEYMOUR, A . H . , LEWIS, G.B., Radionuclides of Columbia river origin in marine organisms, sediments, and water co l l e c ted from the coastal and off-shore waters of Washington and Oregon, 1961-1963 , USAEC Rep. UWFL 86 (1964) 1 - 7 3 . SEYMOUR, A .H. , "Accumulat ion and loss of z inc -65 by oysters in a natural environment" , Disposal of Radioactive Wastes into Seas, Oceans and Surface Waters (Proc. Symp. Vienna, 1966) , IAEA, Vienna (1966) 605-619. PRESTON, A . , The control o f radioactive pollution in north sea oyster fishery, Heligolander Wiss. Meeres. Unters. (1968) 269-79 . SCHELSKE, C.L. , WOLFE, D . A . , HOSS, D.E., "Ecological implications of fallout radioactivity a c cumu-lated by estuarine fishes and mol luscs" , Proc. 3rd Nat. Symp. Radioecology, Oak Ridge, Tennessee, (1971) 791-806. RICE, T.R. , SMITH, R.J., Filtering rates of the hard c l a m (Venus mercenaria) determined with radio-active phytoplankton, Fishery Bull. 129 58 (1958) 73-82 . GALTSOFF, P.S., The e f f e c t of temperature on the mechanical activity of the gills of the oyster (Ostrea virginica Gm. ) , J. Gen. Physiol. 11 (1928) 415 -31 . HOPKINS, A.E., Experiments on the feeding behaviour of the oyster Ostrea gigas, J. Exp. Zoo l . 64 (1933) 469-94 . HOPKINS, A.E. , Temperature optima in the feeding mechanism of the oyster, O. gigas, J. Exp. Zoo l . 71 (1935) 195-208. LOOSANOFF, V.L. , Rate of water pumping and shell movements of oysters in relation to temperature, Anat. Rec. (1950) 108. KRUMHOLZ, L.A. , GOLDBERG, E.D., BOROUGHS, H. , "Ecological factors involved in the uptake, accumulation and loss o f radionuclides by aquatic organisms", Effects o f Atomic Radiation on Oceanography and Fisheries, Publ. No. 551, USA Nat. Acad. Sc i . , National Research Council (1957) 69-79. MISHIMA, J., ODUM, E.P., Excretion rate of 6 5 Zn by Littorina irroratain relation to temperature and body size , Limnol. Oceanogr. 8 (1963) 39-44. GUTKNECHT, J., Zn 6 5 uptake by benthic marine algae. Limnol. Oceanogr. _8 1 (1963) 31-38. BRYAN, G.W. , The accumulation of 137Cs by brackish water invertebrates and its relation to the regula-tion of potassium and sodium, J. Mar. Biol. Ass. UK 43 (1963) 541-65 . BRYAN, G.W. , "The accumulation of radiocaesium by marine and brackish water invertebrates", Nuclear Detonations and Marine Radioactivity, (Proc. Symp. ) , Norwegian Defence Research Establishment (1964) 85-93 . DUKE, T . , WILLIS, J., PRICE, T . , FISCHLER, K . , "Influence of environmental factors on the c o n -centrations of 6 5 Zn by an experimental c ommuni ty " , Proc. 2nd. Nat. Symp. Radioecology, USAEC Rep. C O N F - 6 7 0 5 0 3 ( T I D - 4 5 0 0 ) ( 1 9 6 9 ) 355-62 . CROSS, F.A. , DEAN, J .M. , OSTERBERG, C.L. , "The e f fec t of temperature, sediment and feeding on the behaviour of four radionuclides in a marine benthic Amphipod" , Proc. 2nd Nat. Symp. Radioecology, USAEC Rep. CONF-670503 (TID-4500) (1969) 450 -61 . WOLFE, D .A . , COBURN, C.B., Influence of Salinity and temperature on the accumulation of ces ium-137 by an estuarine c lam under laboratory conditions. Health Phys. 18 (May 1970) 499-505 . O'HARA, J., Cadmium uptake by fiddler crabs exposed to temperature and salinity stress, J. Fish Res. Board. 30 6 (1973) 846. FOWLER, S .W. , BENAYOUN Ghislaine, "Experimental studies on cadmium flux through marine b io ta" , Comparative Studies of Food and Environmental Contamination, (Proc. Symp. Otanierni, 1973) IAEA, Vienna (1974) 159-70 . SKAUEN, D .M. , Radioactive 6 5 Z n in marine organisms in fishers of Island sound and its estuaries, USAEC Rep. TID-13509 (1961). HALSTEAD, B.W., "Tox i c i ty of marine organisms caused by pollutants". In Marine Pollution and Sea Life (RUIVO, M . , Ed.), FAO, Rome (1972) 584-94 . JONES, J.R.E., The relation between the electrolyt ic solution pressures of the metals and their toxicity to the stickleback (Gasterosteus aculeatus L.), J. Exp. Biol. 16 (1939) 425. RAYMONT, J.E.G., The effects of chemica l pollutants on marine organisms, UKAEA Rep. AEEW-M-61 (1960) 1 - 2 9 . RAYMONT, J.E.G., The effects of chemica l pollutants on marine organisms, UKAEA Rep. AEEW-M-145 (1961) 1 - 2 3 .

34 PATEL et al.

D I S C U S S I O N

F. LIEVENS: Before the change in the climate of the continental shelf around 1933, when the summers were very warm and the winters very cold, di f ferences in the temperature of the North Sea water in the coastal region averaged 13-15°C. But there was no change in the biotope, not even in terms of increased numbers or density of the various species of fish.

Do you think the operation of a number of nuclear power plants could affect the biotope of the shelf in any way, even close to the plants, as a result of the release of cooling water?

K.G. VOHRA: The release of cooling waters in the coastal zones are known to affect the distribution and physiology of many native benthic c o m -munities. This has been well documented in IAEA Proceedings 'Environmental Effects of Cooling Systems at Nuclear Power Plants' (Proceedings of a Sym-posium held in Oslo, 1974) published in 1975. During our studies we did not observe any significant effect of temperature in the range 27-35°C, during three months of exposure, on the bioaccumulation of radionuclides by three spec ies of lamellibranchs under field conditions.

C.B. J^RGENSEN: I fee l that we should be rather cautious in identi-fying the rates at which bivalves remove neutral red f r o m solution with the filtration rates, since only an unknown (and perhaps not too well -defined) fraction of neutral red is removed f r o m the water passing through the gil ls. It might be better to speak of c learances of neutral red.

K.G. VOHRA: We fully appreciate Mr. J^rgensen's suggestion. Our main interest was to study the effect of elevated temperatures on the b io -accumulation of radionuclides by bivalves under natural conditions. To understand the field data, therefore , the rate of f i l t rat ion /removal / c learance of neutral red was studied under laboratory conditions. We found that the fraction of neutral red removed f r o m the water passing through the gills was fair ly constant. In fact, we found this parameter to be a good indicator to assist in understanding the effects of low doses (10-100 R) of ionizing radia-tion on blood clams.

O.J. VAN DER BORGHT: You mentioned the decrease in temperature resistance induced by chromium in a mollusc species . Are you sure that the chromium is real ly ingested, and not directly absorbed f r o m the water by an ionic uptake mechanism?

K.G. VOHRA: Our interest was not to understand the mechanisms of chromium uptake during our present studies, but to study the thermal potenti-ation of the chromium effect , i rrespect ive of element 's path of entry, i .e. either through injection or ionic exchange.

A. SAAS: Your study shows a marked increase in the iodine uptake of the various experimental species . I should like to ask you how much of this you attribute to increased metabolism and how much to the phys ico -chemical changes in the iodine induced by temperature variation.

K.G. VOHRA: There are only one or two cases in which the uptake of radioiodine was found to be temperature-dependent. However, we do not attach much biological significance to this observation; whatever increase occurs is most likely to be due to the physico -chemical factors , e.g. the chemical state of the iodine.

IAEA-SM-197/10

THE EFFECT OF TEMPERATURE ON THE UPTAKE AND RETENTION OF 6 0Co AND 6 5Zn BY THE COMMON SHRIMP Crangon crangon (L.)

A. W. van WEERS Reactor Centrum Nederland, Petten, N . H . , The Netherlands

Abstract

THE EFFECT OF TEMPERATURE ON THE UPTAKE AND RETENTION OF 60Co AND 65Zn BY THE COMMON SHRIMP Crangon crangon ( L . ) .

The effect of temperature on the uptake of 60Co and teZn directly from sea water and on the retention after uptake from labelled food by the common shrimp Crangon crangon (L. ) was studied. The mean con-centration factor reached in whole shrimps after 16 to 21 days uptake from sea water ranges from 6 to 10 and from 30 to 60 for 60Co and ^ Z n , respectively. The ef fect of temperature on the uptake from sea water is small for both radionuclides. From the loss of 60Co and ^ Z n , observed when shrimps moulted, it appears that a large fraction of the radionuclides taken up from sea water is bound by the exoskeleton. Moulting frequency and the rate of food uptake increase with temperature. Both radionuclides are assimilated from labelled food and are retained according to a two-compartmental model. A temperature increase of 10°C reduces the biological half-lives of the long-l ived component in the retention of S0Co and 65Zn with a factor of about two. It is concluded that shrimps will accumulate 60Co and ®Zn mainly through the food chain. An increase in temperature will result in a higher rate of uptake of the radionuclides with food and in a shorter biological hal f - l i fe . Consequently the equilibrium concentration factor will be reached sooner.

1. INTRODUCTION

The neutron activation products 6 0Co and 6 5Zn are common constituents of the low- leve l liquid radioactive waste of nuclear power stations. Upon re lease into the marine environment, both radionuclides are likely to be accumulated to a considerable extent by marine biota. According to published data for crustacea, the concentration of the elements cobalt and zinc in the common shrimps Crangon crangon (L.) may be about three orders of magni-tude higher than the concentration in sea water [1, 2] . Laboratory studies carried out at Petten have shown that the common shrimp can accumulate 6 0Co and 6 5 Zn directly f r o m sea water and f r o m labelled food.

The re leases of l ow- leve l liquid waste by nuclear power stations are accompanied by the discharge of waste heat. The release of waste heat may affect the metabolism of the waste radionuclides in marine organisms. The effect of temperature on the uptake of 6 0Co and 6 5Zn f r o m sea water by the shrimp and the effect of temperature on the retention of these radionuclides after uptake f r o m labelled food are the subject of the present report .

2. MATERIALS AND METHODS

Shrimps (Crangon crangon (L.)) , weighing 0.8 to 2.8 g, were collected at the North Sea shore near Petten and maintained in aquaria at about 10°C

35

36 van WEERS

15°C

r - t t t -I • . Oj 5 C

H

60, 'Co

D A Y S

; ' /Ii A / m ' / * / ; / / • / /

a 15 °C

"Co

DAYS

FIG. l . Uptake of 60Co from sea water by non-moulting shrimps at 5°C and 15°C in two replicate experiments. CF: concentration factor. A: • and • mean data for 8 animals. B: • and • mean data for 4 animals. The vertical bars indicated for some of the points represent ± 1 SD.

until needed. Freeze -dr i ed mussel f lesh was given as food twice a week. The animals were used in the experiments after at least one week ac c l ima-tion in the aquaria. In the experiments the shrimps were kept individually in perforated polyethylene cups (6 c m X 6 cm X 8 cm) to enable feeding and moulting to be observed. The salinity of the fi ltered natural sea water used in the experiments ranged f r o m 30 to 34%o. The animals were acclimated to the temperatures of the experiments at a 'rate ' of two days per 5°C di f ference in temperature as compared with the 10°C temperature in the aquaria. Mortality during the experiment ranged f r o m zero to 15%.

In the experiments on the uptake of the radionuclides directly f r o m sea water, four groups of 6 to 10 animals were placed in polycarbonate basins in 3 l itres of sea water. Two basins were kept at 5°C and the other two at 15°C. At each temperature 15 ^Ci 60 Co was added to one basin and 7.5 nCi 65Zn to the other. The same set-up was used for measurements of the

IAEA-SM-197/10 37

10 2o;c

c

05 0 5 10 15 20

— DAYS

FIG.2. Uptake of 60Co from sea water by shrimps at l0°C and 20°C. CF: concentration factor. • : mean data for 7 moulting and non-moulting animals at 10°C. • : mean data for 9 moulting and non-moulting animals at 20°C. The vertical bars indicated for some of the points represent ± 1 SD.

uptake of 60Co and 65Zn at 10°C and 20°C, respectively. The media were refreshed several times during the experiments and 10 ml samples were taken regularly for measurement of the radionuclide concentration. The variation of the 60Co and 65 Zn concentration did not exceed ±5% and ±7.5%, respectively, of the average concentration. Once in every two or three days the animals were placed for about one hour in non-radioactive sea water and were fed non-radioactive mussel f lesh. Before each measurement of the radioactivity of the shrimps, the animals were brief ly rinsed in non-radioactive sea water.

In the experiments on the retention of 60 Co and 6 5Zn taken up f r o m food, digestive glands of mussels which had taken up 60Co or 65Zn f r o m sea water for 3 to 5 days were used as food. In each experiment two groups of shrimps, kept at different temperatures, were given a single feeding of the labelled material. During the subsequent retention period, the shrimps were kept in 40 litre basins having continuously refreshed non-radioactive sea water and the shrimps were given non-radioactive mussel flesh three times a week.

Both isotope preparations used were in chloride f o rm, the speci f ic activities were at least 100 jLiCi/jug (code CKS-1 and ZAS-2 , The Radiochemical Centre, Amersham). Measurements of the radionuclide concentration in shrimps were made by whole-body 7-counting of living animals, utilizing a 3 in X 3 in Nal(Tl) well-type crystal coupled to a single-channel analyser. The uptake and retention could thus be followed for each individual shrimp. The same equipment was used f or all other radionuclide measurements, including the regular counting of a 60Co and a 6 5 Zn standard sample.

3. RESULTS

3.1. Uptake f r om sea water

Animals which moulted during the uptake period lost a large fraction of their accumulated 6 0 Co or 6 5 Zn activity at moulting. At the higher tempera-ture more shrimps moulted in each experiment than at the lower temperature.

38 van WEERS

The direct effect of temperature on the uptake f r o m sea water was judged f r o m the mean uptake data of at least 4 non-moulted animals. This was only possible in the experiments at 5°C and 15°C. The uptake of the radionuclides is expressed as the increase of the concentration factor with time. The concentration factor is defined here as the ratio of the concentration of the radionuclides in whole shrimps ( cpm/g fresh weight) and the average con-centration in the sea water medium ( cpm/ml ) . The results of the experiments on the uptake of 60Co by non-moulted shrimps at 5°C and 15°C, respect ively , are shown in F i g . l . In both experiments the mean concentration factor at 15°C is higher than at 5°C, the d i f ferences , however, being small . In the experiment on the uptake of 60Co at 10°C and 20°C, 2 out of 7 animals moulted in the 10°C group and 6 out of 9 animals in the 20°C group. The mean uptake figures, presented in Fig .2 , include data f r o m moulted animals. There is no di f ference between the mean concentration factors reached by the two groups at the end of the uptake experiment. Three animals of the 20°C group which moulted at days 8, 14 and 15, lost, at moulting, 48%, 75% and 68%, respect ively , of their pre-moult activity. As a result of the high 60Co loss at moulting, the mean concentration factor is temporari ly reduced when one or several shrimps have moulted. The cast exoskeletons continued to accumulate 6 0Co f r o m sea water.

The uptake of 6 5 Zn by non-moulted shrimps at 5°C and 15°C is shown in Fig.3. The mean concentration factor reached at 15°C was about 25% higher than at 5°C in one experiment (Fig.3A) but no dif ference was observed in a replicate experiment (Fig.3B). The results of the experiment on the uptake at 10°C and 20°C are presented in Fig .4 . As 7 out of 8 animals at 20°C moulted within the f irst 9 days, the uptakes shown for this group are mean f igures f or all animals, whereas the uptake data for the 10°C group re fer to non-moulted animals (8 out of 10). Three animals of the 20°C group which moulted at day 9 lost , respect ively , 44%, 49% and 51% of their pre -moult 65Zn activity. In spite of the 6 5Zn losses at moulting, the mean concentration factor reached at 20°C was about 65% higher than at 10°C. The small ef fect of the loss of 6 5Zn at moulting is explained by the high initial rate of 65Zn uptake by moulted animals and by the fact that no additional moults occurred between day 9 and the end of the uptake period. Cast exoskeletons continued to accumulate 6 5Zn f r o m sea water.

3.2. Retention of 60Co and 6 5Zn after uptake f r o m labelled food

The retention of 60 Co and 65 Zn after single uptake with labelled food was measured at 5°C and 15°C and at 10°C and 20°C, respect ively . In Figs 5 to 8, the results of the experiments are presented as the mean percentages of retained activity plotted against time on log- l inear scale . The retention of both 60 Co and 6 5 Zn is d escribed by an exponential model with a short- l ived and a long-l ived component. The retention parameters derived f r o m the curves by the method of least squares are indicated in the f igures . The ef fect of temperature on the 60Co retention can be seen in the di f ferences in the biological half- l i fe of the long-l ived component. Retention curves f or indi-vidual shrimps have been analysed and the data for the long-l ived components are summarized in Table I. The data show that at 5, 10, 15 and 20°C the

IAEA-SM-197/10 39

15 °C

...A * * 5 ° C

/ . A'

/ /

/ ^ I / i: i i

65-7 ZN

0 5 10 15 20 — D A Y S

15 C

r . A

J

65 ZN

i 10

I 15 DAYS

I 20

FIG. 3. Uptake of teZn from sea water by non-moulting shrimps at 5°C and 15°C in two replicate experiments. CF: concentration factor. A: A and • : mean data for 8 and 7 animals, respectively. B: A and • : mean data for 6 and 5 animals, respectively. The vertical bars indicated for some of the points represent ± 1 SD.

40 van WEERS

1 0 0 - |

20 °C

CF

t

5 0 -

10 -

5 -

0 5 10 20

FIG.4. Uptake of 65Zn from sea water by shrimps at 10°C and 20°C. CF: . concentration factor. • : mean data for 8 non-moulting animals. • : mean data for 7 moulting animals and one non-moulting animal. The vertical bars indicated for some of the points represent ± 1 SD.

long-l ived component represents about 20% of the initial activity. The mean biological half- l i fe of this component is about two times shorter at the higher temperature than at the lower .

The data for the long-l ived component in the retention of 6 5 Zn by indivi-dual shrimps are summarized in Table II. The long-lived component accounts for a mean percentage of initial activity ranging f r o m 47% to 74% at the different temperatures. The di f ference between the percentages present in this c o m -ponent at 5°C and at 15°C, respect ively , is statistically significant. The mean biological half- l i fe of the long-lived component is about a factor of two shorter at the higher temperature than at the lower temperature. In spite of a temperature di f ference of 5°C, the mean biological half- l ives measured at the lower temperatures (5°C and 10°C) in the two separate experiments are s imi lar . The same applies to the mean biological half- l ives at the higher temperatures (15°C and 20°C).

3.3. Effect of temperature on feeding and moulting

The observations on feeding and moulting made in the different exper i -ments were pooled for each temperature. The frequencies of food acceptance and moulting were expressed as the number of times that food was accepted or moults occurred per 100 days of observation. The results , presented in Table III, show that the frequency of food uptake and the frequency of moulting

IAEA-SM-197 /10 41

1 0 0 - I ) \

5 0

V

\ \ w

1 0 -

5 -

Th:1.2d.

Tb 2.0 d.

\ /

Tt.12.8d

14 -A— r—

X6-9d. /

5 ° C

15 °C

C o

10 DAYS 2 0

FIG. 5. Retention of 60Co by shrimps at 5°C and 15°C after single uptake of the radionuclide with labelled food . • and • : mean data for 7 and 9 animals, respectively. The long- l ived and the short-lived c o m -ponents are indicated by broken lines. T^: b io log ica l ha l f - l i f e . The vertical bars indicated for some of the points represent ± 1 SD.

increased with increas ing temperature . A s the animals were o f fered a l imited amount of food once every two or three days , the e f fec t of temperature on food uptake may have been l imited by exper imental condit ions. The same applies to the f requency of moulting, which is probably related to the rate of food uptake.

4 . DISCUSSION AND CONCLUSIONS

The l oss of 6 0Co and 6 5 Z n observed at moulting in the uptake exper iments shows that adsorption to the exoskeleton plays an important ro l e in the accumulation of the radionucl ides d i rec t ly f r o m sea water by the common shr imp. As a consequence , the e f fec t of temperature on the accumulation of 6 0Co and 6 5 Z n f r o m sea water is a result of the d irect e f f ec t of temperature on the uptake and of the e f fect of temperature on the f requency of moulting. The latter was strongly influenced by temperature , being 5 t imes higher at 15°C than at 5°C and 2.5 t imes higher at 20°C than at 10°C (Table III).

42 van WEERS

1 0 0 - 1

5 0

1 0 -

5 -

60 'Co

\ \ ^

\ -A ^ -v . \

Tb:1.9d.

Tb:1.6d.

10 °C X:14 .3d .

/ 11 :6.3d.

20 °C J

10 15 20 2 5 D A Y S

FIG. 6. Retention of 60Co by shrimps at 10°C and 20°C after single uptake of the radionuclide with labelled food. • and mean data for 8 animals. The computed curves, the long-l ived and the short-lived c o m -ponents are indicated by broken lines. Tj,: biological hal f - l i fe . The vertical bars indicated for some of the points represent ± 1 SD.

4.1. Uptake f rom sea water

With regard to the uptake of 60Co by non-moulting shrimps, the present study shows that a temperature difference of 10°C has only a small effect on the short-term accumulation f rom sea water. The ratios between the mean concentration factors at 15°C and at 5°C, reached after about 18 days, were 1.1 and 1.3, respectively, in two replicate experiments (Fig . l ) . Long-term accumulation at 5°C and 15°C will be influenced by the moulting frequency. Although the long-term accumulation has not been investigated in the present study, it is likely that the higher frequency of moulting will reduce the rate of increase of the mean concentration of 60Co for a group of shrimps. The results obtained at 10°C and 20°C show that an increased moulting frequency can offset the slightly higher rate of uptake of 60Co at the higher temperature. As has been pointed out elsewhere [3] for the common shrimp, the uptake of 60Co directly f rom sea water at 15°C will not play as important a role as the accumulation of 60Co f rom food. The small effect of temperature on the uptake of Co f rom sea water, observed in the present study, suggests that the same pattern would hold for uptake f rom sea water at lower and higher temperatures.

IAEA-SM-197 /10 43

FIG. 7. Retention o f 65Zn by shrimps at 5°C and 15°C after single uptake of the radionuclide with labelled food . • and • : mean data for 7 and 6 animals, respectively. The computed curves, the long- l ived and the short-lived components are indicated by broken lines. T^: b io logical ha l f - l i f e . The vertical bars indicated for some of the points represent ± 1 SD.

The mean concentration factor of 6 5 Zn in whole shrimps measured at the end of the uptake experiments ranges f r o m 30 to 60. Although equilibrium concentrations in whole shrimps were not attained, the low concentration factors found and the slow increase of the concentration factors for whole animals with time make it unlikely that direct uptake of 65Zn f r o m sea water will lead to concentration factors comparable to published values f o r stable zinc in crustacea. The latter are higher by one to two orders of magnitude (see data presented by Polikarpov [4], Pequegnat et al. [5] and Bryan [2]).

The di f ference between the direct uptake of 6 5 Zn f r o m sea water at 5°C and at 15°C is , apparently, small and was not reproducible under these exper i -mental conditions. The ratios of the mean concentration factors of non-moulting shrimps at 15°C and 5°C, at the end of the experiments, were 1.3 and 1.0, respect ively (Fig.3). Four non-moulting shrimps at 20°C had reached a mean concentration factor at day 8 of 37, which is about 1.5 times higher

44 van WEERS

1 0 0 H

8 0 -

60

> h-> I-O <

<

4 0 -

*> 20

10-

Tb :1.5d. Tb:13.9d.

T h :28.5d.

/ 10 °C

20 °C

T h :2 .0d. 65

ZN

10 15 20 25 — D A Y S

FIG.8. Retention of ^Zn by shrimps at 10°C and 20°C after single uptake of the radionuclide with labelled food. • and A : mean data for 4 animals. The computed curves, the long-l ived and the short-lived components are indicated by broken lines. Tt>: biological hal f - l i fe . The vertical bars indicated for some of the points represent ± 1 SD.

TABLE I. EFFECT OF TEMPERATURE ON THE LONG-LIVED COMPONENT IN THE RETENTION OF 60Co BY SHRIMPS AFTER SINGLE UPTAKE FROM LABELLED FOOD

Temperature Number of

Percentages at time zero Biological half- l ives

Exp. 1 Exp.2 shrimps

mean SD mean SD

5°C 7 58 .2 20 .8 13.5 5 .0

10°C 8 21 .7 7 . 5 16.9 7 .2

15°C 9 23 .7 16.5 8 .8 2 . 2

20°C 8 18.2 8 .7 7 . 5 2 . 3

IAEA-SM-197 /10 45

TABLE II. EFFECT OF TEMPERATURE ON THE LONG-LIVED COMPONENT IN THE RETENTION OF 6 5 Zn BY SHRIMPS A F T E R SINGLE UPTAKE FROM LABELLED FOOD

Temperature

E x p . l Exp.2

Number of shrimps

Percentages at t ime zero

mean SD

Biological hal f - l ives

mean SD

5°C 6 73 .9 9 . 1 3 2 . 6 8 . 4

10°C 4 6 0 . 4 1 4 . 4 3 3 . 7 8 . 0

15°C 7 4 6 . 8 2 0 . 2 16 .5 6 .0

20°C 4 5 8 . 1 13 .0 15 .8 4 . 2

TABLE III. EFFECT OF TEMPERATURE ON FOOD UPTAKE AND MOULTING

Temperature Mean times of

food acceptance per 100 days

Mean number of moults

per 100 days

5°C 16 0 . 7

10°C 24 1 .7

15°C 31 3 . 5

20°C 36 4 . 2

than the mean concentration factor of non-moulting shrimps at 10°C. Data for three individual shrimps at 20°C, which moulted at day 9, show that freshly moulted shrimps rapidly accumulate 6 5 Zn. Within three days the activity of the shrimps exceeded the level reached before moulting. In spite of the loss of 6 5Zn at moulting, the mean concentration factor at the end of this experiment was still 1.6 times higher at 20°C than at 10°C (Fig.4). Although the results obtained at 10°C and 20°C indicate that the direct uptake of 65Zn is influenced by temperature, the ef fect will be small in view of the low concentration factors reached by direct uptake f r o m sea water.

A positive correlation between temperature and uptake of 6 5 Zn f r o m sea water has been reported by Duke et al. [6] f o r mud crabs , by Cross et al. [7] f o r a benthic amphipod, and f o r pelagic euphasiids by Fowler et al. [8l. The magnitude of the temperature ef fect in these studies varied f r o m "minimal" in the range of 7°C to 12°C [7] to a Q 1 0 of 3.1 to 3.6 f o r shor t - term (20 h) 6 5 Zn uptake at 15°C and 5°C [8]. This probably re f lects d i f ferences between the species and between the experimental methods used. Adsorption to the exoskeleton of a significant fraction of 65Zn taken up direct ly f r o m sea water, as observed in the present study f or shr imps, has also been reported in studies with other crustacea [7-10] and is apparently a result of the mode of uptake.

46 IOANNILLI and SMEDILE

4.2. Retention f r o m food

Al l retention data show that shrimps adsorb both 60Co and 6 5Zn f r o m labelled food. The fraction initially present in the long-lived component is about 20% for 60 Co and is 2 to 3.5 times higher for 6 5 Zn. Accordingly a larger fraction of the 65Zn was assimilated f r o m the labelled material . The mean biological half - l ives of the long-lived components at the different temperatures range f r o m 7.5 to 16.9 days for 60Co and f r o m 15.8 days to 33.7 days f o r 6 5 Zn. After long-term uptake of 6 0Co frOm food no l onger -lived component in the retention of the radionuclide by Crangon crangon (L.) is apparent [3]. On the other hand, studies on the 6 5Zn retention by the shrimp Lysmata, carried out by Fowler et al. [11], have shown that some zinc component in this shrimp has a biological half- l i fe of 7 5 to 100 days. A similar long-l ived component of a few per cent of the initial activity may well have escaped detection in the present study with Crangon crangon.

As a significant fraction of both radionuclides is assimilated f r o m food and the turnover of 60Co and 6 5 Zn in shrimps is fairly rapid, it can be con-cluded that uptake f r o m food will be the important route of uptake of 6 0Co and 6 5 Zn by shrimps f r o m their environment. The same conclusion has been drawn with regard to the metabolism of 65Zn in other benthic crustacea by Cross et al. [7] and by Bryan [12],

The retention curves that are plotted in Figure 5, however, indicate that a higher fraction of the initial activity is accounted for by the long-lived component at 5°C than at 15°C. The other retention data given in Figs 6 to 8 and in Tables I and II show that the rate of turnover of 60 Co and 6 5Zn is doubled by a temperature increase of 10°C. As is shown in Table III, the shrimps accepted food more frequently at higher temperatures. Although the ef fects of feeding and temperature have not been studied separately, it is likely that the rates of turnover of the radionuclides are related to the rate of food uptake. According to Bryan [12], the loss of 6 5 Zn f r o m shore crabs , injected with 6 5Zn, was accelerated when feeding was started. The same effect on the loss of 6 5Zn f r o m the amphipod Anonyx sp. was reported by Cross et al. [7], The effect of temperature on the biological half - l i fe of 65Zn in shrimps observed in the present study may well have been caused by the increased rate of food uptake at higher temperatures. This may possibly also apply to the biological half- l i fe of 60 Co, which was affected by temperature in a comparable way. The results of the retention studies apply to retention after single uptake of one particular type of labelled food, whereas chronic re lease of 6 0 Co or 6 5 Zn in a natural environment will eventually result in chronic uptake by shrimps of different kinds of con-taminated food organisms. The fraction of the radionuclides present in the food that will be metabolized by shrimps may depend on the composition of the food. In addition, the turnover of the radionuclides in the shrimp is probably related to the growth rate, which is strongly age-dependent, as has been reported by Meixner [13]. The effect of temperature on the turnover of 60Co and 6 5 Zn may, accordingly, also vary with age. In spite of these uncertainties, some general conclusions can be drawn regarding the effect of waste heat re lease acting in combination with release of the radionuclides. A chronic increase in the temperature of the sea water will result in an increased food uptake and, therefore , in an increased growth rate. Because of the resulting increase of the rate of turnover of the radionuclides in shr imps, equilibrium between the concentrations in shrimps and those in

L A E A - S M - 1 9 7 / 1 0 47

the food organisms will be reached more quickly. The reduction of the biological hal f - l ives of 6 0Co and 6 5 Zn by about a factor of two, as observed in this study for an increase in temperature of 10°C, can be regarded as an indication of the magnitude of the ef fect . Whether, at higher intake rates , the equilibrium levels of 60Co and 65Zn in shrimps will increase depends strongly on whether the concentrations of cobalt and zinc in the animals are under homeostatic control. According to Bryan [14] this is indeed the case for zinc in blood, muscles and gonads of the related spec ies , Homarus vulgaris , but no data concerning the regulation of cobalt or zinc in Crangon crangon are available.

The effect of temperature on the uptake of 60Co and 6 5 Z n by whole shrimps directly f r o m sea water will be small when compared with the ef fect of temperature on the metabolism of the radionuclides obtained f r o m food. However, the adsorption of 60 Co and 65Zn to the exoskeletons of shrimps, which continues after the moults have been cast, will contribute to the removal of the radionuclides f r o m sea water. This may, in particular, be true for the juvenile stages, which have a high surface-to-volume ratio and a higher moulting frequency. At higher temperatures this process will be accelerated.

A C K N O W L E D G E M E N T

The author wishes to express his thanks to Mrs A.H.A. Disco de Neyn and Mr E.E.A. Noordeloos f or their assistance.

R E F E R E N C E S

[ 1 ] FUKAI, R . , MURRAY, C . N . , "Environmental behaviour of rad i o coba l t and radiosi lver re leased f r o m nuclear power stations into aquatic sys tems" , Environmental Behaviour of Radionucl ides Released in the Nuclear Industry (Proc . S y m p . A i x - e n - P r o v e n c e , 1973) , IAEA, Vienna (1973 ) 2 1 7 .

[ 2 ] BRYAN, G . W . , Concentrat ion of z i n c and copper in the tissues o f de capod crustaceans, J. Mar. Biol . Assoc . U . K . 48 (1968) 303 .

[ 3 ] WEERS, A . W . , van, "Uptake o f c o b a l t - 6 0 f r o m sea water and f r o m l a b e l l e d f o o d by the c o m m o n shrimp Crangon crangon ( L . ) " , R a d i o l o g i c a l Impacts o f Releases f r o m Nuclear Faci l i t ies into Aquat i c Environments (Proc . Symp. O t a n i e m i , 1975) , IAEA, Vienna (1975 ) .

[ 4 ] POLIKARPOV, G . G . , R a d i o e c o l o g y of Aquat i c Organisms, North Hol land , A m s t e r d a m (1966) . [ 5 ] P E Q U E G N A T , J. E. , FOWLER, S . W . , SMALL, L . F . , Estimates of z i n c requirements in marine organisms,

J. Fish. Res. Board C a n . 26 (1969) 145. [ 6 ] DUKE, T . , WILLIS, J. , PRICE, T . , FISCHLER, K . , " I n f l u e n c e o f env i ronmenta l factors on the c o n -

centrat ion o f 6 5 Zn by an exper imenta l c o m m u n i t y " , Sympos ium on R a d i o e c o l o g y (Proc . 2nd Nat . Symp. Ann Arbor, 1967: NELSON, D.J . et a l . , Eds), U S A E C - C O N F - 6 7 0 5 0 3 (1969) 355 .

[ 7 ] CROSS, F . A . , DEAN, J . M . , OSTERBERG, C . L . , " T h e e f f e c t of temperature , s ed iment , and f eed ing on the behaviour o f four radionucl ides in a marine benthic a m p h i p o d " , Sympos ium on R a d i o e c o l o g y (Proc . 2nd Nat. S y m p . Ann Arbor , 1967: NELSON, D.J . e t a l . , Eds), U S A E C - C O N F - 6 7 0 5 0 3 (1969) 450 .

[ 8 ] FOWLER, S . W . , SMALL, L . F . , " M e t a b o l i s m of z i n c - 6 5 in euphasi ids" , Sympos ium on R a d i o e c o l o g y (Proc . 2nd Nat. S y m p . Ann Arbor , 1967: Nelson, D .J . et al . , Eds), U S A E C - C O N F - 6 7 0 5 0 3 (1969) 399 .

[ 9 ] RICE, T . R . , "Rev iew o f z i n c in e c o l o g y " , R a d i o e c o l o g y (Proc . 1st Nat. S y m p . , C o l o r a d o , 1961: S C H U L T Z , V . , KLEMENT Jr . , A . W . , Eds), Reinhold Publ. C o r p . , New York (1963) 619.

[ 1 0 ] CROSS, F . A . , FOWLER, S. W . , DEAN, J . M . , Distribution of ffiZn in tissues o f two marine crustaceans determined by autoradiography, J. Fish. Res. Board Can. 2 5 11 (1968) 2461 .

[ 1 1 ] FOWLER, S . W . , RENFRO, W . C . , LAROSA, J . , H E Y R A U D 7 ~ M . , IAEA unpublished d o c u m e n t IAEA-163 (1974) 2 0 .

[ 1 2 ] BRYAN, G . W . , " T h e m e t a b o l i s m of Z n and 6 5 Z n in crabs, lobsters and f resh-water c ray f i sh " , Radio -e c o l o g i c a l Concentrat ion Processes (Proc . Symp. S t o c k h o l m , 1966: ABERG, B . , HUNGATE, F . P . , Eds), Pergamon Press (1967) 1005.


[ 1 3 ] MEIXNER, R . , Wachstum, Hautung und Fortpflanzung von Crangon crangon (L . ) bei Einzelaufzucht, Ber. Dtsch. Komm. Meeresforsch. 20 2 (1969) 93.

[ 1 4 ] BRYAN, G .W, . , Z i n c regulation in the lobster Homarus vulgaris, J. Mar. Biol. Assoc. U. K. 44 (1964) 549.

D I S C U S S I O N

C. HOEDE: Since moulting increases with temperature, should not the moulting be incorporated into the model?

A.W. van WEERS: No, I don't think so . The relative importance of moulting is small when the radionuclides have been taken up f r o m food.

C. STREFFER: Could you comment on the dif ference between your data on the retention of 6 5Zn with the biological half - l ives given in Table II and the data in Figs 7 and 8? How do they fit together?

Secondly, why is there no overall decrease in the biological half - l i fe with increasing temperature?

A.W. van WEERS: As regards the di f ferences in biological half - l ives of 6 5 Zn given in Table II and in Figs 7 and 8, respect ively , I should perhaps point out that the latter were computed f r o m the mean percentages of retained activity. The shape of these curves is affected by di f ferences between indi-vidual shrimps in terms of both the distribution of 65 Zn between the two components and their biological hal f - l ives . This may easily lead to a s o m e -what different result for the least -squares fit applied to the mean retention data, compared with the mean figures obtained f r o m analyses of the indi-vidual retention curves.

To answer your second question, the absence of a gradual decrease in biological half- l i fe of 65Zn with increasing temperature is explained by the fact that the data relate to two separate experiments. Even at the same temperature there is a considerable variation in the mean biological half- l i fe of 6 5 Zn, as measured in separate experiments with shrimps sampled at different t imes.

W.G. HtjBSCHMANN: An interesting feature arising f r o m your data is the very small increase in radionuclide uptake and retention, even for a 10°C increase in temperature. Perhaps you could elucidate in this connection what you mean by the terms ' long-l ived ' and 'short - l ived ' components. Do you have in mind different chemical f o rms of the radionuclides, which behave biological ly differently, or is the differentiation just a means of mathematically analysing the shape of the experimental curves?

A.W. van WEERS: The terms ' long- l ived ' and 'short- l ived ' are used only to indicate the di f ference between the biological half- l ives of the two components found by mathematical analysis of the retention curves . A c c o r d -ingly, no conclusion can be drawn f r o m these data with respect to the different chemical f o rms of the radionuclides present in the labelled food that might be excreted at different rates by the shrimp. Retention curves of the same overal l shape can be expected when the radionuclide is ingested with food in one single chemical f o r m , but is taken up only partly f r o m the digestive system.

R.J. CARMICHAEL: I see that you used the chloride f o r m of cobalt-60 in your tests. In this the normal f o r m obtained f r o m your power station sources? I ask this question because, in my experience, the typical neutron-activated insoluble and particulate cobalt-60 f r o m a pressur ized-water

IAEA-SM " 1 9 7 / 1 0 49

reactor is not taken up bio logical ly . Have you done any work on other chemical f o rms of cobalt-60?

A.W. van WEERS: The studies on the uptake of cobalt-60 f r o m sea -water by shrimps, carried out at our research centre, have been confined to 6 0 Co added to sea-water in the chloride f o rm. Particulate 60 Co released by nuclear power stations may be even less available f o r direct uptake by such organisms. On the other hand, the fact of its presence in particulate f o r m does not prevent uptake of 6 0Co by small f i l t e r - f eeders or by bottom-dwelling detr i tus - feeders , which can be used as food by shrimps.

J.J. COHEN: My comment re fers to your Figs 7 and 8: rather than the data themselves indicating that you have a two-component model , it would seem that you have, in fact , f i rst assumed a two-component model and then treated the data accordingly. Is that true? And, if so , on what basis is a two-component model selected?

A.W. van WEERS: Yes , that is right. The two-component model is the most satisfactory mathematical model f o r describing retention, and I processed the data on the assumption that the retention data could be described by it. I agree , however, that more complicated models fitting the retention data might be used.

IAEA-SM-197/10

INFLUENCE DE LA TEMPERATURE SUR LA CONTAMINATION D'ESPECES MARINES PAR LE FER-59

A. FRAIZIER, J. ANCELLIN CEA, D£partement de protection, Laboratoire de radio£cologie marine, Centre de La Hague, Cherbourg, France

Abstract-Risum£

INFLUENCE OF TEMPERATURE ON THE CONTAMINATION OF MARINE SPECIES BY IRON-59. Interactions between a marine mollusc and fish (Mytilus edulis, Blennius pholis) and iron-59 were

investigated in relation to the physicochemical states of the radionuclide in marine water and to the environ-mental temperature. It appeared that contamination is dependent on temperature; this factor partly influences the physicochemical state of the radionuclide and the metabolic activity of species.

INFLUENCE DE LA TEMPERATURE SUR LA CONTAMINATION D'ESPECES MARINES PAR LE FER-59. Les interactions entre un mollusque et un poisson marins (Mytilus edulis et Blennius pholis) et le fer-59

ont 6t6 6tudi6es en tenant compte des formes physico-chimiques du rad ionuc l ide en eau de mer et en fonction de la temperature du milieu. II est apparu que les phgnomfenes de contamination peuvent etre solidaires des conditions de temperature, qui el les-memes inter vie nnent pour une part dans la physico-chimie du contaminant et l 'activitg mStabolique des esp&ces.

I N T R O D U C T I O N

N o u s nous proposons dans c e t t e e t u d e d ' o b s e r v e r les i n t e r a c t i o n s e s p e c e s - r a d i o n u c l 6 i d e / en f o n c t i o n d ' u n pa ram&t re p h y s i q u e , la t e m p e r a t u r e , s u s c e p t i b l e d ' i n f l u e n c e r les echanges i n t e r v e n a n t e n t r e les organ ismes e t le c o n t a m i n a n t ; e l l e a p o r t e sur d e u x especes m a r i n e s , la M o u l e ( M y t i l u s e d u l i s ) e t la B l e n n i e (B lenn ius p h o l i s ) ; le r a d i o e l e m e n t u t i l i s e a 6fe le fe r 5 9 , sous formes s o l u b l e e t i n s o l u b l e .

1 . O B S E R V A T I O N S P R E L I M I N A I R E S SUR LES PARAMETRES ETUDIES ET LES C O N D I T I O N S E X P E R I M E N T A L ^

1 . 1 . Le f e r en m i l i e u m a r i n

Les teneurs du f e r p resen t n a t u r e l l e m e n t en m i l i e u m a r i n sont e x t r e -m e m e n t v a r i a b l e s . Par e x e m p l e R O B E R T S O N £\ J no te pour I ' O c e a n P a c i f i q u e n o r d - e s t des c o n c e n t r a t i o n s de 13 a 190 p.g/1. l is a t t r i -b u e n t les v a r i a t i o n s observees a I ' a s s o c i a t i o n du f e r a v e c des m a t ^ r i a u x p a r t i c u l a i r e s e t b i o l o g i q u e s con tenus dans I ' e a u . Par a i l l e u r s de grandes d i f -f e r e n c e s sont notees se lon la l o c a l i s a t i o n g e o g r a p h i q u e , la p r o x i m i t e p lus ou moins g rande du l i t t o r a l e t la p r o f o n d e u r . L a p l u p a r t des au teu rs s ' a c c o r -d e n t pour r e c o n n a t t r e I ' e x i s t e n c e p r ^ d o m i n a n t e de formes i n s o l u b l e s du fe r

51


dans I ' o c e a n . L a p r o p o r t i o n de ces formes s e r a i t de I 'o rdre de 80 a 85 % £~2 J £3 J . Le fe r p a r t i c u l a t e e x i s t e r a i t p r i n c i p a l e m e n t sous f o r m e i n o r g a -n i q u e due a F e O ( O H ) e t Fe ( O H ) ^ a d i f f e r e n t s deg r^s de p o l y m e r i s a t i o n ; 7 5 % de formes so lub les presentes s e r a i e n t sous f o r m e de c o m p l e x e s o r g a n i q u e s £ 4 J £5 J £6 J . Se lon c e r t a i n s au teu rs c e p e n d a n t les p r o p o r t i o n s e n t r e fo rmes so lub les e t i nso lub les s e r a i e n t s e n s i b l e m e n t e q u i v a l e n t e s pour I ' 0 c 6 a n P a c i f i q u e N o r d £ b j e t la mer des S a r g a s s e s / " 7 J .

II y au ra l i e u de t e n i r c o m p t e pour I ' i n t e r p r e t a t i o n des resu l ta t s e x p 6 -rimentaux des v a r i a t i o n s p o u v a n t i n t e r v e n i r en ce q u i c o n c e r n e la f o r m e p h y s i c o - c h i m i q u e de ce t e l e m e n t en m i l i e u m a r i n , e t de leurs i m p l i c a t i o n s sur son a c c u m u l a t i o n par les especes .

1 . 2 . Le f e r e n m i l i e u e x p e r i m e n t a l

l l c o n v e n a i t a v a n t d ' a b o r d e r les e x p e r i m e n t a t i o n s sur les processus de c o n t a m i n a t i o n des especes , e t en f o n c t i o n des o b s e r v a t i o n s f o r m u l e e s au p a r a -g raphe p r e c e d e n t , d ' e t u d i e r le d e v e n i r du f e r 59 dans nos m i l i e u x e x p ^ r i m e n -t a u x . 1

L e f e r r a d i o a c t i f a j o u t e i n i t i a l e m e n t sous f o r m e s o l u b l e F e C I ^ a marque une n e t t e t e n d a n c e a s ' e l i m i n e r de I ' e a u , que ce s o i t en p resence d ' e s p 6 c e s a n i m a l e s ou n o n . Les courbes des f i g u r e s 1 - a e t 2 - a r e p r e s e n t e n t la v a r i a t i o n de la r a d i o a c t i v i t e s p e c i f i q u e de I ' e a u en f o n c t i o n du temps , par r a p p o r t a la r a d i o a c t i v i t e m o y e n n e de c e l l e - c i c a l c u l e e pour la d u r ^ e t o t a l e de I ' e x p e r i m e n t a t i o n ( c e t t e d e r n i e r e v a l e u r e t a n t a r b i t r a i r e m e n t c o n s i d e r 6 e comme e g a l e a 1 ) . Ces courbes m o n t r e n t , pour une p e r i o d e de d i x jours e t par r a p p o r t au t a u x i n i t i a l une d i m i n u t i o n n o t a b l e ( d ' u n f a c t e u r 10 a 2 0 ) de la r a d i o a c t i v i t e de I ' e a u des a q u a r i u m s .

Les ana lyses operees par c h r o m a t o g r a p h i e d ' e c h a n g e d ' i o n s s u i v a n t la m e t h o d e d e c r i t e par G U E G U E N I A T £ 8 J i n d i q u e n t ( F i g . 3 - a - b ) q u ' e n eau de mer les fo rmes i nso lub les r e p r 6 s e n t a i e n t un p o u r c e n t a g e i m p o r t a n t de I ' a c t i -v i t e t o t a l e (80 a 9 0 % ) . Ce p o u r c e n t a g e s 'es t r e d u i t en f o n c t i o n du t e m p s , en f a v e u r des formes so lub les a n i o n i q u e s ou n e u t r e s .

Ces c o n s t a t a t i o n s m o n t r e n t d o n e que le fe r i n t r o d u i t en eau de mer sous f o r m e s o l u b l e F e C l g p e u t se t rans fo rmer quas i i n s t a n t a n 6 m e n t en composes i n s o l u b l e s e t s ' a c c o r d e n t a v e c les o b s e r v a t i o n s d ' H A R V E Y £9 J q u i n o t e que I ' a d d i t i o n d ' u n sel f e r r i q u e dans I ' e a u de mer c o n d u i t , par des r e a c t i o n s d ' h y d r o l y s e e t de p o l y m e r i s a t i o n , a la f o r m a t i o n de c o l l o l d e s d ' h y d r o x y d e f e r r i q u e .

Les r ^ s u l t a t s de c e t t e e x p e r i e n c e p r e l i m i n a i r e nous a s s u r a i e n t , pour une p a r t i e de n o t r e e t u d e , la p o s s i b i l i t e d ' o b t e n i r sans d i f f i c u l t e p a r t i c u l i e r e des formes i nso lub les en q u a n t i t e s u f f i s a n t e . M a i s e t a n t d o n n e I ' u n e des c a r a c t S r i s t i q u e s e x p e r i m e n t a l e s ( c o n t a m i n a t i o n d ' e s p e c e s mar ines par des formes i n s o l u b l e s ou so lub les ) i l e t a i t e g a l e m e n t necessa i re de p r o c e d e r a la p r e p a r a -t i o n d ' u n c o n t a m i n a n t c o n t e n a n t une f o r t e p r o p o r t i o n de formes s o l u b l e s . L a r e a l i s a t i o n de c o m p l e x e s o r g a n i q u e s so lub les a e te r e n d u e poss ib le par s o l u -b i l i s a t i o n du f e r 59 par I ' E D T A . Les c h e l a t e s p r o d u i t s sont de fo rmes a n i o n i q u e s ou neut res ( F e Y " , H F e Y , F e O Y , . . . ) .

1 A noter que, du fait de la pr&ence d'entraineui stable dans la source radioactive mfere, l 'apport en fer total correspondait a une surcharge du milieu d'environ 0, 5 5 1 , 5 fig/1.

IAEA-SM-197/22 53

Sans EDTA

Avec EDTA

F I G . l . Evolution, en fonction du temps, de la radioactivity de l 'eau d'aquariums ne contenant pas d'espfeces, contaminSs par le f e r - 5 9 , et places dans des conditions diffgrentes de temperature, a: contamination par des formes insolubles b: contamination par des formes solubles.

L a r a d i o a c t i v i t y de I 'eau c o n t a m i n £ e par ces fo rmes so lub les a m o n t r 6 une d i m i n u t i o n dans le temps b i e n moins i m p o r t a n t e ( d ' u n f a c t e u r 2 - 3 s e u l e -m e n t ) que c e l l e r e l e v e e pour les c o n t a m i n a t i o n s par des formes inso lub les ( F i g . 1 - b e t 2 - b ) . Les c h r o m a t o g r a m m e s pr6sent£s f i g . 3 c - d i n d i q u e n t pour ces formes s o l u b l e s , une f o r t e p r o p o r t i o n i n i t i a l e (80 6 100 %) a l l a n t en d i m i n u a n t au cours du t e m p s , mais d ' u n e f a g o n b e a u c o u p moins m a r q u e e d u r a n t les p remie rs jours que dans le cas des composes i n s o l u b l e s .

Q u e l s q u ' a i e n t les e ta ts du f e r p resen t dans I ' e a u de m e r , i l est E v i d e n t , d'aprfes les f i g u r e s 1 - a - b , 2 a - b , e t 3 , que I ' e v o l u t i o n de la r a d i o -a c t i v i t y de I ' e a u , a i n s i que c e l l e des fo rmes p h y s i c o - c h i m i q u e s , e t a i t l i e e a la t e m p e r a t u r e , c e c i meme en I ' a b s e n c e d'espfeces a n i m a t e s . L ' a u g m e n t a t i o n


FIG.2. Evolution, en fonction du temps, de la radioactivity de l 'eau d'aquariums contenant des espSces, contaminSs par le. fer-59, et places dans des conditions diff£rentes de temperature, a: contamination par des formes insolubles. b: contamination par des formes solubles.

de t e m p e r a t u r e (passage de 5 ° C a 1 5 ° C ) f a v o r i s e v r a i s e m b l a b l e m e n t les r e a c -t ions de p o l y m e r i s a t i o n , la c o a g u l a t i o n des co l lo ' ides e t par su i te la p r e c i p i -t a t i o n du fe r a i n s i que la d e s t r u c t i o n des c o m p l e x e s so lub les ob tenus a v e c I'EDTA. C e c i s e r a i t en r a p p o r t a v e c le f a i t q u ' a peu d ' e x c e p t i o n s pres, la v i t e s s e des c i n ^ t i q u e s des r e a c t i o n s c h i m i q u e s a u g m e n t e tres r a p i d e m e n t a v e c la t e m p e r a t u r e .

1 . 3 . I n f l u e n c e de la t e m p e r a t u r e sur I ' a c t i v i t e m e t a b o l i q u e des especes mar ines e t u d i e e s

E tan t d o n n 6 que la t e m p e r a t u r e a g i t sur la v i tesse des r e a c t i o n s b i o -c h i m i q u e s / 10 J /" 1 1 J on c o n § o i t q u ' e l l e a i t une i n f l u e n c e sur le m e t a -

I A E A - S M - 1 9 7 / 2 2 55

FIG. 3. Evolution dans le temps des pourcentages des formes insolubles et solubles du fer -59 prSsentes dans l 'eau des aquariums pour diffSrentes conditions expgrimentales (presence ou non d'esp&ces, temperature 15°C ou 5°C, contamination par des formes insolubles ou solubles). Formes insolubles: a 15°C; a 5°C. Formes solubles: a 15°C; —.— a 5°C.

b o l i s m e et I ' a c t i v i t e des o r g a n i s m e s . Par e x e m p l e les mouvemen ts r e s p i r a t o i r e s des polssons sont a c c e l e r e s par I ' e l ^ v a t i o n de t e m p e r a t u r e du m i l i e u . II en va de meme pour les M o u l e s ( M y t i l u s ) en ce q u i c o n c e r n e leur r y t h m e c a r d i a q u e , leur c o n s o m m a t i o n d ' o x y g e n e , leur a c t i v i f e de f i l t r a t i o n £ _ / 1 3 J £ 14 J . K I N N E £ \ 5 J cons ta te d ' u n e f a g o n g e n e r a l e q u ' u n e a u g m e n t a t i o n de I ' a c t i -v i t e se p r o d u i t c h e z les Inve r teb res mar ins en f o n c t i o n de I ' e l e v a t i o n de t e m p e r a t u r e .

E n f i n , c h e z la M o u l e comme c h e z la B l e n n i e , c e r t a i n s au teurs c o n s t a -t e n t que I ' a c t i v i t e l i e e au r y t h m e des marees pers is te p e n d a n t un c e r t a i n temps en aquar iums / 1 6 _ / /"~17 J £ 1 8 _ J . Pour e c a r t e r dans une c e r t a i n e mesure les i n c i d e n c e s de ce phenom&ne de p e r i o d i c i t e b i o l o g i q u e sur les mecan ismes memes de la c o n t a m i n a t i o n , i l a pa ru necessa i re de p r o c e d e r , c o m p t e tenu du t y p e d ' e x p e r i e n c e e n v i s a g e , a une a c c l i m a t a t i o n p r e a l a b l e en m i l i e u c o n f i n e des especes c h o i s i e s .

1 . 4 . M i l i e u x e x p e r i m e n t a u x - fo rmes du c o n t a m i n a n t u t i l i s e e s

Les a q u a r i u m s u t i l i s e s , de c a p a c i t e v a r i a b l e (5 a 40 I) c o n t e n a i e n t de I ' e a u de mer f r a f c h e m e n t r e c u e i l l i e au l i t t o r a l , d o n t la t eneu r en f e r s t a b l e n a t u r e l e t a i t de 1 0 - 2 0 JJ.g/1. Du s e d i m e n t m a r i n a e te d ispose au f o n d de ces

56 F RAIZ 1ER et ANCELLIN

a q u a r i u m s . L e r a p p o r t (en po ids ) e a u / s é d i m e n t a tou jou rs é té m a i n t e n u é g a l à 2 . De f a ç o n à ne pas f i x e r t rop r a p i d e m e n t les formes i nso lub les du f e r , i l n ' a pas é té mis en p l a c e de d i s p o s i t i f de f i l t r a t i o n de l ' e a u , c e l l e - c i é t a n t s i m p l e m e n t o x y g é n é e par d i f f u s e u r d ' a i r .

Ces a q u a r i u m s é t a i e n t p l a c é s , s u i v a n t les cas , dans une s a l l e m a i n t e n u e à la t e m p é r a t u r e de 1 5 ° C + 1 ° C , ou dans une chambre f r o i d e à 5 ° C + 1 ° C ; i ls é t a i e n t é c l a i r é s de f a ç o n n o r m a l e ( r y thme d i u r n e - n o c t u r n e - l ' é c l a i r e m e n t d i u r n e a y a n t une i n t e n s i t é au n i v e a u de la su r face de l ' e a u se s i t u a n t e n t r e 100 e t 2 0 0 L u x ) .

Les espèces u t i l i s é e s : la B l e n n i e (B lenn ius p h o l i s ) de t a i l l e moyenne 1 0 - 1 2 c m , e t la M o u l e ( M y t i l u s e d u l i s ) de t a i l l e m o y e n n e 5 - 6 c m , ont é t é i n t r o d u i t e s dans les a q u a r i u m s en même temps que le c o n t a m i n a n t .

Le fe r 59 se p r é s e n t a i t i n i t i a l e m e n t ( s o l u t i o n mère) sous f o r m e F e C I ^ en s o l u t i o n НС I , a v e c e n t r a î n e u r . Le n i v e a u de c o n t a m i n a t i o n des m i l i e u x , à l ' o r i g i n e , é t a i t d ' e n v i r o n 10 p . C i / 1 .

Les c o n d i t i o n s e x p é r i m e n t a l e s n ' o n t pas été i déa les du f a i t de l ' é v o l u t i o n des p o u r c e n t a g e s propres a u x d i f f é r e n t e s formes p h y s i c o - c h i m i q u e s p résen tes , mais dans tous les cas le taux de fo rmes souha i tées é t a i t i m p o r t a n t au temps " z é r o " (80 à 9 0 % pour les formes i nso lub les e t 80 à 100 % pour les fo rmes s o l u b l e s ) . Par a i l l e u r s i l f a u t no te r q u e , c o m p t e tenu de la f o r t e d é c r o i s -sance de la r a d i o a c t i v i t é de l ' e a u des a q u a r i u m s , la c o n t a m i n a t i o n s ' o p é r a i t pour une par t p r é p o n d é r a n t e p e n d a n t les p remie rs ¡ou rs , m i n i m i s a n t a i n s i l ' e f f e t de v a r i a t i o n dans le temps des é ta ts p h y s i c o - c h i m i q u e s du fe r 5 9 .

O n n o t e r a e n f i n que l ' i n t e r v a l l e de temps consacré aux d i f f é r e n t e s e x p é r i m e n t a t i o n s é t a i t r e l a t i v e m e n t c o u r t par r a p p o r t à la p é r i o d e r a d i o a c t i v e du fe r 59 (45 j o u r s ) . Dans ces c o n d i t i o n s i l n ' a pas é té tenu c o m p t e dans l ' e x p l o i t a t i o n des résu l ta ts de la d é c r o i s s a n c e r a d i o a c t i v e n a t u r e l l e du r a d i o -é l é m e n t é t a n t d o n n é que l ' e r r e u r r é s u l t a n t e (de l ' o r d r e de q u e l q u e s %) p e u t ê t r e c o n s i d é r é e comme n é g l i g e a b l e compte tenu des buts q u ' o n se p r o p o s a i t d ' a t t e i n d r e .

2 . RESULTATS

2 . 1 . M o d e s d ' e x p r e s s i o n

Dans c e t t e e x p é r i m e n t a t i o n nous nous sommes e s s e n t i e l l e m e n t intéressés à la d y n a m i q u e de c o n t a m i n a t i o n des espèces e t au p o u v o i r c o n t a m i n a n t du r a d i o n u c l i d e en f o n c t i o n de la t e m p é r a t u r e et des formes p h y s i c o - c h i m i q u e s présentes dans le m i l i e u .

Les courbes r e l a t i v e s à l ' é v o l u t i o n de la c o n t a m i n a t i o n r e p r é s e n t e n t la v a r i a t i o n , dans le t e m p s , de la r a d i o a c t i v i t é s p é c i f i q u e des espèces par r a p p o r t à la v a l e u r m o y e n n e de c e t t e r a d i o a c t i v i t é d é t e r m i n é e pour la t o t a l i t é de la p é r i o d e e x p é r i m e n t a l e ; c e t t e v a l e u r m o y e n n e est a r b i t r a i r e m e n t c o n s i d é r é e comme é g a l e à 1 .

Les n i v e a u x de c o n c e n t r a t i o n des espèces en f o n c t i o n de la t e n e u r du m i l i e u en f e r 59 sont est imés par un " i n d i c e de c o n c e n t r a t i o n " ( l e ) , e x p r i -m a n t la v a l e u r du r a p p o r t : '

R a d i o a c t i v i t é s p é c i f i q u e m o y e n n e de l ' e s p è c e (pour la d u r é e de R a d i o a c t i v i t é s p é c i f i q u e m o y e n n e de l ' e a u l ' e x p é r i m e n t a t i o n )

I A E A - S M - 1 9 7 / 2 2 57

Temperature 15°C. Temperature 5°C.

FIG. 4. Evolution dans le temps de la radioactivity de la chair de Moules placSes dans des conditions diff&entes de temperature (15°C ou 5°C) et contamin£es par des formes insolubles (courbes 1) ou solubles (courbes 2) du f e r -59 .


FIG. 5. Evolution dans le temps de la radioactivity des coquilles de Moules placSes dans des conditions diffSrentes de temperature (15°C ou 5°C) et contaminees par des formes insolubles (courbes 1) ou solubles (courbes 2 ) du fer -59 .

C e t t e n o t i o n d 1 " i n d i c e d e c o n c e n t r a t i o n " nous a s e m b l 6 p r e f e r a b l e

6 c e l l e d e " f a c t e u r d e c o n c e n t r a t i o n " i m p l i q u a n t I ' u t i l i s a t i o n d e d o n n ^ e s

o b t e n u e s l o rsque I ' e s p & c e p r ^ s e n t e u n e c o n c e n t r a t i o n e n 6 q u i l i b r e a v e c c e l l e

d u r a d i o n u c l i d e dans le m i l i e u , ce q u i n ' 6 t a i t pas t o u j o u r s le cas dans

c e t t e e x p e r i e n c e d ' u n e d u r 6 e l i m i t ^ e 6 d i x j o u r s .

L e p o u v o i r c o n t a m i n a n t (Pc) des f o r m e s p o l y m 6 r i s 6 e s e n c o m p a r a i s o n

d e c e l u i des f o r m e s s o l u b l e s est e x p r i m 6 pa r le r a p p o r t s u i v a n t :

p ^ _ Ic (Pour u n e c o n t a m i n a t i o n pa r les f o r m e s i n s o l u b l e s d u f e r 5 9 )

I c (Pour u n e c o n t a m i n a t i o n par les f o r m e s s o l u b l e s d u f e r 5 9 )


2 . 2 . C i n e t i q u e de c o n t a m i n a t i o n

- Par t ie m o l l e des M o u l e s , t empera tu re d ' e x p e r i m e n t a t i o n 1 5 ° C ( F i g . 4 - a )

La courbe 1 represente d e v o l u t i o n de la r a d i o a c t i v i t e s p e c i f i q u e de la cha i r de M o u l e pour une c o n t a m i n a t i o n par des formes inso lub les du fer 5 9 . E l le i n d i q u e q u ' u n e f i x a t i o n rap ide s'est p r o d u i t e pendan t les premieres 48 heures ; apres passage par un max imum la r a d i o a c t i v i t e d i m i n u a i t . La r e d u c t i o n , par rappor t au m a x i m u m , e t a i t a la f i n de la pe r iode e x p e r i m e n t a le d ' u n f a c t e u r 2 - 3 .

La croissance de la r a d i o a c t i v i t e s p e c i f i q u e , pour une c o n t a m i n a t i o n par des formes so lub les a v a i t une a l l u r e r e g u l i e r e (courbe 2) ; la v a l e u r de c e t t e r a d i o a c t i v i t e t e n d a i t a demeurer constante apres un d e l a i de 8 a 10 jours .

- Par t ie m o l l e des M o u l e s , t empera tu re d ' e x p e r i m e n t a t i o n 5 ° C ( f i g . 4 - b )

Dans ce cas I ' a c c u m u l a t i o n des formes inso lub les e t a i t p rog ress ive , sans phase a c c e l e r e e , n i p a l i e r , ni d i m i n u t i o n (courbe 1 ) . II en a I la i t de meme en ce qu i concerne la f i x a t i o n des formes so lub les (courbes 2 ) .

- C o q u i l l e s de M o u l e s , tempera tu re d ' e x p e r i m e n t a t i o n 1 5 ° C ou 5 ° C ( F i g . 5 a - b )

Dans ces deux e x p e r i m e n t a t i o n s et pour chacun des 2 modes de c o n t a -m i n a t i o n (par les formes inso lub les - courbes 1 et so lubles - courbes 2) les c i n e t i q u e s d ' a c c u m u l a t i o n e t a i e n t a n a l o g u e s .

L 'accro issement de la c o n t a m i n a t i o n , rap ide pendan t les premieres 48 heures pour les formes i n s o l u b l e s , m o n t r a i t ensu i te une ne t te t endance a la s t a b i l i s a t i o n .

La f i x a t i o n des formes so lub les , plus l e n t e , se p o u r s u i v a i t sans c h a n g e -ment de ry thme pendan t tou te la duree de I ' e x p e r i e n c e .


2

5 10 J o u r s l i io FIG. 6. Evolution dans le temps de la radioactivity des Blennies placges dans des conditions diff6rentes de temperature (15°C ou 5°C) et contamin£es par des formes insolubles (courbes 1) ou solubles (courbes 2) du f e r -59 .

I A E A - S M - 1 9 7 / 2 2 59

- B l e n n i e s , t e m p e r a t u r e d ' e x p e r i m e n t a t i o n 1 5 ° C ou 5 ° C ( F i g . 6 a - b )

Les c i n e t i q u e s de f i x a t i o n du r a d i o n u c l i d e , pour c h a c u n e de ses f o r m e s , ne m o n t r a i e n t que de legeres d i f f e r e n c e s pour des B lenn ies soumises aux d e u x c o n d i t i o n s de t e m p e r a t u r e .

L ' a c c u m u l a t i o n des formes i n s o l u b l e s e t a i t a c c e n t u e e p e n d a n t les p remie res 48 heures (courbes 1 ) . Ap res passage par un m a x i m u m , la r a d i o a c t i -v i t e s p e c i f i q u e de c e t t e espece e t a i t en d i m i n u t i o n .

La c i n e t i q u e d ' a c c u m u l a t i o n des formes so lub les e t a i t c o n t i n u e , le t a u x d ' a c c r o i s s e m e n t e t a n t t o u t e f o i s m o i n d r e apres 4 - 6 jours (courbes 2 ) , n o t a m m e n t pour la t e m p e r a t u r e de 5 ° C .

2 . 3 . I nd i ces de c o n c e n t r a t i o n

Les i n d i c e s de c o n c e n t r a t i o n ( I c ) d e t e r m i n e s pour la p a r t i e m o l l e des M o u l e e t I ' o r g a n i s m e e n t i e r des B lenn ies pour les c o n t a m i n a t i o n s par les formes inso lub les e t so lub les du fe r 5 9 , e t dans les d i f f e r e n t e s c o n d i t i o n s de t e m p e r a t u r e , sont presentes dans le t a b l e a u I .

- Par t ie m o l l e des M o u l e s

O n p e u t r e m a r q u e r : - que la r e d u c t i o n de t e m p e r a t u r e p r o v o q u a i t une d i m i n u t i o n des v a l e u r s

de ces i n d i c e s , q u e l l e que s o i t la f o r m e p h y s i c o - c h i m i q u e c o n t a m i n a n t e . - que les i n d i c e s de c o n c e n t r a t i o n e t a i e n t s y s t e m a t i q u e m e n t super ieurs

pour des c o n t a m i n a t i o n s ob tenues par des formes i n s o l u b l e s du fe r 5 9 .

- B lenn ies

Les remarques p r e c e d e m m e n t f o r m u l e e s p e u v e n t e t r e a p p l i q u e e s aux i n d i c e s de c o n c e n t r a t i o n r e l a t i f s aux B l e n n i e s .

O n observe par a i l l e u r s que les i n d i c e s de c o n c e n t r a t i o n de la p a r t i e m o l l e des M o u l e s o n t e te n e t t e m e n t super ieu rs a ceux des B l e n n i e s .

2 . 4 . Pouvo i r c o n t a m i n a n t des fo rmes i n s o l u b l e s du fe r 59 par r a p p o r t a ses formes so lub les (Pc)

I l est i n te ressan t de c o m p a r e r les t a u x d ' a c c u m u l a t i o n des formes inso lub les a u x taux d ' a c c u m u l a t i o n des formes so lub les ob tenus dans les memes c o n d i t i o n s . C e t t e c o m p a r a i s o n p e u t a p p o r t e r des renseignements sur les r e a c t i o n s e v e n t u e l l e s des i n d i v i d u s a la c o n t a m i n a t i o n , e t les m o d a l i t e s d ' e c h a n g e s en f o n c t i o n des c o n d i t i o n s du m i l i e u e t des e ta ts p h y s i c o - c h i m i q u e s du fe r 5 9 .

A I ' e x a m e n du t a b l e a u II on p e u t r e m a r q u e r : - que le p o u v o i r c o n t a m i n a n t r e l a t i f des fo rmes i nso lub les s ' a c c r o t t

l o r s q u ' o n abaisse la t e m p e r a t u r e de 15 a 5 ° C . - q u ' i l est plus g rand pour les pa r t i es mo l les des M o u l e s que pour

I ' o r g a n i s m e e n t i e r des B l e n n i e s .

T A B L E A U I . I N D I C E S DE C O N C E N T R A T I O N ( I c ) D U FER 59 POUR DES C O N D I T I O N S E X P E R I M E N T A L E S D I F F E R E N T E S . V A R I A T I O N E N F O N C T I O N DE LA F O R M E P H Y S I C O - C H I M I Q U E D U R A D I O N U C L E 1 D E ET DE LA T E M P E R A T U R E .

C o n d i t i o n s ex p 6 r i m e n t a les

Esp6 ces Fer 59 inso u b l e Fer 5 9 so u b l e

Esp6 ces 1 F a c t e u r I F a c t e u r

5 ° C 1 5 ° C ' d ' a c c r o i s s e m e n t 5 ° C 1 5 ° C 1 d ' a c c r o i s s e m e n t ! de Ic : f (T) 1 d e Ic : f (T)

M o u les 7 4 109

1 1

I 1 , 4 7 4 , 5 1 7 , 2

1 1

! 3 , 8 2 ( c h a i r ) 1

1

i 1 1

B l e n n i e s 5 , 5 5 , 9

1 1

j 1 , 0 7

1 1

0 , 4 7 1 , 8

1 1 1 3 , 8 3

1 1

I A E A - S M - 1 9 7 / 2 2 61

T A B L E A U I I . P O U V O I R C O N T A M I N A N T (Pc) DES F O R M E S I N S O L U B L E S D U FER 59 PAR RAPPORT A U X F O R M E S SOLUBLES - V A R I A T I O N E N F O N C T I O N DE L A TEMPERATURE.

C o n d i t i o n s e x p e r i m e n t a les

Esp^ces

5 ° C 1 5 ° C

M o u les 1 6 , 4 6 , 3 ( c h a i r )

B lenn ies 1 1 , 7 3 , 2

3 . D I S C U S S I O N

En ce q u i c o n c e r n e M y t i l u s e d u l i s les o b s e r v a t i o n s sur P i n f l u e n c e c o m p a r ^ e de la t e m p e r a t u r e sur la c i n e t i q u e e t le n i v e a u de c o n t a m i n a t i o n a t t e i n t m o n t r e n t : - d ' u n e p a r t , q u ' u n e e l e v a t i o n de t e m p e r a t u r e d e t e r m i n e un n i v e a u de

c o n t a m i n a t i o n p lus 6 l e v £ , p a r t i c u I i e r e m e n t pour les fo rmes so lub les ( I c = 1 7 , 2 a 1 5 ° C e t 4 , 5 a 5 ° C )

- d ' a u t r e p a r t , que I ' a l l u r e g e n e r a t e de la c i n e t i q u e de c o n t a m i n a t i o n ne p a r a t t pas s e n s i b l e m e n t m o d i f i e e par un c h a n g e m e n t de t e m p e r a t u r e pour les fo rmes s o l u b l e s , mais q u e , par c o n t r e , pour les fo rmes i nso lub les une e l e v a t i o n de t e m p e r a t u r e s ' a c c o m p a g n e d ' u n e phase de f i x a t i o n i n i t i a t e trfes a c c e l e r e e .

Ces p h e n o m ^ n e s p e u v e n t e t r e en r e l a t i o n a v e c une a c t i v i t e p h y s i o l o -g i q u e plus i m p o r t a n t e d e t e r m i n e e par I ' e l e v a t i o n de t e m p e r a t u r e . La c o m p a r a i -son des donnees r e l a t i v e s a la c i n e t i q u e de c o n t a m i n a t i o n laisse t o u t e f o i s supposer que dans le cas de formes i n s o l u b l e s la f i x a t i o n du p o l l u a n t ne s e r a i t p lus s e u l e m e n t t r i b u t a i r e d ' u n e a c t i o n b i o l o g i q u e : t o u t se passe comme s i , par su i te de I ' e t a t p a r t i c u l a i r e du p o l l u a n t , une c o n t r i b u t i o n p h y s i q u e , f a v o r i s e e par une a c c e l e r a t i o n du r y t h m e de f i l t r a t i o n , v i e n d r a i t s ' a j o u t e r a I ' e f f e t n o r -mal d ' a c c u m u l a t i o n , t e l q u ' o n p e u t I ' o b s e r v e r pour les fo rmes s o l u b l e s . A i n s i s ' e x p l i q u e r a i t que I ' o n cons ta te pour les fo rmes i n s o l u b l e s une r a p i d i t e e t un n i v e a u de f i x a t i o n en phase i n i t i a l e de c o n t a m i n a t i o n , p lus e l e v e s que pour les formes s o l u b l e s . O n r e m a r q u e e g a l e m e n t que la v a r i a t i o n d ' a c t i v i t e m e t a -b o l i q u e , p r o v o q u e e par I ' a u g m e n t a t i o n de t e m p e r a t u r e , a moins d ' e f f e t sur le n i v e a u d ' a c c u m u l a t i o n des formes i n s o l u b l e s ( a u g m e n t a t i o n de I ' i n d i c e de c o n c e n t r a t i o n d ' u n f a c t e u r 1 ,4 s e u l e m e n t pour un passage de 5 ° C a 1 5 C C ) -que sur ce lu i des fo rmes so lub les ( f a c t e u r d ' a c c r o i s s e m e n t e g a l a 3 , 8 pour une meme v a r i a t i o n de t e m p e r a t u r e ) .


Les c i n e t i q u e s de c o n t a m i n a t i o n de B lenn ius p h o l i s ne m o n t r a i e n t pas , en f o n c t i o n des v a r i a t i o n s de t e m p e r a t u r e , de d i f f e r e n c e s tres a p p r e c i a b l e s . Les i n d i c e s de c o n c e n t r a t i o n pour les formes i nso lub les du r a d i o n u c l i d e n ' o n t , de meme que pour la c h a i r de m o u l e , pas e t e p r o f o n d e m e n t m o d i f i e s par le c h a n g e m e n t des c o n d i t i o n s e x p e r i m e n t a l e s ( a u g m e n t a t i o n de I ' i n d i c e de c o n c e n t r a t i o n d ' u n f a c t e u r 1 , 0 7 pour un passage de 5 ° C a 1 5 ° C ) . Le taux d ' a c c u m u l a t i o n des formes so lub les sub issa i t i c i e n c o r e d a v a n t a g e I ' i n f l u e n c e du p a r a m e t r e t e m p e r a t u r e ( f a c t e u r d ' a c c r o i s s e m e n t de I ' i n d i c e de c o n c e n t r a t i o n e g a l a 3 , 8 pour la meme v a r i a t i o n de t e m p e r a t u r e ) .

Le n i v e a u d ' a c c u m u l a t i o n du fe r 59 s e r a i t d o n e e g a l e m e n t , pour c e t t e espece d e p e n d a n t des c o n d i t i o n s de t e m p e r a t u r e en ce q u i c o n c e r n e les formes so lub les et assez peu en ce q u i c o n c e r n e les formes i n s o l u b l e s .

A p r e s la phase i n i t i a l e de c o n t a m i n a t i o n on observe pour les fo rmes p a r t i c u la ires une phase d ' e l im i n a t i o n p a r t i e l l e du p o l l u a n t , aussi b i e n c h e z les moules que chez les b l e n n i e s . Ce p h e n o m e n e est a r a p p r o c h e r de ce q u i a e t e observe pour des formes p o l y m e r i s e e s i nso lub les du r u t h e n i u m 106 / 1 9 J ) on p o u r r a i t I ' a t t r i b u e r a une s o l u b i I i s a t i o n p a r t i e l l e des formes p a r t i c u l a i r e s au c o n t a c t de la m a t i e r e o r g a n i q u e - a c t i o n c o n s t a t e e pour le z i n c dans une eau de mer e n r i c h i e en m a t i e r e o r g a n i q u e a p a r t i r d ' u n e c u l t u r e d ' a l g u e Ch lore I la , /~20 J . II se p e u t aussi que chez la mou le c e t t e " a u t o - e p u r a t i o n " so i t favor isee par un m e c a n i s m e de s e l e c t i o n l i e a la d i m e n s i o n des p a r t i c u l e s £21 J £22 J . U n e r e c e n t e e t u d e de B E R N O U S K A Y A e t a l . £22 J m o n t r a n t que les d imens ions des p a r t i c u l e s du fe r 5 5 , i n t r o d u i t en eau de m e r , sont de I ' o r d r e de 2 jam, v i e n d r a i t a I ' a p p u i de c e t t e hypo these : les resu l ta ts e x p e r i m e n t a u x f o u r n i s par J 0 R G E N S E N e t G O L D B E R G £22 J. e t a b l i s s e n f en e f f e t que chez M y t i l u s e d u l i s les p a r t i c u l e s i n f e r i e u r e s a 1 - 2 | i m , passent a t ravers le syst&me de f i l t r a t i o n , et I ' o n p o u r r a i t a d m e t t r e que la f r a c t i o n de p a r t i c u l e s i n f e r i e u r e s a c e t t e d i m e n s i o n t r a n s i t e r a i t vers les o rganes i n t e r n e s , I ' a u t r e e t a n t r e j e t e e par les p s e u d o - f e c e s apres un c e r t a i n t emps . O n r e m a r q u e d ' a u t r e pa r t que c e t t e sor te d ' e I i m i n a t i o n ne se p r o d u i t pas , c h e z la m o u l e e t se t r o u v e r a l e n t i e c h e z la b l e n n i e a la t e m p e r a t u r e de 5 ° C .

4 . C O N C L U S I O N

Des changemen ts de c o n d i t i o n s du m i l i e u au p o i n t de vue t e m p e r a t u r e o n t e n f r a m e une m o d i f i c a t i o n des e c h a n g e s e n t r e especes e t r a d i o n u c l e i d e : un a c c r o i s s e m e n t de I 'accum'u l a t i o n de c e l u i - c i est o b s e r v e , aussi b i e n c h e z la m o u l e que chez la b l e n n i e , dans des c o n d i t i o n s de v i e a m e n a n t une a u g m e n t a t i o n de I ' a c t i v i t e m e t a b o l i q u e .

Ces m o d i f i c a t i o n s p e u v e n t e t re a t t r i b u t e s , au moins dans un c e r t a i n nombre de cas a I ' e v o l u t i o n de I ' a c t i v i t e m e t a b o l i q u e des especes r e s u l t a n t de ces c o n d i t i o n s e x p e r i m e n t a les . T o u t e f o i s c e r t a i n s types de c o n t a m i n a t i o n ne para issen t pas l ies a I ' a c t i v i t e p r o p r e m e n t d i t e de I ' o r g a n i s m e , mais t r a -d u i s e n t p l u t o t des phenomenes d ' a d s o r p t i o n passive (cas n o t a m m e n t des formes p a r t i c u l a i r e s ) i n t e r v e n a n t au n i v e a u de sur faces d i r e c t e m e n t en c o n t a c t a v e c le p o l l u a n t . De ce f a i t I ' e f f e t de t e m p e r a t u r e se m a n i f e s t e de f a g o n plus m a r q u e e pour I ' a b s o r p t i o n des formes so lub les du fe r 59 que pour ses formes i n s o l u b l e s .

U n p h e n o m e n e de " r e f e t " p a r t i e l du r a d i o n u c l e i d e f a i s a n t su i te a une phase a c c e l e r e e de f i x a t i o n des formes p a r t i c u l a i r e s , a pu e t re observe apres un c e r t a i n temps de c o n t a m i n a t i o n pour la m o u l e e t la b l e n n i e . Ce processus

IAEA-SM-197 /15 63

s e r a i t a t l r i b u a b l e a un mecan isme d 1 " a u t o - e p u r a t i o n " p r o p r e a I ' a n i m a l , ou a la s o l u b i l i s a t l o n des fo rmes p a r t i c u l a t e s par les s e c r e t i o n s o r g a n i q u e s . U n aba issemen t de la t e m p e r a t u r e i n h i b e ce mecan isme chez la m o u l e e t le r a l e n t i t c h e z la b l e n n i e .

R E F E R E N C E S

£ 1 J R O B E R T S O N , D . E . , A s t u d y of the t r a c e e l e m e n t and r a d i o n u c l i d e b e h a v i o u r in a N o r t h e a s t P a c i f i c O c e a n e c o y s t e m , 3 5 0 mi les o f f N e w p o r t , O r e g o n , B N W L 7 1 5 , 2 2 (1968) 9 2 - 1 0 8 .

£2 J L A B E Y R I E , J . , Le fe r dans la m e r , R e v . i n t e r n . O c e a n o g r . m e d . U_ (1968) 1 2 9 - 1 3 9 .

£ 3 J P I R O , A . , P h y s i c o c h e m i c a l states of some t r a c e e l e m e n t s in seawate r w h i c h a re of i n t e r e s t f r om the r a d i o c o n t a m i n a t i o n s t a n d p o i n t , R e v . i n t . O c e a n o g r . m e d . 2 0 (1970) 1 3 3 - 1 4 9 .

£A J D U U R S M A , E . K . , The d i s s o l v e d o r g a n i c c o n s t i t u a n t s of sea w a t e r . In_ : C h e m i c a l O c e a n o g r a p h y ( R I L E Y , J . P . , S K I R R O W , G . , Eds) , A c a d e m i c Press, L o n d o n (1965) 7 1 2 .

£ 5 J M A R C H A N D , M . , C o n t r i b u t i o n a I ' e t u d e de I ' i n f l u e n c e de la m a t u r e o r g a n i q u e d issoute sur la p h y s i c o - c h i m i e d ' e l ^ m e n t s a I ' e t a t de t races dans I ' e a u de m e r , These de D o c t o r a t , U n i v e r s i t e de Paris (1972) 1 3 2 .

£ 6J L E W I S , C . J . , G O L D B E R G , E . D . , I ron in the m a r i n e w a t e r s , J . M a r . Research 1_3 2 (1954) 1 8 3 - 1 9 7 .

£ l 7 M E N Z E L , D . W . , S P A E T H , J . P . , Occu r rence of i ron in the Sargasso Sea o f f B e r m u d a , L i m n o l . and O c e a n o g r . 7 (1962) 1 5 5 - 1 5 8 .

/ ~ 8 J G U E G U E N I A T , P . , E tude sur la p h y s i c o - c h i m i e du r u t h e n i u m dans I ' e a u de m e r , Rappor t C E A - R - 4 1 2 5 (1971) 4 3 .

£ 9 J H A R V E Y , H . W . , N o t e on c o l l o i d a l f e r r i c h y d r o x y d e in sea w a t e r , J . m a r . B i o l . Ass . U . K . 22 (1937) 221 - 2 2 5 .

£ 10 J G A L L A I S , F . , C h i m i e m i n e r a l e t h e o r i q u e e t e x p e r i m e n t a l e ( M A S S O N e t C i e , Eds) , Paris (1963) 401 .

£ 11 J G U E G U E N I A T , P . , G A N D O N , R . , L U C A S , Y . , M e s u r e de la r a d i o a c t i v i t e de I ' e a u de mer en c e r i u m , c o b a l t , f e r , r u t h e n i u m , z i n c , z i r c o n i u m , par p r ^ c o n c e n t r a t i o n sur b i o x y d e de manganese c o l l o i d a l . A p p l i c a t i o n a la mesure de f a i b l e s teneurs de r u t h e n i u m 106 dans I ' e a u de m e r , I . A . E . A . Pane l on Re fe rence M e t h o d s f o r M a r i n e R a d i o a c t i v i t y S t u d i e s , V i e n n e 30 o c t o b r e - 3 n o v e m b r e 1972 (sous presse) .

£\2 J S U M N E R , F . B . , D O U D O R O F F , P . , Some e x p e r i m e n t s upon t e m p e r a t u r e a c c l i m a t i z a t i o n and r e s p i r a t o r y m e t a b o l i s m in f i s h e s , B i o l . B u l l . m a r . b i o l . L a b . Woods H o l e 7 4 (1938) 4 0 3 - 4 2 9 .

£ 13 J C O L I N N I C O L , J . A . , The b i o l o g y of m a r i n e a n i m a l s , SIR I S A A C P I T M A N and S O N S L T D , L o n d o n (1960) 7 0 7 .


£ 1 4 _ 7 W I D D O W S , J . , B A Y N E , B . L . , T e m p e r a t u r e a c c l i m a t a t i o n o f M y t i l u s

e d u l i s w i t h r e f e r e n c e to its e n e r g y b u d g e t , J . m a r . B i o l . A s s . U . K .

51 ( T 9 7 1 ) 8 2 7 - 8 4 3 .

/ ~ 1 5 7 K I N N E , O . , M a r i n e e c o l o g y 1_ W I L E Y - I n t e r s c i e n c e , J . W I L E Y

a n d S O N S L t d , L o n d o n ( 1 9 7 0 ) 6 8 1 .

/ 16 7 R A O , K . P . , T i d a l r h y t h m i c i t y o f r a t e o f w a t e r p r o p u l s i o n i n M y t i l u s

a n d i ts m o d i f i a b i l i t y b y t r a n s p l a n t a t i o n . B i o l . B u l l . m a r . b i o l . L a b .

W o o d s H o l e 1_06 ( 1 9 5 4 ) 3 5 3 - 3 5 9 .

£\1 J J 0 R G E N S E N , C . B . , E f f i c i e n c y o f p a r t i c l e r e t e n t i o n a n d r a t e o f w a t e r

t r a n s p o r t in u n d i s t u r b e d L a m e l l i b r a n c h s , J . C o n s . i n t . E x p l . M e r

2 6 1 ( 1 9 6 0 ) 9 4 - 1 1 6 .

/ ~ 1 8 J G I B S O N , R . N . , F a c t o r s a f f e c t i n g the r y t h m i c a c t i v i t y o f B l e n n i u s

p h o l i s L . ( T e l e o s t e i ) , A n i m . B e h a v . 1_9 ( 1 9 7 1 ) 3 3 6 - 3 4 3 .

£ 19 J F R A I Z I E R , A . , R e l a t i o n e n t r e la f o r m e p h y s i c o - c h i m i q u e d u r u t h e n i u m

1 0 6 e t les p h e n o m e n e s de c o n t a m i n a t i o n obse rves e x p e r i m e n t a l e m e n t

c h e z d i v e r s e s e s p e c e s m a r i n e s . In : " C o m p a r a t i v e S t u d i e s o f F o o d a n d

E n v i r o n m e n t a l C o n t a m i n a t i o n " , O t a n i e m i 2 7 - 3 1 A u g u s t 1 9 7 3 , I . A . E . A .

V i e n n e ( 1 9 7 4 ) 1 3 5 - 1 4 8 .

/ ~ 2 0 J K O S H Y , E . , G A N G U L Y , A . K . , O r g a n i c m a t e r i a l s in t h e m a r i n e

e n v i r o n m e n t s a n d t h e i r i n t e r a c t i o n s w i t h some m e t a l i o n s , B h a b h a

A t o m i c C e n t r e , R a p p o r t B A R C - 4 0 2 ( 1 9 6 9 ) 1 1 0 .

/ " 2 1 / C H I P M A N , W . A . , U p t a k e a n d a c c u m u l a t i o n o f c h r o m i u m 51 b y t h e

C l a m Tapes d e c u s s a t u s , i n r e l a t i o n to p h y s i c a l a n d c h e m i c a l f o r m s ,

h i : " D i s p o s a l o f R a d i o a c t i v e W a s t e s i n t o S e a s , O c e a n s a n d S u r f a c e

W a t e r s " V i e n n e 1 6 - 2 0 m a i 1 9 6 6 , I . A . E . A . ( 1 9 6 6 ) 5 7 1 - 5 8 2 .

£ 2 2 J J j D R G E N S E N , C . B . , G O L D B E R G , E . D . , P a r t i c l e f i l t r a t i o n in some A s c i d i a n s a n d L a m e l l i b r a n c h s . B i o l . B u l l . m a r . b i o l . L a b . W o o d s H o l e 105 ( 1 9 5 3 ) 4 7 7 - 4 8 9 .

£22 J B E R N O U S K A Y A , R . N . , B O G D A N O V , Y u . A . , G R O M O V , V . V . , L I S I T S Y N , A . P . , S P I T S Y N , U . I . , T I K H O M I R O V , V . N . , I n f l u e n c e o f i r o n on the p h y s i c o - c h e m i c a l s t a t e of r a d i o e l e m e n t s in sea w a t e r , S o v i e t R a d i o c h e m i s t r y , a t r a n s l a t i o n o f R a d i o k h i m i y a 13 1 ( 1 9 7 1 ) 1 5 8 - 1 6 C

D I S C U S S I O N

C . D . J E N N I N G S : B y w h a t m e t h o d d o y o u d i s t i n g u i s h b e t w e e n p a r t i c u l a t e and s o l u b l e i r o n ? D o y o u u s e , f o r e x a m p l e , a m e m b r a n e f i l t e r ? I h a v e n o t e d in e x p e r i m e n t s in the P a c i f i c O c e a n that 0 . 3 f i m m e m b r a n e f i l t e r s r e m o v e o n l y a b o u t ha l f a s m u c h i r o n a s c a n b e r e m o v e d b y p r e c i p i t a t i o n t e c h n i q u e s , w h i c h p r e s u m a b l y s e p a r a t e b o t h p a r t i c u l a t e and s o l u b l e i r o n .

J . A N C E L L I N : T h e i d e n t i f i c a t i o n of the s o l u b l e and i n s o l u b l e f o r m s o f 5 9 F e w a s c a r r i e d out b y i o n e x c h a n g e c h r o m a t o g r a p h y . In e a c h c a s e t h e e x p e r i m e n t s i n v o l v e d u s e o f a c o n t a m i n a t i n g m e d i u m in w h i c h t h e r e w a s i n i t i a l l y a h i g h p r o p o r t i o n o f e i t h e r s o l u b l e o r i n s o l u b l e f o r m s . T h e r e w a s a t e n d e n c y w i t h t i m e t o w a r d s e s t a b l i s h m e n t o f e q u i l i b r i u m b e t w e e n the

IAEA-SM-197 /22 65

insoluble f o r m s , which underwent precipitation, and the soluble f o r m s in the contaminating water.

R.J. KIRCHMANN (Chairman): Referr ing to the rapid decrease in soluble 5 9Fe in sea-water , I am wondering whether you measured the con-tamination level of the aerators . Our experience with 54Mn in f resh water has shown that a large part of the radioactivity eliminated f r o m the water is fixed at such sites.

J. ANCELLIN: The use of aerators was necessitated by the fact that we were experimenting in a confined medium. In the same way as the other points of support, e.g. sediments and walls of the aquarium, the aerators may have been the site of some of the radionuclide fixation. It should be pointed out, however, that they represent a reduced surface area as compared with the rest of the equipment.

C.B. J0RGENSEN: How "normal ly" did the mussels behave in the experiment, when kept in standing water for a long period of t ime? Did you measure the rates at which the mussels transported water and removed part ic les , and the e f f i c iency of these p r o c e s s e s ?

J. ANCELLIN: Our experiments were made with animals in a good state of health after an initial period of acclimation in.a confined medium. M o r e -over , the duration of the experiments was deliberately limited to about ten days. It was not poss ible , during this initial stage, to undertake further study of fixation and elimination rates.

O.J. VAN DER BORGHT: I would like to have clarif ication of the following points. What is the physiological signif icance, f o r example in relation to biological availability for the animal, of iron complexed with EDTA or with other organic compounds present in sea-water , or iron re ferred to as "soluble" after filtration of untreated sea-water , and iron re ferred to as "particulate" after evolution in f i ltered sea-water or after contact with sea-water loaded with part ic les?

J. ANCELLIN: We did not attempt to study the signif icance, biological or otherwise, of the different phys ico -chemical f o rms of iron in the medium. We were chiefly interested in the ef fect of temperature on the overall con -tamination resulting f r o m the addition of a radioactive pollutant to the medium, either in insoluble f o r m or as an organic complex.

C. HOEDE: Is the di f ference in the curves for insoluble and soluble iron due to a di f ference in transition rate or to a di f ference in uptake mechanism?

J. ANCELLIN: I should say that the insoluble f orms are initially fixed by a process that appears to be phys ico -chemica l in nature. As far as the soluble f o rms are concerned, the results of additional tests, as yet unpublished, show that their content in the organism depends more on biological exchanges.

C. STREFFER: I would just like to add a comment on the subject of soluble and insoluble iron. The use of EDTA-complexed iron makes the situation somewhat difficult. In this f o r m the iron is soluble in a physico-chemical sense (e.g. f o r filtration), but is " insoluble" in a biological sense, as the EDTA-complex is probably not taken up by the biological organism. For active transport through biomembranes the iron probably requires to be present in the f ree ionized f o r m . This may also explain why what you call "soluble" iron is taken up so slowly in your experiments, as indicated by your Fig.4.

J. ANCELLIN: It has not been definitely proved that iron in the f o r m of an organic complex with EDTA is utilized in the biological sense . It is


observed, however, that a r i se in temperature, which could step up the metabolic rate, is accompanied by a much greater accumulation of the soluble f o r m , both for mussels and blennies, whereas the effect is much less p r o -nounced in contamination by insoluble f o r m s , as indicated in Table I. One is led to think that accumulation of the latter is relatively non-dependent on biological uptake p r o c e s s e s .

Session III

SYNERGISM AND COMBINATION EFFECTS IN AQUATIC SYSTEMS

Chairman: F.B. HA WES (United Kingdom)

I A E A - S M - 1 9 7 / 1 0

SWEDISH STUDIES ON COMBINATION EFFECTS OF THERMAL DISCHARGES IN THE AQUATIC ENVIRONMENT

Some aspects of power plant siting policy

u . GRIMAS

Swedish Environment Protection Board, Stockholm

U. EHLIN Swedish Meteorological and Hydrological Institute, Norrkoping, Sweden

Abstract

SWEDISH STUDIES ON COMBINATION EFFECTS OF THERMAL DISCHARGES IN THE AQUATIC ENVIRONMENT: SOME ASPECTS OF POWER PLANT SITING POLICY.

The design of new transport mechanisms by a direct use of the energy of coo l ing water discharges — heat and kinetic energy — is discussed. An improvement of water quality can be expected in those waters that are overloaded by organic matter for long periods of t ime . The technique of speeding up the mineralization of organic matter by addition of heat and oxygen requires a detailed analysis o f , amongst other factors, the existing hydrological situation and the concentration levels of toxic matter in the basins a f fected by the drawing-off and discharge of coo l ing water. Three situations are identified where the combination of heat and pollution appear to produce negative e f fects .

1. INTRODUCTION

The e f fec ts of coo l ing water d i s charge are general ly re f l e c ted in the f o r m of changes in the compos i t ion of b io log i ca l communit ies and in the charac ter i s t i c s of the e c o s y s t e m within the water areas af fected by the temperature i n c r e a s e . There i s , however , r eason to assume that a number of other e f fects have a cons iderab ly l a r g e r radius of action than the d i rec t influence of the waste heat. Part i cular attention should be paid to the c o m -bined e f fects of heat and di f ferent types of polluting substances , f o r example heavy meta ls , radioact ive waste products , b ioc ides or nutrient e x c e s s e s , whose incorporat ion in b io log i ca l mater ia l is stimulated by heat. This stimulation is the f o r m in which the "heat" is c o n s e r v e d , the resultant products and e f f e c t s having a cons iderably longer " l i f e t i m e " in the aqueous e c o s y s t e m than the heat i tse l f . A part icular aspect of the combined e f fec ts i s that of r e in f o r cement of the negative e f f e c t s , known as s y n e r g i s m . Our exper ience of s y n e r g i s m is based mainly on exper iments on separate spec i e s or individuals. The fact that both lethal doses of and c r i t i ca l exposure t imes to di f ferent toxic substances have a tendency to d e c r e a s e at inc reased t e m p e r a -tures i s , f o r var ious r e a s o n s , di f f icult to demonstrate in the f i e ld . Negative inf luences on vital functions of o rgan isms must be assumed to exist in the e c o s y s t e m long b e f o r e concentration levels are reached that are lethal.

6 9

I A E A - S M - 1 9 7 / 2 2 71

20 H J in W sfe HI A U On! %<

BRAVIKEN ESTUARY

F I G . 2 . The biomass of phytoplankton in coastal waters: m e a n values for August 1 9 6 4 - 1 9 6 8 .

2. GENERAL ASPECTS OF SITING POLICY

In a situation where sufficient experience of different kinds of combination effects is lacking, it is natural that siting policy is characterized by cautious-ness . In Sweden the aim has been to site the nuclear power stations in coastal areas with water of good quality, i .e . far f r o m municipal or industrial pollution. Regional surveys of nutrient contents, phytoplankton, metals in water and sediment composition may serve as guides (Figs 1-4) in siting studies.

This aim will , however, in the long term lead to conflicts with other soc ia l interests, such as open-air activities, leisure faci l it ies and scienti f ic environmental research . The siting of power plants c lose to the more densely-populated areas or to industrial areas can be seen as a future requirement f r o m several points of view, f o r example if the energy is to be used for district heating purposes. The interest in the ef fects would thus change f r o m efforts to limit the damage to f i sher ies , etc . in a relatively undisturbed area, to limiting the ef fects of all pollutants in 'disturbed' areas of water to favour all types of activity and the multiple usage of the water. As regards water management interests, siting in a polluted area requires that the thermal energy of the discharge is used to achieve an improvement in the


( % TOTAL C A R B O N )

FIG. 3 . The correlation between total carbon and various elements in the sediment from three basins of the Stockholm archipelago. In the innermost basin of Askrikefjarden the sediments are under-loaded with respect to iron and phosphorus due to an oxygen deficit for part of the year and overloaded with metals such as chromium, z i n c , copper and lead (Magnus Edgren, unpublished results).

water body. Thus, it seems possible , especial ly in the archipelago basins of the Swedish coastal areas , to improve the "quality of l i fe" f o r the ecosystem by adapting the techniques used f o r drawing off and discharging cooling water to the existing hydrological situation.

3. RELEVANT PROPERTIES OF THE THERMAL DISCHARGE

Heat and kinetic energy in the water are important natural parameters in a water system. Heat has a quantitative aspect, as is a lso the case f o r nutrients, f o r instance. Quantity is a vital factor in modifying the reactions and behaviour of the biological system. Thus neither heat nor nutrients should be considered or treated in the same way as toxic substances which, even in small concentrations, constitute a threat to the biosystem.

Two properties of the surplus heat are of relevance f or the technical solutions that can be considered for its management. First ly , heat influences all biological activity, ranging f r o m production, via metabolism to degradation of organic material . Secondly, the increase of temperature due to the heat input has a relatively short lifetime in the water. Similar properties apply

I A E A - S M - 1 9 7 / 1 0 73

FIG. 4 . The sediment situation in some areas of the Swedish east coast (Magnus Edgren, unpublished results).


to the induced flow of water. The f low can influence all functioning units in the ecosystem, f r o m the production area in the surface layer to the consump-tion areas in the depths; the kinetic energy per se is of short duration, being rapidly dispersed.

Three types of effects are of particular interest in the receiving water body: (a) The heat has a direct ef fect on the activity of individual organisms, which

will , f o r example, influence the catchability of fish; (b) Heat improves incorporation into biological matter of basic elements

that have a considerably longer lifetime in water than the heat itself , i . e . toxic substances;

(c) Heat increases the mineralization rate of organic matter, and the induced water f low increases transport of different elements, such as oxygen.

4. CONSEQUENCES

4.1. Direct effect of heat

The direct effect of the heat depends on the receiving water body 's volume, the cooling area and relevant current systems. In coastal areas, the effects are generally loca l and of interest f o r f ishery in the neighbouring waters. In some situations the direct heating effect can have regional conse -quences, for example by disturbing f ish migration. However, the importance of fishing is limited at present in the receiving bodies that can be considered polluted. Little occupational fishing is pursued in the waters within a direct radius of influence of densely populated areas and industry, and in many cases the marketing of fish f rom such areas is banned. A relocalization of thermal discharges f r o m clean waters to loaded waters cannot thus be considered as b e i n g n e g a t i v e t o f i s h i n g .

4.2. Toxic substances

The accumulation of toxic matter in organic material frustrates the possibility of utilizing the positive ef fects created by each form of enrich-ment in the environment. This problem is thus not exclusive to heat discharges but is an important factor to consider when judging possible combination ef fects of siting in areas with widespread pollution.

Heat stimulates and increases the production of organic material. An important secondary effect is that substances such as biocides and heavy metals can more rapidly reach unsuitable concentrations and even higher final con-centrations in organisms.

Despite the fact that measures have been taken to limit the discharges at source , one can still find accumulations of biocides to considerable levels in organisms. It should be borne in mind, however, that factors such as diffuse spread by drainage f r o m land surfaces or large - s ca le transport by wind make these substances important pollutants in all types of water, whether 'clean' or 'polluted' .

Direct uptake of biocides has been studied in perch (Perca fluviatilis L.) at temperatures of 5 and 15°C in aquaria with doses of 3.0 pplO9 of DDT labelled with 14C (63.9 /nCi/mg DDT), and with doses of 2,2' , 4 , 4 ' , 5, 5' hexa-chlorobiphenyl. The material was analysed for DDT and its metabolites and

IAEA-SM-197 /24 75

TABLE I. MEAN CONCENTRATION AND STANDARD ERROR EXPRESSED IN ppm OF DDT AND PCB SUBSTANCES IN FISH MUSCLE AND EXTRACTABLE FAT FROM MUSCLES AFTER 50 HOURS OF EXPOSURE AT TWO TEMPERATURES a

Temperature DDT DDE PCB (°C) (ppm) (ppm) (ppm)

EXTRACTABLE FAT

5 ( 4 . 0 - 5 . 3 ) 11 ± 0. 7 0. 53 ± 0. 05 5 . 3 ± 0 . 3

1 5 ( 1 4 . 5 - 1 6 . 0 ) 29 ± 2 1 . 0 ± 0 . 2 1 1 . 0 ± 0 . 5

p < 0 .001 < 0 . 0 5 < 0 .001

MUSCLES

5 0 .12 ± 0 .006 0. 0055 ± 0 .0004 0. 055 ± 0 .002

15 0 .28 ± 0 . 0 2 0 .010 ± 0 . 0 0 1 0 . 1 1 ± 0 . 0 0 4

P < 0.001 <0.01 < 0.001

M. Edgren, M. Olsson, L. Renberg, unpublished results.

for PCB using gas chromatography. The addition of labelled DDT permitted liquid scintillation analysis to be made, which enabled the existing DDT back-ground level to be disregarded. The 10°C temperature di f ference between the aquaria was chosen to enable a theoretical doubling of the basic metabolic rate to be studied. The results conf i rm a doubling ef fect (Table I) and a direct ly proportional relationship between basic metabolism and uptake of b ioc ides . It was not possible to demonstrate a correlation between the weight of the individual f ish and the uptake. Even the contents of the.degra-dation product DDE were doubled in the experimental groups at 15°C, which may be interpreted to mean that degradation as well as the uptake is increased at the same rate by the increase in temperature. A l ong- term experiment is in progress .

The metal contents in water and biota can, in principle , be seen as indica-tors of local pollution, and regional investigations along the Swedish coasts have demonstrated high contents connected with waste f r o m industry and built-up areas . The metal contents in the receiving bodies are of direct relevance in calculations of the discharge and accumulation of radioactive material . This is f oremost of concern in the discussion of crit ical groups of the popula-tion in the neighbourhood of a nuclear power plant. Depending on the chemical and physical states, higher background contents of metals in water can give r i se to a lower proportion of corresponding radioisotopes in biological material . The uncertainty in the calculations i s , however, very large. The opposing effects between general toxic ef fects of the metal per se and the blocking of uptake of the radioactive isotope makes it of particular urgency to investigate the chemical f o rms in which these metals occur and can be taken up by the organisms. Furthermore , it is of particular interest to study how the metals in the sediment behave at the higher temperatures, f o r


example during the descent of the cooling water plume in brackish water during the winter; i .e . do the metals become more f ree ly available to the b io logical system.

The overal l increase in biological activity at higher temperatures appears to cause a higher concentration of metals in the organisms, as is the case with b ioc ides . Experiments with zinc on Macoma baltica demonstrate a direct exchange of metal with the environment, a build-up of higher contents at higher temperatures, and a fixation of zinc to the mussel despite leaching possibi l i t ies .

4 .3. Mineralization and transport

The c lass ical cause of water pollution is an over-abundance of organic material . Oxygen has a central role in the p r o c e s s , in particular the avai l -ability and transport of oxygen to the deeper water layers in a basin. The principle f o r the handling of thermal discharges in such areas should be to break up isolated layers with the two kinds of energy available — heat and kinetic. In many types of receiving body the input of energy is modest in comparison with the thermal inertia of the natural system in, f o r instance, open coastal areas . In other receiving bodies with a more complicated morphometr i c structure there are sometimes strategic points in the p r e -vailing hydrological systems where a comparatively restricted input can give r ise to large ef fects . Such areas include the archipelagos, where large tracts now function as leakage areas leaking nutrients, etc . , due to the o v e r -loading with organic material and an oxygen def ic iency, into neighbouring water bodies .

The principle is to strengthen the natural circulation of water between isolated and open waters. In all applications the aim is to eliminate or reduce periods of oxygen def ic iency in isolated areas of the bottom and in deep water by addition of water with a high oxygen content. In such areas the oxygenation reduces the re lease of severa l elements f r o m the sediment, e .g. nutrients, iron and manganese, which in turn leads to positive ef fects both local ly and regionally.

One way of increasing the natural circulation is by direct transport of cooling water f r o m the sea or a clean basin to the polluted water body. If this is not poss ib le , the same effect may be reached by a proper siting and planning of intake and outlet facil it ies in the actual receiving body. The basic circulation pattern in estuaries and archipelago areas with f resh water run-off of any appreciable degree is characterized by an outgoing flow of water in the surface layer and an incoming and more saline compensating f low in the deeper layer . This circulation is driven by the density d i f ference between the f resher water in the innermost part of the basin and the saline water in the sea. Also of importance for the intensity of the circulation is the vert ical mixing p r o c e s s , which transports salt f r o m the deeper layer in the basin to the surface . The intensity of this basic circulation can be optimized or changed to a certain extent by changing the density di f ferences between the receiving basin and the sea or by addition of kinetic energy in, f o r example, the mixing zone between surface water and deeper water. Determining factors f o r the optimum size of the circulation are the run-off volume of f resh water and the topography of the receiving body. Basins without f r esh water run-of f are also of interest in this connection, because density di f ferences

I A E A - S M - 1 9 7 / 1 0 77

and gravitational circulation can be initiated between the recipient basin and the outside water areas by the heat in the cooling water discharge.

When trying to speed up the circulation and mineralization of organic matter by adding oxygen, the balance between the local and regional ef fects must be considered, both regarding the short- l ived heat input and its m o r e long-l ived by-products . A situation that is particularly difficult to judge is that when heat is introduced into the inner portion of a long ser ies of basins bearing a heavy load of nutrients, s ince the products go through a ser ies of recirculations before they finally reach a receiving body where the capacity f o r degradation is large and where biological incorporation and recirculation can be reduced. In this connection it is important to stress the fact that an unfavourable positioning of a cooling water discharge, e .g . just inside the mouth of a f j ord system, can cause the circulation and water renewal in the inner part of the system to deteriorate.

5. EXAMPLES FROM SWEDISH SITE STUDIES

The problems of mineralization and transport have been studied in connection with the planning of sites f o r thermal power stations in Sweden.

5.1. The Stockholm archipelago

One of the most complicated rece iv ing water bodies is the inner part of the Stockholm archipelago. The Askrikef jarden basin was investigated as a site for a 2000 MW(e) nuclear power plant. The basin is characterized by a strong vert ical salinity stratification, high concentrations of nutrients, anaerobic conditions in the deep waters f o r a part of the year , and an ingoing saline current in the deeper layer of 200 m 3 / s as a mean over the 20 m threshold. Here an intake of 100 m3 / s of cooling water f r o m deeper water layers and a discharge into another archipelago basin further out would have had a positive effect on the water circulation. The energy available would, however, have been insufficient to exert a greater influence on water c i r cu la -tion in the long ser i es of basins out towards the Baltic Sea. It was shown in the nearby Vartan basin that, under basical ly s imilar conditions, an increased water temperature of about 3 to 4°C during the vegetation period would increase the production of organic carbon f r o m 36 to 56 tonnes. The probable result would have been that the polluted front moves further out into the archipelago.

5.2. The estuary of Braviken

During the last year a proposed site for a 6000 MW(e) nuclear power plant has been investigated at Tunaberg, c lose to the mouth of the 45 km long and narrow Braviken estuary (Figs 5, 6). The town of Norrkoping, with some 100 000 inhabitants and having heavy industry, is situated in the innermost part of the estuary. Paper pulp industries are located along the r iver Motala Strom, with a mean run-off of 100 m 3 / s . The r iver water, as well as the water in the inner part of Braviken, is heavily polluted. The effect on the Braviken estuarine circulation of a cooling water discharge of 300 m 3 / s has been studied in a two-dimensional numerical model employing the basic equations of motion and conservation of salt and heat. The results available so far show that very negative ef fects on the circulation can be caused by an

FIG. 5. The Braviken Estuary.

I A E A - S M - 1 9 7 / 1 0 79

V E L O C I T Y AT T H E S I L L

• NO INTAKE O BOTTOM INT A SURFACE INT + BOTTOM INT X SURFACE INT

-12 .50 VELOCITY CM/S

-7 .50 -2 .50 2.50 7 .50

TAU = 0 . TAU = 0 . T AU = 0 . TAUl T TAU( T

12.50

S u m m e r . a om

VELOCITY CM/S -12.50 -7 .50 -2 .50 2.50 7.50 12.50

• NO INTAKE TAU-O . O SURFACE INT TAU = 0 . A BOTTOM INT TAU = 0 . + BOTTOM INT TAU(T ) X SURFACE INT TAU(T )

Winter

FIG. 6. Effects of the estuarine circulation of a coo l ing water discharge of 300 m 3 / s w i t h A T = 10°C ( coo l ing water temperature rise) from the planned Tunaberg power station.

Computed veloc i ty profiles at a section Lono-Jarkno-Lovvik in Braviken, well inside the coo l ing water outlet -intake area. The computed effects of surface and bottom intakes are shown (outlet is always at the surface). Computations have been made for no winds (TAU = 0) and for a period with t ime-dependent winds (TAU(T) ) . The t ime-dependent period starts with a 1. 5 day storm from the west, which turns to a 1 . 5 day storm from the east. After these 3 days there are 17 days of c a l m . The veloc i ty profile is taken after this ca lm period. The numerical model was developed by Dr. W. Wilmot of the Swedish Meteorological and Hydrological Institute, and is not yet published.

improper arrangement of intake and outlet f o r the cool ing water in the mouth of the estuary. A retardation of the estuarine c irculat ion in the inner parts of Braviken could cause an increase in pollution and a change in the t e m p e r a -ture and salinity conditions — of importance f o r the functioning of the b i o -sys tem of the estuary .

5.3. The Sodertalje archipelago

Another pro j e c t under d i s cuss ion is a power station at Sodertal je , at the head of a long and narrow sys tem of threshold bas ins . A smal l f o s s i l -fuelled plant designed f o r d istr ic t heating and power production is planned


f o r the innermost basin which has, amongst other things, a high concentration of nutrients and an oxygen deficit in deep water areas . The mean fresh water run-off is about 4 m 3 / s , and at certain periods is almost nil. A cooling water discharge of about 10 m 3 / s in the actual basin would cause density di f ferences in the water areas further out which, during dry periods with a smal l run-o f f , would cause a gravitational circulation of the same order as that induced by the f resh water. This would be of great value to the water area, especial ly when the circulation induced by wind is weak. A problem which needs further analysis, however, is the high concentration of mercury in the sediments of the actual basin. The heating and oxygenation may cause these deposits in the sediment to be released more rapidly into the f ree water mass . The r isk of a mercury shock in the outer regions can thus be considered to be of decis ive importance f o r the realization of the pro ject .

6. CONCLUSION

The examples given illustrate three cases where cooling water discharges in polluted areas appear to end up in producing negative effects — the d i s -charge in the innermost part of a long ser ies of semi -enc losed basins, in the mouth of a large estuarine basin, and due to combination effects with certain toxic metals such as mercury . These somewhat discouraging results do not repudiate the theoretically good possibil ity of designing new transportation mechanisms in order to speed up the mineralization of organic matter by addition of heat and oxygen. The archipelago areas , estuaries and threshold basins frequently found on the coasts of Sweden are of interest in this respect . In choosing between possible s i tes , areas have to be identified where the available energy of the discharge, normally considered to be lost , can be used to improve water quality.

D I S C U S S I O N

S. HARTWIG: Did you make any calculations relating to interaction between the warmer cooling water and the air above the water? And did you calculate any poss ib le change in the microc l imate?

U. GRIMAS: No such studies have yet been made, but they are planned. Detailed analyses will be per formed by the Swedish Meteorological and Hydrological Institute in the biotest basin of Forsmark. This basin covers an area of water of about 1 km2 and is situated in the outer archipelago, a few kilometres f r o m the shore and the power plant.

S. HARTWIG: I should also like to ask whether there have been any protests or other reactions f r o m the population living near the proposed station s i tes? Do you discuss the problems involved with the local population?

U. GRIMAS: Yes, there have been protests f r o m the population in several areas proposed for siting. It is worth recording , incidentally, that a negative decision taken by the local government authorities is enough to prevent siting in the given area. Information is regularly provided f or the population living near a station, for instance on the eco logical effects expected, and f ishermen in the area are asked to help with sampling operations, obtaining f i shery

L A E A - S M - 1 9 7 / 1 0 81

statistics, and so on. In the areas where power stations have already been set up the protests have been rather few, but demands f or information are much in evidence.

O.J. VAN DER BORGHT: You mentioned the possibility of a 'mercury shock' through relative heating up of mercury-containing sediments. Is this just a hypothesis, or did you obtain proof of it under your experimental conditions ?

U. GRIMAS: There are some published experimental results showing that the methylation rate of mercury increases with temperature. It seems more intensive in certain cases , for instance under aerobic conditions. Thus, there is a r i sk of increased methylation, especial ly during the winter period when the descending cooling water plume can be expected to come into contact with the sediments in the deeper areas of the basin.

K.'HUBEL: Do all power plants planned in the Swedish archipelagos have direct water cooling, or will they be equipped with cooling towers , especial ly for ouse during the warmer months of the year?

U. GRIMAS: All Swedish power plants in operation use a direct water cooling system. Cooling towers have been envisaged mainly f or large outlets in inland waters, or in heavily polluted waters. The cooling capacity of the Swedish coastal waters is high and the natural reserves of cold water are large . Cooling towers do not seem to be required in these regions , to judge f r o m the observed environmental e f fects .

IAEA-SM-197/10

EVALUATION OF THE THERMAL EFFECTS OF A NUCLEAR POWER PLANT

E. IOANNILLI, E. SMEDILE Ente Nazionale per l'Energia Elettrica, Rome, Italy

Abstract

EVALUATION OF THE THERMAL EFFECTS OF A NUCLEAR POWER PLANT. The approach used by EN EL to deal with problems related to the prediction and assessment of the

impact upon the environment of the Caorso Nuclear Power Plant is presented. The predictive studies include consideration of the effects of the intake structures, entrainment through the condensers, the thermal plume and chemical discharges. The environmental control consists of a very detailed assessment of the biological resources and chemical parameters in the pre-operational phase, to be compared statistically with a new assessment during operation.

1. INTRODUCTION

Although there are many causes of altered temperature reg imes in the aquatic habitat, such those resulting f r o m dams, irrigation pract ices or industrial waste heat, one speci f ic source , the s team/e le c t r i c generating industry, appears to pose the greatest threat due to the energy discharged in the cooling water [ 1 ]. One of the key concerns in studying the alteration of aquatic habitats is how much heated waste water f r o m power plants may be deposited in a spec i f i c environment without degrading it [2] .

The ENEL, realizing the magnitude of this problem, has taken the necessary measures to ensure that every effort is made to minimize the thermal impacts of power plants. ENEL groups are acquiring the necessary information to choose sites and to design new power plants with due con-sideration f or the environmental requirements.

In Italy, the only f resh water body which can sustain direct cooling of a large power plant is the River Po; several existing ENEL plants are and some new ones will be located on this r iver .

It was deemed necessary to assess , on a quantitative basis , the ef fects on the ecology of this r iver of the thermal release of a large power plant.

2. GENERAL CHARACTERISTICS OF THE STUDY PROGRAMME

The general scheme of the study programme is shown in Fig. 1. The starting point is the engineering features of the proposed plant that are of eco logical interest. These together with the most evident environmental features f o r m the basis of a programme established to take into cons ider -ation both predictive studies (left-hand side of F i g . l ) and the a posteriori assessment of the environmental impact (right-hand side of F ig . l ) .

83


CHECK OF PREDICTION MODEL AND INTERPRETATION OF RESULTS

FIG.l. Block diagram illustrating the investigation.

The predictive studies involve laboratory work, model research and experimentation on an existing plant located on a site biological ly s imilar to the proposed site.

These studies are intended to permit of the preparation of a predictive model which could be cautiously applied to predicting the ef fects of the p r o -posed and future plants.

The models presently available f o r predicting the future ef fects of some technological act, such as discharging cooling water, on a r iver ecosystem are not reliable. This is because of the extreme complexity of such e c o - • systems and the singular lack of information on even the simple ef fects of any environmental factor acting on its own on any one element of the system.

It was, therefore , also deemed necessary to conduct a poster ior i assessments to check the predictions.

We assumed that our objectives could be attained through a prec ise and exhaustive description of the biological and chemical characterist ics occurring during the pre-operational and operational phases. By comparing the p r e -operational and operational situation with adequate prec is ion and using statistical methods, adverse ef fects on the environment would be detected and could be measured.

The activities carr ied out to make the comparison possible are reported here under the heading 'Environmental Control ' . The combined results of the Predictive Studies and the Environmental Control will permit of a rather complete analysis of the mechanisms involved when a power plant interacts with a r iver ecosystem. ENEL has f i rst applied these concepts in the environ-mental programme for the Caorso Nuclear Power Plant.

IAEA-SM-197 /22 85

3. THE PLANT AND THE SITE

The Caorso plant (882 MW(e) BWR) is located on the River Po near Piacenza, Italy.

Construction was started in 1970 and will be completed during early 1976. River water will be pumped at a rate of 36 m3/s for cooling the condensers in the once-through condenser cooling system, and will be discharged via an open channel slightly downstream. The temperature r ise of the cooling water across the condenser will be about 12°C; the residence time of the water in the discharge canal will be about 1 hour.

At Caorso, the River Po flow rate is about 1000 m 3 / s (yearly average); about 2 km downstream there is a dam serving the Isola Serafini hydro-e lectr ic station (Fig.2).

The construction of this dam has raised the water level , with a consequent decrease in flow velocity and flooding of the tributaries. The hydroelectr ic plant discharges though an artif icial channel (Fig.2) so that the original reach of the r iver downstream of the dam normally contains isolated pools of stagnant water except under large flow conditions.

4. ENVIRONMENTAL CONTROL

Environmental Control is primari ly concerned with the possible ef fects of the power plant on the 'direct r e s o u r c e s ' , that is on all actual or potential uses of the r iver by man. It is for interpretation purposes, and also to d is -criminate against the influence of the power plant on the environment due to ef fects of a different nature, that we take into consideration, in the same way, all important ' factors ' ( l ower - leve l organisms, chemical parameters , etc.) which can affect these resources .

4.1. Control of 'direct r e sources '

4.1.1. F isher ies

The River Po in the vicinity of the Caorso Plant sustains a sizeable professional and sport f isher ies . Some twenty species of f ish are present, some of these being very abundant.

It was estimated that roughly 150 tonnes of f ish are taken each year f r o m the 20 km reach of the r iver shown in Fig.2. The relative worths of each fish species f r o m a commerc ia l and sporting point of view was esta-blished by direct contact with local f ishermen.

The result of this enquiry is a relative index of value ( r a n g i n g f r o m 1 (Alosa fallax nilotica) to 4.5 (Alburnus alburnus alborella). This index p e r -mits of the calculation of a value index of a catch, V, using the formula:

where pt is the weight of f ish of species i. To keep a check on the fish population, twelve sampling stations have

been established along the r iver (Fig.2). Stations 61, 62 and 63 are upstream of the power plant and represent the control sample variation with t ime, stations 21, 22 and 23 are in the most affected zone, slightly downstream of

FIG.2. The site and the sampling stations.

IAEA-SM-197/10 87

PERCENT REDUCTION OF CATCH AVERAGE

FIG.3. Power curves for the comparison of catch averages for summer stations 01, 02, 03, 81, 83, 91, 92, 93 downstream.

the discharge canal, stations 81, 82 and 83 are located some 2 km down-stream of the outfall, while stations 91, 92 and 93 are located some 10 km downstream of the outfall and represent the recovery zone. These stations are fished every month using several standardized fishing methods.

The "catch per unit ef fort" (CPU) and the "value index of the catch" V are calculated f or each station and each fishing method; after the power plant starts up, a factorial analysis of varience will be undertaken to check if there are significant di f ferences between upstream and downstream stations, and between pre-operational and operational periods, and further, if there is any interaction between the two factors .

To obtain an idea of what statistical power (1 -/3) will be obtained in doing these comparisons, power curves were calculated and are shown in Fig.3 (one f or each fishing method and one for all methods combined). The CPUs have been assumed to have a l og -normal distribution. The graph actually re fers to a comparison between operational and pre-operational periods, during the summer, considering only the downstream station pooled, under the hypothesis that the variance will remain constant over the operational period.

The results seem to be quite good since we are able to detect a 60% reduction with 90% confidence. The value index of a catch will be analysed by non-parametric methods.

IOANNILLI and SMEDILE

The health of the fish is also to be kept under surveillance by establishing the proportions of infected or infested fish and other b iometr ic parameters before and after plant start-up. Lastly, a routine analysis of stomach con-tents of the several species of f ish is made by separating and measuring the volumes of the most important food items to establish their relative import -ance. This study is intended to represent a link between the fish study and the macroinvertebrate study. The concentrations of the most important radionuclides discharged f r o m the plant are routinely determined f r o m fish samples.

4.1.2. Aquatic birds

The River Po proper and the shallows along its banks at Caorso sustain a sizable population of aquatic birds. About 150 species are present, more or less trophically or otherwise linked to the r iver .

For some selected spec ies , nesting sites, number of nesting couples, egg deposition, birth, mortality and feeding habits have been determined.

In addition, a census using a trip survey method (two standard routes each 20 km long) and mapping methods over a 25 ha area are being conducted.

4.1.3. Other resources

The water of the River Po is extensively used f or irrigation purposes in the rich agricultural land lining its banks; it is not, at present, used as a source of potable water.

We believe that discharge f r o m the power plant will not affect these and other potential uses of the r iver . Notwithstanding that, we are keeping a check on the most important chemical and radiochemical parameters to be able to assess any ef fects which might occur .

4.2. Control of factors affecting resources

The 'direct r esources ' of the River Po can be affected by discharges other than that of the power plant as well as other factors ; examples are: (a) Variation of the level of pollutants not attributable to power plant opera-

tion, i .e. coming f r o m municipal, industrial and agricultural sources ; (b) Variation of the biomass and/or the spec i f i c composition of organisms

of the lower trophic levels due to (a). The items listed under (a) are controlled f or the entire study period by

monthly sampling and analysis of the general water quality, of the inorganic nutrients, and of the indicators of municipal, industrial and agricultural discharges.

The ef fects l istedunder (b) are controlled using a sampling grid which covers the zone which might become affected and a control zone, assessing the b i o -mass and speci f ic composition of the fauna and f lora linked trophically to the f ish population.

4.2.1. Bottom-dwelling macroinvertebrates

Macroinvertebrates dwelling on the bottom are sampled at each of 14 permanently fixed stations, taking four repl icates per station.

IAEA-SM-197 /24 89

The poss ib le variat ion of b i o m a s s and spec i e s compos i t ion of the popu-lation are contro l led with respec t to the same f a c t o r s (time and location) as f o r f ish.

Macro inver tebra tes assoc iated with the macrophytes are sampled e v e r y three months (bimonthly during springt ime) ; eight repl i cate samples are co l l ec ted at each station, and a complete taxonomic analysis i s conducted.

Macro inver tebrates are also sampled with ar t i f i c ia l substrates (Hi l sen-hoff and Hester -Dendy) upstream and downstream of the power plant d ischarge , in o rder to contro l the var iabi l i ty of the natural substrates .

4.2.2. Phytoplankton and zooplankton

Phytoplankton and zooplankton are sampled e v e r y month at each of f ive stations; four rep l i ca tes are taken at each station. T a x o n o m i c compos i t ion and ch lorophyl l -a concentrat ions are determined.

4.2.3. Macrophytes

Macrophytes present in the area have been c lass i f i ed and accurate ly mapped to detect any poss ib le variat ion of s p e c i e s compos i t ion and b i o m a s s in the future.

5. PREDICTIVE STUDIES

As a general rule , the best approach to predict ing the impact of a power plant on the l o ca l environment is to use laboratory information and related data f r o m an existing plant located near the proposed new site so that biot ic c h a r a c -t e r i s t i c s are s imi lar . The La Casel la power plant (1260 MW(e) , oi l f i red ) , which is on the R i v e r Po (40 km upst ream of Caorso ) , r epresents a s imi lar b iocenot i c pattern and was se lec ted as the site f o r conducting predict ive studies.

5.1. Laboratory studies

T i m e - t e m p e r a t u r e re lat ionships are being obtained f o r s e v e r a l f ish s p e c i e s present in the R iver Po using appropriate ' thermal shock equipment ' .

Up to now, the res i s tance of Ictalurus moe las and Anguilla anguilla to sudden temperature i n c r e a s e s ( A t - v a l u e s between 11 and 16°C) f o r dif ferent acc l imat ion temperatures have been tested. The e f f e c t s of a c c l i -mation temperature on thermal r e s i s t e n c e were also determined f o r s e v e r a l s p e c i e s of f i shes . The 24 hours L T 5 0 f o r Ictalurus m o e l a s and the 100 LT g 0

f o r Anguilla anguilla have been a s s e s s e d . F r o m the exper imenta l data obtained under contro l led condit ions, the

At lethal to 50% of the test o rgan i sms was evaluated. The resu l ts obtained, of c ourse , pertain only to the conditions of the test and to the l i f e - h i s t o r y stage used.

5.1.1. The e f fec t of chlor ine on f i shes

Chemica l d i s charges f r o m the power plant include the chlor ine in ter -mittently put into the cool ing water s y s t e m to kill fouling o rgan i sms . Present exper imental e f f o r t s are l imited mainly to work on the e f fec t of chlorine on oxygen consumption by Ictalurus m o e l a s .


FLOATING CAGES FLOATING CAGES

FIG.4. La Casel la Plant: exper imenta l equ ipment l a y - o u t .

5.2. Plant studies

Plant studies are carr ied out in a small laboratory located near the La Casella power plant. This laboratory (Fig.4) is supplied with water coming f r o m the River Po and the discharge canal.

In addition the ' system' includes 3 f ish culture units ( composed of floating cages , 300 cm X 2 50 cm) located in the discharge canal, in the River Po ahead of the intake and in the mixing zone.

5.2.1. Stress on fish in the intake

The stress on fish caught in the intake system is being studied in the following investigations:

(a) Collection of information f r o m the operating personnel and in inspections to evaluate the number and species of f ishes impinging on the intake screen;

(b) Laboratory tests to gain information on the swimming speed of the more common fish species .

At this t ime, Cyprinus carpio and Ictalurus moelas have both been t e s -ted in a swimming chamber.

5.2.2. Effects of entrainment through the cooling system

The more important biological components which may be entrained in the cooling system of a power plant are f ish eggs, larvae and plankton.

IAEA-SM-197 /10 91

Phytoplankton and zooplankton are col lected bimonthly at the mouth of the intake structure and at the outfall. The following analyses are made on all samples: enumeration and identification of each species ; estimation of the size of the organisms; determination of chlorophyll and other pigment concentrations.

P r i m a r y productivity studies and investigations on the heterotrophic utilization of dissolved organic material by microorganisms sampled in the intake and outfall are also per formed. During the period May to October, when the number of f ish larvae and eggs are expected to be greatest, a more intensive sampling programme is conducted.

5.2.3. Effect of the cooling water on the growth rate, reproduction and behaviour of f ish

The effect of cooling water on the growth rate, reproduction and general behaviour of fish is considered in the following studies: (a) Laboratory evaluation of di f ferences in the growth rate; gross conversion

ef f ic iency and digestion rate of Ictalurus moelas kept in tanks supplied with either water f r o m the intake or f r o m the outfall of the power plant.

(b) Studies of the influence of two different temperature conditions on spawning and development rates of Ictalurus moelas and Cyprinus carpio. In addition, the influence of heated discharges on the growth rate and

gross conversion e f f i c iency for Cyprinus carpio are studied using floating cages.

6. CONCLUSIONS

The approach to environmental problems as applied to the Caorso Nuclear Power Plant is very comprehensive, including both the prediction and the assessment of power plant impact.

Study programmes of such an amplitude are fully justified when their results can be used to evaluate the impact of power plants sited in s imilar ecosystems; this is the situation f or the River Po, on which several power plants are already located and on which new power plant sites are being considered. It is hoped that the progress of environmental sc iences will render the predictive models more reliable in order that a poster ior i assessments could be limited to particular aspects.

R E F E R E N C E S

[ 1 ] MIHURSKY, J.A. , KENNEDY, V .S . , Water temperature criteria to protect aquatic l i f e , Am. Fish. S o c . , Spec. Publ. No 4 (1967) 20 -32 .

[ 2 ] CAIRNS, J., Coping with heated waste water discharges from steam electr ic power plants, Bio Sci. 22 7 (1972) 411 -20 .

D I S C U S S I O N

F.B. HAWES (Chairman): I should like to ask whether ENEL is obliged to undertake such an extensive research project , or whether it is doing so for its own private purposes.


E. IOANNILLI: ENEL is required to submit a prel iminary environ-mental report to the Italian national nuclear energy authority (CNEN) at the construction permit stage of a nuclear power plant. A second report must be submitted at the time of application for an operating l icence; this report must satisfy any queries raised after review of the prel iminary report. However, the extensive studies now being carr ied out at the Caorso site are something more than was actually requested, and are motivated by ENEL's special interest in the River Po, where several power plants are already in operation and where it may be possible to site additional plants in the future.

M.J. KOSKELO: Is there an independent authority in Italy which checks the results of a study undertaken by the operator or the constructor of a power plant? And, if so, does this authority undertake investigations of its own?

E. IOANNILLI: The Italian national nuclear energy authority (CNEN) reviews the results of environmental studies, but has not so far conducted any independent investigations of its own.

Y.J. SOUSSELIER: Could you give us an idea of the cost involved in a project of the kind described?

E. IOANNILLI: A rough cost estimate for the f irst year ' s work, includ-ing both the environmental control and predictive study phases, would be one million US dollars.

R.J. KIRCHMANN: How many people are employed in your studies, i .e . the f ield survey and the laboratory experiments, and what sort of quali-fications do they have?

E. IOANNILLI: The laboratory engaged in field studies at the Caorso site employs a staff of 18, most of whom are qualified at the technician level. In addition, we use consultants who are experts in environmental sc iences , together with about 15 taxonomic experts (with Ph. D. degrees) f r o m Italian Universities and natural history museums. For predictive studies we employ about ten people, mostly of high educational level.

C.B. J^RGENSEN: How do you measure the growth e f f i c ienc ies of f ish in the floating cages? Do you have any measurement results f o r growth e f f i c ienc ies under caged conditions, or f o r the ef fects of the thermal discharge?

E. IOANNILLI: The cages have only been in operation for a few months, so no final results are available yet. The cages contain several hundred specimens of Cyprinus carpio of the same size , and at f ixed time intervals we measure the weight and length of the f ish so as to evaluate their p e r -centage growth.

B . L . OLLA: If the highest natural summer temperature is 27°C, by how much do you expect it to increase as a result of plant operation? Also , what is the predicted effect of such thermal levels on the f ish species present during this season?

E. IOANNILLI: The temperature of 27°C mentioned in my paper is the maximum recorded ambient r iver temperature. Summer temperatures normally do not exceed 24°C. It is quite possible, however, that the f ish may be displaced f rom the warmer zone when the plant is operating at full capacity.

In any event, the r iver water temperature will be lower than (27+12)°C, i .e . 39°C, due to mixing. In fact, assuming complete mixing, it will be no more than about 1°C above ambient downstream f r o m the Isola Serafini hydroelectr ic plant, which is 1.8 km below the point of discharge.

IAEA-SM-197 /5 93

K. HUBEL: Have you a general plan for the construction of power plants along the whole Po r iver system over the next 20 - 30 years and, if so, will it take account of the overal l ef fects observed f r o m this station?

G. DINELLI: Extensive investigations have been made recently by ENEL on the cooling capacity of the River Po. Using a unidimensional simulation model , the thermal ef fects produced by cooling water discharges along the r iver have been studied under different sets of hydrological and meterio logical conditions, and the most probable temperature levels evaluated.

The r iver /a tmosphere energy balance has been checked experimentally f r o m in situ measurements made at three ENEL weather stations located along the River Po. One of these is situated about two ki lometres down-stream f r o m the Caorso power plant at present under construction.

These studies suggest that, even under severe environmental conditions, the overal l cooling capacity of the r iver will be adequate f or several thousand megawatts of installed thermal or nuclear power. Thus the siting of new power stations on the r iver seems to present no particular problems as far as the near future is concerned.

F. HEISE: When you build a power station, do you take into consideration the fact that additional industrial plants may be attracted to the neighbour-hood and thereby increase the amount and types of pollution?

E. IOANNILLI: For the Caorso project we monitor the water, both upstream and downstream f r o m the power plant, f o r possible variations in the pollution level of the r iver ; this procedure is independent of station operation.

I don't think that a new power plant will automatically promote the introduction of more industries into the; area.

C.R. FONNE: Can you tell us a little more about the regulations on thermal re leases in f o r ce in Italy? I see that the temperatures you mention f or the Caorso station alone are very high in summer, f o r example a 39°C maximum with AT - 12°C for the re lease prior to mixing.

E. IOANNILLI: At present there are no regulations on thermal d is -charges applicable to the whole of Italy; there are instead directives issued by the Ministry of Health to the peripheral authorities coming under its jurisdiction.

In addition, regulations applicable on a regional basis are being intro-duced. The thermal standards f or Caorso have been formulated on the basis of the Ministry of Health directives by the authority (CNEN) responsible for the environmental aspects of the Caorso power station, and are as follows: maximum temperature, 100 m downstream f r o m the discharge is 30°C; maximum AT averaged for the most heated 2 5% of any r iver section, 100 m downstream f r o m the discharge is 3°C. We will check the degree of compliance with these standards in the f ie ld , by thermal mapping and moni -toring, during the f irst year of operation; we also hope to have by that time some results of the eco logical programme, reflecting the true impact that the power plant has made, f o r submission to the authorities for use in taking decisions.

J . -M. LAMBOTTE: Do you provide the population concerned with regular information based on your studies? And what is the general attitude of the public towards the plant?

E. IOANNILLI: ENEL has arranged several meetings with local groups and organizations to discuss the environmental aspects of the power plant. In addition, we keep the relevant regional and national authorities informed


of our environmental activities and also invite them to visit our laboratories and f ield installations.

C. HOEDE: Since you monitor radiochemical parameters as well, could you say where the main body of the radioactive waste goes?

E. IOANNILLI: We at present monitor the background contamination of several components of the ecosystem and will continue to do so when the station starts operating.

I think, however, that power stations such as Caorso are advanced enough to handle liquid waste process ing , and will not re lease any activity of pract i -cal importance.

P.G. ROLLIN: I would like to ask you your personal view, or else the o f f ic ia l policy of ENEL, as regards the techniques f or hot water discharge. Do you consider it preferable , for instance, to ensure that the effluents re leased are thoroughly mixed as soon as possible so as to reduce the heating effect , or is it better to let the unevenness of the temperature p e r -sist so that the aquatic organisms can then gravitate towards their own pre ferred temperature zones?

E. IOANNILLI: Up to now ENEL has always designed and built s truc -tures f or surface discharge; but I think that this problem has to be dealt with on a c a s e - b y - c a s e basis .

Unfortunately, there is not much data available on the actual impact of power station thermal re leases at present f o r any type of discharge. I there-fore think each utility should keep on for the time being with its normal engineering practice (apart f r o m compliance with the thermal standards arbitrari ly imposed).

IAEA-SM-197/10

BIOLOGICAL EFFECTS OF SIMULATED DISCHARGE PLUME ENTRAINMENT AT INDIAN POINT NUCLEAR POWER STATION, HUDSON RIVER ESTUARY, USA*

G.R. LANZA*, G.J . LAUER*, T . C . GINN, Patricia C. STORM, Lois ZUBARIK New York University Medical Center, Institute of Environmental Medicine, New York,

United States of America

Abstract

BIOLOGICAL EFFECTS OF SIMULATED DISCHARGE PLUME ENTRAINMENT AT INDIAN POINT NUCLEAR POWER STATION, HUDSON RIVER ESTUARY, USA.

Laboratory and field simulations o f the discharge plume entrainment o f phytoplankton, zooplankton and fish were carried out at the Indian Point Nuclear Station, Hudson River estuary, USA. Phytoplankton assemblages studied on two dates produced different response patterns measured as photosynthetic activity. Chlorophyll-a levels did not change following simulated entrainment. Possible explanations for the differences are discussed. The two abundant copepods Acartia tons a and Eurytemora affinis appear to tolerate exposure to discharge plume AT without adverse effects. Copepods subjected to plume entrainment may suffer considerable mortality during periods of condenser chlorination. In general, the amphipod Gammarus spp. did not appear to suffer significant mortality during simulated entrainment. Juvenile striped bass, Morone saxatilis, were not affected by simulated plume transit before and during plant condenser chlorination; however, a simulated "worst possible case" plume AT produced statistically significant mortalities.

1. INTRODUCTION

The routine operational regimes of nuclear-fueled steam-electric generating facilities include massive withdrawal of water from aquatic ecosystems (lakes, rivers, estuaries, oceans) to supply once-through condenser cooling and service water systems. The withdrawal of cooling water may be viewed as pro-ducing three general categories of biological impact as follows: (1) impingement on intake screens (organisms too large in any one dimension to pass through the screens), (2) pumped entrain-ment through the plant condenser cooling water system (organisms small enough to pass through the screens), and (3) discharge plume entrainment (organisms of all sizes entrained into the cooling water disposal area). Among the three categories, the biological effect of discharge plume entrainment has received the least amount of research effort. Organisms entrained into power plant discharge plumes are subjected to elevations in tem-perature (AT), increased turbulence, and altered water flow velocity and density. During certain periods, chemical agents are added to de-foul power plant condenser cooling lines and are superimposed upon other potential stresses as residuals.

* Present address: Ecological Analysts, Inc. , Northeast Laboratory, RD No. 2 Goshen Turnpike, Middletown, N . Y . 10940, USA

* This research was funded by a grant from the Consolidated Edison Company of New York, Inc.

95


The vast majority of studies accomplished to date have focused upon fresh water fish species with little or no attention to important organisms occupying lower levels of the food web. Further scrutiny of the scientific record reveals a distinct lack of information on the effects of introducing thermal and chemical additions to estuarine ecosystems, particularly with regard to biological structure and function.

2. CHARACTERIZATION OF THE STUDY AREA

The Indian Point facility is situated in the relatively healthy mid-portion (oligohaline sector) of the Hudson River estuary. In this area, the river is 1372 to 1524 m wide with a maximum depth of 25.9 m and a cross-sectional area of approxi-mately 15 793 m2. The generating complex will soon be comprised of thr3e nuclear-fueled units with a combined capacity of 2103 MW (e) . The water used by all three units flows through a common discharge canal and is returned to the river through a series of submerged discharge ports situated along a 72.6 m length of the canal terminus. Figure 1 provides a schematic representation of the vertical profile of the Indian Point cooling water discharge plume using the Hirst round-jet model for base-case conditions. During the maximal operational demand, the multi-plant complex will shuttle Hudson River water from the intake points to the discharge plume area at a rate of 129.8 m3/s. Changes in the discharge plume configuration occur with altera-tions in plant operational mode, and according to tidal movement.

FIG. 1. Schematic representation o f the vertical profile of the Indian Point plant discharge plume using the Hirst round-jet model for base-case conditions. (Details show time (s) from discharge port and tempera-ture (°C) above ambient.)

The aquatic organisms subject to entrainment in the dis-charge plume area vary with a complex array of environmental factors which change on diel, seasonal and yearly cycles. Im-portant among these organisms are the lower-level food web com-ponents (e.g. phytoplankton, zooplankton) that occupy essential roles in supporting ecosystem function.

IAEA-SM-197/16 97

-2.4 m-

«- Marker

Float

30.5 cm

30.5 cm

L

•1.7m-

Chain

I x

1.8m

X Surface

FIG. 2 . Organism exposure rack used in simulated plume entrainment (see Appendix for container specifications).

3. PLUME ENTRAINMENT STUDIES - GENERAL METHODS AND MATERIALS

Preliminary laboratory and field studies simulating the effects of discharge plume entrainment upon representative Hud-son River biota were completed in 1974. The research program was structured to develop study approaches with applicability to power plant discharge plume studies in general. Experimental design focused on producing information of predictive value with emphasis on observing the following: (1) organism groups rep-resenting major levels of aquatic food webs in general, (2) simultaneous exposure of organisms from different trophic levels to the Indian Point thermal plume in the presence and absence of chlorine application, (3) both the "immediate" and latent ef-fects of exposure to the plume, (4) simulations of "worst pos-sible case" discharge plume entrainment to provide a conserva-tive data base.

Field studies involved the exposure of phytoplankton, macrozooplankton and fish to discharge plume and control areas by attaching submerged containers appropriate for each organism to floating racks (Figure 2). Studies were done in the presence and absence of chlorine application (hypochlorite solution) used to de-foul power plant cooling water condenser lines.

The following general procedure was adhered to during the plume transit experiments. Several passes were made by boat

Plant

A T

* Control Rack

• Plume Rack

A B C D E F G H I J K L M

Approximate Locale at Five Minute Intervals

FIG. 3. Transit-temperature profiles in the absence o f chlorination ( 1 9 7 4 - 0 8 - 2 2 ) .

IAEA-SM-197 /25 99

through the Unit 1 and 2 discharge plume area measuring tempera-tures with a YSI Model 43-telethermometer (Yellow Springs In-strument Co., Yellow Springs, Ohio, U.S.A.). When the highest surface AT was located, the experimental organism exposure rack was lowered into the plume. At the same time, a rack was placed in a non-plume (control) area of the river. The racks were per-mitted to drift in the river for one hour under the influence of local tidal/current movement. The approximate locale of each rack and the water temperature was recorded at five minute in-tervals throughout transit. Water samples were taken at least three times within each transit period (beginning, midway, end) and returned to the laboratory for chlorine analysis using an amperometric titrator (Wallace and Tiernan Co., Belleville, N.J., U.S.A.). Water temperature and chlorine were also moni-tored in the power plant (at the condensers and in the discharge canal) to characterize levels entering the plume.

Organisms were retrieved following simulated plume transit, immediately returned to the laboratory for short-term mortality examination and retained for observation of latent mortality.

Initial experiments designed to test the effectiveness of organism cages in plume transit indicated that the mesh netting required to retain microzooplankton was too fine to permit ade-quate water exchange to the cage interior. As a result, a laboratory simulation of microzooplankton plume entrainment was devised for use in lieu of caged transit through the plume.

Other field experiments involved the immersion of caged macrozooplankton in the discharge canal prior to, and during chlorination to provide a "worst possible case" simulation of plume entrainment. Laboratory studies of zooplankton and fish also involved observations on the effects of "worst possible case" plume AT simulation in the presence and absence of plant chlorination. The studies emphasized mortality estimates; how-ever, some preliminary observations were made on macrozooplankton behavioral patterns as temperature attraction-avoidance. Figures 3-6 are graphic summaries of field observations characterizing the simulated plume transit on the organism exposure racks. All locale plots (A-M) are estimates based on shoreline reference points noted at each five minute interval of the exposure period. Figures 3 and 4 represent ex-periments done during August in the absence and presence of Unit 1 chlorination. Figures 5 and 6 summarize ob-servations from similar experiments completed in September.

Statistical treatment of data from phytoplankton experiments consisted of one way analysis of variance and the Scheff^s Test for differences between means {1}. Experimental data from micro-zooplankton (Acartia tonsa, Eurytemora affinis), macrozooplankton (Gammarus spp.) and fish (Morone saxatilis) were subjected to RXC Contingency Table Analysis using the G-test {2}. If an analysis indicated a significant effect of treatment on survival, an a posteriori simultaneous test procedure was conducted to re-veal all non-significant subsets of rows and columns.

AT (+) Chlori nation

A Control Rack

• Plume Rack



FIG. 4. Transit-temperature profiles in the presence of chlorination (1974-08-22). Rack in plume showed virtually no movement.

0 8 R Power Plant

A T

* Control Rack

• Plume Rack




AT (+) Chlorination

* Control Rack

• Plume Rock




IAEA-SM-197 /25 103

4. PHYTOPLANKTON

4.1 Methods and Materials

Studies designed to characterize the effects of discharge plume entrainment upon Hudson River phytoplankton assemblages included measurements of photosynthetic activity as 14C uptake rate, and cell chlorophyll a content as an indication of the photosynthetic potential of the algal community.

Phytoplankton assemblages were prepared as follows: Sep-arate four liter samples were collected from the river adjacent to the intake structures, and from the discharge plume areas and used respectively as control and experimental material. Control samples were collected and incubated two hours before each experimental set was collected. Experimental bottles were mixed and aliquoted as CD three 300 ml light (transparent) pro-ductivity bottles, (2) three 300 ml dark (shielded against light with black tape and an outer- layer of aluminum foil) productivity bottles and (3) three 300 ml bottles for chlorophyll a analysis and algal taxonomy. Productivity bottles were inoculated with 10 yC of NaHl4C03. Chemical analyses of pH and CaC03 were also carried out.

Following the exposure period, each of the latter three bot-tles were divided into four 50 ml sub-samples for chlorophyll a analysis, and the remaining 100 ml was used for algal taxonomy. Algal identification and chlorophyll a were limited to the sur-face samples. During an experiment, triplets consisting of one light, one dark and one chlorophyll a - taxonomy bottle were suspended from the experimental transit rack (Figure 1) at each of three depths: 1.27, 91.00 and 183.00 cm below the water sur-face. Following the one-hour transit rack exposure, the bottles were transferred to a stationary incubation rack attached to a dock in ambient temperature water at the same three depths for the additional time required to complete the 4-hour incubation for 1 4C uptake. The control transit rack carried three 300 ml light bottles, one each at 1.27, 91.00 and 183.00 cm depth and a second 300 ml bottle at 1.27 cm for surface chlorophyll a and taxonomic examination. Control rack dark bottles were incubated in a continuous flow trough receiving ambient temperature river water.

All productivity bottles were incubated in situ to maximize simulation of light and temperature variation with depth. Tem-peratures were measured at the surface with a YSI telethermometer and at 91.00 and 183.00 cm depth with a weighted temperature-salinometer probe (Electrodeless Induction Salinometer - Tempera-ture Instrument, Beckman Instrument Co., Cedar Grove, N.J., U.S.A.).

At the initiation of each incubation a set of incident sub-marine light readings were taken with a Kahl radiometric photo-meter (Kahl Scientific Instrument Co., El Cajon, Calif., U.S.A.). Light absorbed by a photocell was measured on a small ammeter and converted to yW/cm2 using a set of correction factors cali- , brated with the instrument. The yW/cm2 are converted to cal/cm2-s by the following formula taken from the IBP Handbook #12 {3}.

T A B L E I. E X P E R I M E N T A L R E S U L T S O F S I M U L A T E D P H Y T O P L A N K T O N P L U M E E N T R A I N M E N T

Photosynthet ic Depth Depth of Euphotic Light Temp A c t i v i t y Chlorophyl

Assemblage (cm) Zone (m) (cal/cm2- s) (°C) ( m g C / m 3 -h) (mg/m 3 )

Control 1, .27 1 .98 1 . 96 ~2 25. 8 3 0 . 2 7 1 . 6 9 91, .00 1, . 80 ~3 25. 8 6 .96

183, .00 2 .20~* 25 . 8 6 . 2 6

AT 1, .27 1 .98 1, . 96 ~2 29 . 1 28 .00 1 . 8 5 91, .00 1, . 80 ~3 28 . 3 1 0 . 9 4 2 . 0 7

183, .00 2, . 2 0 " " 28 . 2 1 . 9 8 1 . 1 9

Control 1, .27 1 . 9 8 1, . 96 ~2 25. 8 2 5 . 2 9 1 . 2 6 91, .00 1, . 80 ~3 25 . 8 9 .73

183 , .00 2, . 20 25 . 8 4 . 6 5

AT with 1. ,27 1 .98 1, . 96 ~2 31 . 3 2 2 . 4 8 2 . 0 7 Chlor. 91, ,00 1, . 80 ~3 29 . 9 3 . 6 9 2 . 2 0

183, .00 2, . 2 0 " " 30 . 9 . 4 . 4 6 1 . 8 3

Control 1, .27 1 .83 1, . 1 0 " 2 24 . 0 19 .55 1 . 0 0 5 91, .00 3 , , 70-1* 24 . 0 5 . 8 2

183, .00 1, . 27 " * 24 . 0 3 . 8 9

AT 1. .27 1 .83 1. , 1 0 " 2 28 . 4 13 .67 1 . 3 9 91, .00 3. . 7 0 " " 28 . 4 1 3 . 1 9 1 . 2 2

183, .00 1, 28 . 4 1 . 9 3 1 . 2 0

Control 1, .27 1 .83 3. . 69~2 24 . 0 2 8 . 0 6 1 . 4 9 91, .00 3. , 69~3 24. 0 1 1 . 5 9

183, .00 3. .30""* 24 . 0 2 4 . 4 7

AT with 1, .27 1 .83 3. . 69~2 28 . 4 15 .49 1 . 3 8 Chlor. 91 .00 3, . 69~ 3 28 . 4 9 . 6 8 1 . 2 6

183, .00 3. . 3 0 " * 28 . 4 0 . 1 8

7 4 - 0 8 - 2 2

7 4 - 0 9 - 1 2

I A E A - S M - 1 9 7 / 2 5 105

yW/cm^ x 1 x 4.185 = cal/cm^.s 1 x 106

Light values were used to calculate solar radiation at the water surface and the depth of the euphotic zone (Table I).

Photosynthesis was measured using the uptake rate as described by Steeman Nielsen {4} and modified by Saunders, et al. {5}. After incubation, samples were brought into the lab-oratory. A set of four 50 ml aliquots were taken from each bottle. These were then filtered using a millipore apparatus with . 45y, 47 mm filters. Suction was provided by a vacuum pump maintained at 15 inches Hg to prevent cell breakage. Each sample was rinsed with filtered river water to remove any non-absorbed radioactvity. Each filter was then placed in a liquid scintillation vial containing 20 ml of Triton X-permafluor cock-tail. Carbon 14 uptake was measured in a liquid scintillator following the procedure of Wang & Willis {6}. Chemical quenching was corrected using a set of homogenously quenched standards (Amersham Searle Co., U.S.A.).

Total carbon was calculated using the table from Saunders, et al. relating pH, alkalinity and temperature. These para-meters were then used in the following formula to calculate photosynthesis {5}.

P = r x f x c x l x Total Volume x 103

R N Volume Filtered

r = dpm of light bottle - dpm of dark bottle R = dpm of added 1 4C f = isotope correction factor C = carbon (mgC/1) N = incubation time

103 = conversion to mgC/m-*

Chlorophyll analysis followed the method of Strickland & Parsons {8}. A set of four 50 ml aliquots were filtered with 1 ml of dilute magnesium carbonate as a buffer using a millipore apparatus and GFC glass filters. After filtration the filters were homogenized in 90% acetone with a tissue grinder. Following 1 hour to allow complete extraction, samples were centrifuged. The fluorescence of chlorophyll a in the supernatant was mea-sured with a Turner Model 111 fluorometer (G.K. Turner Assoc., Palo Alto, Calif., U.S.A.). After the initial fluorescence measurement, the samples were acidified with 4N HC1, held for 5 minutes, and a reading of phaeophytin absorption was taken with the fluorometer.

Chlorophyll a and phaeophytin a were calculated as follows:

mg Chlorophyll a/m3 = FD T (Rg-RA) x Total Volume x ml ext. T-l Volume Filtered 10

3 mg Phaeo-pigment/m = F D T (TRA-Rfi)x Total Volume x ml ext. T-l Volume Filtered 10

T A B L E II. SUMMARY OF THE ANALYSIS OF THE OBSERVED EFFECTS OF SIMULATED PHYTOPLANKTON PLUME ENTRAINMENT Plume compared to control at each depth O = no effect ; + = increase ; - = decrease

E f f e c t of AT E f f e c t of AT with C h l o r i n a t i o n

Photosynthetic Chlorophyl l a Photosynthet ic Chlorophyl l a Date Depth (cm) A c t i v i t y Content A c t i v i t y Content

1974-08 -22 1 . 2 7 0 0 0 0 9 1 . 0 0 0 0 - 0

1 8 3 . 0 0 0 0 0 0

1974-09 -12 1 . 2 7 9 1 . 0 0

1 8 3 . 0 0

0 + 0 0 0

0 0 0

0

IAEA-SM-197/25 107

= door factor Calibration of the fluorometer using a comparison of readings on a Beckman DB spectrophotometer where:

F = Ca/ R

= 11.6E 6 6 5 - 1.31E 6 4 5 - 14E 6 3 0

Absorbtion readings taken at the indicated wave-lengths on the spectrophotometer R = fluorescent reading of the same sample as above t = ratio of sample before and after acid. At the time of the following analysis:

F D = .00161 t = 2.15

A 250 ml sample for phytoplankton counts and identifica-tion was preserved with Lugol's iodine solution.1 Upon return to the laboratory aliquots of 25, 50 or 100 mis were prepared depending on organism density. Each aliquot was filtered using a 1.2u, 47 mm gridded filter.- After filtration, filters were dried and then mounted on slides with Permount.2 Ten strips were counted on each slide. The number of phytoplankton cells/ liter was calculated by the following formula:

X = — (F) (P)

where:

X' = number of phytoplankters per liter C = organisms counted F = fraction of filter counted P = portion of liter filtered

4.2 Results

Table I summarizes the results of experiments carried out to examine the effects of simulated plume entrainment upon phytoplankton assemblages. The results of comparing control and experimental assemblages at each depth are outlined by date in T a b l e I I . Comparisons not demonstrating significant differ-ences between control and experimental groups at the 95 percent confidence level following single classification analysis of variance and the Scheff£s Test are denoted by 0. Those compari-sons with significant differences are denoted by + or - to in-dicate a respective increase or decrease in photosynthetic activity and/or chlorophyll a content.

where

Ca

1 Lugol 's iodine solution consisted of 40 g iodine, 80 g potassium iodide, 80g glacial acetic acid, 50 ml glycerine and 50 ml 95% ethanol in 800 ml distilled water.

2 Permount — Ace Scientific Supply C o . , I n c . , Linden, NJ, USA.

TABLE III. TAXONOMIC PROFILE OF SURFACE PHYTOPLANKTON ASSEMBLAGES Percent composit ion

Percent of T o t a l I d e n t i f i e d

Date Assemblage C e l l s / 1 Diatoms Greens Bluegreens Chrysophytes Euglenoids

74 -08 -22 Control 1. .27x10 6 70. .57 27, .66 - 1 . 7 7

AT 2. .21x10® 67. .48 31. .91 1. .42 1 . 2 2

Control 2. . 3 2 x l 0 6 62. .52 32. .23 4. .85

AT with c h l o r i n a t i o n 2. .14x10® 57. .56 37. .18 3, .15 2 . 1 0

7 4 - 0 9 - 1 2 Control 7. .60x10 s 33. .14 63. .61 — 3 . 2 5

AT 8. ,10x10 s 41. .83 55. .40 0. .55 2 . 2 2

Control 1. , 03x10® 37. .12 59. .83 0. .87 2 . 1 8

AT with c h l o r i n a t i o n 1. 01x10® 36. ,61 59. 93 1. ,79 1 . 7 9 1 . 7 9

I A E A - S M - 1 9 7 / 2 5 109

The vast majority of phytoplankton assemblages exposed to simulated plume transit during August, 1974 (Figures 3 & 4 ; Table II) displayed no measurable effects on photosyn-thetic activity or chlorophyll a content. One exception was a decrease in 14C uptake noted in the assemblage exposed to AT with chlorination at 91.00 cm depth. Similar experiments per-formed in September, 1974 at a different river ambient tempera-ture resulted in decreased photosynthetic activity in surface samples receiving AT with and without chlorination. Accompany-ing the apparent decreased surface activity was an increase in photosynthetic activity in the assemblages exposed to AT only at 91.00 cm depth, and a decrease in activity in the assemblage ex-posed to AT with chlorination at a depth of 183.00 cm (Table II). In agreement with the previous experiments, no differences were observed in the chlorophyll a content of all assemblages.

Taxonomic profiles of phytoplankton assemblages are given in Table III. Surface assemblage density values expressed as cells per liter, and the percent composition of each major algal group indicate that similar phytoplankton communities represented control and experimental groups on a given exposure date. Table IV provides taxonomic profiles of dominant organisms noted in the study assemblages.

The decreases in surface photosynthetic activity noted during the simulated plume entrainment studies completed in September, 1974 (Tables I and II) appear to be the result of AT alone, and AT with low level (< 0.05 ppm) total residual chlorine.

Several factors individually or in concert may help to ex-plain the observed differences in community response noted be-tween study dates (August and September, 1974). The overall taxonomic structure of the phytoplankton communities studied on both dates are similar in that each is composed of greater than 90 percent diatoms and green algae. However, if we compare per-centages of major algal groups on one date with the same groups on another date (e.g. diatoms in August and greens in August with the same groups in September) we note a shift in dominance from diatoms in the August assemblages to greens in the Septem-ber assemblages (Table III). Diatoms noted on both dates were composed largely of the same species, Cyclotella glomerata. If we compare green algae on both dates, we note that the increase in percent composition of greens in September assemblages is not accompanied by a corresponding increase in the most dominant group of greens, i.e. the coccoids. The overall increase ob-served in the green algal groups is due to species other than coccoids, some of which, are unidentifed organisms included in the "other" category (Table IV). Thus, there exists the pos-sibility that some or all of these "other" species were more sensitive to the stresses encountered during simulated plume en-trainment.

Other major factors worthy of consideration in comparing the different photosynthetic responses are the different ambient tem-peratures to which the assemblages were acclimated prior to ex-posure to stress, the magnitude of the AT superimposed on that ambient temperature as opposed to the overall temperature at-tained, and the changing temperature regime through which the assemblages drifted.

110 LANZA et al.

TABLE IV. TAXONOMIC PROFILE OF SURFACE PHYTOPLANKTON ASSEMBLAGES Dominant organisms

Assemblage

Percent of Total Examined

C y c l o t e l l a glomerata Coccoids Other

1974-08-22 Control

AT

Control

AT with c h l o r i n a t i o n

67 .73

6 2 . 8 0

5 9 . 0 3

5 4 . 4 1

2 2 . 6 9

1 9 . 3 0

2 3 . 8 8

2 5 . 0 0

9 . 5 7

17 .88

17 .08

20 . 58

1974-09-12 Control

AT

Control

AT with c h l o r i n a t i o n

2 7 . 8 1

3 6 . 0 1

31 .88

3 0 . 9 4

3 6 . 6 9

28 .53

36 .68

2 8 . 2 5

3 5 . 5 0

3 5 . 4 6

3 1 . 4 4

4 0 . 8 1

In the case of plume simulations in which no change in sur-face photosynthetic activity was noted (8/22/74) the phyto-plankton assemblages were collected at a river ambient tempera-ture of between 26.0-27.0°C and exposed to a changing AT with a maximum of 4.5°C (Figures 3 ,4 ). Plume simulations dis-playing decreased surface photosynthetic activity (9/12/74) were done with phytoplankton assemblages collected at a lower river ambient of 23.5-24.0°C receiving a changing AT attaining a maxi-mum of 6.0°C (Figure 5 , 6 ) .

5. MICROZOOPLANKTON


Microzooplankters were collected from the power plant in-take structure on the day preceding, or morning of an experi-ment with a 0.5 m diameter, #20 mesh (76y) nylon net. Prior to use in an experiment, the collection debris (including dead or-ganisms) was allowed to settle out of each sample while the or-ganisms were maintained in a continuous-flow water bath at am-bient river temperature.

Microzooplankton were exposed to simulated plume entrain-ment by immersing caged organisms in controlled-temperature water baths. Immersion baths consisted of 200 ml dishes (11.0 cm diameter; 3.5 cm high) placed in larger, continuously mixing water baths (Magni-Whirl Incubator, Blue M Co., Blue Island, Illinois, U.S.A.) at a set temperature. All experimental tem-peratures were recorded in the 200 ml baths receiving immersion cages.

IAEA-SM-197 /25 111

Immersion cages were comprised of transparent plastic cy-linders (2.0 cm diameter; 2.2 cm high) fitted with 76y mesh ny-lon net bottoms. Organisms were introduced by adding a 10 ml aliquot of the collected material to each cage. Therefore, the number of organisms per cage on a particular date depended upon the density of organisms present. Four replicate cages were prepared for each control and experimental group.

Simulated exposure to plume AT was accomplished by immers-ing caged organisms in water baths maintained at the maximum AT observed in the power plant plume during experimentation. Con-trol cages were simultaneously immersed in baths at ambient river temperature. Following the one hour immersion, cages were transferred to ambient holding baths.

Simulated exposure to plume AT with chlorination was ac- . complished as follows: A water sample was collected from the power plant condenser as soon as chlorine residual was detected. Chlorinated condenser water was diluted to produce 50 and 25 percent of the collected condenser level. Two sets of three 200 ml water baths, each containing 100, 50 and 25 percent of the condenser chlorine level were prepared. One set was placed in a water bath (Magni-Whirl Incubator; Blue M Co., Blue Island, Illinois, U.S.A.) maintained at plume temperature,while the other was placed in a continuous flow trough receiving river water at ambient temperature. Organisms in immersion cages were exposed to each temperature-residual chlorine level by transferring cages from one water bath to another at 20 minute intervals for one hour. Cages were placed in 100 percent chlorinated condenser water for the initial 20 minutes and transferred to 50 and 25 percent dilutions for the remaining time intervals. Following exposure, all cages were suspended in a 9.46 I tank receiving flowing river water at ambient tem-perature with supplemental aeration. One half of the organisms were observed for immediate effects one hour after exposure and the remainder were examined for latent effects twenty-four hours later.

5.2 Results

Tables V & VI summarize the results of copepod survival following exposure to consecutive dilutions of Indian Point dis-charge water. In all cases there were no statistically signi-ficant differences between the survivals of ambient exposure groups (controls) and test groups exposed to simulated plume temperatures. Test groups exposed to chlorinated samples (both ambient temperature and heated) displayed consistently lower survival rates than organisms maintained at ambient tempera-ture.

The exposure of E. affinis to chlorinated water samples at simulated plume temperatures resulted in no survival of 19 test organisms 24 hours after exposure (Table VI). E. affinis ex-posed to chlorinated water at ambient temperature also displayed reduced survival when compared with controls; however, the per-cent survivals were significantly higher than the survivals in heated, chlorinated samples. These data indicate that the com-bined stresses of temperature and chlorine resulted in higher

112 LANZA et al.

TABLE V. IMMEDIATE SURVIVAL (1 h) OF COPEPODS EXPOSED TO SIMULATED PLUME BIOASSAYS Ambient temperature = 24.0°C; plume temperature = 29.1°C; condenser chlorine (total residual) = 0.44 m g / f

Species Ambient

Percent

Plume

Survival

Chlorinated Ambient

Chlorinated Plume

Eurytemora 99.1 96.9 86.4 74.1 a f f i n i s (116) 1 (96) (81) (85)

Acartia 100.0 94.8 34.8 11.7 tonsa (32) (39) (46) (60)

1 Number of test organisms.

TABLE VI. LATENT SURVIVAL (24 h) OF COPEPODS EXPOSED TO SIMULATED PLUME BIOASSAYS Ambient temperature = 24.0°C; plume temperature = 29.1°C; condenser chlorine (total residual) = 0.44 mgjS

Percent Survival

Species Ambient Plume Chlorinated

Ambient Chlorinated

Plume

EurYtemora a f f i n i s

80.0 (70) 1

61.4 (57)

30.2 (53)

0 (19)

Acartia tonsa

80.0 (30)

85.7 (21)

0 (35)

0 (23)

1 Number of test organisms.

latent mortalities than chlorine alone, whereas temperature without chlorine present did not result in detectable mortali-ties .

A. tonsa exposed to chlorinated water at plume and ambient temperatures displayed 100% mortality within 24 hours (Table VI). Significant reductions in the survival of A, tonsa exposed to chlorine were also noted within 1 hour after testing (Table V).

In summary, the two abundant copepods, A. tonsa and E. affinis appear to tolerate exposure to Indian Point discharge plume AT without adverse effects on survival. However, copepods experiencing plume entrainment may suffer considerable mortali-ty during periods of condenser chlorination.

6. MACROZOOPLANKTON


Gammarus spp. (Gammarus daiberi and Gammarus tigrimis) was selected as the primary test organism to be used in the pre-

IAEA-SM-197 /25 113

liminary plume entrainment studies in 1974. These amphipods are the most abundant macroinvertebrates entrained in the condenser cooling water system at Indian Point. Test organisms were col-lected at the Indian Point Unit 1 intake stations and maintained in the laboratory for at least 4 8 hours prior to experimentation. Microscopic examination of the experimental collections revealed that they were composed primarily of Gammarus daiberi.

Prior to experimentation, 40 Gammarus spp. were randomly sorted into each test container (Figure 2). The containers were constructed of polyethylene jars with areas of the sides (63 x 63 mm) and tops (45 x 45 mm) removed and covered with 571y mesh nylon netting. During the experiment, the test containers were suspended from the floating transit rack (Figure 2). The experimental procedure consisted of three exposure sites:

1) A control area in the Hudson River outside of the de-tectable influence of the Indian Point thermal plume.

2) A 1-hour drift through the Indian Point plume initiated at the confluence of the discharge jet with the water surface.

3) A 1-hour exposure in the Indian Point discharge canal at Station D-2, located just prior to the submerged diffuser ports.

Following plume exposure the test organisms were immediate-ly transported to the Indian Point laboratory and examined for viability. Living organisms were then placed into 800 ml bat-tery jars (20 per jar) and maintained for 5 days after plume ex-posure in Freas Model 818 incubators (Precision Scientific Co., Chicago, Illinois, U.S.A.) which were set at Hudson River ambient temperature.

The aquatic plant Myriophy1lum sp. and assorted green algae served as substrate and food for Gammarus spp. The amphipod's diet was also supplemented with finely ground commercial fish food and pre-soaked maple leaves.

6.1.1 Temperature and Chlorine Avoidance

Laboratory studies were designed to examine the response of Gammarus spp. to heated and chlorinated discharge water in an experimental avoidance chamber (Figure 7). The chamber was constructed of 0.64 cm thick plexiglass. Overall dimensions are 908 nun x 451 mm x 152 mm. The chamber is divided by a vertical plexiglass sheet which separates quadrants 1 and 4. Intake and effluent water are injected at the rates of 5.45 &/min (10.90 £/min total flow) into quadrants 1 and 4, respectively. Constant flow is maintained by head boxes. Some mixing occurs in quad-rants 2 and 3 before the water passes through a 571y mesh nylon screen prior to the drain. Dye studies revealed no transfer of water between quadrants 1 and 4.

During operation the water depth in the chamber was 22 mm. Lighting was provided by two 4 0 W cool-white fluorescent tubes suspended 1.3 m above the chamber.

Experimental procedure consisted of introducing 8 Gammarus spp. simultaneously into the centers of quadrants 1 and 4. Counts of the numbers of organisms in each quadrant were then

114 LANZA et al.

Effluent Water

Intake

Water

FIG. 7. Experimental avoidance chamber.

TABLE VII. SURVIVAL OF Gammarus spp. FOLLOWING 1-HOUR EXPOSURES IN THE INDIAN POINT DISCHARGE CANAL AND DISCHARGE PLUME ON 22 AUGUST, 1974 Ambient temperature = 25.8°C; discharge temperature = 33.0°C

Percent Survival

Station Chlorination n Immediately

af ter exposure 5 Day

Control no 40 100 92.5

Plume no 40 100 85.0

D-2 no 40 100 92.5

Control yes 40 100 87.5

Plume yes 40 100 90.0

D-2 yes 40 100 65.0

TABLE VIII. SURVIVAL OF Gammarus spp. FOLLOWING 1-HOUR EXPOSURES IN THE INDIAN POINT DISCHARGE CANAL AND DISCHARGE PLUME ON 12 SEPTEMBER, 1974. Ambient temperature = 24.0°C; discharge temperature = 32.1°C

Percent Survival

Immediately Station Chlorination n af ter exposure 1 Day 5 Day

Control no 40 100 97 , .5 77 .5

D-2 no 40 100 100 , .0 87.5

Plume no 40 100 97. .5 75.0

Control yes 40 100 100, .0 80.0

D-2 yes 40 100 97, .5 77.5

Plume yes 40 100 97, .5 67 .5

0.64cm Plexiglass

4 i i Drain

IAEA-SM-197 /25 115

made at 5-minute intervals for 60 minutes. Counts were made by two observers, one counting quadrants 1 and 2, the other count-ing quadrants 3 and 4. Temperatures at the mid-depth (11 mm) at points A through G (Figure 7) were measured at 5-minute in-tervals by a YSI telethermometer. Testing of the chamber with Hudson River ambient water introduced into both sides revealed that Gammarus spp. moved freely throughout the four quadrants.

A total of four experiments were conducted during a period when Hudson River ambient temperature varied from 15.3 to 16.0°C. Indian Point discharge temperature ranged from 22.1 to 23.2°C. In the two control experiments, Indian Point intake water was introduced into both sides of the chamber. The two avoidance experiments consisted of introducing intake-heated discharge water and intake-chlorinated heated discharge water.

All of the Gammarus spp. used for temperature-chlorine avoidance were maintained in the laboratory and examined for viability 24 hours after testing.

6.2 Results

The survival of Gammarus spp. exposed to the Indian Point discharge plume using the transit rack is summarized in Tables VII and VIII. There was 100% survival of all test organisms im-mediately after plume exposure. During normal plant operation on August 22, there were no differences between the 5-day sur-vival rates of organisms exposed in the plume, discharge canal or controls maintained outside of the plume. The survivals of Gammarus spp. exposed to the chlorinated plume in the river and at Station D-2 on August 22 were also not different from control survival. There was, however, a reduced survival of those or-ganisms exposed at Station D-2 when compared with the test group maintained in the plume (Table VII).

On September 12 (Table VIII) there were no detectable dif-ferences in latent survival rates among the controls, D-2 or plume exposure groups tested either before or during chlorina-tion. Reduced control survivals during this experiment limits the detection of more subtle differences in latent mortality.

Table IX summarizes the survival of amphipods exposed to "worst possible case" simulation of plume entrainment at dis-charge canal Station D-2. On July 25, during operation of both Indian Point units and chlorination of Unit 2, there were no de-tectable differences in the latent survivals of controls and test groups maintained for 1 hour in the discharge canal. On August 1, the Unit 1 discharge was diluted by a factor of 50% by the operation of two Unit 2 circulating pumps without AT. The amphipods Gammarus and Leptocheirus plumulosus exposed during this period also displayed no reductions in 5 day latent survival when compared with controls.

Preliminary temperature avoidance experiments on Gammarus spp. conducted during normal plant operation at Indian Point (without chlorination) are presented in Table X. The distribu-tion of test organisms in the avoidance chamber indicates that at an ambient temperature of 15.6-15.7°C, there is no detectable response of Gammarus to an approximate 7.3°C AT. The relative

116 LANZA et al .

TABLE IX. SURVIVAL OF Gammarus spp. and Leptocheirus plumulosus FOLLOWING 1-HOUR EXPOSURES AT THE INTAKE AND DISCHARGE CANALS DURING CONDENSER CHLORINATIONS ON 2 5 JULY AND 1 AUGUST 1974

Percent Survival

Date Species Station Temp (°C) n

Immediately a f t e r exposure 5 Day

25 July Gammarus Control 26 .2 40 100 90 .0

D-2 33 .3 40 100 92 .5

1 August Gammarus Control 25.3 40 100 97 .5

D-2 28 .2 40 100 97 .5

Leptocheirus Control 25.3 30 100 96 .7 plumulosus

D-2 28 .2 30 100 93 .3

TABLE X. DISTRIBUTION OF Gammarus spp. IN THE EXPERIMENTAL TEMPERATURE AVOIDANCE TROUGH Tests were conducted during periods of no condenser chlorination

Intake-Intake Time

(min) 1 2 3 4 1 2 3 4

0 5

8 3 7 4

8 2

8 4 5 1

8 6

10 6 2 4 4 5 4 2 5 15 2 8 4 2 6 4 2 4 20 3 4 4 5 5 5 4 2 25 2 5 3 6 3 4 8 1 30 3 8 1 4 2 7 3 4 35 3 6 3 3 0 5 10 1 40 2 5 5 4 0 10 4 2 45 1 5 5 5 1 9 5 1 50 10 5 1 0 0 4 9 3 55 6 6 4 0 0 9 5 2 60 6 6 3 1 0 9 5 2

Mean 95% C . I .

3 .92 + 1 .64

5.58 3 .42 3 .00 ±1.07 ±0 .83 ±1.27

2.17 + 1.48

6 .25 + 1 .51

4 .83 2 .75 ±1 .82 +1.05

occurrence of Gammarus differed among quadrants 1 through 4 in both intake-intake and intake-discharge experiments (Table X). However, there were no apparent differences between the intake-intake and intake-discharge occurrence of Gammarus in quadrants 3 and 4.

The results of monitoring temperature and chlorine levels during the temperature avoidance studies are summarized in Table XI. Note that no residual chlorine (< 0.05 ppm) was seen in the intake samples during the experimental period while a range of < 0.05 to 0.40 was detected in the discharge.

IAEA-SM-197 /25 117

TABLE XI. TEMPERATURE AND CHLORINE DATA COLLECTED DURING TEMPERATURE AVOIDANCE STUDIES

Measurement Point I Box

X Temperature( C)

D Box

Intake-Intake 15.6

Intake-Discharge

(no CI) 15 .7

Intake-Intake 15.4

Intake-Discharge (during CI) 15 .3

15.6 15 .7 15.8 15.9 15 .9 15.9 15.9 15.8

15.7 15.9 16 .0 18.8 22 .5 22 .7 22.8 23.0

15 .4 15 .6 15.7 15.8 15.

15 .3 15 .4 15.6 19 .1 21 . !

15 .7 15.7 15.7

22 .1 22 .1 22.3

Total Chlorine Residual(mg/1) I Box D Box

Intake-Intake X 0 .0 (2 experiments) range 0 .0

0.0 0.0

Intake-Discharge X 0 .0 0 .0 (no C I ) range 0 .0 0 .0

Intake-Discharge X 0 .0 0 .16 (during C I ) range 0 . 0 0 . 0 3 - 0 . 4 0

During chlorination Gammarus spp. avoided quadrant 4, which receives undiluted discharge water (Table XII). The num-bers of Gammarus spp. counted in quadrant 3 were not reduced when compared with pre-chlorination levels. However, all of the test organisms occurring in quadrant 3 during chlorination were positioned centrally near the drainage screen. Dye studies revealed considerable dilution of the heated effluent near the division between quadrants 2 and 3. It appears that Gammarus spp. were able to detect the presence of chlorinated effluent entering quadrant 4 and maintain themselves in areas of little or no chlorine concentration.

Within 24 hours after testing, no mortalities were noted in any of the test groups.

Previous studies have indicated that Gammarus spp. pump-entrained in the Indian Point cooling water systems during con-denser chlorination display increased initial and latent mor-talities when compared with survival during periods of no chlori-nation {8}. Planktonic organisms entrained in the Indian Point condenser cooling water system during normal operation may ex-perience chlorine concentrations in the approximate range of < 0.05 to 0.50 ppm. Since only half of a unit's condensers is chlorinated at a time, the chlorine concentration of the cooling water flow is reduced approximately 50% at the confluence of the condenser water boxes. Moreover, further chlorine dilution may

118 LANZA et al.

TABLE XII. DISTRIBUTION OF Gammarus spp. IN THE EXPERIMENTAL TEMPERATURE AVOIDANCE TROUGH DURING CONDENSER CHLORINATION

Time (min) 1

Intake- Intake

4

Intake-Chlor . Discharge

Time (min) 1 2 3 4 1 2 3 4

0 5

8 6 5 3

8 2

8 8 4 3

8 1

10 6 5 3 2 4 7 5 0 15 5 2 7 2 6 10 0 0 20 4 5 6 1 6 6 4 0 25 4 6 3 3 6 7 3 0 30 3 7 4 2 _ * - - -

35 3 6 6 1 6 9 1 0 40 6 5 4 1 5 6 5 0 45 4 8 2 2 7 6 3 0 50 2 6 3 5 7 6 3 0 55 2 8 4 2 6 6 4 0 60 2 8 6 2 5 8 3 0

Mean 3 . 9 2 5 . 9 1 4 . 2 5 2 .08 6 .00 6 . 8 2 3 . 0 9 0 . 0 9 95% C . I . + 1 . 0 0 ± 1 . 1 0 ± 1 . 0 2 + 0 .69 ±0 .74 + 1 . 1 1 + 1 . 0 2 ± 0 . 2 0

* missed observation

result from the cooling water flow from other units. Consequent-ly, organisms subjected to plume entrainment are exposed to re-duced chlorine concentrations when compared to pumped entrained organisms. In general, it appears that the plume chlorine and temperature combinations resulting from multi-unit operation of the Indian Point station are not directly lethal to Gammarus spp.

7. FISH


Experiments on the effects of simulated plume entrainment of juvenile striped bass (Morone saxati1is) included laboratory and field observations. Juvenile fish used in each study were obtained from the Verplanck hatchery (Consolidated Edison Com-pany-Texas Instruments, Inc.) where they were derived from a Hudson River roe taken in late May 1974 by commercial fisher-men in the Indian Point area.

All fish were transferred from the Verplanck hatchery and acclimated to holding facilities in the New York University Indian Point wet lab, 72 hours prior to use in an experiment. Pre-experiment holding facilities consisted of 81 H (56 x 41 x 36 cm) fiberglass flow-through aquaria receiving a continuous supply of ambient Hudson River water. Each aquarium was also kept in a shallow trough of flowing river w&ter to help maintain ambient Hudson River water temperature. Approximately 100 Morone saxatilis with an average standard length of 62.84 mm (S.E. = 0.30) J were held in each aquarium and fed daily on Tetramin.

3 Formalin preserved.

IAEA-SM-197/25 119

FIG. 8. Schematic of Indian Point cooling water diversion routes with observed discharge canal chlorine levels during "worst possible case" plume entrainment simulation.

Constant aeration provided supplementary oxygen, and the labora-tory fluorescent lighting was on automatic photoperiod providing 12 hours light/12 hours dark per daily cycle.

The same basic procedure was used to prepare fish for all experiments. Each replicate group was isolated from holding aquarium just prior to exposure by randomly selecting and plac-ing ten fish into a plastic test cage with five panels (top and sides) of 1.0 mm mesh size netting (see Appendix 1 for dimen-sions) . Cages were kept submerged in a 75 I pail half-filled with ambient Hudson River water until the beginning of the ex-periment. Mesh was omitted from the cage bottom to allow re-tention of sufficient water to keep the fish submerged during transfer from the holding pails to the study site.

Field studies simulating the plume entrainment of juvenile striped bass involved the transit of caged fish through the Indian Point discharge plume on the organism exposure rack (Fig-ure 2). Four replicate groups of ten fish each were drifted through the plume for one hour in the absence of power plant chlorination followed by a equivalent drift with different fish in the presence of chlorination. Separate control rack drifts were done for each experiment, and all drifts were done on the same day to minimize differences in plume configuration (exclusive of tidal change). Transit rack movement patterns during the experimental period are displayed in Figures 5 and 6.

120 LANZA et al.

TABLE XIII. NUMBER OF JUVENILE Morone saxatilis MORTALITIES FOLLOWING SIMULATED "WORST POSSIBLE CASE" DISCHARGE PLUME ENTRAINMENT AT (UNITS 1 AND 2) AT THE INDIAN POINT NUCLEAR STATION

24 hours Immediate* Post -exposure

Total Control Replicate Dead Alive

1 1 2 3 7 2 0 0 0 10 3 0 2 2 8 4 0 1 1 9

AT Replicate

1 5 0 5 5 2 5 0 5 5 3 6 0 6 4 4 5 0 5 5

* Immediately following one hour exposure.

Laboratory experiments involved the exposure of juvenile striped bass to one type of simulated "worst possible case" plume AT using heated cooling water diverted from the plant dis-charge canal prior to, and during chlorine application. In these experiments, water was pumped through PVC pipelines from the intake and discharge canals to control and experimental ex-posure aquaria in the Indian Point wet lab. The aquaria held 37.85 i (51 x 31 x 27 cm) and canal water was allowed to enter and overflow the aquarium sides continuously during the course of an experiment. The exposure consisted of immersing four re-plicate cages in an aquarium for one hour. Chlorine levels were measured in all experiments to characterize residual levels during chlorination, and to confirm the absence of detectable levels when no chlorination was occurring. A schematic of the cooling water diversion routes, and a graphic summary of observed total residual chlorine levels is provided in Figure 8. At the conclusion of an experiment, fish were examined for immediate mortality and survivors were retained for 24 or 96-hour periods to permit observation of latent effects. Survivors in each re-plicate group were placed in separate 37.85 £ (51 x 31 x 27 cm) glass covered aquaria filled with filtered Hudson River water at ambient temperature. All other holding conditions were the same as described for pre-experimental periods.

7.2 Results

Tables XIII - XVI provide the results of experiments simu-lating the plume entrainment of Morone saxatilis juveniles. Tables XV & XVI summarize the results of exposure to the dis-charge plume using the transit rack. No immediate mortality was noted in juvenile fish exposed to plume AT alone (Figure 5, Table XIII) or plume AT with Unit 1 chlorination (Figure 6, Table XIV). Observations for latent mortality in groups exposed

IAEA-SM-197 /25 121

TABLE XIV. NUMBER OF JUVENILE Morone saxatilis MORTALITIES FOLLOWING SIMULATED "WORST POSSIBLE CASE" DISCHARGE PLUME ENTRAINMENT AT (UNITS 1 AND 2) WITH CHLORINATION AT THE INDIAN POINT NUCLEAR STATION

24 hours Immediate* Post-exposure


1 1 0 1 9 2 1 1 2 8 3 1 0 1 9 4 1 0 1 9

AT with Chlorination Replicate

1 5 0 5 5 2 5 0 5 5 3 4 0 4 6 4 2 0 2 8

* Immediately following one hour exposure.

TABLE XV. NUMBER OF JUVENILE Morone saxatilis MORTALITIES FOLLOWING EXPOSURE TO THE INDIAN POINT NUCLEAR STATION DISCHARGE PLUME

Post -Exposure time in hours I* 24 48 72 96


1 0 0 0 0 0 0 10 2 0 0 0 0 0 0 10 3 0 0 0 0 0 0 10 4 0 0 0 0 0 0 10

AT Replicate

1 0 0 0 1 0 1 9 2 0 0 0 0 0 0 10 3 0 0 0 0 0 0 10 4 0 0 0 0 0 0 10

* Immediately following one hour t r a n s i t exposure.

to plume AT and plume AT with chlorination indicated one and two dead fish respectively at 72 hours post-exposure. Control groups had 100% survival over the 96-hour period. Statistical examina-tion indicated that the observed differences in mortality be-tween the experimental and control groups were not significant.

Tables XIII & XIV provide the results of the laboratory simu-lations of "worst possible case" discharge plume entrainment at

122 LANZA et al.

TABLE XVI. NUMBER OF JUVENILE Morone saxatiles MORTALITIES FOLLOWING EXPOSURE TO THE INDIAN POINT NUCLEAR STATION DISCHARGE PLUME DURING UNIT 1 CHLORINATION

Post -Exposure time in hours I* 24 48 72 96

Total Control Replicate Dead Al ive

1 0 0 0 0 0 0 10 2 0 0 0 0 0 0 10 3 0 0 0 0 0 0 10 4 0 0 0 0 0 0 10

T with Chlorination Replicate

1 0 0 0 1 0 1 9 2 0 0 0 1 0 1 9 3 0 0 0 0 0 0 10 4 0 0 0 0 0 0 10

* Immediately following one hour t rans i t exposure.

the Indian Point station. Immediate mortalities in juvenile fish exposed to simulations of a plume AT of 6.8°C reached 50 percent in three replicate groups and 60 percent in the fourth group. Control groups at the river ambient temperature of 24.0°C had one mortality in one replicate group (10 percent) and 100 percent survival in the other three groups (Table XIII).

Observations for latent mortality (24 hours post-exposure) indicated no additional deaths in any experimental group with 2, 0, 2 and 1 additional deaths in control replicate groups 1, 2, 3 and 4 respectively (Table XIII).

Immediate mortalities of juvenile fish exposed to simula-tions of a plume AT of 6.9°C and residual chlorine levels at-taining 0.16 ppm during Unit 2 chlorination (see Figure 8 for measured chlorine levels during the exposure period) ranged from 20-50 percent mortality with control mortalities of 10 per-cent or one fish per replicate (Table XIV). Observations for latent mortality (24 hours post-exposure) indicated no addition-al deaths in any experimental group with one added mortality in one control replicate group (Table XIV).

Statistical analyses using 8 x 2 Contingency Tables showed significant differences, but the G-test on all possible combina-tions or rows and columns failed to reveal the location of the differences. When all control, plume AT and plume AT with chlorination exposure groups were combined by group to form 2 x 2 contingency tables, analysis indicated significant dif-ferences in mortality between all control and experimental groups at immediate and latent observation times.

IAEA-SM-197 /25 123

Contingency table analysis (8 x 2) on the numbers dead and alive upon immediate and latent observations for each AT and AT with chlorination group from field transit and laboratory simu-lations shows no significant differences among the eight rows. Additional comparisons made among the control groups, AT groups, and AT with chlorination groups failed to detect any significant differences; therefore, indicating that observed chlorine levels did not appear to add significant mortality to that produced by AT.

The present studies are interesting in light of recent lab-oratory investigations on the temperature preference of Hudson River striped bass juveniles {9}. The results of these studies indicate that fish acclimated to an ambient temperature of 24.0°C exhibit preference for a temperature of 29.0°C during 1.5 hour exposure periods. If populations of striped bass juveniles ex-hibit temperature preference in the natural habitat, movement into plume areas elevated to the preferred temperature (29°C) could be anticipated. The resulting plume temperatures would be only 1.8-1.9°C below those observed to produce significant mor-talities at similar exposure times in the present studies. Thus, future studies should include careful field surveys of plume areas, and investigations of the temperature preference-avoidance patterns of striped bass juveniles acclimated to temperatures of 24.0°C and above. Emphasis should be placed on preference, avoidance, and avoidance breakdown patterns and the effects of residual chlorine on those patterns.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the invaluable assistance of the following: Ms. Judy Lefkowitz for statistical analyses, Ms. Karen Eichorn for phytoplankton identification,~^Mr. Roger Sparling for graphics, and Ms. Julie Cordisco for typing the manuscript.

REFERENCES

{1} Scheffe, H., Analysis of Variance, Wiley, New York (1959) 6 6 .

{2} Sokal, R., Rohlf, J., Biometry, W.H. Freeman Co., San Fran-cisco, California (1969) 582.

{3} Vollenweider, R. (ed.), A Manual on Methods for Measuring Primary Production in Aquatic Environment IBP Handbook No. 12, F.A. Davis Co., Philadelphia (1969) 41.

{4} Steemann Nielsen, E., Use of Radioactive Carbon (C-14) for Measuring Organic Production in the Sea, J. Cons. Sit. Explor. Mer. 18 (1952) 117.

{5} Saunders, G., Trama, F., Backman, R.W., Evaluation of a Modified 14C Technique for Ship Board Estimation of Photo-synthesis in Large Lakes, Great Lakes Res. Div. Pub. 8 (1962).

124 LANZA et al.

{6} Wang, C.H., Willis, D.L., Radiotracer Methodology in Biological Science, Prentice Hall, New York (1965) 382.

{7} Strickland, J.D.H., Parsons, T.R., A Practical Handbook of Seawater Analysis, Fisheries Research Board of Canada (1972) 310.

{8} Ginn, T.C., Waller, W.T., and Lauer, G.J., The Effects of Power Plant Condenser Cooling Water Entrainment on the Amphipod, Gammarus spp., Water Res. (1974) 937.

{9} Texas Instruments Incorporated, Hudson River Ecology Study in the Area of Indian Point (1974) V-7.

Appendix 1. SPECIFICATIONS OF ORGANISM CONTAINERS,

Phytoplankton Bottle

Height- 13.21 cm Diameter- 5.08 cm Volume- 300 ml

Macrozooplankton Cage

Top- 10.0 cm square (approximately 4.50 cm square 0.571 mm mesh panel)

Sides- 13.5 cm high (approximately 6.30 cm square 0.571 mm mesh panel)

Bottom- 8.5 cm square (no mesh) Volume- 946 ml

Fish Cage

Top- 12.5 cm square (approximately 9.00 cm square 1.0 mm mesh panel)

Sides- 17.0 cm high (approximately 9.00 cm square 1.0 mm mesh panel)

Bottom- 9.0 cm square (no mesh) Volume- 1.946 1

D I S C U S S I O N

F . B . HA WES (Chairman): Have I understood correct ly that the plume is jetted into the Hudson? Is this done by pumps o r through building up a head of water by restrict ing f low?

G . R . LANZA: Y e s , the discharge configuration I descr ibed has 12 rectangular ports (1.22 m X 4 .57 m) located 3.35 m below the mean low-water level . Ten of these ports are fitted with adjustable gates permitting regulation of flow through the submerged ports at 3 . 0 m / s . The remaining two ports are not adjustable and must be kept either completely open o r c losed . The water exit velocity can only be controlled by port

IAEA-SM-197 /25 125

opening adjustments, which regulate the head on the open ports . Head requirements on the c irculator water pumps are partially determined by the water level in the discharge canal.

J . J . COHEN: You stated that a simulated wors t - case plume produced significant mortal i t ies . Can I assume that this means the 'statistical s ignif icance ' under your experimental conditions. Otherwise the statement might give the impress ion that there could be a significant reduction in the striped bass population of the Hudson River estuary. Is this what you intended?

G . R . LANZA: Y e s , I was re ferr ing to statistical s ignif icance. Direct extrapolation of the results to actual striped bass populations is not at present feasible f o r many reasons . For example, the studies described in our paper are prel iminary in nature and are , of necess i ty , limited to small numbers of a single life stage ( i . e . juvenile) of striped bass . At this phase of the research , we are a long way f r o m providing accurate estimates of the ultimate ef fect of plume entrainment on striped bass populations.

S. HARTWIG: In several countries there are fish fa rms associated with nearby power stations. In view of your mortality f igures for m i c r o -organisms, do you see any chances of fish farms being established near the station site under discussion?

G . R . LANZA: To my knowledge, studies of the feasibility of fish production in controlled pond environments, i . e . fish farming, have not been given serious consideration at Indian Point. A lot would depend upon which fish spec ies came into question. Striped bass would not be a spec ies readily producible in conventional ponds. This type o f f i s h production is under study at power stations elsewhere in the USA, as well as in Europe.

J. SHAH: In the light of your work, what general constraints do you suggest on, f irst , the siting of multiple nuclear power plants on estuaries, and, second, the design of cooling water discharge outfall. I realize that some of the constraints would be speci f ic for speci f ic s ites , but some general constraints can obviously be deduced f r o m your studies.

G . R . LANZA: The importance of estuaries as "b io f i l t e rs " between r iver and ocean, as areas of unique productivity, and as spawning grounds for many important spec ies is well recognized. One would hope to see great care exerc ised in considering estuarine areas as power plant sites. In general , power plants of any fuel type should be sited by carefully matching a spec i f i c locality within a given ecosystem with a particular power plant design and operational mode. If the match is not possible, then we must accept that fact . We should also consider the type and location of other power plants in the same estuary in order to anticipate correct ly multi-plant impact.

H. FUCHS: Are there any plans for a fourth unit at the Indian Point s ite? If so, would you say that r iver water cooling would still be possible in view of the results of your studies?

G . R . LANZA: There are no such plans to my knowledge. Originally, there were pro jects for other nuclear facil it ies in the general area of Indian Point, but they have not been pursued in recent years . This is largely due to opposition by certain groups of the population.

P . G . ROLLIN: Studies carr ied out in France in water heated by a thermal power station have shown a marked increase in the photosynthetic activity of phytoplankton due to the temperature r i se . The studies were made, incidentally, between May and August, which is a period when

126 LANZA et al .

phytoplankton is abundant. Your investigations, on the contrary, indicate a drop in activity. I am wondering how this discrepancy can be explained.

G . R . LANZA: That question could best be answered by comparing your data with ours . It would be particularly interesting to compare the details of the community structure ( e . g . kinds of species and numbers of each kind), of our respect ive algal assemblages and also to compare the levels of 14C activity, chlorophyll -a content and temperature r eg imes . As you wil l reca l l , we found different responses with different communities during our studies. A l so , the assemblages in our studies were probably exposed to different environmental conditions than those observed by your group. F o r example, our assemblages were exposed to a changing, rather than a constant, temperature regime f o r a relatively short period, i . e . one hour.

IAEA-SM-197/10

EFFECT OF ENTRAINMENT IN POWER STATION COOLING SYSTEMS STUDIED USING PERIPHYTIC COMMUNITIES

E. SMEDILE Ente Nazionale per l'Energia Elettrica, Rome

V. PARISI Parma University, Italy

Abstract

EFFECT OF ENTRAINMENT IN POWER STATION COOLING SYSTEMS STUDIED USING PERIPHYTIC COMMUNITIES.

In the context of ecological research on the impact o f power stations on the aquatic environment this paper describes evaluations o f such impacts on suspended organisms entering the plant cooling system entrained in the cooling water. A particular dynamic study of entrainment is the comparison o f the ability o f suspended organisms sampled in the river water ahead of the plant and in the discharge canal to co lonize immersed substrates. The dynamics of colonization has been examined in aquaria in which water was circulated that had come either from the intake or from the outfall o f La Casella Power Plant. The numbers o f systematic groups, their corresponding biomasses and the dimensional structure of animal and plant populations were determined. The data col lected show how a temperature rise modifies the characteristics o f a periphytic community and the dynamics of colonization o f immersed substrata.

1. INTRODUCTION

The environmental ef fects of power plants can be c lassi f ied in two categories : (A) Ef fec ts occurr ing within the plant; those involved with the water removed

f o r cooling purposes and organisms within that water; (B) Ef fec ts occurr ing outside the plant; those involved with the ef fects of

the cooling water discharge on the source body of water and its biota. Biota affected by internal impacts are those entrained in the cooling

water and drawn involuntarily into the plant. Small life f o rms are carr ied through the cooling system and are discharged with the effluent water.

The principal changes occurr ing during their passage through the cooling system are : increase in pressure caused by the pumps, r ise in temperature, injection of b ioc ides , turbulence in the pumps at the entrance to the condenser tubes and in the discharge culverts. Markowski [1 ] was among the f irst to study the ef fects of a power plant on plankton. He compiled data for 12 power stations ( fresh water, estuarine water, sea water) in England.

More recently Mihursky [ 2 ] , Morgan and Stross [ 3 ] , Heinle [ 4 ] and Koops [ 5 ] for estuarine sites, Witheouse [ 6 ] and Brauer et al. [ 7 ] for lacustrine sites , and Foster et al . [ 8 ] and Coutant [ 9 ] for r i ve rs , have studied the damage to organisms caused by passage through the power station. These studies were aimed at quantifying the di f ference in biota

127

128 SMEDILE and PARISI

composition between the intake and outfall and to evaluate the detrimental e f fects on the organisms found. However, it is questionable [10 ] whether results of short - term intake and discharge entrainment studies can be used to study the actual or l ong- term ef fects of power plant entrainment upon organisms.

The above-mentioned entrainment and post-entrainment culture studies, which may be very ef fect ive in the evaluation of ef fects on zooplankton, seem too difficult to make for power stations located near r ivers characterized by very poor plankton.

F o r such situations, it seems particularly useful to utilize a more dynamic study method for evaluating the nature of entrainment ef fects , such as the comparison of the ability of suspended organisms, sampled both in the r iver water upstream of the plant and in the discharge canal, to colonize immersed substrata.

This approach is no substitute f or intake and outfall sampling, but it provides additional information on the entrainment ef fects and the techniques that can be applied to alleviate the problem in a power plant.

The present study is carr ied out as part of the co-ordinated hydro -bio logical investigations intended for evaluating the internal impacts of the La Casella Power Plant.

The La Casella plant is an o i l - fuel led 1260 MW(e) power plant located on the River Po downstream of one of the most industrialized regions of northern Italy.

The biota entering the plant are composed mainly of autotrophic organisms; the r iver periphytic community is very complex, its allochtoncus component often f o r m s a large portion of all organisms present.

The importance of periphytic communities in thermal eco logy studies has always been recognized; many authors [ 11 -13] have used the periphyton to evaluate di f ferences existing before and after the plant. There are , how-ever , no data concerning the use of artif icial substrata in the entrainment studies.

F o r the purposes of the present study the f irst experimental approach was to evaluate the early colonization of substrata in aquaria in which water was being circulated that came f r o m either the intake or outfall of the La Casella Power Plant.

2. METHODS

The experimental apparatus compr ises two 100 litre aquaria (one f o r the " co ld " and the other for the " w a r m " water) and microscope sl ides which are suspended in the aquaria to serve as substrates f o r colonization.

This experimental apparatus is operated under controlled conditions of light and temperature. The illumination is derived f rom eight solar lamps. The lamps are switched on and off automatically to simulate the external conditions: in particular, f r o m 5 to 9 a . m . four lamps were lit; f r o m 9 a . m . to 7 p . m . all eight lamps were lit; f r o m 7 to 9 p . m . again only four lamps were lit; while for the remaining 12 hours all the lamps were turned of f . The maximum luminous intensity at the surface of the water was 1200 lux.

The " co ld " water came directly f r om the River Po, while the "warm" water came f r o m the discharge canal in an open circuit; the water flow was

IAEA-SM-197/16 129

about 4000 m J / m i n . The microscope slides were suspended vertical ly in the aquarium grouped 3 X 3 ; eight groups were of untreated sl ides, while eight further groups of slides were treated with a thin layer of special Agar Noble Difco 1% to simulate an organic input.

E v e r y 24 hours we sampled two groups of sl ides (one untreated, one treated with agar) for both the cold and warm aquaria. The samples were immediately processed , with counting and identification of organisms being done under m i c r o s c o p e s at a magnification of X 200.

F o r every group composed of three sl ides, three counts were made. For each slide 20 m i c r o s c o p i c ' f ie lds ' were counted. The actual counts made under the microscope were extrapolated to determine the number of organisms o r number of individual spec ies per unit of surface (cm2) of slide.

The b iomasses were estimated in relative units (R. U . ) by measuring with the mic rometr i c ocular the size of the organisms and, by computation, the volume of the s imi lar geometr ic f o rm was obtained. The investigation covered a period of eight days, f r o m 8 July to 15 July 1974. During this period the power plant operation was constant apart f r o m the 5th day, when there was a shutdown (Fig. 1). The chemical parameters (pH-value and conductivity) of the water were s imilar in the two aquaria; the oxygen

(Text continues on page 139.)

July 1974 FIG. 1. La Casella Power Station. Gross electrical power.

CO o

FIG.2. La Casella Power Station. Diurnal variation of temperature (inlet and outlet).

IAEA-SM-197/6 131

July 1974

FIG. 3. Daily fluctuations o f water level o f the River Po.

TABLE I. COMPOSITION OF BIOSESTON SAMPLED IN THE 'COLD' AND 'WARM' AQUARIA Phytoplankton c e l l / i ; zooplankton individuals/m3 .

'Cold ' 'Warm'

Diatoms 800 000 800 000

Green algae 400 000 350 000

Total phytoplankton 1200 000 1 150 000

Copepods 2 000 2 500

Cladocerans 800 500

Rotifers 30 000 25 000

Total zooplankton 32 800 28 000


Q

<M *" < zui3 jed s||ao

FIG. 4 . Dynamics o f colonization o f substrata by diatoms. A — centimetre; B — data expressed as R. U. per square centimetre.

data expressed as cells per square CO CO


O

jUUD Jed SUdO

540-1 CILIATED PROTOZOA

450

DAY

KEY:

• Glass slides (cold) o Glass slides (warm) • Glass slides with agar (cold) • Glass slides with agar (warm)

FIG. 5. Dynamics of colonization of substrata by ciliated protozoa. A — data expressed as cells per square centimetre; B — data expressed as R.U. per square centimetre.

ROTIFERS

KEY:

B Glass slides (cold) o Glass slides (warm) • Glass slides with agar (cold) • Glass slides with agar (warm)

FIG. 6. Dynamics of colonization of substrata by rotifers. A — data expressed as individuals per square centimetre; B — data expressed as R.U. per square centimetre.

SCALE H = 10 O R G A N I S M S

COLD

G L A S S SLIDES

W A R M

GLASS SLIDES W I T H AGAR

S I Z E V IV I I I II

<1 I

EE 3 T~ T

FIG. 7. Dimensional structure of periphytic community on the 3rd day. Size I £10 fjm Size IV 41 - 80 pm Size II 11 - 20 jjm Size V 81 - 160 (jm Size III 21 - 40 jjm

IAEA-SM-197/6 139

content was > 7 m g / l in both cold and warm aquaria. Figure 2 shows the temperatures of the River Po and of the discharge canal: the maximum intake-discharge temperature dif ference was 7°C. The water level of the r iver was constant during this period (Fig. 3).

F o r re ference we sampled the bioseston entering the aquaria f r o m both the intake and the outfall. The compositions were very s imi lar (Table I).

3 . RESULTS AND DISCUSSION

3 . 1 . Dynamics of colonization

The dynamics of colonization of diatoms, protozoa and rot i fers is illustrated in Figs 4, 5 and 6.

F irs t day. The organisms colonizing the glass slides were principally diatoms, green algae, flagellata and ciliated protozoa. There was no evident dif ference between different substrates and different thermal conditions (Table II).

Second_da^. On V . F . 1 there was a conspicuous increase of diatoms, while green algae were constant (the algae were generally more abundant at the " co ld" temperature) ; ciliated protozoa increased particularly in A . F . j rot i fers appeared (Table III).

Third da^. Typical di f ferences between substrata appeared. On V . F . the primary producers showed a remarkable increase in both density and b iomass . Some uncommon groups like Gastrotricha appeared. O n A . F . a decrease of diatoms and ciliata with a simultaneous increase of green algae and roti fers were observed . On V. C. a decrease of the b iomass of primary producers and an increase of Ciliata Peritr icha were observed . Some f latworms appeared. O n A . C . , diatoms and ciliata (except f o r C. Peritricha) decreased and green algae increased (Table IV).

Seventh_day. The detritus caused serious problems in the counting; so we limited the microscope examination to the most obvious organisms. Rot i fers showed a very large increase on V . C . and A . F . ; Gastrotricha showed a small increase , and some Oligocheta appeared.

3 . 2 . Dimensional structure

Our previous paper [14 ] recognized the importance of the size of the organisms colonizing the substrata under different thermal Conditions. Figure 7 shows the dimensional pyramids for different thermal conditions for each substrate.

The V . F . pyramid is the most regular; either organic or thermal input modi f ies this structure markedly.

Computing the sum of the di f ferences between the dimensional c lasses for pairs of glass s l ides , it is possible to draw a diagram to illustrate this dif ference (Fig. 8).

1 V. F. = Slides (river temperature); A. F. = Slides (with agar, river temperature); V. C. = Slides (canal temperature); A . C . = Slides (with agar, canal temperature).


TABLE II. 'FIRST DAY' NUMBER OF ORGANISMS BELONGING TO PRINCIPAL GROUPS FOUND ON THE SUBSTRATES Density expressed as cel ls per cm2 ; b iomass ( ) expressed as R. U. per cm2 ; mean of three countings.

V.F. V . C . A . F. A . C .

Diatoms 79 (18) 100 (39) 65 (49) 77 (50)

Green algae 113 (7) 38 (4) 160 (6) 125 (57)

Ciliated protozoa (Peritricha)

91 (45) 30 (14) 10 (11) 0

Ciliated protozoa (others)

96 (27) 0 96 (79) 27 (20)

Flagellata (small forms)

200 (5) 124 (3) 253 (V 219 (5)

TABLE III. 'SECOND DAY' NUMBER OF ORGANISMS BELONGING TO PRINCIPAL GROUPS FOUND ON THE SUBSTRATES Density expressed as cel ls per cm2 ; b iomass ( ) expressed as R. U. per cm2 ; mean of three countings.

V. F. V. C. A . F. A . C .

Diatoms 1483 (404) 81 (303) 1402 (335) 725 (163)

Green algae 112 (52) 172 (30) 115 (10) 53 (110)


146 (160) 18 (16) 231 (225) 104 (98)


224 (209) 62 (39) 277 (194) 110 (62)


1636 (50) 160 (5) 2061 (63) 367 (11)

Rotifers 10 (29) 7 (47) 0 23 (141)

IAEA-SM-197/6 141

TABLE IV. "THIRD DAY' NUMBER OF ORGANISMS BELONGING TO PRINCIPAL GROUPS FOUND ON THE SUBSTRATES Density expressed as ce l ls per cm 2 ; b i omass ( ) expressed as R . U . per cm2 ; mean of three countings.

V. F. V . C . A. F. A . C .

Diatoms 2118 (701) 210 (110) 335 (205) 329 (238)

Green algae 1011 (40) 39 (4) 300 (35) 124 (22)


60 (53) 203 (39) 114 (42) 157 (100)


239 (311) 63 (33) 187 (229) 73 (62)


5648 (173) 245 (7) 835 (26) 255 (8)

Rotifers 42 (205) 7 (59) 21 (112) 10 (29)

Gastrotrics 10 (30) 7 (18) 0 5 (16)

Flatworms 0 5 (57) 0 7 (57)

• " " (DISCHARGE TEMPERATURE;

O >< WITH AGAR (RIVER TEMPERATURE)

• » (DISCHARGE TEMPERATURE)

FIG. 8. Schematic view o f the differences between the experimental conditions. (The distance is the sum o f the differences between the substrates regarding dimensional classification, e . g . if Ai is the biomass o f the first size class for V. F . , A2 for V. C . , and Bj is the biomass of the second size class for V. F . , Bt for V. C . , the distance is (|AX - A2| + | Bx - Bzl + ).

4 . CONCLUSIONS

Although our experimental data are yet preliminary and more invest i -gations are necessary , it seems possible to draw some conclusions.

4 . 1 . F r o m a comparison of the 'patterns' of colonization it is possible to hypothesize that the functional capacity of the tygmophil organisms of the bioseston is not affected by the passage through the condensers .

On the V . F . substrate a higher density and greater abundance is found; this i s more evident for the primary producers than f o r other systematic groups.


4 . 2 . The analysis of dimensional structure (Figs 7 and 8) seems to conf i rm that V. F . may be termed the 'natural condition'. Both the para-meters , temperature and substrate, modify the dimensional structure, with otherwise only small d i f ferences .

4 . 3 . Both the dynamics of colonization and the dimensional analysis allow one to conclude that the early colonization method may be useful in explaining some aspects of entrainment e f fec ts .

R E F E RE N C E S

[ 1 ] MARKOWSKI, S. , The cooling water o f a power station: a new factor in the environment of marine and fresh water invertebrates, J. Anim. Ecol. 28 (1951) 243.

[ 2 ] MIHURSKY, J. A. , Patuxent thermal studies: Summary and recommendations, University o f Maryland, Natural Resources Inst. , Special Rep. No. 1 (1969).

[ 3 ] MORGAN, R. P . , STROSS, R. G. , Destruction of phytoplankton in the cooling water supply o f a steam electric station, Chesapeake Sci. _10 3, 4 (1969) 165.

[ 4 ] HEINLE, D . K . , Temperature and zooplankton, Chesapeake Sci. _10 (1969) 186. [ 5 ] KOOPS, F. B. J. , Hydrobiological investigations on the consequences of the use of surface water for

cooling purposes in the Netherlands, Paper at 9th WEC-CME (Detroit, 1974). [ 6 ] WITHEOUSE, J. W . , Some aspects o f the biology o f Lake Trawsfynydd, a power station cooling pond,

Hydrobiologia 38 2 (1971) 253. [ 7 ] BRAUER, G. A . , NEILL, W . H . , MAGNUSON, J. T . , Effects of power plants on zooplankton distribution

and abundance near plants effluent, Water. Res. 8 7 (1974) 485. [ 8 ] FOSTER, R. F. , JASKE, J. , TEMPLETON, W. L. , "The biological cost of discharging heat to rivers",

Proc. 4th Int. Conf. Peaceful Uses At. Energy (Proc. Conf. Geneva, 1971) _11, UN, New York, and IAEA, Vienna (1972) 631.

[ 9 ] COUTANT, C . C . , Effects on organisms of entrainment in cooling water, Nucl. Safety 12 6 (1971) 600. [ 1 0 ] JOHNS HOPKINS UNIVERSITY, Electric Power Research Institute, Cooling Water Research Project RP 49,

5th Progr. Rep. (1973). [ 1 1 ] OWEN, B.B. , Columbia River Periphyton Communities under Thermal Stress, Battelle Northwest Rep.

BNWL-1550, Vol. 1, part 2 (1971). [ 1 2 ] TAYLOR, P.W. , Thermal Effects on the Periphyton Community in the Green River, Tennessee Valley

Authority Technical Report (1973). [ 1 3 ] COUTANT, C . C . , OWEN, B.B. , Productivity of Periphyton Communities under Thermal Stress,

Battelle Northwest Rep. BNWL-1306, V o l . 1 , part 2 (1970). [ 1 4 ] SMEDILE, E. , PARISI, V. , Primi risultati di esperienze condotte in ambiente controllato sugli effetti

di apporti organici e termici sulle biocenosi perifitiche, l 'Ateneo Parmense £ 1 (1973) 3.

D I S C U S S I O N

Y . S . SOUSSELIER: I would like to say, as a comment on your paper, that I feel it very important to continue the type of studies you have descr ibed , on re leases f rom coal - and o i l - f i red thermal power stations. The combined e f fects of thermal and chemical effluents are not, after all , speci f ic to nuclear power plants and apply likewise to conventional power stations. This is all the more true in that the radioactive effluent re leases f r o m nuclear plants are extremely small . I therefore think the experience gained with conventional plants should be used in conjunction with the other studies presently under way.

E . SMEDILE: Yes , I certainly agree . The problems presented by conventional and nuclear power plants are very s imilar and the research methods used are basical ly the same .

Session IV

EFFECTS OF CHEMICAL RELEASES ON RADIONUCLIDE UPTAKE

Chairman: J. WEBER (The Netherlands)

IAEA-SM-197/10

TECHNIQUES DE DETERMINATION RAPIDE DES EFFETS DE SYNERGIE RADIONUCLEIDES — POLLUANTS

A. SAAS, A. GRAUBY CEA, Departement de protection, Centre d*etudes nucl£aires de Cadarache, St-Paul-lez-Durance, France

Abstract-R6sum£

TECHNIQUES FOR RAPID DETERMINATION OF EFFECTS OF SYNERGY BETWEEN RADIONUCLIDES AND POLLUTANTS.

The authors present a number o f chromatographic techniques for rapid determination of synergy between radionuclides and various compounds in water. The first technique consists in studying how the chemical equilibrium o f iodine varies in the presence o f various organic and mineral compounds. The second makes it possible to define the effects o f synergy within a given hydrographic basin. A third technique deals with the effects of synergy in ground water in the presence o f various types o f irrigation water. Finally, to complete this set of techniques, the authors define the mobility potential o f a radionuclide in a given aqueous effluent.

TECHNIQUES DE DETERMINATION RAPIDE DES EFFETS DE SYNERGIE RADIONUCLEIDES - POLLUANTS. Les auteurs presentent un ensemble de techniques chromatographiques permettant de determiner

rapidement les effets de synergie entre les radionucleides et les diff&rents composes presents dans l 'eau. La premiere technique consiste a Studier la variation de l'dquilibre chimique de l ' i ode en presence de divers composes organiques et miner aux. La seconde permet de definir les effets de synergie & 1'interieur d'un bassin hydrographique donne. Une troisifeme traite des effets de synergie dans les eaux du sol en presence de diverses eaux d'irrigation. Enfin, pour harmoniser l 'ensemble de ces techniques, on definit le potentiel de mobility d'un radionucl&ide dans une eau de rejet d6terminee.

INTRODUCTION

Dans le cadre des etudes radioecologiques des sites nucleaires , il est necessaire d'evaluer globalement l ' ensemble des parametres susceptibles d 'avoir un effet sur la dynamique d'un rejet d'effluents radioacti fs dans un bassin hydrographique donne. Si la nature physico-chimique du rejet a ete etudiee d'une facon prec ise pour suivre son evolution, i l semble que la qualite des eaux dans lesquelles sont relaches les effluents n'ait pas encore retenu toute l'attention necessa ire . Le role de la qualite des eaux a recu une confirmation a poster ior i par des re leves in situ de la radioactivite des sediments du cours d'eau [ 1 j . II parait utile a present de pr6voir cas par cas les ef fets de synergie entre les radionucleides et les eaux. C'est pourquoi nous nous s o m m e s attaches & mettre au point des techniques originales adequates qui permettent d 'apprec ier rapidement les facteurs devolut ion de la nature physico-chimique des radionucleides re je tes . Au cours de travaux anterieurs [ 2 - 4 ] nous avions deja esquisse des techniques identiques pour evaluer les effets de synergie entre l 'eau d ' irrigation et les

145

146 SAAS et GRAUBY

so l s . La presente etude a pour but d 'exposer un ensemble de techniques rapides pour evaluer les d iverses interferences et de definir, a partir de ces donnees, la notion de « potentiel de mobilite des r a d i o n u c l i d e s » .

1. PRINCIPE GENERAL DES TECHNIQUES UTILISEES

L 'ensemble des techniques chromatographiques utilis6es se fonde sur l 'etude de la reaction d'un rejet d'effluent avec le milieu liquide rencontre. Pour cela nous disposons une fraction du rejet , soit sur du papier chromato graphique, soit sur des plaques de gel de si l ice impregnees de divers constituants, et nous utilisons le milieu liquide comme solvant; l 'eau distillee serv ira d*element de re ference . Apres migration, une autoradio-g raphy permet de loca l i ser les r a d i o n u c l i d e s et les differents composes f o rmes ; la mobilite est appreciee par la position sur la plaque par rapport au temoin. Les variantes de cette technique (impregnation par des compos6 connus ou des eaux connues, impregnation avec des 6changeurs d'ions) permettent de prevoir differentes reactions ainsi que les variations physico-chimiques du radionucleide au cours du rejet et lors de son transport dans la veine liquide. La figure 1 donne un apercu d'une autoradiographic apres migration en presence d'eau de mer sur des plaques de gel de silice impregnees de diverses res ines .

GEL DE SILICE IMPREGNE( D O W E X 5 0 x 8 - H * )

Sr M n Co C e Cs Zn Fe Na Sb

GEL DE SILICE IMPREGNE ( D O W E X 2 x 8 - OH")

Sr M n Co Ce Cs Zn Fe Na Sb

FIG. 1. Aperqu d'une autoradiographic aprfes migration. Vecteur: eau de mer.

IAEA-SM-197 /14 147

2. TECHNIQUE DE DETERMINATION DE L'EVOLUTION PHYSICO-CHIMIQUE D'UN REJET SOUS L ' E F F E T DES COMPOSES ORGANIQUES ET MINERAUX PRESENTS DANS L'EAU

Certains re jets radioactifs renferment plusieurs f o r m e s chimiques dif férentes du même radioélément; c 'est le cas notamment des éléments métalliques et des anions, qui peuvent prendre plusieurs valences ou f o r m e r des complexes à charge variable. Dans ces conditions, les polluants présents dans le milieu sont de nature à faire évoluer ces f o r m e s . Nous i l lustrons cette technique par l ' exemple de l ' i ode . Dans un rejet liquide nous pouvons trouver principalement cinq f o rmes chimiques: des iodures et polyiodures, des iodates, des periodates, des iodes organiques et enfin de l ' iode l ibre . Le cyc le biologique, l es modalités de transfert et les facteurs de concentration dans les différents milieux varient en fonction de la forme chimique considérée . Il nous a paru important de déterminer rapidement les effets de synergie des principaux constituants de l ' eau à l 'aide d'une technique rapide.

A cet effet , on divise une plaque de gel de si l ice en bandes; chaque bande est imprégnée d'une aliquote (0,5 ml) d'un constituant du milieu: calcium, f e r , zinc, acides aminés, phénols, e t c . ; on dépose ensuite une aliquote de l 'effluent renfermant l ' iode (2 à 20 /Л selon le taux de dilution du rejet) ; un témoin est constitué par l 'effluent seul. Le mélange est ensuite chromatographié à l 'aide d'un solvant (éthylacétate, méthanol, NH4OH 1 / 5 , 50 /13 /10) ; ce mélange permet de séparer les différentes f o rmes chimiques de l ' iode; une autoradiographie, suivie d'une détection radioactive, permettent de comparer l 'évolution des f o rmes chimiques de l ' iode par rapport au témoin. Dans une autre communication à ce même Colloque [ 5 ] l ' e f fet du pH sur l 'équil ibre est i l lustré. La figure 2 montre les effets synergétiques pour quelques c o m p o s é s . L'étude sur 60 composés minéraux et organiques a permis de voir l ' influence de chacun d'eux: complexation par les acides aminés, formation d'iode libre en présence des corps réducteurs, apparition d ' iodures plus ou moins solubles avec certains minéraux, diminution des iodures sous l 'ef fet d'un pH acide, e tc .

3. TECHNIQUE DE DETERMINATION DE L'EVOLUTION PHYSICO-CHIMIQUE D'UN REJET DANS UN BASSIN HYDROGRAPHIQUE DONNE

Cet exemple est illustré par un rejet en eau douce qui rejoint la mer . La technique consiste à déposer sur une plaque de si l ice imprégnée de résine Dowex 50 une aliquote d'effluent, puis à faire migrer cet effluent en présence de l'eau du fleuve; les composés f o rmés réagiront par la suite avec d iverses qualités d'eaux: saumâtre, eau de m e r . On peut ainsi suivre un ou plusieurs composés dans un bassin hydrographique donné. La figure 3 montre l 'évolution du fer dans le milieu. On voit aussi apparaître progressivement les composés anioniques, puis des complexes organiques. La figure 4 montre l 'évolution du cobalt. Par rapport au fer , nous constatons que dans l 'eau de mer il ne subsiste plus de f o rmes cationiques mais uniquement des complexes cationiques ou anioniques. La figure 5 récapitule la migration des r a d i o n u c l i d e s dans le bassin rhodanien; on constate une forte complexation du manganèse, du zinc, du cobalt. L 'anti -moine, par contre, évolue assez peu dans le milieu; en revanche on peut

148 SAAS e t GRAUBY

5E.P*?I'Il9ri _D_E?_fORMES DE LTODE

100 % I I iodates mn periodales t- l iodures

potyiodures" fe^ polyiodures E S I C H 3 I

iodates • l2

x : formes hydratges

Pourcentage par rapport a la depose

REPARTITION DES FORMES DE L' IODE

1 0 0 %

50 -

I I iodates t i l l periodates • polyiodures I—1 io dares

iodates EH C-H3I • l2

Pourcentage par rapport ^ la depose

T MN ZN CU Ni T Fel FeU Aim

INFLUENCE.. OES M y A U X . .SUR LES. .FORMES

PHYS ICO-CHIMIQUES DE LTODE

INFLUENCE,? 1 ! J - E P - EJ _DE_L> LUMINIUM

SUR LESjFORMES PHYSICO- CHIMIQUES

DE L'lODE

organique

' 3 6 H 2 °

MnCI2 _ZnCJ2 CuSO.4 Ni(NP3)2 Fem Fell Aim

FIG. 2 . Effets synergetiques pour quelques c o m p o s e s .

IAEA-SM-197/16 149

F E R

Migra t ion

Depose

S U P P O R T : GEL s

I M P R E G N E

^ Complexes anioniques

^ Complexes organiques

^ Formes cationiques

M OE D O W E X 5 0

VECTEUR ! D ! EAU DISTILLEE F ! EAU DE F L E U V E - D ' IRRIGATION S I EAU SAUMATRE M I EAU DE MER

FIG. 3. Evolution du fer dans le milieu.

C O B A L T

S U P P O R T I GEL DE S I L I C E I M P R E G N E DE D O W E X 5 0

VECTEUR I D : EAU DISTILLEE F I EAU DE FLEUVE - D' IRRIGATION S ! EAU SAUMATRE M i EAU DE MER

FIG. 4. Evolution du cobalt dans l e milieu.

150 SAAS et GRAUBY

S O D I U M CESIUM S T R O N T I U M

migration

4% H i I M depose

D F S M D F S M D F S M

MANGANESE Z I N C CERIUM migration

depose D F S M D F S M D F S M

V E C T E U R : D • Eau distill6e S: Eau saumatre F : Eau de f leuve - d'irrigation M : Eau de mer

FIG. 5. Migration des radionuclides sur gel de silice impregni de rSsine (Dowex 50 X 8 H+).

IAEA-SM-197/16 151

vo ir l 'apparition de complexes pour le ces ium. Ces differentes illustrations permettent d 'entrevoir devolution des effluents radioactifs et contribuent a esquisser une prospective des divers ef fets de synergie dans le mil ieu.

4 . VARIATION DE L'EQUILIBRE SOUS L 'EFFET DES PARAMETRES DU MILIEU - DEFINITION DU POTENTIEL DE MOBILITE

Nous utilisons egalement une methode chromatographique pour determiner les variations de l 'equil ibre physico-chimique du r a d i o n u c l i d e sous Paction de l 'ensemble des parametres . Nous impr6gnons entierement les bandes de gel de s i l ice avec des solutions de re jet , de so l s , d'eaux d' irrigation; on peut ainsi suivre l ' influence des parametres du milieu. La figure 6 illustre les effets de synergie entre l 'eau d ' irrigation et la solution du so l .

Z I N C C E S I U M

SOL. Calcaire Acide Calcique

FIG. 6. Exemple de synergie entre l'eau d'irrigation et la solution du sol. Impregnation d'une plaque avec les hydrosolubles.

152 SAAS et GRAUBY

Nous avons choisi trois types de sols : brun calcaire , brun calcique et brun acide. La figure montre la mobilite du radionucleide en presence du meme type d'eau d ' irrigation. Nous voyons que pour le zinc l 'acidite du sol favorise la migration, tandis que pour le cesium l 'e f fet sol est tres attenue. D'autres exemples sont presentes dans une autre communication a ce meme Colloque [ 5 ] .

Af in d'etablir une liaison entre ces d iverses methodes, nous avons ete amenes a definir le potentiel de mobilite. Sur une plaque de gel de s i l ice , nous deposons un complexe d'EDTA du radionucleide et nous comparons les dif ferentes distances parcourues par les divers composes f o r m e s en presence des eaux de re jets . Cette technique s'applique en vue de l ' implanta-tion des sites nucleaires pour examiner les parametres suivants: pH, temperature, colloi'des en suspension, DCO, DBO, charge saline totale.

CONCLUSION

Cet ensemble de techniques chromatographiques, que nous avons i l lustrees par quelques exemples , repond a quelques questions relatives aux incidences des re jets radioactifs sur l 'environnement; el les peuvent etre appliquees directement aux etudes d'implantation de sites nucleaires . L'extension de ces techniques a d'autres milieux — eau de pluie, eau de ruissel lement, eau du sol , eau de nappe — a permis de suivre revolution physico-chimique des r a d i o n u c l i d e s en milieu liquide. Les resultats obtenus permettent de prevoir la forme sous laquelle un radionucleide arr ive au sol ou a la plante par migration, a la nappe par infiltration, voire a la station de traitement des eaux potables destinees a la consommation humaine.

R E M E R C I E M E N T S

Les auteurs desirent r e m e r c i e r ic i Mmes M. Favre et J. Rapenne, MM. P. Gille et A . Giuliani de la collaboration qu'ils leur ont apportee au cours de cette etude.

R E F E R E N C E S

[ 1 ] BOVARD, P. , GRAUBY, A . , FOULQUIER, L. , PICAT, Ph. , «Etude radioecologique du Bassin rhodanien — StratSgie e t b i l a n » , Environmental Behaviour o f Radionuclides Released in the Nuclear Industry (C.R. Coll . Aix-en-Provence, 1973), AIEA, Vienne (1973) 507-23.

[ 2 ] SAAS, A. , GRAUBY, A . , « Mecanismes de transfert dans les sols cultivSs des radionucl ides rejet&s par les centrales electro-nucleaires dans le systfeme f leuve-sol i r t igue-nappe» , Ibid. , p . 2 5 5 - 6 9 .

[ 3 ] SAAS, A . , GRAUBY, A. , «Techn iques d'etude de la diffusion et de la migration des radionucl ides dans les s o l s » , 10 e Congr&s int. Science du sol, Moscou, 2 (1974) 341-49.

[ 4 ] GRAUBY, A . , SAAS, A . , «Etude de la migration du sodium dans les sols a l 'aide du radiosodium, Problfemes lies l ' i r r igat ion» , 10 e Congres int. Science du sol, Moscou, 10^(1974) 92-102.

[ 5 ] BOVARD, P. , GRAUBY, A . , SAAS, A. , SCHAEFFER, R. , « I n c i d e n c e de la charge polluante des eaux sur le comportement des radionucl&ides», ces comptes rendus, IAEA-SM-197/14.

D I S C U S S I O N

Y . J . SOUSSELIER: My f irst question relates to caesium. Judging f rom the chromatography tests you have descr ibed, the caesium appears to be fixed to a relatively smal ler extent than the other radionuclides. We

IAEA-SM-197 /16 153

have found, however, in actual cases of radioactive pollution that caesium was retained extremely well .

The second point I want to raise concerns the activity level of the effluents with which you experimented. A r e these levels comparable with what might be expected f r o m the accidental pollution of a r iver , o r are they much higher?

A . SAAS: The apparent mobility of caesium in our chromatographs is eas ier to understand when you take into account the mobility potential. The caesium is rapidly fixed on the sediments, but in the presence of organic compounds, the fraction of it remaining in the water is mobile and it is this fraction that represents a potential contamination downstream f rom the site of r e l ease .

Regarding your second point, the activity of the effluent used is about 10"3 Ci . The amount of mineral and organic material deposited ranges f r o m 10 to 50 ng, except in the case of the more important elements, e . g . calc ium, sodium, potassium, e t c . , f or which the deposit varies f r o m 100 to 500 iug. It should be pointed out, furthermore, that this method enables us to measure the minimum quantity at which phys ico -chemica l transformation o c curs , this being an important parameter f or the release and also for calculating the dilution.

J . SHAH: I would like to mention that considerable experience has been gained on the subject of the mobility of radioactive isotopes at Perch Lake, near Chalk River . Very little isotope movement has been noted and this applies particularly to caesium. Hence I tend to agree with Mr. Sousse l ier ' s remarks on the movement of that element.

The soil will naturally act as a massive retention column, however, for agricultural uses of water (contaminated with radioactive material) , and hence the plant uptake i s very important. The type of vegetation irrigated i s also a significant consideration. This factor needs a careful assessment for ultimate water use.

I would suggest that field studies be undertaken so as to delineate isotope transport in contaminated water, biological mediation and end water use more c lear ly .

A . SAAS: The presence of organic matter and clays in sediments may result in the fixing of the caes ium. Hence its mobility is reduced. It i s only the presence of extensive organic pollution that may cause movement of the caesium to vary.

With regard to so i l s , it is certain that the chemical f o r m in which the radionuclide is deposited in the soi l by the irrigation water is of great importance for the movement in the soil and uptake by plants. The quality of the irrigation waters is likely to induce considerable changes in the mechanism by which the radionuclides are transferred, and the phys i co -chemical state of the radionuclides in the soil may be changed completely.

W . G . HUBSCHMANN: Your F ig . 2 showing the composit ion of the different iodine compounds in rain water, sea water and so on, is very interesting. I am wondering whether this iodine might stem f r o m the explosion of nuclear devices .

Further, do you think that your experimental technique could also be applied to identification of the various chemical f o rms of iodine in liquid waste (and perhaps also gaseous waste) f r o m a nuclear power plant?

A . SAAS: The variation in the phys ico -chemical f o r m s of iodine was observed by means of 125I within the context of re leases f r o m irradiated

154 SAAS et GRAUBY

fuel reprocess ing plants. Iodine is highly sensitive to organic and mineral substances present in the medium. We studied synergistic e f fects f o r about sixty organic and mineral compounds. In the case of gaseous effluents, we observed the formation of methyl, ethyl, allyl, vinyl, butyl and isobutyl iodides . In a liquid medium the physico -chemical balance varies with pH-value and the redox potential of the medium. Under these conditions we observed a complete cycle with physical change and transfer in all the compartments of the medium, i . e . soi l , plants, water (including ground water) , air , the food chain. Furthermore , the transfer p r o c e s s may be revers ib le .

G. R. LANZA: How important do you feel the mediation by biological systems, both direct and indirect , to be relative to the synergies you descr ibed? F o r example, we know that certain species of aquatic bacteria can influence the ionic state of iron, i . e . convert bivalent iron to the trivalent form,, or that the physiological activity of algal communities can alter the O2 level of an aquatic system in a diel cyc le . Could not changes of this nature influence the reaction between radionuclides and contaminants?

A . SAAS: Microbial action, more especial ly , bacterial action, is undoubtedly a factor influencing chemical synergy between chemical pollutants and radionuclides. This e f fect is c learly seen in so i l s . If a cobalt complex formed in the water is introduced by irrigation, the cobalt can easily migrate. A f ter biodegradation the cobalt is retained by the soi l . In the event of microbia l inhibition of the soil by an antibiotic, the complex continues to migrate and may at that moment be reincorporated into the groundwater. Thus microbial activity of the medium in certain instances alters the synergist ic e f fects observed between the chemical pollutants and rad io -nuclides.

J. WEBER (Chairman): Surfaces can play an important part in chemical react ions , and the water transported through the soil may be affected thereby; hence, the chemical interactions and retention may also be affected. Do you consider these interactions should be taken into account, and, if so, how could one do so?

A . SAAS: Yes , the surfaces act as a sort of brake in synergistic e f fec ts . At the same time, the water surrounding the physical surfaces serves as a vehicle for transfer of the radionuclides and pollutants, although a compound forming in the irrigation water may or may not show an affinity f o r soil co l lo ids . If it does, the radionuclide is retained; if it doesn't , it migrates with the water and only biodegradation can alter chemical behaviour.

IAEA-SM-197/10

TRACE ELEMENT INTERACTIONS IN , THE ESTUARINE ZONE OF

THE ANASCO RIVER, PUERTO RICO*

D. A. WOLFE National Marine Fisheries Service, Beaufort, N. C . , United States of America

W.O. FORSTER* R. McCLIN*? F. G. LOWMAN Puerto Rico Nuclear Center, Mayaguez, Puerto Rico

Abstract

TRACE ELEMENT INTERACTIONS IN THE ESTUARINE ZONE OF THE ANASCO RIVER, PUERTO RICO. The Anasco River on the west coast of Puerto Rico is highly stratified near the mouth, so that

gradients from fresh water to full oceanic salinity occur abruptly over short distances, both vertically and horizontally. To study the behaviour of trace elements and radioisotopes in this compact estuarine zone, bottom sediments and river water from different depths in the stratified layers were sampled periodically at several stations during 1969-1970. Stable iron, manganese, aluminium, scandium and cobalt were analysed by neutron activation in the sediment cores and in suspended particulate matter retained on 5 - 8 fim filters upon successive filtration of the water. The filtered water samples were analysed only for soluble iron. The distribution and concentrations of these stable elements were examined for seasonality and salinity-dependency, and were compared with the distribution of radioisotopic tracers in experimental river water-seawater mixtures. These mixtures consisted of unfiltered Anasco River spiked with Eu, 125Sb, U 3Sn, 110 A g m , 65 Zn, 60 Co, 59Fe and 5 4Mn and then mixed in different proportions with filtered seawater to produce a stepwise salinity gradient from 100% fresh water to 95% seawater. After 5-10 days, the mixtures were fractionated, and the radioisotopes were determined in the soluble phase, the suspended particulate and the sedimented material. Concentrations of aluminium, scandium and iron in the parti-culate matter recovered on 0 .45 (im filters were inversely related to salinity whereas manganese and cobalt showed no consistent correlation to salinity. In the tracer experiments 5 4Mn, 5 9Fe, 6 5 Zn. 110 A g m and 155Eu showed higher fractional solubilities as the salinity increased. The field results for iron and the radioisotope experiment were consistent with both the formation of suspended particulate material at low salinities and the desorption o f trace metals from suspended material as salinity increased. These processes appeared most important below 15%o salinity.

1. INTRODUCTION

In the estuarine zone, f resh water f r om r ivers becomes progressively-mixed with seawater, and the resultant changes in the physical and chemical characterist ics of the aqueous medium affect trace element distributions between soluble and particulate phases. The individual ef fects of selected

15This research was jointly supported by the National Marine Fisheries Service and the USERDA (formerly USAEC) under Agreement No. AT(49 -7 ) -5 and by the Puerto Rico Nuclear Center.

*Present address: Division of Biomedical and Environmental Research, USERDA, Washington, DC 20545, USA.

**Present address: Puerto Rico Water Resources Authority, San Juan, Puerto Rico.

155

156 WOLFE et al.

phys ico -chemica l variables, some antagonistic and some synergistic with others, have been demonstrated to occur under certain conditions [ 1 - 5], but the net effect of simultaneous or sequential p rocesses in a single estuary still defies effective modell ing. We have attempted to achieve an improved understanding of trace element distributions and fluxes in the abiotic components of an estuarine environment in the lower Anasco River through multi - isotopic tracer experiments in artif icial salinity gradients and comparison of these experimental results with direct environmental observations.

The distribution of several trace elements and fall-out radioisotopes has been studied in the marine waters, sediments and organisms of Anasco Bay, 1 - 8 km off the mouth of the Anasco River [ 6 - 10]. Selected trace elements have also been analysed in the soluble and particulate fractions of Anasco River water upstream f rom the point of mixing with marine waters [8], In this paper, we present data on selected trace elements, primari ly in suspended particulate matter and sediments f r o m the stratified estuarine zone of the lower r iver channel extending approxi-mately 3 - 4 km upstream f r o m the mouth, and f r o m the shallow 2 m deep) marine area up to 400 metres directly out f r om the mouth of the r iver . We also conducted t racer experiments in the laboratory to study the changes in elemental distributions between soluble and suspended phases as fresh and salt water are mixed; preliminary results were presented elsewhere [11]. Additional experiments are reported here and the results are discussed in relation to the elemental distributions and abundances observed in the f ield.

2. DESCRIPTION OF THE STUDY AREA

The Anasco River is the largest of three major r ivers flowing west-ward into coastal waters of western Puerto Rico (F ig . l ) . It drains an area of 514 square ki lometres (total length of basin is 29 km) in which the exposed minerals and rocks are mainly extrusive (igneous, andesitic and basaltic rocks) or sedimentary rocks containing volcanic or igneous debris . The headwaters of the r iver originate at about 1000 m elevation, and the r iver flows through an upland region where the soils are mainly of the sub- lateric red acid type and contain silty clays. The broad alluvial valley of the lower r iver is about 8 km long; the alluvium reaches a known depth of 79 m and consists largely of silty clays which vary f r o m neutral to slightly acidic [6, 7, 12].

Puerto Rico has a pronounced rainy season, which causes wide varia-bility in the flow and the turbidity of the Anasco River . F o r 1960-66 the mean daily r iver discharge was 122 f t 3 / s during January-March, 279 f t 3 / s during Apri l -June, 356 f t 3 / s during July-September, and 390 f t 3 / s during October -December . During the rainy season, the daily discharge frequently exceeded 1000 f t 3 / s , and ocasionally exceeded 2000 f t 3 / s . During periods of low flow between December and May, the discharge is much more stable with the seasonal minimum usually in the range of 60-90 f t 3 / s ; the lowest daily rate reported was 57 f t 3 / s [13, 14]. Whereas in the wet season the r iver was usually brown in colour and frequently was a raging muddy torrent, the r iver mouth nearly shoaled over and turbidity was much reduced during the dry season. The unequal semi-diurnal tide has a mean

IAEA-SM-197 /14 157

FIG. 1. Anasco Bay and Mayaguez Harbour on the west coast of Puerto Rico, showing location of sampling stations used in this study. The dotted line represents a series of stations studied previously by Lowman et al. [ 6 ] and discussed in the text.

maximum amplitude of 38-40 cm at the mouth of the r iver , and at high tide during periods of low r iver flow a wedge of saline water penetrated almost 3.5 km inland. The major circulation patterns of Anasco Bay proper have been described elsewhere [6, 7].

3. METHODS

3.1. Field sampling

Sampling stations are shown in F i g . l . Most intensive sampling was at station C, about 400 m straight outside the mouth of the r iver at slightly over 2 m depth, and at station E, just inside the r iver channel at about 2.6 m depth (low tide).

Surface water was collected with a bucket and poured into 20 litre polyethylene containers. Subsurface water was pumped through 10 mm Tygon tubing, using a centrifugal pump with a neoprene impel ler . Sampling was done at irregular intervals during the wet season, September-November 1969, and the dry season, December 1969-April 1970. On any particular sampling day, water samples and sediments were taken in

158 WOLFE et al.

vertical prof i les at a single station or at a ser ies of stations selected to encompass the maximum possible gradient of salinity. The total number of samples taken at various salinities were approximately evenly divided between wet and dry seasons (see Table II).

Water samples were f i ltered immediately or transported back to the Puerto Rico Nuclear Center and fi ltered within 48 hours. All samples were fi ltered success ively through 5 jum (or 8 /urn) and 0.45 ;um f i l ters (Mi l l ipore 1 ) . The col lected particulate matter was air dried on the fi lter in an open beaker; the f i lters were moistened with absolute ethanol and ignited. The f i l ters burned completely, leaving only partially ashed parti-culate matter f r om the water samples. These were weighed and subsampled for neutron activation analysis.

Sediment cores were col lected with a Phleger co rer ; the cores were extruded f rom the polyethylene tubes, sectioned and dried (90°C for 24-48 h). Dry sediment and particulate matter were analysed by neutron activation in a neutron flux of 2.5 X 1012 n / c m 2 • s with comparator standards of Al, Sc, Mn, Fe and Co. Potential analytical e r r o r arising f r o m the metal content of the Mill ipore f i lters was evaluated through comparison with the values obtained by Robertson [15] and with periodic analyses of f i lter blanks. Maximum e r r o r s were estimated for the particulate matter recovered on 0.45 |wn f i l ters as <0.1% for Fe , <2% for Sc and < 5% for Co. Total soluble iron was determined in the fi ltered water samples by the co lor imetr i c method of Strickland and Parsons [16].

3.2. Experimental mixtures of r iver water and seawater

The basic experimental design was described by Fors ter et al. [11] but, in certain of these preliminary experiments, not all the added radio-activity was recovered , and the l osses , furthermore, were not accounted for . We conducted several experiments to improve our experimental design. In all of these, we added usually 155Eu, 125Sb, 1 1 0Agm , 54Mn,

An, 60Co and occasionally 113Sn and 5 9 Fe, to a large volume of f resh water f r o m the Anasco River (unfiltered or HA 0.45 /um fi ltered). The HC1 stock solutions of radioisotopes were neutralized with NaOH immediately pr ior to mixing. Unfiltered r iver water included the total load of suspended sediment. Seawater was f i ltered (HA 0.45 ium) before use and then mixed with the labelled r iver water in 10-litre polyethylene containers. F o r example, mixtures containing 5, 15, 25, 50, 75, 90 and 100% r iver water were prepared in our ultimate experimental design.

The mixtures were incubated for 5-10 days with frequent agitation. Radioactivity was then fractionated by the following procedure: the water was carefully pumped off the settled sediment through a 0.45 fum filter (Fraction 1) and into an identical clean 10-l itre container. The sediment (Fraction 2) was collected f r o m the f irst container, and the walls of the container were washed 3 t imes with 4N HNO3 and 3 t imes with distilled water to remove adsorbed activity (Fraction 3). Soluble radionuclides were coprecipitated in the second container by the addition of FeO.3 and

1 Mention of trade names does not imply endorsement by the National Marine Fisheries Service, NOAA.

IAEA-SM-197 /14 159

NH4OH. The precipitate of Fe(OH)3 was collected on a fi lter (Fraction 4), and 1 litre of the filtrate was then evaporated (Fraction 5). The walls of the second container were then washed in the same way as those of the f irst (Fraction 5).

Fractions 1 and 2 represented particulate activity, and Fract ions 4, 5 and 6 represented soluble activity. Fraction 3 was activity adsorbed onto the walls of the container directly or onto particulate matter (including microorganisms) adhering to the container, whereas Fract ion 6 contained activity adsorbed directly f r o m solution onto the polyethylene. The content of radioisotopes in each fraction was determined with a 10 cm 3 Ge(Li) detector and a 1024 channel gamma spectrometer .

4. TRACE ELEMENTS IN^SEDIMENTS

Elemental composit ion of whole unfractionated sediments f r om the top 5-10 cm of c o res f r o m various sampling locations are summarized in Table I. No consistent changes in any element were detectable as a func-tion of either mean water salinity at a station or instantaneous overlying salinity; the only notable point was that Mn and Fe were more abundant on the average in sediments f r om well upstream (above the periodic penetra-tion of salt water) than at the mouth of the r iver or in the bay. This relationship was seen also in the Newport River estuary in North Carolina [17].

Lowman et al. [6] analysed sediment cores f r o m the dotted line transect shown in F i g . l . Their data showed 700 /Jg/g Mn, 55 Mg/g Fe and 25 ng/g Sc in sediments about 1.6 km offshore at a depth of 8 metres . These values decreased approximately linearly out to 8 km at 37 0 metres where the Mn was about l / 7 , the Fe about l / 5 , and the Sc about 1 /3 to 1 / 4 of the values on the island shelf.

5. TRACE ELEMENTS IN SUSPENDED SEDIMENTS

Quantitative separation of material by particle size was precluded by the non-selectivity of Mil l ipore f i l ters [18, 19]. The particulate matter retained on the 5 or 8 /um fi lter was quite variable f r om sample to sample, and the f i lter clogging time seemed to be also a function of salinity — fresh water samples clogged both f i lters more rapidly. Although the relative concentrations of different particle sizes were not quantified, chemical composition could be determined for the material which passed through the f irst f i l ter and was retained by the 0.45 /urn f i l ter .

The absolute concentrations and relative amounts of 5 to 8 /urn parti-culate matter and 0.45 /um particulate matter exhibited seasonal and salinity dependence. During the dry season, the mean total suspended load of the r iver was 11.4 m g / l o r about 1 / 6 that of the wet season. The mean con-centration of 0.45 /um particulate matter recovered increased f r o m 1.2 m g / i in the wet season to 3.1 m g / i in the dry season. This increased recovery of the 0.45 jum fraction was possibly due to the reduction in total suspended sediment load and concomitant decreased clogging of the 5 or 8 jum fi lter.

OJ o

TABLE I. ELEMENTS IN ANASCO RIVER SEDIMENTS AND SUSPENDED PARTICULATE MATERIAL RETAINED ON 5 OR 8 /um MILLIPORE FILTERS Mean ± one standard deviation

Station No. o f samples Manganese

( m g / g ) Aluminium

( m g / g ) Iron

( m g / g ) Scandium

(Mg/g)

Cobalt (Mg/g)

SEDIMENTS

A 3 0 .90 ± 0 .03 91 ± 8 . 5 57 ± 10 16 ± 0 . 6 26 ± 2. 2

B 3 0. 94 ± 0. 05 88 ± 11 49 ± 22 16 ± 1 . 4 25 ± 2 . 2

C 3 0. 86 ± 0 .26 117 ± 30 75 ± 32 18 ± 3 . 9 19 ± 11

D 1 0 . 7 4 119 109 26 26

E 12 0. 95 ± 0 .22 105 ± 12 61 ± 26 17 ± 2 . 9 28 ± 5. 4

F 1 0. 99 97 59 19 23

G 1 0. 91 112 132 23 39

H 1 0. 62 95 90 23 26

I 1 1. 24 90 107 27 29

J 2 1 .36 ± 0. 04 99 ± 9. 7 83 ± 5 . 9 16 ± 1 . 3 28 ± 12

SUSPENDED PARTICULATE MATTER

E 12 1. 52 ± 2 . 3 1 113 ± 64 66 ± 23 20 ± 10 36 ± 12

Upstream 8 2. 08 ± 1 .51 109 ± 35 75 ± 15 20 ± 3 . 4 30 ± 9. 9

TABLE II. SUMMARY OF TRACE METAL CONCENTRATIONS IN SUSPENDED PARTICULATE MATERIAL RECOVERED ON 0.45 irn MILLIPORE FILTERS A F T E R A PRIOR FILTRATION THROUGH EITHER 5 OR 8 p m FILTERS

Samples were clustered on the basis of the season when col lected and of the salinity of the water sample; Mean ± one standard e r r o r

Clustered by salinity Clustered by season A l l samples

< 15°/oo 15 20<7oo > 20 °joo Wet Dry

Manganese ( m g / g ) 1 . 7 9 ± 0 . 3 7 1 . 3 8 ± 0 . 2 3 3. 49 ± 1. 49 1. 45 ± 0. 56 2 . 37 ± 0. 54 0 . 7 4 ± 0 . 2 3

A l u m i n i u m ( m g / g ) 3 8 . 7 ± 8 . 9 69 .7 ± 1 4 . 2 44 . 4 ± 26. 0 1. 4 ± 0 . 8 54. 7 ± 12. 8 10. 4 ± 4. 6

Iron ( m g / g ) 62. 0 ± 9 . 1 72. 6 ± 8 . 0 6 0 . 7 ± 18. 5 5 0 . 7 ± 2 0 . 2 76 . 1 ± 13. 0 4 0 . 1 ± 9. 5

Scand ium (Mg/g) 12. 5 ± 2 . 5 18. 6 ± 3. 9 1 7 . 6 ± 9 . 0 3 . 3 ± 0 . 6 1 8 . 7 ± 3 . 6 2 . 6 ± 0 . 8

Coba l t ( p g / g ) 5 3 . 8 ± 7. 0 6 1 . 6 ± 10. 7 5 6 . 7 ± 2 1 . 5 43 . 8 ± 1 0 . 1 7 1 . 2 ± 9 . 1 2 6 . 5 ± 7 . 1

N 41 18 7 16 25 16

162 WOLFE et al.

TABLE III. SUMMARY OF IRON CONCENTRATIONS IN SOLUBLE AND PARTICULATE PHASES

Clustered by salinity and by season; Mean ± one standard e r r o r

Clustered by salinity Clustered by season Fraction

< 15% o 15-20<7oo > 20 <>}oo Fraction < 15% o 15-20<7oo > 20 <>}oo Wet Dry

5 or 8 /am particulate ( m g / g ) 7 1 . 4 ± 5 . 4 79 .9 ± 12.7 58. 2 ± 4. 9 70 .6 ± 4 , 0 65 .7 ± 6 . 4

0 . 4 5 (jm particulate ( m g / g ) 72 .6 ± 8 . 0 60 .7 ± 18 .5 50 .7 ± 2 0 . 2 7 6 . 1 ± 13 .0 4 0 . 1 ± 9. 5

Soluble ( f ig / i) 32 .7 ± 1 2 . 4 44. 9 ± 20. 2 33 .7 ± 10.3 17.7 ± 2 . 3 5 3 . 4 ± 12 .9

The ratio of 0.45 nm particulate material recovered to 5 or 8 /um particulate material tended to decrease with increasing salinity during the wet season, but showed no correlation with salinity during the dry season. This observation during the wet season is inconsistent with the tendency for fresh water samples to clog f i l ters more rapidly than saline waters, and may suggest a net reduction of finely divided suspended material in the downstream section of the r iver . Such a reduction could be explained by flocculation of small particles with increasing salinity.

Mean concentrations of Mn, Al, Fe , Sc and Co in suspended particulate material recovered on 5 or 8 f i l ters at station E or at upstream stations were similar to those seen in bottom sediments f rom the same stations (Table I). The variation in these results arose mainly f r om seasonal di f ferences, and there were no detectable systematic correlations between salinity and trace metal composition in this bulk fraction of the suspended particulate. Freshwater suspended material showed higher mean elemental concentrations than were measured in the nearshore marine sediments (Table I).

Unlike the 5 -8 pim suspended particulate matter, in the suspended material recovered on 0.45 jum fi lters certain trace metals exhibited marked relationships with respect to salinity and season. Al l the elements analysed were less concentrated in this fraction during the dry season than in the wet season (Table II). Aluminium and scandium concentrations in 0.45 jum suspended material showed consistent inverse relationships with respect to salinity in all sampling prof i les with salinity gradients. This inverse relationship is ref lected also in Table II, where analyses are clustered according to salinity range of the water sample and the season when sampled. Aluminium was below detection limits in nearly all samples of 0.45 /im particulate material f r o m high salinity water. The decreasing trends for Al and Sc in 0.45 /um recovered particulate material could represent f locculation of aluminium-sil icate clays with increasing salinity. During the wet season (September to December 1969), iron concentrations on 0.45 v m suspended particulate matter also showed consistent inverse relationships with respect to salinity, but this trend was not evident in the samples collected during January-April 1970. Manganese and cobalt concentrations in 0.45 nm suspended matter showed no consistent trends with salinity in the 13 ser ies of samples with either horizontal or vertical salinity gradients.

IAEA-SM-197 /18 163

6. SOLUBLE IRON

Total soluble i ron was highly variable in the 0.45 jum Mil l ipore-f i ltered water samples, especial ly at higher salinities. There were no consistent trends of soluble iron in the salinity gradients sampled on various dates. Values in freshwater were generally 5-15 jug/ i . As salinity increased, variability also increased, with values in the range 2-50 Mg/ i . On 19 January and again on 2 1 Apri l soluble Fe was between 100-200 ng/1. On these dates, the water was covered with a pronounced organic scum even at the mouth of the r iver . The scum apparently arose f r o m a sugar mil l about 4 km upstream where unknown quantities of soluble cane wastes and machine oil were released. Most intensive cane process ing activity coincided approximately with the dry season, and occasionally the surface water and the shoreline vegetation were coated with a black oily residue. The r iver was sometimes depleted of oxygen during this period and smelled of H2S. The increased organic content and probable associated microbia l activity during the dry season may have promoted the formation of soluble organic -metal complexes at the expense of the particulate-sorbed metal content.

During the dry season, when suspended particulate matter concentra-tions were lower and soluble Fe concentrations were highest (Table III), the soluble Fe occasional ly reached 20-30% of the total Fe carried in the water column. Normally, however, particulate Fe accounted for 97-99% of the total. At t imes of peak flow, soluble Fe was only 0.1% of the total. A similar preponderance of the particulate f o rm was described for the suite of Columbia River radionuclides, but in that r iver particulate radio-nuclides were generally 98% or more of the total [20]. The non-conservative behaviour of soluble Fe seen by Boyle et al. [4] in the Merr imack River estuary was not found in the salinity gradients of the Anasco River .

In the material recovered on 0.45 jum f i l ters , Fe was less concen-trated in the dry season than in the wet season, which was opposite to the trend for soluble Fe (Table III). Iron concentration in the 0.45 /um parti-culate matter showed a consistent inverse relationship with respect to salinity in sampling pro f i les only during the wet season, even though the overal l mean values for both seasons are lower at elevated salinities.

7. RADIOTRACER EXPERIMENTS WITH ARTIFICIAL MIXTURES OF RIVER WATER AND SEAWATER

7.1. Recovery of radionuclides

Even when the experimental containers were acid-washed during the fractionation scheme, substantial portions of the added radioactivity were lost in certain treatments (Table IV). Recovery was dependent principally upon (a) the radioisotope, (b) the salinity of the experimental mixture, and (c) the total suspended content of the r iver water. Table IV shows recovery of six isotopes f r o m seven experimental mixtures of different salinities, compared to analyses of five independent aliquots of labelled r iver water sampled during the preparation of the mixtures. Highest r e cover i e s were generally observed at high salinities (5% river water) for all nuclides,

TABLE IV. ESTIMATED PERCENTAGE RECOVERY OF RADIONUCLIDES ADDED TO RIVER WATER-SEAWATER MIXTURES OF DIFFERENT COMPOSITIONS

Experiment of 4 August 1970

Counts per minute per

Radionuclide 10 litres of Percentage river water composit ion

Radionuclide river water; mean ± S. D . 100 90 75 50 25 15 5

(N = 5)

M n - 5 4 1382 ± 76 37 38 45 56 84 90 82

Fe-59 1040 ± 61 42 39 39 53 112 81 93

Zn -65 702 ± 90 40 36 39 53 81 79 55

A g - l l O m 684 ± 76 41 42 53 75 92 82 96

Sb-125 900 ± 185 104 93 87 59 60 95 97

Eu-155 792 ± 196 41 36 67 67 99 64 110

X = 50 8 X = 47. 3 X = 55. 0 X = 60. 5 X = 88 0 X = 81. 8 X = 88. 8 Mean ± SE SD = 26. 1 SD = 22. 5 SD = 18 .9 SD = 8. 8 SD = 17. 7 SD = 10. 7 SD = 18. 8

SE = 10. 7 SE = 92 SE = 7 . 7 SE = 3 . 6 SE = 7. 2 SE = 4. 4 SE = 7 . 7

X = 40. 2 X = 38. 2 X = 48. 6 X = 60. 8 X = 93. 6 X = 79 . 2 X = 87. 2 Mean ± SE, excluding Sb SD = 1. 9 SD = 2. 5 SD = 11 .8 SD = 9 . 8 SD = 12. 5 SD = 9. 5 SD = 20. 6

SE = 0. 9 SE = 1. 1 SE = 5 . 3 SE = 4 . 4 SE = 5. 6 SE = 4. 2 SE = 2

TABLE V. T O T A L SOLUBLE ACTIVITY FOR TRACER RADIONUCLIDES ADDED TO VARIOUS MIXTURES OF RIVER WATER AND SEA WATER, 4 AUGUST 1970, AS PER CENT OF RECOVERED ACTIVITY

Total sediment concentration was 96.6 mg j i in the undiluted r iver water

Radionuclide 100 90

Percentage river water composit ion

75 50 25 15 5

M n - 5 4 1 .7 1 . 3 2. 8 4 . 7 4 . 7 9 . 3 20

Fe-59 2 .7 2 . 7 3 . 6 1 . 1 4 . 7 3 . 2 22

Zn -65 0 . 4 a 0. l a 0. 2 a 6 . 5 6 . 0 16 2. 9 a

A g - l l O m 4 . 1 6 . 9 4. 1 5 . 2 7 . 7 17 39

Sb -125 97 97 97 98 95 97 70

Eu-155 1 . 0 6 . 6 15 14 12 18 24

Mean ± SE, exc luding Sb X = 2 . 0

SD = 1. 5 SE = 0 . 7

X = 3 . 5 SD = 3 . 1 SE = 1. 4

X = 5 . 1 SD = 5 .7 SE = 2 . 6

X = 6 . 3 SD = 4. 8 SE = 2 . 1

X = 7 . 0 SD = 3. 0 SE = 1 . 4

X = 12 .7 SD = 6 . 3 SE = 2 . 8

X = 21 .6 SD = 12. 9 SE = 5 . 8

a Insignificantly low counts in soluble fractions.

166 WOLFE et al.

TABLE VI. TOTAL SOLUBLE ACTIVITY OF RADIONUCLIDES ADDED TO VARIOUS MIXTURES OF RIVER WATER AND SEAWATER, 11 MAY 1970, AS PER CENT OF RECOVERED ACTIVITY

Total suspended sediment concentration was 10.1 m g / f in the undiluted r iver water. Recovery f or this experiment is discussed in the text

Radionuclide 100 100

Percentage river water composition

60 60 5 5

M n - 5 4 35 41 92 88 91 80

Co -60 90 93 98 86 35 61

Zn -65 83 91 96 90 82 95

A g - l l O m 96 94 92 95 79 77

Sb-125 99 100 100 100 99 98

Eu-155 31 46 67 34 25 57

and recovery decreased progress ive ly toward lower salinities f o r all nuclides except 125Sb. Similar patterns of relative recovery were obtained in the experiments reported by Fors ter et al. [11], but no checks were made to determine the absolute recovery . In those early experiments, the settled sediment was scrubbed f r o m the containers with a rubber-tipped glass rod, but the sides of the containers were not washed with acid. F r o m the distribution of 125Sb, almost exclusively in the recovered soluble fractions (Tables V and VI), and f r o m the fact that recovery of 125Sb was not affected by salinity s imilarly to the other radionuclides (Table IV), one can surmise that the observed experimental l o s ses o c cur -red in the particulate fractions, or in adsorbed material not removed by acid washing f rom the sides of the container. This conclusion is further substantiated in that total soluble 125Sb consisted almost exclusively of Fract ions 4 and 5 (the coprecipitate and evaporated residue) instead of being adsorbed onto the sides of the second experimental container. Furthermore, for radioisotopes other than 125Sb, coprecipitation e f f i c iencies (percent of total soluble fractions represented by Fe(OH)3 coprecipitate) generally exceeded 80% (Table VII). A notable exception was 60Co, for which coprecipitation ef f ic iency was under 80% in five of six tr ials . Thus recovery of the soluble fraction of the radioisotopes may be considered quantitative, and analysis of the results depends upon one 's interpretation of the physical f orm of the unrecovered radioactivity adsorbed in the experimental container.

The amount of suspended sediment contained in the experimental r iver water affected not only the resultant distribution of radionuclides (Tables V and VI), but also seemed to affect the recovery relationship. In the experiment of 11 May 1970, where six mixtures of three different salinities were prepared, the suspended sediment concentration was about 10 m g / i . In this experiment, only three replicate aliquots of the labelled r iver water were analysed for total introduced activity. The total relative radioactivity recovered f r o m each of the two 5% r iver water treatments

I A E A - S M - 1 9 7 / 1 8 167

slightly exceeded the mean for these three replicate aliquots. The two experimental values were thus combined with the three initial aliquots as the basis f o r radioactivity added to the mixtures. The mean sum of all radionuclide activity added per 10-litre volume of r iver water was 12 000 ± 862 (SE) counts per minute for the above five determinations. Compared to this value, the mean recovery for the other four treatments was 10 100 ± 3 1 9 (SE) o r about 83%. No trend with varying salinity was observable . In this experiment, with low concentrations of suspended sediment, therefore , mean recovery of the isotopes was significantly higher than that obtained in the experiment of 4 August 1970 (Table IV), when the suspended concentration was almost tenfold higher.

In the experiments reported by F o r s t e r et al. [11], the recovery of individual radionuclides generally exhibited both patterns and magnitudes s imilar to those in Table IV. These early experiments contained unknown concentrations of suspended material, but in most cases there was a visible f i lm remaining on the inside of the container after removal of the settled sediment. This was also the case at low salinities with the high sediment concentrations of the 4 August experiment (Tables IV and V), even with acid washing. As noted by Fukai and Huynh-Ngoc [21], it is unclear what proportion of the radioactivity contained on the sides of the experimental container represented material actually precipitated or adsorbed onto adhering particulate matter instead of ions adsorbed directly f r om solution onto the polyethylene. The large dif ference in magnitude of activity on the walls of the f irst and second containers, however, suggests that nearly all of the radioactivity left in the f irst container must have been associated with particulate material .

Activity could also have been lost to the walls o f the second container, but the Fe(OH)3 precipitate adhering to the walls after filtration dissolved readily during the acid washing. This activity represented a small f rac -tion of that recovered with the bulk of the coprecipitate or in the residual soluble fraction. Since the remnants of Fe(OH)3 recovered in the acid wash were not combined with the coprecipitate, the coprecipitation e f f i c iencies shown in Table VII are somewhat low.

If it is assumed that the soluble fraction of each radionuclide was recovered quantitatively, the data f r o m all experimental treatments, including those descr ibed by Fors ter et al. [11], can be re-evaluated by correct ing for relative recovery at different salinities. Since the recovery was greatest in 5% river water, the soluble fraction in other mixtures can be normalized to nuclide concentrations calculated.from this highest salinity treatment. The effect of this correct ion is shown in Fig.2 for an experiment in which both the r iver water and the seawater were pre -f i ltered (HA 0.45 (im) pr ior to mixing [11].

7.2. Effect of salinity on radionuclide solubility

Isotopes of Mn, Fe , Zn, Ag and Eu followed generally the same trend of very low solubility in f resh water with a gradually increasing solubility up to about 25% salinity and a progress ive ly greater increase at higher salinities. Of the above five isotopes, 155Eu and 110AgIn tended to have the highest per cent solubilities, while 6 5 Zn and 5 9 Fe showed the lowest (Fig.3) . The increasing trend was also most erratic for 6 5Zn and Fe .

CTJ 00

TABLE VII. COPRECIPITATION EFFICIENCIES (PER CENT) FOR TRACER RADIOISOTOPES COPRECIPITATED SIMULTANEOUSLY FROM 10 LITRES OF WATER BY ADDING CARRIER F e C l 3 AND THEN NH4OH TO pH 9.3 ±0 .2

Radionuclide 100 a 90 75

Percentage river water composit ion

6 0 b 50 25 15 5 a

M n - 5 4 80 ± 8 . 9 83 95 90 ± 4 87 100 91 87 ± 2 . 7

Fe-59 85 96 99 - 76 100 51 81

C o - 6 0 39 ± 1 . 8 - - 33.± 9 - - - 73 i 8. 3

Z n - 6 5 97 ± 0 . 4 c c 98 ± 0 . 3 94 100 100 - 93 ± 3 . 3

A g - l l O m 96 ± 1 . 4 92 99 100 ± 0 84 94 99 85 ± 5 . 4

Sb-125 25 ± 6. 6 48 53 30 ± 1 . 2 90 61 49 60 ± 5 . 5

Eu-155 86 ± 8. 0 81 32 86 ± 5 . 9 28 68 100 74 ± 14

a Means of 3 observations, except for 60 Co (2) , 5 9Fe (1) , and 6 5 Zn (2) , with standard errors, k Means o f 2 observations, with standard errors. c Total soluble activity too low for valid measure o f coprecipitation e f f i c i e n c y .

IAEA-SM-197 /18 169

M n , C o , Z n - w i t h antibiotics

Eu, corrected for recovery

100 5 0

PERCENTAGE RIVER WATER C O M P O S I T I O N

FIG. 2. Distribution o f Mn, Co, Zn and Eu between soluble and particulate fractions in mixtures o f filtered seawater and filtered river water, showing ef fects o f penici l l in and streptomycin. The uppermost sets of lines represent soluble activity as a percentage o f the soluble plus particulate radioactivity recovered; the lower sets of lines represent the same data for soluble activity expressed as a percentage of added radioactivity.

The means of the five nuclides represent the general trend of solubility over most of the salinity range. The value for 6 5 Zn in 5% r iver water is suspect, because the total amount of 6 5Zn recovered was too low for accurate determination. Values f or 5 4Mn, 5 9 Fe and 6 5Zn were consistently somewhat lower ( less soluble) than the mean, whereas 1 1 0Agm and 155Eu were more soluble than the f ive- isotope average (Fig.3) . Antimony-125 exhibited high solubilities throughout the entire salinity range. The mean total 125 Sb recovered f r o m seven experimental mixtures was 767 ± 6 1 (SE) counts per minute, compared to the amount added, 900 ± 83 (SE) counts per minute (Table IV). Since no consistent trend in solubility of 125Sb occurred with salinity, it apparently does not appreciably enter particulate f o r m s .

170 WOLFE et al.

SALINITY (PARTS PER T H O U S A N D )

10 2 0 3 0

100 9 0 25 15 5 0

P E R C E N T A G E RIVER W A T E R C O M P O S I T I O N

FIG. 3. Distribution of 5 4 Mn, 5 9Fe, 6 5 Z n , 1 1 0 A g m , 125Sb and 155Eu between soluble and particulate phases in the experiment of 4 August 1970. Values for 125 Sb are shown ± one relative standard deviation. Extreme values are identified for each seawater mixture; other points are marked by mean values for all 5 isotopes (excluding 125Sb) are connected by the dotted l ine.

IAEA-SM-197 /18 171

A. Percent Particulate Activity

A / B

100

90

80

70

60

50

40

30

20

10

100 90 25 15 5 0

PERCENTAGE RIVER WATER C O M P O S I T I O N

FIG. 4. Mean percentage o f particulate radioactivity for 5 4 Mn, 5 9Fe, 65 Zn, 110 A g m and 155Eu from Fig. 3. (A) and concentration of added particulate material (B) in the various seawater mixtures in the experiment of 4 August. The increasing curvilinear function represents the percentage of radioactivity on particulate material per m g / 1 of particulate material .

Interpretation of the changes in soluble activity with increasing salinity (Fig.3) is not simple, because the concentration of suspended particulate matter added to the experimental containers was also a variable (Fig.4) . When the particulate activity is expressed in relative concentration per unit weight of added particulate matter, the concentration of particulate radioisotopes increased s imilarly to the increase of soluble activity with salinity (Figs 3 and 4). These data were replotted (Fig.5)

172 WOLFE et al.

L O G PERCENT SOLUBLE

FIG. 5. Relationship between percent soluble radioactivity and percent particulate activity per unit of particulate material for the 4 August experiment (means o f values for 5 4 Mn, 5 9Fe, 65 Zn, 110 A g m and 155Eu from Figs 3 and 4). Salinities are noted in parentheses for each value.

IAEA-SM-197 /18 173

2 . 6

2 4

Mean for54Mn,59Fe,65Zn, O 110m. 155-

Afl , Eu

• Mean forS4Mn,59Fe,6SZn 155c • Eu 110m.

10 15 20 25 30 35

SALINITY (PARTS PER THOUSAND)

FIG. 6. Ratio of percent particulate radioactivity per unit o f particulate material to percent soluble radioactivity as a function of salinity in the experiment o f 4 August.

174 WOLFE et al.

after the pattern of a Freundlich adsorption isotherm according to the following equation:

f per cent particulate activity \ , , , , . . . l o g U g / i added particulate matter J = l o g K + n l ° g (per cent soluble activity)

where K and n are empir ical constants. The experimental data showed a linear relationship for five of the seven experimental water mixtures, which suggested that a single adsorption mechanism was dominant in the salinity range of 8 to 33%Q . A strong deviation toward increased adsorp-tion of activity onto particulate matter occurred at low salinity and high particulate matter content. Sonnen [22] observed a similar discontinuity with salinity in his studies of zinc adsorption by sediments. At salinities greater than that of 5% seawater zinc adsorption tended to follow a'single Freundlich adsorption isotherm quite different f r om that in fresh water. Per unit of soluble zinc, adsorbed zinc was higher in fresh water than in saline water, and the slope of the adsorption isotherm was less in f resh water [22]. We saw the same pattern for the means of our five radio-isotopes (Fig.5) . These same data were replotted as the ratio of relative particulate isotope concentration to percent soluble concentration ( i .e . per cent particulate activity per m g / i particulate matter divided by per cent soluble activity) against salinity (Fig.6). F o r the f ive- isotope mean, the lowest particulate isotope content occurred at about 8- 10%o salinity. This inflection was clearly dominated by 155Eu, which showed a pronounced tendency toward greatest solubility at intermediate salinities. Data f or 5 4Mn, 5 9 Fe and 6 5Zn continued to decrease in particulate isotope concentration into a salinity range of about 15-20%0 . Silver- 110m, on the other hand, showed no consistent change in particulate/soluble ratios (Fig.6) .

P r o c e s s e s or factors which could contribute to the discontinuity of the adsorption isotherm for 54Mn, 5 9 Fe , 6 5 Zn and 155Eu at 8-18%o salinity include: (a) As the salinity increases f r o m fresh water up to about 8-12%0 , adsorbed radioisotopes may be selectively removed, thereby reducing the slope of the adsorption isotherm f rom that predicted at higher salinities. The presence of strictly fresh water bacteria or microalgae, however, could have produced similar results . Antibiotics promoted solubility of the isotopes at all salinities (Fig.2), but exerted the greatest influence at low salinities ( i .e . l ess than 7%0); (b) Another possible origin of the salinity discontinuity in the isotherm was a sa l in i ty dependent change in the concentration of particulate matter present. Particulate activity formed in seawater—river water mixtures when both water samples were f i ltered pr ior to mixing (Fig.2) . The greatest amounts of particulate activity of 54Mn, 6 0Co and 6 5 Zn occurred at low salinities. If additional particulate material was formed at low salinities in the 4 August experiment (Figs 3 and 5), one would expect concomitant increases in adsorption and a resultant overestimate of the concentration of radioactivity on the particulate material . Since the adsorption of radioisotopes at low salinity was indeed higher than would have been predicted by back-extrapolation of the linear portion of the adsorption isotherm above 8.8%o salinity (Fig.5), the hypothesized particulate formation at low salinities appears feasible. In another study, Wolfe and Jennings [23] found higher

IAEA-SM-197 /18 175

concentrations of fall-out 5 5 Fe and 106Ru in brackish-water c lams f r o m estuarine areas between 3 and 15%o salinity than in those f rom 0-3%o and hypothesized that the metals were more available biological ly above 3%o because of increased formation of particulate isotope.

8. SUMMARY AND CONCLUSIONS

8.1. The bulk of suspended particulate material recovered f rom Anasco River water samples on 5 and 8 nm f i l ters contains concentrations of Mn, Al, Fe , Sc and Co similar to those found in f resh water sediments. These concentrations are generally somewhat higher than those found in the marine sediments of Anasco Bay at the mouth of the r iver .

8.2. Concentrations of Al , Sc and Fe in the finely divided suspended particulate material recovered on 0.45 jum f i l ters after passage through a 5 or 8 /urn f i lter were inversely related to the salinity of the water sample, whereas Co and Mn showed.no consistent relation to salinity. This inverse relationship was much more pronounced in the wet season when total suspended content was higher by about a factor of six than during the dr ier winter months.

8.3. The concentrations of Mn, Al, Fe , Sc and Co on the 0.45 yum suspended fraction were all higher during the wet season than during the dry season due to a change toward larger mean particle s ize .

8.4. In experimental r iver water-seawater mixtures, 125Sb remained largely soluble i rrespect ive of salinity or concentration of suspended particulate material; whereas 54Mn, 5 9 F e , 6 5Zn, i1 0Agm and 1 5 5Eu all showed lower fractional solubilities at high contents of suspended material, and also tended to increase in solubility as the salinity increased.

8.5. The experimental r iver water-seawater mixtures suggested the desorption of adsorbed radioactivity f r om suspended particulate material as salinity increases to about 8%o salinity, or the formation of particulate material at low salinities (or both). The apparent inflection point for these p r o c e s s e s was about 8-9%o salinity for 155Eu, and was in the range of 10- 20%o for 54Mn, 59 Fe and 6 5Zn.

8.6. The overal l study suggests the further need f or analysis of larger numbers of samples col lected sequentially as mixing occurs within a salinity gradient, with simultaneous determination of soluble and parti-culate f o r m s of metall ic elements. Such an approach should include size fractionation of suspended particulate material to whatever extent possible, especial ly for suspended colloidal material <0.45 jum. It would further-more be desirable to utilize several different extraction techniques to distinguish various phys ico -chemica l fractions of the metal in the suspended material as has been per formed for sediments [18, 24, 25].

R E F E R E N C E S

[ 1 ] BRADFORD, W. L . , A Study on the Chemical Behaviour of Zinc in Chesapeake Bay Water Using Anodic Stripping Voltammetry, Ph.D. dissertation, Johns Hopkins Univ . , Univ. Microf i lms No. 72 -24 , 958 (1972).

[ 2 ] EVANS, D . W . , CUTSHALL, N. H . , "Effects o f ocean water on the soluble-suspended distribution of Columbia River radionuclides", Radioactive Contamination of the Marine Environment (Proc. Symp. Seattle, 1972), IAEA, Vienna (1973) 125.

176 WOLFE et al.

[ 3 ] MURRAY, C . N . , MURRAY, L . , "Adsorption-desorption equilibria o f some radionuclides in sediment-fresh-water and sediment-seawater systems". Radioactive Contamination of the Marine Environment (Proc. Symp. Seattle, 1972), IAEA, Vienna (1973) 105.

[ 4 ] BOYLE, E. , COLLIER, R. , DENGLER, A. T . , EDMOND, J . M . , NG, A. C . , STALLARD, R. F . , On the chemica l mass-balance in estuaries, Geoch im. Cosmochim. Acta 38 (1974) 1719.

[ 5 ] O'CONNOR, T . , The adsorption of copper and cobalt from aqueous solution onto illite and other substrates, Ph. D. dissertation, Univ. Rhode Island, Univ. Microfi lms No. 74 -16 , 872.

[ 6 ] LOWMAN, F. G . , QUINONES, L . , M1RO, M . , OLIVER DE PADOVANI, I . , RAMOS, E. , ROMAN DE VEGA, V . , BIELEN, H . J . , 'Investigations of trace e lement distribution in marine waters and sediments", 5th Inter-American Symp. Peaceful Application of Nuclear Energy (Valparaiso, Chile , 1964), Pan-American Union. Washington, DC (1965) 241.

[ 7 ] LOWMAN, F. G . , STEVENSON, R . A . , McCLIN-ESCALERA, R. , LUGO-UFRET, S . , "The effects of river outflows upon the distribution patterns of fallout radioisotopes in marine organisms", Radioecological Concentration Processes (ABERG, B . , HUNGATE, F. P . , Eds), Pergamon Press (1966) 735.

[ 8 ] LOWMAN, F. G . , PHELPS, D. K . , McCLIN, R. , ROMAN DE VEGA, V . , OLIVER DE PADOVANI, I . , GARCIA, R .J . , "Interactions of the environmental and b io log ica l factors on the distribution of trace elements in the marine environment", Disposal of Radioactive Wastes into Seas, Oceans and Surface Waters (Proc. Symp. Vienna, 1966), IAEA, Vienna (1966) 249.

[ 9 ] STEVENSON, R. A . , LUGO-UFRET, S . , DIECIDUE, A . T . , "Trace e lement analyses of some marine organisms", 5th Inter-American Symp. Peaceful Appl icat ion o f Nuclear Energy (Valparaiso, Chile , 1964), Pan-American Union, Washington, DC (1965) 233.

[ 1 0 ] PHELPS, D. K. , "Partitioning o f the stable elements Fe, Zn, Sc and Sm within a benthic community , Anasco Bay, Puerto Rico" , Radioecological Concentration Processes (ABERG, B . , HUNGATE, F. P . , Eds), Pergamon Press (1966) 721.

[ 1 1 ] FORSTER, W . O . , WOLFE, D. A . , LOWMAN, F. C . , McCLIN-ESCALERA, R. , "Trace e lement inter-actions between river water and seawater", Radionuclides in Ecosystems (NELSON, D . J . , Ed . ) , 3rd Nat. Symp. Radioecology, USAEC CONF-710501-P2 (1973) 807.

[ 1 2 ] BOGART, D . B . , ARNOW, T . , CROOKS, J. W . , Water Resources of Puerto Rico - A progress report. Water Resources Bulletin No. 4 US, Geological Survey and Commonwealth of Puerto Rico (1964) vii + 102 pp. + App. A.

[ 1 3 ] KIPPLE, F. P . , et a l . , Water Records of Puerto Rico, 1958-63, US Geologica l Survey (1968) xii + 353 pp.

[ 14] RICKHER, J. G. , et al. , Water Records of Puerto Rico 1964-67, Vol . 2 - South and West Slopes, US Geological Survey (1970) 308 pp.

[ 1 5 ] ROBERTSON, D. E . , Role of contamination in trace e lement analysis of sea water, Anal. Chem. 40 7 (1968) 1067.

[ 1 6 ] STRICKLAND, J. D. H . , PARSONS, T . , A manual of sea-water analysis, Fish. Res. Board. Can. Bull. No. 125 (1960) 185 pp.

[ 1 7 ] CROSS, F. A . , DUKE, T . W . , WILLIS, J. N . , Biogeochemistry of trace elements in a coastal plain estuary: Distribution of manganese, iron and zinc in sediments, water.and polychaetous worms, Chesapeake Sci . 11 4 (1970) 221.

[ 1 8 ] DU1NKER, J. C . , VAN ECK, T . M . , NOLTING, R, F . , On the behaviour of copper, z inc , iron and manganese, and evidence for mobi l izat ion processes in the Dutch Wadden Sea, Netherlands J. Sea Res. 8 2 - 3 (1974) 214.

[ 1 9 ] SHELDON, R . W . , SUTCLIFFE Jr. , W . H . , Retention of marine particles by screens and filters, Limnol. Oceanogr. 14 3 (1969) 441.

[ 2 0 ] ROBERTSON, D. E. , SILKER, W.B. , LANGFORD, J .C . , PETERSEN, M. R. , PERKINS, R . W . , "Transport and depletion of radionuclides in the Columbia River", Radioactive Contamination of the Marine Environment (Proc. Symp. Seattle, 1972), IAEA, Vienna (1973) 141.

[ 2 1 ] FUKAI, R. , HUYNH-NGOC, L. , "Studies on the c h e m i c a l behavior of radionuclides in sea-water. I. General considerations and study or precipitation o f trace amounts of chromium, manganese, iron, cobalt , z inc , and cer ium" , Radioactivity in the Sea, IAEA Publ. No. 22 (1968) 26 pp.

[ 2 2 ] SONNEN, M. B . , Zinc adsorption by sediments in a saline environment. Report COO-1264 -1 , Civi l Engineering Studies, Sanitary Engineering Series No. 24, Dept. Civi l Engineering, Univ. of Illinois, Urbana (1965).

[ 2 3 ] WOLFE, D. A . , JENNINGS, C . D . , "Iron-55 and ruthenium-103 and -106 in the brackish-water c l a m , Rangia cuneata", Radionuclides in Ecosystems (NELSON, D . J . , Ed. ) , 3rd Nat. Symp. Radioecology, USAEC CONF-710501-P2 (1973) 783.

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[ 2 4 ] HUGGETT, R .J . , CROSS, F. A . , BENDER, M. E . , "Metals in sediments and biota from tidal rivers", Mineral Cycling in Southeastern Ecosystems (Proc. Symp. Augusta, Georgia, 1974), (in press).

[ 2 5 ] WOLFE, D . A . , THAYER, G. W . , ADAMS, S . M . , "Manganese, iron, copper and z inc in an eelgrass (Zostera marina) c ommuni ty " , Proc. 4th Nat. Symp. Radioecology (Corvallis, Oregon, 1975), (in press).

D I S C U S S I O N

E. IOANNILLI: When establishing the correlation between the soluble fraction of the various elements and salinity, did you control the dissolved-oxygen concentration? This factor definitely affects the solubility of iron and manganese.

D.A. WOLFE: In our field sampling programme, we obviously could not control the dissolved oxygen. We did, however, measure it normally during the wet season, when the r iver was more turbulent; then the oxygen approached saturation values, whereas during the dry season, when the dissolved organic content was apparently high, the dissolved-oxygen concentration occasionally approached zero . At these t imes, soluble iron increased to very high values, while the particulate iron content was lower .

In the experimental containers, the dissolved oxygen was not controlled. The isotope mixture was stirred into the river water in a large open container immediately pr ior to mixing with the f i ltered seawater in varying proport ions. Thus the chemical and biological oxygen require-ment associated with the r iver water was variable in the containers. These containers were stored at room temperature, with frequent shaking, for periods of 5 to 10 days. During this t ime, I would expect diffusion of atmospheric oxygen through the thin polyethylene walls of the container to occur , with a tendency to equalization of the initial di f ferences in dissolved-oxygen concentration.

G. GHERSINI: F irst a comment. We have conducted experiments along similar lines to yours with Po r iver water; these suggest that the fractions col lected with 5(8) (im f i l ters and 0.45 to 5(8) jum f i l ters consist essentially of clay and organic matter, respectively. This fact could explain many of the anomalous correlations that you pointed out in your results.

I should like to ask you how you plan to correlate the data you obtained for the total metal content in the particulate matter with the behaviour of radionuclides released into the water. They obviously interact only with metall ic f o rms adsorbed (or somehow bound) to the surface of the particulate matter itself .

D.A. WOLFE: First , as regards your comment, I should say again that I haven't much confidence in the size discrimination character ist ics of Mill ipore f i l ters . It does seem probable that most of the clays appeared in the first f i lter (5 or 8 pm) . We did not characterize organic content, so I cannot corroborate your suggestion. I suspect, though, that the 0.45 pm fi lter also retained a considerable portion of material smaller than 0.45 jum in diameter — including colloidal particulate inorganic matter. While we do not know the composition of the materials retained on the two f i l ters , it is c lear that the second one retained particulate matter of much smaller size than the f irst , and that this small particulate material exhibited salinity-dependent transformation of the metal content.

178 WOLFE et al.

I agree with the point of your question. As I indicated in my concluding remarks , it will be very important to incorporate into future studies not only the size fractionation of suspended particulate material but also differential extraction techniques for separating various fractions of the metals contained in it. Thus, one might consider the use of, f irst , MgCl2 solutions f or displacing adsorbed metall ic ions f rom particulate surfaces; second, organic solvents for extraction of organical ly-complexed metals; third, dilute HC1 for extraction of precipitated or co-precipitated metals deposited on particulate surfaces ; or, fourth, hot, concentrated HNO3 for dissolution of all non-crystall ine metals in the particulate material . Some or all of these approaches would provide much more insight into the mechanisms of metal transport through estuaries than the neutron activation analysis of total metal content applied in this paper.

I A E A - S M - 1 9 7 / 1 4

INCIDENCE DE LA CHARGE POLLUANTE DES EAUX SUR LE COMPORTEMENT DES RADIONUCLEIDES

P. BOVARD CEA, DSpartement de protection, Centre d'&tudes nuclSaires de Fontenay-aux-Roses, Fontenay-aux-Roses

A. GRAUBY, A. SAAS CEA, Departement de protection, Centre d'6tudes nucl£aires de Cadarache, St-Paul-lez-Durance

R. SCHAEFFER Electricity de France, Paris, France

Abstract-R<fsum<£

EFFECT OF THE POLLUTANT BURDEN OF WATER ON THE BEHAVIOUR OF RADIONUCLIDES. The authors describe the e f fect o f pollution o f waterways on the transfer o f radionuclides. Their first

example concerns modif ications o f the chemica l equilibrium o f iodine as a function o f pH-value . Variations in the mobi l i ty o f several elements under the inf luence o f COD are then studied, and an example o f how the mobi l i ty potential o f a number o f radionuclides evolves from the point o f release up to the irrigation limit is presented. Finally, interactions between irrigation water and groundwater are dealt with. The work reveals four main types o f factors capable o f leading to synergic effects: physical factors (pH-value, temperature), chemica l factors (saline burden, COD), m i c r o - b i o l o g i c a l factors (BOD) and extrinsic factors (water reg ime , uti l ization).

INCIDENCE DE LA CHARGE POLLUANTE DES EAUX SUR LE COMPORTEMENT DES RADIONUCLEIDES. Les auteurs dScrivent les incidences de la pollution des cours d'eau sur le transfert des radionucleides.

Le premier exemple developpe relate les modif ications de l 'equilibre chimique de l ' i ode en fonction du pH. On 6tudie ensuite revo lut ion de la mobi l i tS de quelques elements sous l ' e f f e t de la DCO. Les auteurs presentent ensuite un exemple d 'evolution du potentiel de mobil itS de plusieurs r a d i o n u c l i d e s du point de rejet jusqu'S la borne d'irrigation. Enfin, on developpe les interactions entre les eaux d'irrigation et l 'eau du sol . L'ensemble de ces travaux met en ev idence quatre facteurs principaux susceptibles de provoquer des effets de synergie: facteurs physiques (pH, temperature), facteurs chimiques (charge saline, DCO), facteurs microbiologiques (DBO), facteurs extrinseques (regime de l ' eau , utilisation).

INTRODUCTION

L e s b i l a n s e t a b l i s d e p u i s q u e l q u e s a n n e e s o n t f a i t r e s s o r t i r q u e l e

r e j e t r a d i o a c t i f n e p o u v a i t e t r e e x t r a i t d e s o n c o n t e x t e e t q u ' i l y a v a i t i n t e r -

a c t i o n s u r l e c o m p o r t e m e n t d e s r a d i o n u c l e i d e s d e l a q u a l i t e d e s e a u x , e l l e -

m e m e f o n c t i o n d e s c o n d i t i o n s n a t u r e l l e s ( h y d r o l o g i e - c l i m a t o l o g i e . . . ) e t d e s

c o n d i t i o n s a r t i f i c i e l l e s ( a c t i v i t e s h u m a i n e s , r e j e t s , p o l l u t i o n . . . ) £ 0 •

179

180 BOVARD et al.

L a qualite des eaux est envisagee ici dans son sens le plus large. Son incidence est etudiee a plusieurs niveaux :

- au niveau de l'eau, vehicule de la contamination (dilution, transfert . . . ),

- au niveau de l'eau, source de la contamination (pour les organismes vivants aquatiques, pour les cultures par l'intermediaire de l'irrigation) .

Ainsi, une etude sur le sodium [2j a montre que lors de la migration de cet element dans le sol, la charge saline de l'eau d'irrigation prenait le pas sur l'effet du type de sol a partir de 35 mg/l de sodium. De m e m e on a mis en evidence la presence dans le sol irrigue de complexes organo-mineraux formes dans le fleuve ou sont effectues les rejets radioactifs [3] .

II a ete, par ailleurs, largement demontre que la forme physico-chimique sous laquelle le radionuclide est rejete intervient dans son compor-tement et son evolution dans les differents milieux dans lesquels on le retrouve.

Nous essaierons ici d'illustrer le role de la charge polluante sur ce c o m p o r -tement en presentant quelques exemples relatifs aux principaux parametres qui servent a determiner le degre de pollution : pH, oxydo-reduction, charge saline, D B O , D C O .

1. MODIFICATIONS DE L'EQUILIBRE CHIMIQUE DE L' lODE EN FONCTION DU pH

Dans les rejets radioactifs, tout c o m m e dans les cours d'eau, l'iode se trouve a des degres d'oxydation variable : iodure, iodate, periodate, iode vapeur, iode organique, etc ... Ce melange de formes physico-chimiques est susceptible d'evoluer en fonction des conditions du milieu. O r le cycle biolo-gique d'un iodure est tres different de celui de l'iode lie a un complexe orga-nique par exemple. De m e m e des elements mineraux ou organiques rejetes par l'industrie sont susceptibles de faire varier le degre d'oxydation.

Dans l'etude relatee ici, il s'agit de determiner le role du p H dans les modifications de l'equilibre chimique de l'lode quand celui-ci varie entre 3 et 8. C o m m e le montre la figure 1, l'action du p H se traduit par un boule-versement de l'equilibre : iodure, iodate, periodate, iode vapeur et iode or-ganique. Ainsi la teneur des iodures augmente avec le p H de 50 & 75 °/„, tandis que parallelement la forme I„ diminue. L e periodate pour sa part disparaft pratiquement a partir de p H 4. L'autoradiographie (fig. 2) illustre d'une fa?on indubitable l'evolution du phenomene.

L'equilibre physico-chimique est egalement perturbe par des ele-ments mineraux presents en faible teneur : manganese, zinc, fer, alumi-nium, cuivre. Lors d'un rejet, generalement acide, on assiste done, sous l'action de l'effet tampon du fleuve, a une evolution de l'equilibre physico-chimique qui aura une importance capitale et dont depend notamment son comportement ulterieur dans les differents milieux. Ceci laisse presager une difference de comportement dans une riviere de regions calcaires a p H

IAEA-SM-197 / 14 181

% 1 0 0

50

0 — • io dates I 3 . — . periodates " 1 — i polyiodures " • — • C M 31 • — • 12 » • — a iodures

3 4 5 6 7 8 PH

FIG. 1. Repartition des formes chimiques de l ' iode en fonction du pH (en pourcentage).

migration

• t f f f

* I " Iorg

( iode

iode organique)

(iodures polyiodures)

( iodates)

* \ o ;

deposed flMBHBHBHHHHHHHHHHH * I04

p H 3 4 5 6 7 8 (periodatesl

S o l v a n t : ETHYLACETATE - M E T H A N O L - A M M O N I A Q U E 1 / 5 I 5 0 / 1 3 / 1 0 )

FIG.2. Variation des formes de l ' iode en fonction du pH (migration sur gel d e s i l i c e ) , tampons acfitiques.

182 BOVARD et al.

relativement eleve ( c o m m e le RhSne - 7 a 8) et une riviere de zone grani-tique a p H plus faible. Ceci peut avoir des repercussions d'une certaine im-portance en cas d'accident.

2. EVOLUTION DE LA MOBILITE DE QUELQUES ELEMENTS

L'evolution de la mobilite de plusieurs radioelements a ete etudiee a l'aide d'une technique, deja presentee par deux d'entre nous, qui consiste a reveler la reaction des eaux et des radioelements sur un support de gel de silice impregne ou de resines [3j.

L'etude du suivi des rejets le long d'un cours d'eau permet de cons-tater des comportements differents ou la teneur en sels mineraux et en composes organiques joue un r61e dans le deplacement plus ou moins ac-centue de tel ou tel radionucleide. L a figure 3 montre l'effet obtenu, a partir de cinq elements : Cesium 137, Sodium 22, Cobalt 60, Manganese 54 et C e r i u m 141 sur quatre types d'eau de composition organo-minerale variee. L e r61e de la qualite des eaux apparaft sans equivoque.

Des le rejet le manganese et le cobalt se complexent tres rapidement avec la matiere organique presente dans le fleuve et sont vehicules a l'etat de complexes organiques a charge variable. Leur evolution est conditionnee par deux m e c a n i s m e s principaux : la degradation biochimique du complexe (DBO), l'insolubilisation par la charge saline notamment par les ions calcium et les metaux. A u m o m e n t du contact avec les eaux saumStres et l'eau de m e r , des complexes anioniques apparaissent en quantites importantes et dans l'eau de m e r le cobalt est pratiquement entierement sous forme complexee.

L e cerium quant a lui ne se complexe qu'en milieu saum&tre ou marin. Dans l'eau du RhSne il est surtout vehicule a l'etat colloidal.

L e cesium et le sodium sont solubles mais retenus par le complexe absorbant des sediments. lis sont vehicules par le debit solide du fleuve. Neanmoins lors du passage dans les eaux saumStres et lors du debouche en m e r ils passent a l'etat soluble et sont tres mobiles. Le cesium notamment se fixe partiellement sur des composes organiques.

Afin d'illustrer le role de la matiere organique des cours d'eau vis-a-vis des nucleides nous avons determine le pourcentage de formes comple-xes dans une eau du RhSne a charge saline constante mais avec une teneur en matiere organique exprimee en D C O variable. Nous constatons pour tous les nucleides une croissance du pourcentage des formes complexes au fur et a m e s u r e que la D C O augmente. Cette croissance est plus ou moins rapide, mais a partir d'une D C O de 10 mg./l le taux de complexation atteint 65 a 90 °/> selon le nucleide et qu'a 15 mg/l ce taux fluctue entre 80 et 100 °/0 (figure 4).

II ressort de toutes ces observations que pour une certaine charge organo-minerale une eau est susceptible de mobiliser la quasi-totalite d'un radionucleide.

IAEA-SM-197 /14 183

Cs Na Co

P Rh В M D Rh В M

FIG. 3. Chromatographie sur gel de si l ice. Evolution du fleuve à la mer.

De même ces mécanismes conditionnent la disponibilité des radio-n u c l i d e s v i s - à - v i s des organismes vivants, et peuvent, par exemple, ex -pliquer certaines di f férences de comportement en milieu dulcicole et en milieu marin.

184 BOVARD et al.

FIG. 4 . Complexations organiques dans le Rh6ne en fonction de la demande chimique en oxygSne (DCO).

FIG. 5 . Potentiel de mobilitS de quelques nuclSides dans un rSseau hydrographique (Rhin) par rapport 1 la mobilitS sur gel de silice du complexe EDTA -radionuclSide.

IAEA-SM-197 / 1 4 185

3. EVOLUTION PHYS ICO-CHIMIQUE DE PLUSIEURS RADIONUCLEIDES DU POINT DE REJET A LA BORNE D'IRRIGATION

Entre le point de rejet et son utilisation par l'agriculture ou l'in-dustrie, l'eau circule dans le fleuve et des canalisations diverses. A u cours de ce cheminement la forme du radionucleide evolue. Ainsi avons-nous essaye de reconstituer l'evolution du rejet le long du parcours de l'effluent. Pour permettre une meilleure exploitation des r£sultats obtenus nous avons utilise la notion de potentiel de mobilite qui est le rapport de mobilite sur gel de silice d'un complexe E D T A - radionucleide avec la mobilite du radio-nucleide en presence de l'eau du fleuve [4j . L a figure 5 illustre les varia-tions obtenues dans un cas particulier. E n ce qui concerne la qualite de l'eau elle-meme nous constatons une epuration partielle : la D C O diminue de 11 mg/l a 5,5 mg/l sur une distance de 16 k m . Pour ce qui est de la c o m -plexation des radionucleides nous observons :

- une augmentation dans le fleuve apres le rejet surtout pour le cerium et le zinc.

- dans le canal principal ou le debit est assez fort, le taux de complexation chute graduellement sauf pour le cesium qui a un potentiel faible au depart. Cette chute est assez comparable a celle de la D C O .

- dans le canal secondaire, le temps de sejour est propice a une degradation des colloi'des organiques ; de ce fait le potentiel de mobilite chute rapide-ment du moins pour le cerium.

- dans la rigole d'irrigation, le potentiel de mobilite baisse legerement ; neanmoins une partie des radionucleides arrive a la borne d'irrigation sous forme de complexes mobiles.

L'etude du potentiel de mobilite integre done dans sa resultante le taux d'epuration biochimique de l'eau (la charge saline etant a peu pres constante dans un reseau hydrographique donne et & une epoque donnee). O n constate aussi que le zinc suit a peu pres la variation de la D C O ; dans notre cas precis l'epuration de l'eau reduit proportionnellement la mobilite de cet element. Cette action est encore plus accentuê dans le cas du cerium.

4. INTERACTION EAU D'IRRIGATION - EAU DU SOL

Une nouvelle evolution du radionucleide se produit lors du contact de l'eau d'irrigation avec la solution du sol et le sol lui-meme. Pour mettre en evidence cette synergie deux etapes sont n^cessaires : - determination de l'interaction : eau d'irrigation/solution de sol (fig. 6).

- determination de l'interaction : solution de sol/radionucleide (fig. 7). L a composition de la solution du sol est fonction du type de sol et

des conditions temporaires du milieu (humidity, temperature, etc...).

L e transfert des radionucleides dans les sols est lie a la presence des formes hydrosolubles apportees par les eaux d'irrigation, une forte pro-portion en reste hydrosoluble et est capable de migrer en profondeur [5j.

186 BOVARD et al.

BC Be BA G BC Be BA

Cs

• fff

D= eau distillee G = c a n a l d'irrigat ion BC \ Be (= impregnation avec BA J hydrosolubles du sol et

migration par eau d'irrigation G

BC = sol brun calcaire Be = sol brun calcique BA - sol brun acide

P G BC Be BA

FIG. 6. Interaction hydrosolubles — eau d'iirigation (migration sur gel de silice).

N o u s c o n s t a t o n s s u r l a f i g u r e 7 que l a s o l u t i o n du s o l a g i t s p e c i f i q u e -m e n t s u r c h a q u e r a d i o n u c l e i d e : c o m p l e x e s o r g a n i q u e s s o l u b l e s et i n s o l u b l e s du c e s i u m ; c o m p l e x e s p l u s ou m o i n s s o l u b l e s du m a n g a n e s e , c o m p l e x e s p a r -t i e l l e m e n t i n s o l u b l e s du c e r i u m .

Si l ' o n s u p e r p o s e a p r e s e n t l ' e a u d ' i r r i g a t i o n , on r e m a r q u e un c o m -p o r t e m e n t n o u v e a u qui peut s e t r a d u i r e p a r une a u g m e n t a t i o n ou une d i m i n u -t i o n de l a m o b i l i t e . L a f i g u r e 6 i l l u s t r e l a r e d u c t i o n de m o b i l i t e d a n s l e c a s

IAEA-SM-197 /14 187

C E S I U M S T R O N T I U M

T » p e t r m b run biun de SOI a c I de calcique calcaire

M A N G A N E S E

M I G R A T I O N S U R P A P I t R

t y p e bran brun brun de SOI , c i ' e calcique caleairt

C E R I U M

Type brun brun brun de sol aci<« calcique calcaire

FIG. 7 . Influence de la composition chimique de la solution du sol sur la mobilitS (chromatographic des hydro solubles).

du f e r , du z i n c et m e m e du c e s i u m . D a n s d ' a u t r e s c a s c o m m e l ' a n t i m o i n e p a r e x e m p l e , l a s o l u t i o n du s o l a u g m e n t e l a m o b i l i t y en l e c o m p l e x a n t f o r -t e m e n t . L e s m e c a n i s m e s de c e t t e s y n e r g i e e a u d ' i r r i g a t i o n - e a u du s o l s o n t l i £ s a u x p a r a m e t r e s s u i v a n t s :

- p r e c i p i t a t i o n et i n s o l u b i l i s a t i o n d e s c o m p l e x e s en p r e s e n c e d ' i o n s c a l c i u m .

- s o l u b i l i s a t i o n p a r l e s c o l l o i ' d e s o r g a n i q u e s et l e s i o n s a l c a l i n s .

- v a r i a t i o n du p H et de l a c o m p o s i t i o n de l a s o l u t i o n du s o l .

- p o t e n t i e l d ' o x y d o - r e d u c t i o n de l a s o l u t i o n du s o l .

- p h e n o m e n e s b i o c h i m i q u e s et m i c r o b i o l o g i q u e s .

188 BOVARD et al .

CONCLUSIONS

D'autres exemples pourraient etre donnes de l 'action de la qualite des eaux sur le comportement des radionucleides dans les eaux douces. Cette action y est beaucoup plus divers i f iee qu'en milieu marin du fait meme que dans ce dernier la qualite des eaux est plus homogene, a la fois dans le temps et dans l ' e space .

En resume les facteurs qui interviennent sont de quatre ordres :

- les facteurs physiques : pH, temperature - 11 " chimiques : charge saline , teneurs en complexants, teneur en

matiere organique . . . - les facteurs microbiologiques (par leur action indirecte) - 11 " extrinseques : variations du regime et du debit naturelles et

art i f i c ie l les , utilisation de l 'eau . . .

L'utilisation de l 'eau est sur le plan de la protection un element i m p o r -tant car c ' e s t elle qui conditionnera souvent la nuisance des radionucleides.

La "qualite" de l 'eau est en fait la resultante des quatre groupes de

parametres cites plus haut.

Le cours d'eau a deux fonctions principales qu'il est necessaire de preserver :

- Tout d 'abord c ' e s t un milieu naturel dont il faut assurer la sante et la peren-nite.

- Ensuite c ' e s t une source de matiere premiere (l 'eau) pour les besoins do -mestiques, agricoles et industriels.

Ces differentes fonctions ont suivant les cas un degre de sensibilite et de priorite differents.

Si l ' on fait abstraction de l ' e f fet thermique (qui n'est pas de notre competence) nous pensons que la fonction critique est la fonction alimentaire, ce qui explique notre ef fort dans le domaine de l 'etude du comportement des eaux d ' irrigation.

Parmi les parametres guidant a la fois la repartition des rad io -nucleides et leur forme chimique dans le sol on peut retenir :

- la charge saline to tale, - la teneur en matiere organique et son origine, - la teneur en sels alcalins notamment en sodium.

qui sont mis en competition avec ceux inherents au sol ou au radioelement l u i - m e m e .

D'une maniere generale, la charge saline de l 'eau d ' irrigation favo-r ise la penetration en profondeur du radioelement et augmente parallelement les f ormes hydrosolubles en profondeur.

IAEA-SM-197 / 1 4 189

Les composes organiques et les complexants chimiques sorit de nature a augmenter la mobilite des r a d i o n u c l i d e s dans les so ls .

Le phenomene de complexation des r a d i o n u c l i d e s avec les composes organiques presents dans les eaux d ' irrigation represente sur le plan de la radioprotection un risque potentiel de premier ordre qui necessite une con -naissance de l ' e co log ie loca le . La notion de biodegradation des composes o r -ganomineraux est de nature a modi f ier les risques de contamination des sols et des nappes. La teneur en alcalins, en sodium en particulier, constitue pour les eaux d ' irrigation un parametre qui favorise la migration des radio -n u c l i d e s . Son action est double : elle augmente la solubilite des composes organiques presents dans les so ls , elle contribue au maintien en solution des composes organiques presents dans les eaux d ' irrigation et inhibe de cette faôn l 'action des ions calc ium.

Pour terminer nous croyons necessa ire de rappeler que la qualite des eaux en un point donne n'est pas une constante mais qu'elle varie avec le temps non seulement sous l ' influence des conditions naturelles mais aussi sous cel le de l 'act ion de l 'homme, qui paradoxalement, est souvent la plus dif f ic i le a prevo ir .

R E F E R E N C E S

[ 1 ] BOVARD, P . , GRAUBY, A . , FOULQUIER, L. , PICAT, Ph. , « E t u d e radioeco log ique du Bassin rhodanien — Strategic et b i l a n » , Environmental Behaviour o f Radionuclides Released in the Nuclear Industry (C .R . C o l l . , A ix -en -Provence , 1973), AIEA, Vienne (1973) 507-23 .

[ 2 ] GRAUBY, A . , SAAS, A. , « E t u d e de la migration du sodium dans les sols a l 'a ide du radiosodium, Problemes lies l ' i r r i g a t i o n » , 1 0 e Congrfes int. Sc i ence du sol, Moscou, 1£ (1974) 92-102.

[ 3 ] SAAS, A . , GRAUBY, A . , « M e c a n i s m e s de transfert dans les sols cultives des r a d i o n u c l i d e s rejetes par les centrales electro-nucleaires dans l e systSme f leuve-so l i r r i g u e - n a p p e » , Environmental Behaviour o f Radionuclides Released in the Nuclear Industry (C .R . Co l l . A ix -en -Provence , 1973), AIEA, Vienne (1973) 255 -69 .

[ 4 ] SAAS, A . , Contamination des sols par des dfechets radioactifs industriels, Mecanismes et facteurs de migration et d e v o l u t i o n , Sc i . Sol 4 (1973 ) 255 -64 .

[ 5 ] BOVARD, P. , GRAUBY, A . , « C y c l e des rad i onuc l ides rejetSs dans les eaux par l 'industrie nuc l fea ire» , XIII e Journees de l 'hydraulique, Paris, 1974, SociSte hydrotechnique de France, & paraltre.

D I S C U S S I O N

A. BAYER: Do you think that, at the present level of knowledge, it would be possible to build a model predicting the concentration of radio -nuclides in a r iver system due to nuclear facil it ies likely to be built there during the next few decades ? And what accuracy would you expect f r o m such a predictive model?

P .L . BOVARD: Our studies have provided important data f or developing a predictive system, but at the moment there is no such model in existence. It seems on the face of it that the predictions calculated by such a model might be marred by a rather large e r r o r factor due to the fluctuation in the contamination of the r iver . But even now we could predict certain very mobile radionuclides in the drainage network.

190 BOVARD et al .

J. SHAH: In view of the interaction between radioactive materials and chemical contaminants in a speci f ic water body, I feel that consideration should be given to proper land use planning. The location of chemical industries within the vicinity of a nuclear power station site could be appropriately regulated to minimize any potential synergistic problems that might limit water use.

The radioactive effluents and emissions f rom nuclear power stations during normal operation are very small indeed. Basically, control is required f or regulation of effluent discharges f rom chemical industries. Effluent loading needs to be consistent with the best practicable technology. The fundamental cr i ter ia should be that water quality is not degraded.

P .L . BOVARD: The interaction between chemical pollution and radio -nuclides i s , I would say, a problem speci f ic to a given area and limited to water use. It is still true, though, that small amounts could be displaced as a result of this chemical synergism and the radionuclides might then be transported over long distances; hence, in terms of the protection and monitoring of the site, these effects should be taken into consideration. This is especial ly true of cobalt.

Y.J . SOUSSELIER: Figure 5 in your paper seems to indicate an increase in the mobility of some radionuclides, notably cerium and zinc, in the r iver section, while the COD remains constant. Is there any special reason for that?

P .L . BOVARD: In the given instance the increased mobility is due to a hydroelectr ic power station which makes the r iver water turbulent. This churning-up ef fect , together with oxygenation, promotes mobility of some of the radionuclides and thereby greatly reduces the COD.

Session V

SYNERGISM AND COMBINATION EFFECTS FROM RELEASES TO THE ATMOSPHERE

Chairman: Y . J . SOUSSELIER (France)

IAEA-SM-197 /14

POSSIBLE FUTURE EFFECTS ON THE POPULATION OF THE FEDERAL REPUBLIC OF GERMANY OF GASEOUS RADIOACTIVE EFFLUENTS FROM NUCLEAR FACILITIES*

G. SCHWARZ, H. BONKA, K. BRUSSERMANN Kernforschungsanlage Jiilich

D. BRENK Rheinisch-Westfalische Technische Hochschule Aachen, Aachen,


Abstract POSSIBLE FUTURE EFFECTS ON THE POPULATION OF THE FEDERAL REPUBLIC OF GERMANY OF GASEOUS RADIOACTIVE EFFLUENTS FROM NUCLEAR FACILITIES.

In this paper the potential radioecological consequences resulting from an expanded nuclear industry in the Federal Republic of Germany are assessed for a period of about 100 years. The potential spatial total-body dose, and the expected t ime-dependent dose distribution for the whole population due to radioactive gaseous releases are described considering contributions due to 3 H , 85 Kr and 133 X e . The results are suitable for indicating the long-term trend o f the degree of retention o f radioactivity necessary. Moreover, a risk estimation in the form o f the expected number of cancer cases is assessed, including effects from aqueous discharges and globally distributed nuclides.

The radioecological ef fects arising f r o m an increasing exploitation of nuclear energy to meet the energy demand are attracting more and more public interest. This work aims to determine, for the Federal Republic of Germany, whether the consequences of such increased use of nuclear technology can be reconci led with the public demand for a better environment and quality of life, and to what degree this might be possible . While the greater part of the previous discussions of the release of radioactive substances were limited to a study of the ef fects of individual nuclear faci l i t ies , this paper gives estimates of and descr ibes the conse-quences of having a large number of facil it ies involved in the nuclear fuel cyc le , covering a t ime-span of 100 years . The discussion is limited to nuclides of particular import in radioecology [1], namely tritium (3 H) and two rare gases ( 8 5 Kr and 1 3 3Xe).

1. REQUIREMENTS AND ASSUMPTIONS

The great complexity of the inter-relationships involved in this problem require assumptions and the introduction of limitations, the most important of which are summarized br ie f ly below.

* This study has been supported by the Federal Ministry of the Interior under contract No. St. Sch, 600.

193

194 SCHWARZ et al.

TABLE I. PROBABLE RADIOACTIVE EFFLUENTS (Ci /a) DISCHARGED FROM NUCLEAR POWER PLANTS AND REPROCESSING PLANTS TO THE ATMOSPHERE

Nuclide Nuclear power plants (1000 MW(e)) Reprocessing plants (50 000 MW(e)) without retention

BWR PWR HTR LMFBR BWR/PWR HTR LMFBR

3 H

85 Kr

133 Xe

5 0

7 0 0

2 5 0 0

20

700

2500

10

120

40

1000

7000

1 x 106

1 x 1 0 7

0 . 6 X 1 0 6

2 X 1 0 7

1 .2 X 106

0. 6 X 107

Radioecological studies in the Federal Republic of Germany start out f rom an energy prediction which calls for an increase of the installed e lectr ica l generating capacity (conventional and nuclear) f rom the present 67 GW to 540 GW in 20703 i .e . a prediction period of 100 years . The share of nuclear energy is expected to r ise f r om the present 5% to almost 97% at the end of the planning period. This means that, up to 1985, the prediction agrees well with the atomic and overall energy programmes of the Federal Republic, which plan for a nuclear share of ~ 45% by as early as 1985. Potential reactor sites are determined on the basis of the regional energy demand analysis and are aiming for energy production c lose to the consumer, while taking into consideration the engineering and economic development potential of the different reactor types. The siting prognosis for fuel reprocess ing plants has been made bearing in mind their speci f ic siting, logistic and safety-engineering requirements.

The gaseous release rates f r om the stack (see Table I) underlying these calculations are values based on experience, i .e . operational experience to the degree possible for existing reactors , or estimates developed f rom model concepts. The predicted values for fuel reprocess ing plants are determined by the fuel-element-dependent heavy-metal through-put and a fuel element decay period of about 180 days. Moreover , in the case of fuel reprocess ing plants most of the activity released is in the effluent air [1],

Both in the locality around a contamination source and, with modi f i ca -tions, also for the region in which it is situated, the activity concentration in the atmosphere is calculated by means of Taylor ' s statistical diffusion model , but using the diffusion parameters of McElroy [3], which may be considered representative for regions having a major ground roughness. The diffusion conditions, which differ f r om one site to another, especially the local wind-direction distribution, are taken into consideration by sub-dividing the entire Federal Republic of Germany into nine siting categories, with uniform mean diffusion conditions applying within each siting category [2].

However, with very great distances f r om a source, i .e . up to about 500 km and thus beyond the zone of a single siting category, the wind-direction distribution prevailing at the site is used to describe the activity distribution on a mesosca le . This will result in a systematic e r r o r in the calculation which, however, can be considered acceptable in comparison to the diff iculties involved in simulating activity transport over very great distances.

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In addition, for the purposes of this study, it has been stipulated that all pollution sources have a uniform effective emission height of 100 m.

In the case of the two rare gases, 8 5Kr and 1 3 3Xe, only the direct radiation f r o m the plume or contaminated air can be considered relevant for the determination of the radiation exposure of the population. Conse-quently, the skin is subject to the greatest exposure, shielding the parts more sensitive to radiation, such as the gonads, b lood- forming organs, etc. , f r o m the beta radiation, which has a low penetrating power. Con-sequently, only the 7-radiat ion having the greater penetrating power may be considered as providing a contribution toward total-body exposure — in the case of 8 5 Kr this is about 1% of the skin dose. On the other hand, exposure due to 3H, which is incorporated by inhalation and ingestion (and which is assumed to be homogeneously distributed throughout the body), must be considered exclusively a total-body dose. The submersion dose due to 3H in the air is small compared to that of the two rare gases and is neglected in the following discussion.

2. SPATIAL AND TIME-DEPENDENT TOTAL-BODY EXPOSURE

All the calculations carr ied out, with the assumptions as mentioned, take into consideration the different retention factors in the facil it ies generating the greatest emissions ( i .e . fuel reprocess ing plants). Some of the results, especially the spatial dose distribution, are discussed with re ference to the total-body dose in the following paragraphs.

Figure 1 shows the spatial total-body dose due to a f i r s t -pass exposure by 3H and 1 3 3Xe for a total installed generating capacity of 100 GW - both conventional and nuclear - in 1982 (following forecasts , this being the f irst operating year (1975) of the f irst industrial -scale fuel reprocess ing plant). A retention of 99% is assumed for the fuel reprocess ing plants, while the reactors are taken to emit activity in accordance with Table I. The contribution to the y- radiation dose that is generated during 8 5Kr decay is small with the high degree of retention stipulated, so that it can be neglected here.

The prof i le of the isopleths is c learly characterized by the two fuel reprocess ing plants, one of which is operating on a site in southern Germany 1 that has a pronounced prevailing southwesterly wind, while the other plant is to be sited in northern Germany. The other 36 emiss ion sources , primari ly power reactors having much lower emission rates and whose sites can be recognized as individual peaks in F i g . l , have a lower impact. The maximum dose is about 0.53 m r e m / a in the immediate environs of the north-German fuel reprocess ing plant. In the case of the reactors the maximum values are lower by at least one order of magnitude.

The total-body exposure at a later time, 1990, corresponding to a total installed generating capacity of 200 GW, and now including some 95 reactor sites and three fuel reprocess ing plants, is shown in Fig.2. In addition to a few pronounced maxima in the environs of the fuel reprocess ing plants, notice must be taken of the large number of doses of approximately the same level , based on the forecasts calling for an

1 The experimental plant at Karlsruhe.

FIG. 1. Tota l -body dose due to airborne 3 H and 133 X e in the year 1982 (99°lo retention of 3 H in reprocessing plants).

FIG. 3. Total -body dose due to airborne 3 H and 1 3 3Xe in the year 2070 (99% retention o f 3 H in reprocessing plants).

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increasing number of breeder reactors , which have a relatively high 1 3 3Xe emission as compared with other reactor types (see Table I). How-ever, it should be borne in mind that the maxima have changed but insigni-ficantly as compared with the preceding graph. However, doses which were previously encountered only in very limited local it ies are now more frequent and cover larger areas.

Figure 3 shows the total-body exposure due to radioactively con-taminated plumes f rom nuclear facil it ies at the end of the prediction period, corresponding to 540 GW of installed generating capacity. There are now some 300 reactor sites, some of these including several individual units of 1000 Mff (e ) each, and a total of 14 fuel reprocess ing plants. It is seen that in particular the background exposure caused by the large number of emission sources has increased considerably as compared with the preceding graphs. Where many emission sources are concen-trated within a small area, such as the industrial district of the Ruhr, even the background exposure is considerably above that of the surrounding areas. However, each site is still effectively represented by a peak. The maximum annual total-body dose is approximately 0.75 mrem, i . e . less than 1 m r e m / a , provided that about 99% of the 3H and 85Kr are retained in the fuel reprocess ing plants.

3. TOTAL-BODY DOSE DISTRIBUTION IN THE POPULATION

If the total-body dose at a certain place and time and the population distribution are known, it is possible to state the dose distribution for a specif ied group of the population, e.g. the population of the Federal Republic of Germany. Figure 4 shows the dose distribution functions of total-body exposure due to 3H, 8 5Kr and 133 Xe , it being stipulated that 99% is retained in both the original and future large industrial fue l - reprocess ing plants. If the distribution curves for different t imes are compared, the development with time for the stipulated retention conditions can be observed.

It can be seen that, at the present time, the range of dose values covers about three decades with, however, only about 0.1% of the popula-tion receiving an annual total-body dose greater than 0.01 mrem, with a maximum dose of ~0 .4 m r e m / a , while the remaining 99.9% of the popula-tion are exposed to doses smaller than 0.01 m r e m / a . As the f irst large industrial fuel reprocess ing plant is commissioned (taken as 1982), the range of values narrows considerably due to the fact that, while the higher values change only insignificantly, the low dose values are increased. Given a 99% retention in the reprocess ing plant, the maximum is estimated to be ~0.5 m r e m / a . This trend is found to continue for the entire period covered by the prediction. Thus, towards the end of the prediction period, i . e . in 2070, the doses range between a maximum of 0.75 m r e m / a and a minimum of 0.01 m r e m / a . 99% of the population are subject to exposures ranging between the minimum (0.01 m r e m / a ) and about 0.03 m r e m / a so that, compared with the total population, only a minority is subject to the higher radiation exposures .

FIG. 4. Time-dependent distribution of the total -body dose due to airborne 3 H , 85Kr and 1 3 3 Xe to the population of the Federal Republic of Germany (99% retention in reprocessing plants).

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4. TIME-DEPENDENT TOTAL-BODY AND SKIN DOSES

A better grasp of the variation with time of the radiation exposure of different organs due to a f i r s t -pass exposure can be obtained as fo l lows.

Figure 5 shows the mean total-body exposure (this is the mean dose over the area considered) due to 3H, 85Kr and 1 3 3Xe for different reten-tion factors in fuel reprocess ing plants. Taking into consideration all the emission sources that are relevant at the present time, the calculations yield a mean total-body dose of about 0.001 m r e m / a , resulting primari ly f r om the tritium emission of the sole German fuel reprocess ing plant, the experimental one at Karlsruhe. In the event that 99% retention of 3H and 8 5Kr can be achieved in the future in all forecast fuel reprocess ing plants, the mean total-body exposure on the basis of the 2070 generating capacity predictions will reach values of about 0.02 m r e m / a .

1970 2000 2040 2070

YEAR

FIG. 5. T ime-dependent averaged total-body dose due to airborne 3 H, 85Kr and 1 3 3Xe for different retention factors (RF) in reprocessing plants (RP).

(If, on the other hand, as a purely theoretical exerc ise , complete emission of all the 3H and 8 5Kr nuclides generated in the fuel repro -cessing plants is hypothesized, the mean dose will r ise by about three orders of magnitude, reaching a saturation value of about 1 m r e m / a towards the end of the prediction period. In that case the maximum total-body doses corresponding to this curve would be about 50 to 100 m r e m / a , found in the immediate environs of the reprocess ing plants, given an effective stack height of 100 m.)

The skin exposure resulting f r o m the release of radioactive substances, determined in a fashion similar to that for the total-body dose descr ibed above, can be seen in Fig.6 for different retention factors in the fuel repro -cessing plants. As was already pointed out in the introduction, this value

202 SCHWARZ et al.

1970 2000 2060 2070

YEAR

FIG. 6. T ime-dependent averaged skin dose due to airborne 3 H , 85 Kr and Xe for different retention factors (RF) in reprocessing plants (RP).

is considerably greater than the total-body values, pr imari ly due to direct beta irradiation f rom the rare gases, 8 5Kr and 1 3 3 Xe, diffusing into the atmosphere. Thus, the mean skin exposure at the present time is about 0.004 m r e m / a , predominantly due to the experimental reprocess ing plant (whose annual 8 5 Kr emission rates were assumed to have a value of 68 000 C i /a [4] for the purposes of this calculation).

Given 99% retention in fuel reprocess ing plants, it i s possible , even in the foreseeable future, to maintain the mean skin dose at under 0.1 m r e m / a , with maxima reaching 8 m r e m / a in the environs of fuel reprocess ing plants. However, were all three nuclides to be emitted without retention in the effluent air f r o m the fuel reprocess ing plants, the mean skin dose would reach values of 8 m r e m / a , while maxima as high as 600 m r e m / a could occur . These f igures make it c lear that the unrestricted re lease of these nuclides would not be feasible. Consequently, in view of national and international recommendations for radiological protection, the initial retention rate for 3H and 8 5Kr must be at least 90%, the long- term requirement, however, being 99% retention.

5. EVALUATION OF RESULTS

To date, attempts to estimate and evaluate the danger or risk involved in subjecting populations to radiation exposure have failed because of the absence of a clear, acceptable concept for weighing usefulness and risk. Hence, any evaluation is limited by the limitations inherent in the available concepts.

I A E A - S M - 1 9 7 / 1 8 203

One qualitative method is to compare the radiation exposure due to nuclear faci l it ies to the natural radiation background. Detailed studies carr ied out in the Federa l Republic of Germany have shown that the natural radiation exposure of the gonads, bone-marrow and other vital organs of the human body is approximately 100 m r e m / a , fluctuating over a range of about 30 m r e m / a ; this applies to the major portion of the population. If one now demands that the radiation exposure f r o m man-made sources must have a reasonable ratio to natural radiation exposure, or be smaller than its fluctuation range, one can state that there will not be any significant increase in radiation risk as compared with that due to natural radiation. However, this condition can only obtain if the nuclides of greatest radioecological significance are retained to a great degree.

Another, more quantitative procedure is to determine the radiation-induced cancer and leukaemia rate. It is a known fact that almost all the results in this respect are based on epidemiological investigations per -formed on the survivors of the nuclear bomb detonations of Nagasaki and Hiroshima. These detailed investigations have resulted in dose -e f fec t relationships of which the l inear-relationship model must be considered the most conservative estimate for radiological protection purposes as long as the details and effective magnitudes are not known to better accuracy . According to Jacobi [5], the total-body irradiation of a popula-tion of one mill ion by X - r a y s , gamma or beta rays will cause an annual mean value of l ess than 40 radiation-induced cancer cases (including leukaemia) per unit of dose. An estimate of the radiation r isk f or the total population of the Federal Republic of Germany, i . e . 62 mill ion persons, based on this dose -e f fec t relationship, is shown in Table II. F o r completeness ' sake, it appeared meaningful to include in this con-sideration the other exposure paths which have not been taken into consideration ear l ier in this paper, such as radiation exposure due to waste waters discharged into r ivers , investigated for the Rhine and the Danube and assuming an appropriate use as potable water, as well as the contributions to the dose caused by globally diffused nuclides, especial ly o oc

H and Kr. The details of the calculation for the two last-named exposure paths are not discussed in detail here (see Ref . [1]). However, the table shows that the individual exposure paths can have greatly differing weights in the total pattern, and the pattern changes with t ime. Whereas, in 1975, it is still possible to speak of equivalence of the different exposure paths, provided that they are used in accordance with the requirements, very different considerations will be necessary in the future, depending on the degree of retention in the fuel reprocess ing plants.

The overal l balance can now be used to obtain an estimate of the radiation-induced cancer rate (including leukaemia). As expected, the present cancer rate caused by nuclear faci l it ies, based on the l inear dose -effect relationship and in line with comparison to the natural background exposure, is very low, being less than one radiation-induced cancer case per annum, a condition which will continue to exist beyond the turn of the millenium. If all the stated nuclides were released without retention, an increase of up to a maximum of five radiation-induced cancer cases per annum would have to be expected by the end of the prediction period. If we compare these f igures with those of the incidence of spontaneous cancer cases , which is about 150 000 cases per annum in the Federal

TABLE II. POTENTIAL POPULATION DOSES DUE TO GASEOUS AND AQUEOUS EFFLUENTS FROM NUCLEAR FACILITIES IN THE FEDERAL REPUBLIC OF GERMANY, AND THE RESULTING RADIATION-INDUCED CANCER RATE AS A FUNCTION OF YEAR OF PROGNOSIS

RF = retention factor ; RF = 100 corresponds to 99% retention

1975

RF = 100 for waste air of repro. plants

1990

Total release via waste air

of repro. plants

RF = 100 for waste air of

repro. plants

2070

Total release via waste air

o f repro. plants

Radiation exposure due to gaseous effluents (first-pass exposure only)

(man • r e m / a ) 36 176 8 600 1070 54000

Potential radiation exposure due to drinking water from Rhine and Danube rivers

(man • r e m / a ) <44 <540 <1460

Radiation exposure by globally distributed H - 3 and Kr-85

(man • rem/a ) 28 95 900 800 60 000

Total population-dose ^ ( m a n . r e m / a ) <108 <810 <10 000 <3300 <115 000

Radiation induced c a n c e r -rate to the population o f the FRG (62 mi l l . pers . ) ( l in. dose-resp. relationship) a

(cases /a) 0 .005 0. 03 0 . 4 0. 1 5. 0

a Linear dose-response relationship according to Jacob i [5 ] : a = 40 cases per 106 rem.

k For comparison, the population dose for the Federal Republic of Germany due to natural radiation is 6.2 X106 m a n - r e m / a .

IAEA-SM-197 /18 205

Republic of Germany, it is c lear that we can hardly speak of any signifi-cant increase . Moreover , it is becoming increasingly more difficult, if not imposs ib le , to prove any injury in the population due to the normal operation of nuclear power faci l i t ies . Yet it is not possible to exclude with absolute certainty any such occurrence within the stated l imits .

6. CONCLUSIONS

The result of this investigation on potential radioecological conse-quences indicates that the complete emission of all radionuclides generated during normal operation, especial ly of fuel reprocess ing plants, will be thoroughly unacceptable. In accordance with national and international recommendations f or radiological protection, it will be necessary , in the future, to retain the SH and 8 5Kr generated in fuel reprocess ing plants at a level of about 90% to 99% (RF = 100). An estimate of the risk, to the degree that this is quantifiable at all in the f o r m of a prediction of induced cancer cases in the population, suggests that this i s insignificant as compared with spontaneous cancer incidence.

However, it should, in conclusion, be emphasized that all the results and conclusions obtained must be understood and evaluated bearing in mind the initial assumptions made, the meaningfulness of some of these being difficult to estimate, especial ly the long- term development potential (as has been ef fect ively shown in the recent 'energy c r i s i s ' ! ) . Yet the results are sufficient to indicate the long- term trend of the radiological burden. Moreover , they afford a possibil ity of stating the l imits of radia-tion exposure and the sources that require the strictest control, thus contributing towards planning for the future and, hence, towards a more factual trend in the discussions with the interested public.

R E F E R E N C E S

[ 1 ] BONKA, H., et al . , Kernforschungsanlage Julich Rep. Jiil-1220(July 1975). [ 2 ] BRENK, H . D . , VOGT, K . J . . Kernforschungsanlage Julich Rep. j t iL -1142-ST (Dec . 1974). [ 3 ] McELROY, J. L. , J. Appl. Meteorol . 8 1 (1969) 19. [ 4 ] KIEFER, H . , KOELZER, W. , Kernforschungszentrum Karlsruhe Rep. KFK-1818 (1974). [ 5 ] JACOBI, W. , Proc. Schweiz . Vereinig. fur Atomenergie (SVA), March 1973.

D I S C U S S I O N

A . BAYER: One main dif ference in the t ime-dependence of the maximum doses via the gaseous and liquid pathways should, I think, be noted. In your paper the upper limit f o r the whole-body dose via the gaseous pathway is nearly time-independent in the region 0.5 to 0.75 m r e m / a — given the assumptions you have made — over a time span of approximately 100 years . This probably stems f r o m the fact that, at a site where a 1500 t / a reprocess ing plant is built, there will not be a

206 SCHWARZ et al.

second one during this time span. If, on the other hand, we look at the maxi' mum (potential) dose via the liquid pathway, as derived f rom the maximum concentration in the r iver water (e.g. the Rhine at the border between Germany and the Netherlands, or the Danube at the Austro -German border) , we can expect a strong time-dependence due to the fact that every new plant erected in the region of those r iver systems will nearly additively contribute by its liquid re leases to the maximum concentration at the two border sites. I wonder whether you have considered the space-dependent structure of the population density?

G. SCHWARZ: Thank you for your comment. As regards the question, we collected data on the population distribution at "Landkreis" (rural district) level, assuming a homogeneous distribution within such a district .

P . TOMAS: I would be interested to know whether you consider in your calculations the contribution made by radioactive sources in neigh-bouring countries, e .g. France, Switzerland, the Netherlands etc. , to the dose distribution in the Federal Republic.

G. SCHWARZ: We have not considered the influence of re leases f r o m neighbouring countries, but we plan to do so in future experiments.

J.J. COHEN: Your analysis seems to me to be rather limited in that you consider only the sources of radiation in the Federal Republic of Germany and exposure to the West German population. I re fer in this context to the work of Knox and Peterson 2 , who found that as a result of operation of a fuel reprocess ing plant in the USA the largest incremental population dose was to the Asians, simply because the population of Asia is so large. In the same regard, the dose to the population of the Federal Republic f r o m West German sources would be a small fraction of their total dose in that the West German nuclear power industry is a relatively small fraction of the world total. Could you comment on this?

G. SCHWARZ: We based our calculations on a global energy demand analysis and estimated the whole-body dose f rom re leases f r o m all countries, but it was applied (in Table II) only to the population of the Federal Republic of Germany. I would r e f e r you to Ref. [1] of my paper in that connection.

J. WEBER: What is the maximum dose due to tritium in drinking water according to your calculations?

G. SCHWARZ: The potential whole-body dose due to tritium in potable water is at the present time less than 0.01 m r e m / a . According to predictions, by the end of the planning period (2070) we can expect values of about 0.4 m r e m / a .

E . - A . HAMPE: Further to the preceding discussion, I would like to point out that the consequences for the Federa l Republic of Germany will be severer by at least a factor of 5 when the 'second pass ' , i . e . the contri-bution f rom the rest of the world, is taken into account.

In view of the fact that col lective dose data are sometimes wrongly understood, I would like to suggest that in the final version of your paper to be published you include in Table II the man - rem data due to natural background radiation. The risk of misinterpretation of your results will thereby be reduced.

2 KNOX, J . B . , PETERSON, K. R . , Estimates of dose to northern hemisphere groups from 85Kr emitted by a single nuclear- fuel reprocessing plant, Nuc l . Safety 13 2 (1972).

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Since the study includes the HTR fuel cyc le , I wonder whether you also considered the contribution of 1 4 C

to population dose? G. SCHWARZ: Thank you for the comment. So far we have not

included the contribution of radiocarbon in our considerations. We plan to do so, however, in the near future.

B. LINDELL: A rough calculation on the basis of your f igures . indicates a total col lect ive dose f or the Federal Republic of Germany of 0.1 man • rem /MW(e) • a, if none of the nuclides f r o m the process ing plants are retained. This is about one third of the UNSCEAR estimate, which conf irms that the global dose commitment may be a factor of three t imes the Federal Republic value.

Applying an 'equivalent cost ' of about US $200 per man - r em (a figure which is currently used), you will find that retaining the nuclides with, say, RF = 100 would justify an annual cost of US $200 000 to $600 000, for each 1000 MW(e) power plant.

W.G. HUBSCHMANN: I have a more basic question to ask. In F igs 4 and 5 of your paper you indicate the whole-body dose due to 85Kr, among other nuclides. But this nuclide mainly produces a skin dose. Did you treat that skin dose as a whole-body dose in the calculations, or did you take into account the lower biological ef fect iveness of skin irradiation?

G. SCHWARZ: Yes , 8 5Kr is mainly responsib le ' for a skin dose. As a whole-body dose, which is about 1% of the skin dose, we only considered the effect of the 7-radiat ion emitted during 8 5Kr decay.

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SYNERGISTIC EFFECTS OF ATMOSPHERIC RELEASES OF RADIOACTIVE GASES AND S0 2 IN INDUCING NUCLEATION IN THE ATMOSPHERE

K. G. VOHRA

Bhabha Atomic Research Centre, Trombay, Bombay, India-

Abstract

SYNERGISTIC EFFECTS OF ATMOSPHERIC RELEASES OF RADIOACTIVE GASES AND S0 2 IN INDUCING NU CLEATION IN THE ATMOSPHERE.

The paper deals with a study related to the combined ef fects of S0 2 and ionizing radiations in the formation of condensation nuclei in the atmosphere. Estimates of beta dose rate in the air for normal releases of 41 Ar, short-lived noble gases and tritium from reactor stacks, and releases of S0 2 from fossil-fuelled power plants are presented. Experimental studies carried out include spontaneous formation of condensation nuclei in the filtered air and correlation of the formation rate with ambient levels of S0 2 , radon and 41 Ar. It has been shown that the combined e f fec t of S0 2 and ionizing radiations can give a larger production of condensation nuclei than normal photo-oxidation of S0 2 in sunlight. Mechanisms of nucleus formation and possible atmospheric effects of increasing the background concentration of condensa-tion nuclei have been discussed in relation to their role in inadvertent modif icat ion of loca l and global c l imate . The need for extensive basic research and field studies to establish control measures for any possible c l imat ic impact of future large-scale use of nuclear power has been emphasized.

1. INTRODUCTION

In most of the studies on the e f fects of re leases f r o m n u c l e a r

facil it ies emphasis has been on the assessment of radiation dose rece ived by man through a variety of internal and external exposure routes. During the last few years consideration has also been given to the thermal ef fects of effluents f r o m nuclear power stations and their possible eco -logical and environmental implications. However, little attention has been paid to the impact of stack re leases of radioactive gases on the chemistry of the atmospheric environment in relation to their role in inadvertent modification of the climate and weather through ion-induced nucleation ef fects . The f irst paper on this aspect was presented by the author at the IAEA Symposium on Physical Behaviour of Radioactive Contaminants in the Atmosphere, held in Vienna in November 1973 [1]. It was shown unequivocally by laboratory experiments that low doses of ionizing radia-tions in the air can catalyse nucleation when SO2 and certain oxidizing species are present in the air . The problem was considered in relation to radioactive re leases f r o m multiple nuclear faci l it ies. Dose rates in the plume air and vert ical spread of plume were computed for different diffusion categories and it was shown that beta dose rates in the air f r o m normal re leases are high enough to make a significant contribution to the

209

210 VOHRA

formation of condensation nuclei of atmospheric interest. In this paper, synergistic ef fects of atmospheric re leases of SO2 and radioactive gases have been considered in m o r e detail, based on the results of further extensive laboratory experiments. Mechanisms of nucleus formation and possible atmospheric ef fects of increasing aeroso l background have also been discussed.

It is noteworthy that the progress in power generation by foss i l fuels would lead to the release of increasing amounts of SOs and a multiplicity of nuclear power plants would increase the ionizing radiation dose in the air . Therefore studies on the combined ef fects of these two types of emiss ion on the atmospheric environment merit serious consideration. The ionizing radiation dose in reactor stack plumes can give r ise to very rapid conversion of ambient SO2 to nuclei by photochemical and ion-induced reactions. These nuclei can increase the global aeroso l background, which has an important role in cloud formation processes and in maintaining the atmospheric radiation balance.

2. RELEASES FROM NUCLEAR AND CONVENTIONAL POWER STATIONS

During the next few decades, the development of the nuclear power industry will be quite rapid and, by the year 2000, a major portion of the wor ld ' s e lectr ical generation is expected to derive f rom nuclear energy. This would require a few thousand reactors of different types dotted all over the world. The radioactive gases in the effluents f r om these reactors , which can contribute a significant dose in the air, consists of short- l ived noble gases, 41 Ar and tritium, the latter being important for the CANDU type of reactors . The nature of radioactive effluents and their concentrations at the stack exit depend on the type of reactor . The concentration and dose rate in the air are a maximum at the stack exit and decrease with distance. The release rates are highly variable, depending on the fraction of defective fuel in the reactor [2], The normal release rates are only a small fraction of the permiss ib le release rates. These are generally of the order of 20 m C i / s , corresponding to a beta dose rate in the air of about 600 m r a d / h f or 4 1Ar and short- l ived noble gases, and about 10 mrad /h for tritium [1]. A major contribution to the dose in the plume air comes f rom the beta activity, with only a small contribution f rom gamma rays. The decrease in dose rate with distance depends on the degree of dilution, and under slightly unstable daylight conditions (Pasquil l 's category C) the centreline beta dose rate at a distance of 100 metres is estimated to be 30 mrad /h . These f igures are only estimates but they are useful for considering the nucleation ef fects based on laboratory studies.

One can also estimate the SO2 concentration in the air f r om the opera-tion of conventional power stations based on foss i l fuel. These stations constitute the world 's major source of electricity supply today. They release a variety of pollutant gases, including SO2, NO x , CO, CO2 and smoke particulate matter. Release of SO2 depends on the type of fuel used (coal or oil) and the percentage of sulphur in the fuel. The concentra-tion of S0 2 in the fuel gas is generally quite high. F o r example, a 1000 MW plant using 1.12% sulphur coal will re lease about 8000 kg of SO2 per hour and the SO2 content of the flue gas is estimated to be around 1500 ppm [3].

IAEA-SM-197 /14 211

The concentration rapidly decreases by atmospheric dilution. Under slightly unstable daytime conditions dilution factors are such that the concentration is estimated to be reduced to around 1 ppm along the plume centreline at a distance of 1 km. The daily average concentrations of SO2 in the ambient air in urban areas range f rom about 1 to 20 parts per hundred mill ion. The mean lifetime of SO2 in the urban air is f r om 1 to 4 days and its conversion to sulphate particles is an important loss mechanism.

In the gas - to -part i c le conversion processes studied here it is neces -sary for a suitable oxidant to be present also. A variety of oxidants are produced in the polluted urban air by photochemical e f fects . Important amongst these are N 0 2 , 0 3 , O, peroxy radicals and singlet molecular oxygen [4].

This general information on the re lease of radioactive and non-radioactive substances into the atmosphere provides the background for considering the nucleation ef fects likely to be produced in the atmosphere f rom these re leases .

3. THE NATURE OF NUCLEATION EFFECTS TO BE CONSIDERED

The ion-induced nucleation ef fects to be considered here involve complex chemical reactions and physical aggregation processes which lead to the formation of prenucleation embryos and submicron part ic les . Two important basic p r o c e s s e s are (a) homogeneous nucleation leading to the formation of small partic les, and (b) heterogeneous nucleation involving growth of existing particles to f o rm larger part ic les . With SO2 as the nucleating agent, the reaction products consist of H2SO4 and other sulphates formed by further reactions. The nucleation rate, i .e . the rate of formation of part ic les f r om the gas phase, depends on several factors ; ionizing radiations increase the nucleation rate by mechanisms not fully understood. Some of the possible mechanisms will be discussed in a later section. The homogeneous nucleation rate also depends on the concentra-tion of partic les already present. In the presence of these partic les , chemica l ly - formed nucleating species condense on them and lead to growth in their size (heterogeneous nucleation). This can decrease the homo-geneous nucleation rate. Both of these ef fects are important in the atmosphere in the present context.

4. EXPERIMENTAL STUDIES

Extensive experiments have been carr ied out to study the effect of ionizing radiation dose on particle formation in the air containing low concentrations of SO2. Studies were carr ied out at the BARC site at Trombay, Bombay. The place was found to be particularly suitable for these studies because of the location of a coal and oil f ired thermal powe,r station and a 40 MW experimental reactor (CIRUS) within a distance of about 2 km f r o m the sampling site (F ig . l ) .

Experiments included the study of the spontaneous formation of nuclei in the filtered air and controlled experiments with tank gases . A 12-l itre Pyrex reaction vesse l was used for particle formation studies. The r eac -tion vesse l could be evacuated and fil led with filtered air using Mil l ipore

212 VOHRA

FIG. 1. Map showing the location of sampling point at BARC, Trombay.

f i l ters . The particle concentration in the reaction vesse l was measured by a Gardner small -part ic le counter manufactured by M e s s r s . Gardner Assoc iates . In samples of atmospheric air containing low concentrations of SO2 and radioactive gases, spontaneous formation of particles was studied by filling the air into the reaction vesse l after filtering, and then measuring the concentration of particles formed at different t imes after fil l ing. F o r studies of ion-induced nucleation in pure gas mixtures, the reaction vesse l could be irradiated with low doses of gamma radiation using an external 6 0 Co source . Some of the results relevant to the synergistic e f fects of radioactivity and SO2 in the atmospheric air are summarized below.

IAEA-SM-197 /14 213

T I M E ( MINUTES )

FIG. 2. Concentrations of particles formed in the reaction vessel at different times after filling with filtered air: (a) under normal ionization; (b) with ionization dose rate of 5 mrad/h .

4.1. Samples of f i ltered free air containing normal concentrations of SO2 and natural radon give r ise to spontaneous formation of part ic les which can be measured by the nucleus counter.

4.2. Part ic le formation in the f i ltered air shows very striking diurnal and seasonal e f fects . The particle formation rate is a maximum during the afternoon hours on days with bright sunshine. The seasonal ef fects depend on cloud cover and wind direction, and a minimum is observed during the summer monsoon season.

4.3. The particle formation rate showed a striking correlation with the concentration of total oxidants in the air .

4.4. Close correlat ion was observed between the maximum concentra-tion of partic les formed in the reaction vesse l and the total concentration of partic les in the ambient air .

4.5. There was a striking dependence of particle formation on SO2 concentration, very low concentrations giving negligible formation rates.

4.6. At higher concentrations of SO2 in the ambient air (> 2 pplO9) , the particle formation rate was found to correlate with the radon content of the air as well as with 4 1 Ar content of the air .

4.7. Irradiation of the reaction vesse l with low doses of gamma radiation, after filling it with f i ltered air, always showed a very large increase in particle formation rate.

214 VOHRA

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D A T E O F S A M P L I N G

FIG. 3. Graph showing concentrations o f particles formed in the filtered air, sulphur dioxide and radon at 15. 00 hours IST during Apri l -May 1975.

The concentrations of SO2 in the ambient air were in the range of 1 to 100 pplO9 . There was no significant formation of particles at concentrations below 2 pplO9 . The radon content of the air ranged f r o m 50 to 300 pCi / m 3 of air . Relative 4 1Ar activity was estimated as counts per minute and ranged f rom 150 to 900 counts in the 41Ar channel (using a 2.5 in X 2.5 in dia.Nal(Tl) detector with a single-channel analyser). On several occas ions high concentrations of SO2 and radon occurred at the same time. Exceptionally high rates of particle formation were observed when SO2 and radon were both high in the afternoon hours, possibly due to photochemical formation of the oxidant aiding nucleation.

In the reaction vesse l used, particle formation starts when fi ltered air is filled in, r i ses to a peak level and then starts declining. This behaviour has been explained in detail by Walter [5]. A typical study with a sample of ground-level air containing 20 pplO9 of SO2 filled into the reaction vessel ' during afternoon hours on a bright sunny day is shown in Fig .2 . The lower curve shows particle formation under normal conditions and the upper curve shows the effect produced by a gamma exposure dose rate of 5 mrad/h , showing almost an order of magnitude increase in the peak particle concentration.

Figure 3 shows daily variations of S02, radon and peak concentrations of particles formed in the fi ltered air, during the period Apr i l -May 1975.

1AEA-SM-197/3 215

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The figure shows concentration data centred at 15.00 hrs Indian Standard Time. Figure 4 gives a plot of daily variations in the nucleus concentra-tion in the free air and peak concentrations of particles formed in the fi ltered air, f o r the same period.

5. DISCUSSION OF RESULTS

These experiments have clearly shown that the combined effect of SOs and ionizing radiations can give a larger production of condensation nuclei than normal photo-oxidation of SO2 in sunlight. The diurnal variations observed, with a peak in the afternoon, are attributed to the solar ef fect in the formation of the oxidant. For a detailed discussion of the likely nature of the oxidant, re ference should be made to an earl ier paper by the author [6].

A striking feature of Fig.3 is that the peaks of nucleus concentration occur only when there is an increase in SO2 concentration or radon content of the air, or both. Figure 4 shows a striking correlation between the concentration of nuclei in the free air and the peak concentration of nuclei formed in the fi ltered air . During the time of this study, 4 1Ar concentra-tions were fairly constant in the afternoons. However, an increase in 41 A r during the morning hours was always accompanied by an increase in nucleus concentration whenever the SO2 concentration was above 2 pplO9 ,

216 VOHRA

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FIG. 5. Correlation between radon content of the air and concentration of particles formed in the filtered air per parts per 109 of sulphur dioxide in the air.

The ro les of natural radon and 41 Ar f rom the CIRUS stack are similar insofar as they ionize the air and aid nucleation. The results of the experiments also show that ionization aids nucleation and the effect is independent of the rate of photo-oxidation of SO2. The following procedure has been followed for assessing the magnitude of the effect, based on radon which showed more striking daily variations than did 41 Ar . .

F o r the data col lected at 15.00 hrs Indian Standard Time it is assumed that the conversion rate of SO2 by photo-oxidation was constant during the period of study represented in Fig.3. For this period, the peak concentra-tion of particles formed in the fi ltered air per pplO9 (parts per billion) of SO2 has been plotted against the concentration of radon (Fig.5) . The graph shows a scatter of points with a trend towards an increase in particle concentration with increase in radon concentration. During this period the 4 1 Ar concentration did not show any significant variations. The results of Figs 2 and 5 c learly show the effect of ionization on the nucleation rate. The scatter of points in Fig.5 shows that nucleation could also be catalysed by some chemical reactants, producing ef fects analogous to the effect of ionization.

IAEA-SM-197 /14 217

There are two other aspects of the problem which should be considered, viz . (a) the mechanism of nucleus formation, and (b) possible atmospheric ef fects of increased aeroso l background. These are discussed below.

5.1. Mechanism of nucleus formation

These experiments have shown that even very low doses of ionizing radiations can catalyse nucleus formation by SO s , provided that the oxidizing species f ormed by photochemical reactions are also present in the air. The mechanisms of nucleus formation by SO2 at low concentra-tions are rather complex and are not fully understood. Several reactions are possible , involving different species reacting with SO2. The main initiating step is the oxidation of SO2, followed by reaction with ambient water vapour to f o rm H 2 S 0 4 and the onset of nucleation in the H2S04—water system. In the presence of water vapour, concentrations of H2SO4 as low as 4 X 10"5 ppm can nucleate particles [7].

In this scheme it is necessary to consider the species responsible for oxidation of S0 2 and the mechanisms by which the ionizing radiations catalyse particle formation following oxidation. It has been suggested that excitation of SO2 molecules by solar radiations initiates oxidation by atmospheric oxygen [8]. However, laboratory experiments have shown that this mechanism is too slow and may not be important in the atmosphere. In the polluted urban air, oxygen atoms formed by photolysis of N 0 2 can oxidize SO2 to SO3. This may also not be very important, since oxygen atoms will be primari ly lost by reaction with more abundant oxygen molecules . Other possible reactions involve oxidation by singlet oxygen, OH and HOs radicals , and ozone in the presence of certain olef inic hydro-carbons [9], All these oxidation reactions involve solar radiations either in excitation p r o c e s s e s or in the formation of an oxidizing species and may be quite important.

One must now consider how ionizing radiations aid nucleation of part ic les . Part ic les can be formed by purely radiolytic reactions at sufficiently high dose rates [10] - by f ree radical mechanisms. How-ever, these are of little significance in the present studies where we are considering significant ef fects produced by very low doses . Therefore it is necessary to consider new mechanisms. Several possible mechanisms have been described in detail in a recent paper [11] and it is of interest to consider these br ie f ly . Castleman [12] has proposed a mechanism based on clustering of S 0 2 molecules around H 3 0 + and NO+ ions. McKnight [13] has proposed the formation of certain charge -spec i f i c complex ions which constitute embryos which grow by further chemical reactions with polar gases such as SO2. Vohra et al. [14, 15] have pro -posed the formation of condensation nuclei by recombination of hydrated positive and negative ions. There have been several suggestions involving clustering of molecules around negative ions [16, 17] leading to the f o rma-tion of c lusters of molecules . It has also been suggested that radio-lytically formed H 2 0 2 can f o rm a clathrate structure with up to 80 molecules of water [18], Such a structure could probably be stabilized by an SO2 molecule reacting with H2O2 forming H2SO4.

In all the above ionic mechanisms it is necessary to have at least one ion pair per particle formed. Our experiments have shown, however, that several part ic les are formed per ion pair. Therefore it is necessary

218 VOHRA

TABLE I. IONIC REACTIONS PROPOSED FOR THE MECHANISM OF NUCLEUS FORMATION

Mechanism Reactions

1. Radiolytic formation of H 2 S 0 4 nuclei

2. Chemica l reactions on ion centres

3. Ionic recombination reactions

4. Clustering around negative ions

5. Explosive growth reactions

2SOz + 0 2

so3 + H20

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2S03 ( M / N = 1)

H 2SO 4

( X . n H j O ) "

(X • n H 2 0 ) " + n 'S0 2 > (X . n H 2 0 . n ' S 0 2 ) (Followed by reactions)

H 3 0 + ( H 2 0 ) n + H S O 4 -

H 3 0 + ( H 2 0 ) n H S 0 ; -

X " + n H j O

H 3 0 + ( H 2 0 ) n + NH3 -

N H j ( H 2 0 ) n + i + H2 SO4

H 3 0 + + n H 2 0

H 3 0 + ( H 2 0 ) n H S 0 l

H 2 S 0 4 ( H 2 0 ) n + 1

X " ( H 2 0 ) n

N H j ( H 2 0 ) n + 1

N H 4 H S 0 4 ( H 2 0 ) n + H30" t

> H 3 0 ( H 2 0 ) n

(Sequence repeats)

to cons ider some chain mechanisms . An attractive mechanism suggested by Cof fey and Mohnen [19] is based on hydrated H 3 0 + ions and NH3 . The NH;(H 2 O) n ion f o rmed by an i on -mo lecu le react ion of these two spec ies can react with an ambient acid molecule forming a hydrated salt molecule and regenerating the ion. Although HC1 was used in their experiments , f orming hydrated ammonium chloride nuclei , the mechanism should be applicable with H 2 S 0 4 as well . However , this would not explain the striking ef fect of ionizing radiations on nucleation in mixtures of tank nitrogen and oxygen with S 0 2 but without added ammonia [6]. Table I gives a summary of all the react ions d iscussed above.

5.2. Discuss ion of poss ib le atmospher ic e f fects

It i s of value to consider the poss ib le atmospheric e f fects of an increase in the aeroso l background. These depend on the composit ion, s ize and concentration of the part i c les . Any H 2 S04 part ic les initially f o r m e d can react with atmospher ic gases , particularly NH3 , to f o r m complex salt nuclei . In view of the abundance of NH3 in the atmosphere, a ma jor f ract ion of part ic les would consist of NH4HSO4 and ( N H 4 ) 2 S 0 4 , in addition to H 2 S 0 4 i tse l f . Nuclei of mixed composit ion wil l also be f o r m e d . The stable part ic les wil l be in the Aitken size range with a maximum somewhere between 0.01 to 0.1 jum. Part ic le concentrations would be highly variable, depending on the formation rate and atmospher ic dilution fac tors . The part i c les are hygroscop i c and can be very e f fect ive as condensation nuclei [20].

The poss ib le atmospher ic e f fec ts resulting f r o m an increase in part ic le concentrations include changes in the Climate on a l oca l as wel l as on a global sca le . The magnitude of any loca l effect would also depend on other man-made sources of par t i c l es . However , the part ic les d iscussed

IAEA-SM-197 /14 219

above could be more significant as compared with other industrial sources because the size range and chemical composition favour the formation of cloud condensation nuclei (CCN). It is significant that the mass of CCN is an extremely small fraction of the total industrial emiss ions of particulate matter and the p r o c e s s e s for the formation of these nuclei must be very selective [21]. Synergistic ef fects of SO2 and ionizing gases may indeed provide a very effective source of CCN. The increased formation of CCN can lead to modif ications in the local and regional pre -cipitation pattern.

In the l a rge - s ca l e use of nuclear and conventional power over the next few decades, the global ef fects of increasing the background level of aeroso ls can attain serious proportions. The background level r e f e r red to here is the fairly uniform occurrence of aeroso ls above the mixing layer, with concentrations in the range of 200 to 500 partic les per cubic centimetre [22]. The source of this background aeroso l level is not fully understood. The major fraction of these partic les constitute active CCN. Most of these CCN are volatile and consist of ammonium sulphate partic les . They help in the formation of clouds, which control the atmospheric radiation balance by increasing the albedo. Therefore any perturbations in their concentration can show cl imatic ef fects on a global scale . Continuous formation of submicron partic les in the reactor plumes can increase the concentration of background aeroso l and the CCN fraction of these. This indeed is an important area for extensive basic research and for field studies aimed at establishing control measures f or any possible c l imatic impact of future l a rge - s ca l e use of nuclear power.

Aeroso l s are also important in the scattering and absorption of solar radiation, depending on particle size and other physical and chemical character ist ics . The net effect of aeroso l background increase is reduc-tion in temperature due to backscattering of a fraction of the solar energy input. It has been estimated that a factor of four increase in global aeroso l background concentration may be sufficient to reduce the surface temperature by 3.5°K. If sustained over a period of several years , such a temperature decrease over the whole globe is believed to be sufficient to tr igger an i ce age [23].

It i s likely that the normal background aeroso ls are also formed by natural sulphur dioxide in the air , by mechanisms similar to those proposed in this paper, with natural ionizing radiations playing a vital ro le . In this connection it may be interesting to know that as early as 1899, C .T .R .Wi l son published a paper entitled "On the Condensation Nuclei Produced in Gases by the Action of Roentgen Rays, Uranium Rays, UV light and Other Agents" , and suggested these as possible sources of atmospheric nuclei [24]. Although particle formation by ionizing radiations has been reported by several workers , no ser ious investigations of atmospheric interest have been undertaken.

A C K N O W L E D G E M E N T S

I wish to express my thanks to P.V.N. Nair, M.C. Subba Ramu, A .M. Mohan Rao and T.S. Muraleedharan for their help in the experimental programme. I also wish to thank S. Sadasivan for many useful discussions related to this study.

220 VOHRA

R E F E R E N C E S

[ l ] VOHRA, K. G . , "Possible role of radioactive releases from multiple nuclear facilities in the nucleation processes in the atmosphere", Physical Behaviour of Radioactive Contaminants in the Atmosphere (Proc. Symp. Vienna, 1973), IAEA, Vienna (1974) 109.

[ 2 ] UNITED STATES ENVIRONMENTAL PROTECTION AGENCY, Environmental Analysis of Uranium Fuel Cyc le . Part II - Nuclear Power Reactors, Tech . Rep. Series E P A - 5 2 0 / 9 - 7 3 - 0 0 3 - D , USEPA, Washington, DC (1973).

[ 3 ] PERKINS, H. C . , Air Pollution (PERKINS, H. C. , Ed. ) , McGraw Hill, New York (1974) 260. [ 4 ] PITTS Jr. , J . N . , "Photochemical Air Pollution: Singlet Molecular Oxygen as an Environmental

Oxidant" , Advances in Environmental Sciences (PITTS, J. N . , METCALF, R. L. , Eds), W i l e y -Interscience, New York (1969) 289.

[ 5 ] WALTER, H . , Aerosol Sc i . 4 (1973) 1. [ 6 ] VOHRA, K. G . , NA1R, P. V . N . , MURALEEDHARAN, T . S . , Aerosol Sci . 3 (1972) 225. [ 7 ] MIRABEL, P . , K A T Z , J. L . , Current work on nucleation, Aerosol Sci . 5 (1974) 115. [ 8 ] GERHARD, E. R. , JOHNSTON, H. F . , Ind. Eng. Chem. (1955) 972. [ 9 ] STAUFFER, D . , MOHNEN, V. A . , KIANG, C . S . , Aerosol Sci . 4 (1973) 461.

[ 1 0 ] HART, E.J . , SCHMIDT, K. H . , VASUDEVAN, K . N . , Sc ience 180 (1973) 1064. [ 1 1 ] VOHRA, K . G . , Radiation Research — Biomedical , Chemica l and Physical Perspectives (NYGAARD, O . F .

ADLER, H . I . , SINCLAIR, W . K . , Eds), A c a d e m i c Press, New York (1975). [ 1 2 ] CASTLEMAN, A. W . , Current work on nucleation, Aerosol Sci. 5 (1974) 116. [ 1 3 ] McKNIGHT, L. G. , Bell Telephone Laboratories, Whippeney, New Jersey, "Clustering of ions:

atmospheric chemistry and aerosol particulate background" (private communicat ion) . [ 1 4 ] VOHRA, K. G. , NA1R, P. V . N . , Aerosol Sci . 1 (1970) 127. [ 1 5 ] VOHRA, K. G. , VASUDEVAN, K . N . , NAIR, P. V. N . , J. Geophys. Res. 75 (1970) 2951. [ 1 6 ] VOHRA, K. G. , SUBBA RAMU, M. C. , VASUDEVAN, K . N . , Atmos. Environ. 3 (1969) 99. [ 1 7 ] LOEB, L. B. , Basic Processes of Gaseous Electronics, University o f California Press (1955). [ 1 8 ] ALLEN, L. B. , KASSNER, J. L. , J. Col lo id . Interface Sci . 30 (1969) 89. [ 1 9 ] COFFEY, P . , MOHNEN, V. A. , "Explosive growth reactions induced by N H j ( H 2 0 ) n cluster",

24th Ann. Mtg Gaseous Electronics Conference, Gainsville, Fla. (1971). [ 2 0 ] TWOMEY, S . , J. Atmos. Sci . 28 (1971) 377. [ 2 1 ] TWOMEY, S . , Atmos. Environ. 8 (1974) 1251. [ 2 2 ] JUNGE, C. , J. Rech. Atmos. (1963) 185. [ 2 3 ] RASOOL, S . I . , SCHNEIDER, S. H . , Sc ience 173 (1971) 138. [ 2 4 ] WILSON, C. T . R . , Philos. Trans. R. Soc . London, Ser. A 192 (1899) 403.

D I S C U S S I O N

S. HARTWIG: Apart f r om the radioactivity due to the nuclear industry, there is quite a lot of other radioactivity that originates f r o m the atmo-sphere, in the form, f o r example, of c o smic rays, spallation products, natural activity, and ions f r o m other sources . Do you believe that on a global scale the radioactivity f r om power stations will really contribute as much as you suggest to the formation of nuclei?

K.G. VOHRA: The effect of c o s m i c rays on nucleation may be quite important in the upper atmosphere. Releases f r o m nuclear power stations would add to the global background aeroso l in the lower troposphere, which is an important region f or the formation of clouds. The ionization pro -duced by spallation products would be too low to give r ise to nucleation ef fects .

J. WEBER: In the Netherlands we have found a certain correlat ion between the radon concentration and the concentration of other pollutants in the atmosphere, which tallies with what is shown in your paper. It has always been ascr ibed to a common origin — the atmospheric conditions.

IAEA-SM-197 /14 221

When an inversion i s present, all concentrations increase . Could these atmospheric conditions explain your findings, at least to some extent?

K.G. VOHRA: The atmospheric conditions certainly play a ro le , e .g. high radon concentrations are often associated with inversions. We have found that the SO2 increase depends on wind direction as well .

J. CHRISTENSEN: The smoke emitted f rom conventional power plants contains radioactive substances, for instance in the f o rm of f ly -ash. The radiation f rom these substances will, of course , contribute to some extent to nucleation in the surrounding atmosphere.

On the strength of your experiments, what do you estimate the order of magnitude of this effect to be at the present t ime?

K.G. VOHRA: In conventional power stations the radiation dose f r o m radioactive substances, e .g. radium, is too low to cause any nucleation ef fects . However, in the case of nuclear power stations there may be a significant effect at some reactor sites, and it would be useful to carry out thorough studies.

IAEA-SM-197 /20

ADVANTAGES OF NUMERICAL ATMOSPHERIC DISPERSION CALCULATIONS FOR ESTIMATING DISPERSAL AND COMBINATION EFFECTS OF STACK RELEASES FROM THE NUCLEAR INDUSTRY

H. SCHULTZ, E. VOELZ, C.D. WUNEKE Technische Universitat Hannover, Hanover,


Abstract

ADVANTAGES OF NUMERICAL ATMOSPHERIC DISPERSION CALCULATIONS FOR ESTIMATING DISPERSAL AND COMBINATION EFFECTS OF STACK RELEASES FROM THE NUCLEAR INDUSTRY.

An estimation of environmental pollution calculated using the idealized Gaussian distribution mode l to describe processes of atmospheric diffusion suffers from restrictions in the mode l , i . e . it assumes stationary homogeneous conditions in the atmosphere, a parallel mean wind f low with no (or at most linear) velocity shear, and constant turbulence characteristics within the plume. These assumptions are oversimplif ications: for instance topographic ef fects , wind shear, t ime-dependent wind variations and the case of strong loca l interactions of the pollutant with other components in the atmosphere ( e . g . fog , smog, rain, or other pollutant plumes) are ignored. Previous attempts to overcome the disadvantages using a purely numerical evaluation of the differential equations describing the transport, diffusion and any reactions of the pollutants in the atmosphere were unsuccessful, since 'art i f i c ia l diffusion' ef fects were observed that led to unacceptable errors when great distances or long times were considered. At present, the best method of solving this problem appears to be the use of a combined Eulerian-Lagrangian numerical approach, cal led the par t i c l e - in - c e l l method, which was developed in the USA. The method has been, tested successfully by making comparisons with typical Gaussian calculations over long t ime intervals or large distances: it was also applied to several actual transport problems involving complex topographies with wind variations in t ime, and to the effects of c h e m i c a l reactions and loca l rainfall . This method, avoiding the undue simpli f ication of the Gaussian calculat ion and the inherent f ictitious diffusion patterns of the purely numerical evaluation seems to be particularly suited to solving atmospheric pollution transport problems under complex conditions that may occur in the neighbourhood of large nuclear power stations.

1. INTRODUCTION

A Gaussian diffusion model with turbulent diffusion parameters is one frequently used to estimate the environmental ef fects of a i r -borne pollution clouds. The mean pollutant concentration distribution can be calculated for distances up to 10 km f rom a point source, provided the wind and the turbulence field can be treated as uniform in space and t ime. Unfortunately this very versati le function cannot reasonably be used when the assumption of atmospheric homogeneity is not realist ic , for example whenever the wind shear shows a non-linear variation with height, or when topographic irregularit ies exist, or if time-dependent wind variations occur during the atmospheric transport of the pollutants.

In each of the above cases , there are different transport and diffusion characterist ics within the original Gaussian cloud. Hence the cloud shape is deformed such that it can no longer be described by the Gaussian function.

223

224 SCHULTZ et al .

Similar difficulties ar ise with this model if p rocesses occur within the cloud itself that lead to locally differing values of the pollutant concentration, deforming the original Gaussian distribution. One example of such a process is that of rainfall passing through the cloud, the rain having locally differing densities.

Another, more interesting situation is the interaction of clouds of chemical pollutants. At strong concentrations of the pollutants, a number of typical reactions may occur that lead to new compounds or radicals which may have undesirable propert ies .

Normally the rate of such reactions will be proportional to the product of the concentrations of the reactants, or to some power of the concentrations. Hence, two interpenetrating Gaussian clouds would create another Gaussian distribution for the reaction products, which can, in principle, be calculated f r o m the two original Gaussian distributions. But if the pr imary Gaussian distributions are significantly deformed by unequal loss of reacting pollutants, there is no longer any simple relation between the shape of the pr imary and secondary pollutant clouds.

Attempts have been made to overcome these and other difficulties arising f r o m various inhomogeneities by dividing a cloud into individual portions that can be treated as Gaussian clouds, each emanating f r o m a theoretical point source . This is repeated whenever a portion has reached a dimension for which the Gaussian distribution no longer applies [ 1 ] . Unfortunately this method is so expensive in calculation time and requires so much care in making the appropriate stepwise division into the small portions that only a few investigations of this type have been made [ 2 ] , This procedure seems to be less advantageous than a totally numerical treatment using speci f ic 'boxes ' , having individual transport and diffusion characterist ics within each box, and interconnecting them with their nei ghbours.

At present, the most realist ic calculations of pollutant dispersion f or inhomogeneous atmospheric conditions and of the production or depletion of pollutants by photochemical or inter-molecular reactions apply pure numerical methods using either speci f ic boxes (Eulerian approach) or spec i f i c cloud parcels (Lagrangian approach). In both cases , the atmospheric volume considered is divided into separate ce l ls , re ferred either to the space system or to the cloud, respect ively , for which the transport equation, including wind transfer and turbulent dispersion, can be simulated by expansion to a correlated finite di f ference equation system in time and space. Beginning with a convenient initial pollutant distribution over some cel ls , the system of connected finite di f ference equations is solved stepwise for the transport in space and the variations of the transport parameters over the corresponding time intervals [ 3] .

Within the frame of this calculational method, both time and space -dependent changes of the wind direction, wind speed and turbulence parameters , can easily be taken into account for the period in which the pollutant cloud is expanding, assuming that the necessary local meteorological and other data are available. This assumption, crucial for many applications of the method to pollution in the atmosphere over industrial areas , is not as important f or the case of interaction between two properly definable pollution clouds. F o r this case, a different problem ar ises , characterist ic of finite di f ference methods, that given by a possible propagation and increase of e r r o r s due to the truncation e r r o r s inherent in finite di f ference equations

IAEA-SM-197 /14 225

j = l

( a )

r i .10

i I .23

1 20 !

.47 . J I

0.06-

Ax

2-dimensional case = -

C ( c )

Kx(C2+C3-CrC4) A X ( C 1 + C 2 + C 3 + C 4 )

i = 1

( b )

FIG. 1. (a) Typical ' b o x ' mesh (2-dimensional view).

(b) Calculation of cellular concentrations with weighting of the particle positions (2-dimensional view).

( c ) Calculation of diffusion velocity by finite difference algorithm.

used instead of the real differential equations. These so-called arti f ic ial diffusion ef fects are avoidable only if a special relationship is obeyed between the steps in both time and space. Within a complex set of time and space steps, this requirement can obviously only be fulfilled for one point at one time; this failing cannot be avoided and it has often seriously handicapped applications of this method.

2. THE HYBRID EULERIAN-LAGRANGIAN METHOD

A realistic attempt to apply a numerical method to problems of interacting pollutant clouds and the secondary products was f i rst made possible when a hybrid Eulerian-Lagrangian method, the so-called part i c le -in -ce l l calculation, was developed and successful ly applied by Sklarew et al. [ 4 ]

226 SCHULTZ et al .

(TRANS \ transport! I . A? I

\ I

pseudovelocities at

particle-positions /

*

chem. reaction

coeff icient

CHEMR chem.

reaction

chem. reaction

coeff icient

CHEMR chem.

reaction

/ /

/

VOW IK volume weighting

resp. concentratic

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\ particle-specie: at the centres

new concentration at the centres

VOWIR volume weighting

resp.particle pos

weighted masses at particles

positions

diffusion velocit ies

at the corners

/ MET0DAT

FIG.2 . Flow chart of c o d e .

IAEA-SM-197 /20 227

and Lange [5 ] in the USA. This technique enabled the arti f icial diffusion to be reduced to at least the degree necessary f o r obtaining realist ic results f r o m calculations of cloud interactions. This success could be obtained with the help of so-called 'marker part i c les ' , representing a quantity of pollutants initially present in the fixed boxes. These particles are initially statistically distributed in space and time, based on a given source concentra-tion distribution. Their paths within a time step, either within the original cel l or penetrating into a neighbouring cell , are given by the wind and diffusion parameters . Such individual paths are naturally different and can be better adjusted to the box dimensions than when a pure evaluation of the diffusion equation in an Eulerian grid is undertaken.

The basic feature of this method is the introduction of a so-called pseudo-velocity

u(u, v, w) = u w + uD (1)

which combines the transport ef fect due to the advection wind velocit ies u w (u w , v w , w w ) and the diffusion effect due to effective diffusion velocit ies uD(uD, vD , wfr). While the advection velocity u w has to be taken f rom the mean wind field, the effective diffusion velocity uD is derived f r o m the di f ferences in the concentration, C, between adjacent boxes, according to the relation:

K UD = £ ' grad C (2)

K being the diffusion coeff icient, which depends on the turbulence in the atmosphere. Combining the two veloc it ies , the transport diffusion equation

~ + u w • grad C = div (K grad C) (3)

is rewritten:

~ + div (C • u) = 0 (4)

The calculation starts f r o m the values of the advection wind speed u^ at the corners and of the mean concentration C at the centres of the boxes, as given in Fig . l a . To get the effective wind values at the particle positions in the cell a linear interpolation is made between all contiguous corners to each particle position. In a similar manner the mean cellular concentration is derived f r o m the particle positions by a comparable volume weighting procedure, as is shown for the two-dimensional case in Fig . lb .

Having obtained these mean cellular concentrations Q calculated as discussed above, the next step is to obtain the effective diffusion veloc i t ies uD at the corners by a finite di f ference algorithm, as shown in Fig . l c for the two-dimensional case . Then the diffusion velocit ies and advection velocit ies at the corners are added and the next linear interpolation to particle positions fo l lows.

Figure 2 shows the flow chart f o r a corresponding code, which is under development in our institute. The main flow is indicated by thick lines,

228 SCHULTZ et al .

whereas the thinner lines in the interior indicate the calculations of chemical reactions. In the top right-hand corner the selection of adequate space and time steps for the calculation is indicated. More details may be found in the papers of Sklarew et al. [ 4 ] and Lange [ 5 ] .

Since chemical reactions occurring in the atmosphere tend to remove pr imary pollutants while creating secondary ones, it is possible to encode these effects by changing the mass of the particles during the calculation or by creating new part ic les . The code allows one to simulate molecular and photochemical reactions, and radioactive decay by introducing source or sink terms, S, for the production or l oss of pollutants. F o r the concentra-tion Cj of pollutant species i with the pseudo-velocity uû^, Vj, Wj) one obtains a linear differential equation for the time dependence:

9Cj at

9ujCj dx

3viCi 3wiCi ay 3z + Si (5)

The source or sink term, S^ may or may not depend on its concentration Ci and/or the concentrations of the other pollutants, C j , or products of these concentrations. The general case can be written:

Si = S ^ q , C j ) = - X ^ + ^ X j C J + ^ ( C i , C j ) (6)-

j

Here F ^ C ^ Cj) represents any function linking C j and C^ that contributes to the production or loss of the species i, and Xj is the effective reaction coef f ic ient .

This system, having as many differential equations as there are reactants, can be solved by numerical methods provided that (1) pollution transport and diffusion, and (2) chemical reactions and radioactive decay can be treated in separate and distinct calculational steps.

The great number of possible chemical reactions, with their multiplicity of sources and sinks, require an enormous amount of calculation time and effort . Eschenroeder [ 7] used the idea of a single 'effective reaction' , by which many similar parallel reaction chains are combined into one equation, with corresponding 'ef fective parameters ' . These 'effective react ions ' , of course , need no longer correspond to realist ic single elementary r e a c -tions, and they have to be adjusted stepwise to the varying concentrations of the reactants. So finally, for the stepwise calculation, one single differential equation for the variation within the time step of the mean net concentration for each pollutant (excluding transport effects) is derived:

^ F i - R i C i ( 7 )

In this equation, Ft summarizes the contributions of all reactions which generate the pollutant i, while the term R i Q represents the sum of all reactions which cause a loss of pollutant concentration C^. As mentioned above, equation (7) can be included into the flow chart of the code by introducing a weighted mass f o r the marker part ic les . The corresponding . flow chart is shown in the interior of Fig . 2.

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100

90

80

70

E 5 0

5 50 u £ 40 a M 30 T3 > 20

10

0 -10

Arc D

Arc C

f (OOOO1 ADPIC Grid

V

Sampler No. 2 3 i 5 6 7 8 9 10 11 12 1314 I ' l l ' r -

-24 -16 -8 0 +8 *16 Distance ( k m )

( c )

- 6 0 - 4 0 - 2 0 0 20 40

X distance ( k m )

( a )

10

10

~ 10"'

10''

10"

— Field data ' x ADPIC

Gaussian plume: category C stabi l i ty

Sampler No.

5 6 7 8

-15 -10 - 5 0 Distance (km)

( b )

•10

FIG.3. (a) Position of the samplers on the arcs for the plume measurements at NRTS, Idaho Falls.

(b) Integrated activities on arc C for samplers and Gaussian and ADPIC calculations.

( c ) Integrated activities on arc D for samplers and ADPIC calculations.

(Reprinted with permission from Lange and Knox [ 9 ] . )

3. DISCUSSION

The paper by Sklarew et al. [ 4 ] gives an example of such a calculation using the computer program NEXUS/P, which is based on the part i c l e - in -cel l method, for concentration distributions of pollutants, NO, NO2, HC, O3 and HNOg, in the Los Angeles area. A time interval of 16 h is considered. The combined effects of emissions f r o m power stations, re f ineries , air transport and street traff ic are investigated. A comparison

230 SCHULTZ et a l .

of the calculated concentrations with the measured values showed that the results of the calculations were very sensitive to the values of the effective parameters for the reactions. F o r instance, the calculation indicated a considerably faster oxidation of NO to NOs than was actually measured. It is c lear that any such system should relate as c losely as possible to the true chemical or other reactions.

Additionally, the par t i c l e - in - ce l l technique enables one to calculate the influence of a potential wash-out on the surface concentration of a pollutant by storing a certain fraction of mass loss per cycle for each marker particle cumulatively in a two-dimensional surface deposition array. F o r instance, such problems may become important after a reactor accident, if the increased release of radioactive pollutants into the atmosphere generates fog or smog due to the combined effect of radioactive pollutants and vapour re leased f r o m a neighbouring cooling tower of the power station, which might result in localized rainfall. In this case the increased local, wash-out of radioactive pollutants to the surface can be calculated by the par t i c l e - in -cel l method, including any deformation of the pollutant cloud caused thereby and the ef fects of wind velocity shear and wind direction shear.

Some parameter studies on these effects made with the program AD PIC are reported in the.paper by Lange and Knox [ 9 ] . As one example, a three-hour re lease in the National Reactor Testing Station, Idaho Falls , of 1 3 1I-methyl iodide was calculated and subsequently the results were compared with field measurements. The dispersion and transport of the 'cloud' occurred over a complex topography with high mountains on one side of the cloud path.

Figure 3a shows the position of the source and the line of measuring points. Figure 3b shows the integrated measured values and the correspond-ing results calculated by a combined Gaussian trajectory method and by the par t i c l e - in - ce l l method for arc C. The length of the path traversed by the cloud was about 50 km. It is c lear that the par t i c l e - in - ce l l calculation agrees far better with the measured values than does the Gaussian calculation.

Another problem of combined ef fects that may be better solved by making numerical transport calculations than by making Gaussian calcula-tions may be seen in the following example. In contrast to rural areas, where real conditions are sometimes c lose to the idealized model of dispersion and for which Gaussian calculations are, therefore, quite s u c c e s s -ful, the atmosphere over large cities and industrial areas is characterized by having more complex vertical temperature prof i les , a sharper decrease of wind velocity near the ground and greater roughness of the surface. In consequence a bell-shaped volume of warmer air results. This, depending on the time of day and the season, may be m o r e or less separated f rom the rural surroundings by inversion layers or steps in the wind prof i le . Therefore most of the interesting 'combined e f fects ' occur within this bell-shaped envelope over the city.

This envelope can be thought of as comprising three layers . The f i rs t layer extends f r o m the ground to the upper l imit of buildings and is charac -terized by very low vertical atmospheric exchange within the streets. The sources of atmospheric pollution are mainly the exhaust gases of motor cars and other traff ic , these contributing, in particular, CO, C0 2 and c a r b o -hydrate components. The second layer is positioned above the buildings, the sources being mainly flue gases f r o m household f i res and s imilar other sources , the. smaller industrial plants contributing in the main the sulphur-containing pollutants. Whereas the sources within these two lower layers

IAEA-SM-197 /20 231

can be considered as nearly homogeneous surface sources , the third layer contains only equivalent point sources , such as high stacks f r o m large industrial plants.

In general, the effluents remain within the atmospheric volume over a city for longer periods than over rural areas due to the lower wind velocit ies and higher temperatures in city atmospheres. The effluents, therefore, have a greater chance of reacting with each other. Hence, within these meteorological ly complex layers there may be sources and sinks f or pollutants that are complex and which cannot be simulated by one single idealized Gaussian model for calculational purposes. As a consequence, such a city atmosphere volume has to be divided into many subvolumes (boxes) of different s izes but chosen to have the meteorological factors , source distributions and reaction probabilities as uniform as possible within the boxes. Additionally to the calculation of transport and reaction processes , a major problem will be to provide an adequate description of the wind field and diffusion parameters within the complex bell-shaped layer over a large city or industrial area.

4. SUMMARY

A prel iminary investigation of the generation and distribution of pollutants as a consequence of chemical and other reactions acting in combination with atmospheric transport p ro cesses shows that the simple, idealized Gaussian distribution model can often not be used. However, calculations using a purely numerical di f ference method to obtain a solution of the differential equations for transport and diffusion likewise have a poor level of success since, in these methods, the so -ca l led 'arti f ic ial diffusion' factors introduce large e r r o r s when longer times or larger distances are considered.

Useful advances in solving such complex problems have been made using the par t i c l e - in - ce l l method. This may be seen f r o m the results of the f irst applications of this method to real ist ic problems in the USA. It appears valuable, therefore, to develop a numerical calculation computer program based on this latter method to d iscover if it would be possible to solve the prob lem of interactions between pollutants during atmospheric dispersion p r o c e s s e s . Such problems are of interest in studies of the local interactions of stack effluents f r o m large nuclear power plants with neigh-bouring pollutant sources .

R E F E R E N C E S

[ 1 ] McCORMICK, R . A . , GUTSCHE, B . , Meteorologie der Luftbeimengungen, Inst. f . Theor. Meteorologie der Freien Univ. Berlin (1969) .

[ 2 ] GUTSCHE, B . , Ein Verfahren zur Untersuchung des Einflusses der Physik der planetarischen Grenzschicht auf d ie Ausbreitung von Luftbeimengungen, Inst. f . Theor. Meteorologie der Freien Universitat Berlin (1973) .

[ 3 ] MacCRACKEN, M . C . , CRAWFORD, T . V . , PETERSON, K . R . , KNOX, J . B . , Initial Application of a Multi-Box Air Pollution Model to the San Francisco Bay Area, Lawrence Livermore Laboratory, University of California Rep. UCRL-73944 (1972) .

[ 4 ] SKLAREW, R . C . , FABRICK, A . J . , PRAGER, J . E . , A par t i c l e - in - ce l l method for numerical solution of the atmospheric diffusion equation, and application to air pollution problems, System, Science and Software, 3 SR-844 (1971) .

232 SCHULTZ et al .

[ 5 ] LANGE, R . , ADPIC - A Three-Dimensional Computer Code for the Study of Pollutant Dispersal and Deposition under Complex Conditions, Lawrence Livermore Laboratory, University of California Rep. UCRL-51462 (1973) .

[ 6 ] SCHULTZ, H . , WUNEKE, C . - D . , Analyse der Ergebnisse des US-Plowshare-Programms zur Priifung der Ubertragbarkeit auf d ie Ausbreitung radioaktiver Stoffe bei Reaktorstorfallen, Arbeitsgruppe fur Techn . Strahlenschutz der Techn. Univ. Hannover Rep. ATS-THU-1077 (1975) .

[ 7 ] ESCHENROEDER, A . Q . , MARTINEZ, J .R . , Mathematical Modeling of Photochemical Smog, AIAA 8th Aerospace Science Meeting (New York, January 1970).

[ 8 ] CRANDALL, W . K . , MOLENKAMP, C . R . , WILLIAMS, A . L . , FULK, M . M . , LANGE, R . , KNOX, J . B . , An Investigation of Scavenging of Radioactivity from Nuclear Debris Clouds. Research in Progress, Lawrence Livermore Laboratory, University of California Rep. UCRL-51328 (1973) .

[ 9 ] LANGE, R . , KNOX, J . B . , Adaptation of a Three-dimensional Atmospheric Transport Diffusion Model to Rainout Assessments, Lawrence Livermore Laboratory, University of California Rep. UCRL-75731 (1974) .

D I S C U S S I O N

C. HOEDE: The differential equations f or each of the Cj concentrations may have to be treated differently when the chemical reaction rate is to be taken into account. Did you consider that fact?

H. SCHULTZ: F r o m the differential equation for the reaction dynamics we determined the possible e r ro rs with large time steps and then adjusted the latter accordingly.

C. HOEDE: Yes, I see . In similar calculations we have found it convenient to use analog computers, since qualitative agreement seems more important than quantitative accuracy . Perhaps a hybrid computer system could be of advantage?

H. SCHULTZ: Well , the use of analog computers might be of advantage for the smaller regions for the different effective reaction parameters , but they would not work so well f o r the many regions with different properties that are considered in the paper.

S. HARTWIG: I don't think I quite understood your remark regarding the stability and convergence of parabolic differential equations. As far as I know, stability depends on the mesh s izes in time and space, and their interrelationship. If you start with the co r rec t relationship, your solution of the equation is stable, though solving it may be a lengthy procedure. Can you comment on this?

H. SCHULTZ: Since the c o r r e c t relationship between mesh size in time and space depends on the velocity distribution, we can satisfy this relationship only for individual p laces . On the other hand, the introduc-tion of the pseudo-velocity gives a transport equation for a compress ib le pseudo-gas with a pseudo-density equal to the pollutant concentration. The problem can therefore be solved as correc t ly as the dilution of the pseudo-gas can be simulated by the stepwise motion of a statistical array of marker partic les under the influence of the stepwise, newly calculated pseudo-veloc i t ies at each particle location.

IAEA-SM-197 /20

DISCUSSION OF POSSIBLE EFFECTS DUE TO MIXING OF RADIOACTIVE AND THERMAL RELEASES TO THE ATMOSPHERE FROM NUCLEAR POWER PLANTS

W.G. HUBSCHMANN, K. NESTER, J.G. WILHELM Kernforschungszentrum Karlsruhe, Federal Republic of Germany

Abstract

DISCUSSION OF POSSIBLE EFFECTS DUE TO MIXING OF RADIOACTIVE AND THERMAL RELEASES TO THE ATMOSPHERE FROM NUCLEAR POWER PLANTS.

As the number of reactors, stacks and coo l ing towers at a power plant site increases, mixing of dry radio-active o f f -gas with a moist coo l ing tower plume will occur often enough to require study. For the purposes of this paper, it is assumed that a 100 m high stack of a 1000 MW(e) nuclear power plant lines up with a wet coo l ing tower in the main wind direction. The mechanism of mixing at various wind velocit ies is discussed. As compared with the dry o f f -gas p lume , two additional mechanisms influencing the radiological e f fec t of the released activity c o m e into play: (a) the activity concentration near the ground is reduced by the strong buoyancy of the moist p lume , whereas (b) the wash-out of aerosols by natural precipitation is increased. The radiological e f fect of noble fission gas release is reduced, but in the case of radioiodine the two effects partly compensate each other. Future reactors intended for large nuclear power plant sites, therefore, should be equipped with an e f fec t ive iodine retention system. If this is provided, the mixing of the dry and moist plumes helps to decrease further any radiological impact of nuclear power plants to an almost negligible level .

1. THE PROBLEM

In common with most European countries, most of the nuclear power plants going into operation in the Federal Republic of Germany, now and in the near future, are or will be equipped with wet cooling towers . As long as only one or two reactors are installed at a given site, mixing of the dry radioactive o f f -gas f r o m the stacks with the wet cooling tower plumes will occur sufficiently infrequently not to cause a speci f ic problem. But as the number of reac tors , stacks and cooling towers at a site increases , not only are the total radioactive emissions f r o m the site increased but mixing of radioactivity and moisture will occur more often, eventually becoming a regularly recurr ing process . Therefore it is of interest to discuss whether (a) wash-out or rain-out could cause an increased radioactive deposition, for instance of the radioiodine, or (b) the strong buoyancy of the wet plume could help to decrease the radiological impact on the environment.

2. MIXING OF STACK AND COOLING TOWER PLUMES

Natural draught wet cooling towers of large nuclear power stations are on average about 150 m high, whereas the stack height is only about 100 m. Mixing of the two plumes is , therefore , mainly restr icted to cases in which the wind direction coincides with the directions parallel to the line connecting a stack and a cooling tower.

233

234 HtJBSCHMANN et al.

Two different situations fall into this category: A. The wind blows f r o m the stack to the cooling tower. At low wind

veloc i t ies , the stack o f f -gas will r ise due to its momentum to some 20 to 30 metres above the stack mouth. If the plume passes the cooling tower at that height, there is a good chance that it will be caught in the eddies around the cooling tower mouth and be entrained into the vapour plume. The higher the wind velocity, the more gradually does the moist plume r ise upward. As its entrainment occurs mainly in the lower ' invisible ' part of the plume, at medium wind velocit ies both plumes can come close enough together for the lower stack plume to be sucked or entrained into the moist plume. At higher wind velocit ies mixing may already occur in the cavity below the cooling tower mouth.

B. The wind blows f r o m the cooling tower to the stack. At the higher wind velocit ies the cooling tower plume passes the stack at low altitude, thus being able to entrain the dry o f f -gas .

Since it is difficult to speci fy the percentage of cases in which mixing will occur , a 'worst case ' situation is assumed for the purposes of the d is -cussion, i .e. the direction and sense of ' cool ing tower to the stack' coincides with the main wind direction (case A), and generally mixing occurs in the main wind direction sector . This assumption ensures that any effect due to the plumes mixing is at a maximum.

3. IODINE DEPOSITION ON THE GROUND

Of the different radionuclides that are released through the stack to the atmosphere, radioiodine has potentially the greatest radiological effect; this is based on the well-known transfer of iodine along the pasture -* cow -••milk-* small child pathway, the crit ical organ being the thyroid. It is data on the pasture^- cow-* milk pathway which are, in general, required in licensing procedures in the Federal Republic of Germany. As the aerosol deposition is greatly affected by the mixing of the o f f -gas and the vapour plumes, the radio -iodine compounds are considered f irst . As iodine-131 in elemental f o r m is most important in this respect , the calculations are, here, limited to this iodine nuclide.

Dry deposition of iodine on the ground depends on the physical and chemical f o r m of the iodine, the nature of the ground surface (e.g. grass density) and the meteorological conditions. Usually the deposition is des -cribed by a deposition velocity, Vd, which is defined as the deposition rate ( C i / m 2 - s ) per activity concentration in air near the ground (Ci /m3 ) . . Hoffman shows in a recent literature survey [ 1] that average values of vd range f rom 0.5 c m / s to 1 c m / s . The upper value will be used here. Further, 50% of the deposited iodine will be assumed to be retained on the grass .

During natural precipitation the aeroso ls are washed out of the plume, thus increasing the deposition rate. The portion of airborne material washed out per unit time is called the wash-out coefficient (s_1). As elemental iodine is released in gaseous f o rm, a wash-out coefficient X= 0.9 X 10"4 s"1

is appropriate f o r a rain intensity of 1.35 m m / h (see Re f . [ 2 ] ) . Let us consider the wash-out f r o m the mixed plumes. As we are con-

cerned with rainy weather, the water vapour content of the ambient air is c lose to saturation and the cooling tower would show a long visible plume containing a condensed cloud of water droplets. Due to their s ize , these

IAEA-SM-197 /14 235

droplets are washed out by raindrops much more ef fect ively than are the smaller aeroso l particles. Therefore a wash-out coeff icient X = 6X10'4 s"1

is assumed for this process (taken f r o m Ref . [2] ) . If the dry o f f -gas mixes in the f ree atmosphere with the vapour plume, only part of the elemental iodine will be absorbed by the cloud droplets, the fraction depending on drop size and density, degree and duration of mixing, as well as on other var i -ables. As experimental results in this field are lacking, it is assumed that 60% of the iodine is absorbed by the cloud droplets. If this mixed plume is exposed to natural rainfall, the iodine will be washed out with an average wash-out coeff icient X = 4 X 1 0 " 4 s"1 . This is an increase by a factor of 4.5 as compared with the wash-out f r o m the dry o f f -gas plume.

Other ef fects that are frequently quoted in discussions of cooling tower plumes are the drift deposition and the rain-out of droplets that have grown large enough to precipitate f r o m the plume to the ground. These ef fects are taken into account as fol lows. Modern power plant cooling towers are equipped with very effective drift eliminators. The drop s izes in the residual drift are small enough for the drops to remain entrained in the plume (see [3]). Therefore drift deposition is neglected. But the droplets grow and eventually become large enough to precipitate f r o m the plume. On their way to the ground they pass through unsaturated ambient air. Since we have considered large cooling towers of about 150 m in height, most of these droplets will re -evaporate before reaching the ground, due to the time spent in falling through the unsaturated air [4] . Therefore rain-out will be a small effect as compared with wash-out and it may, therefore , be neglected here.

The total iodine deposition f r o m the dry o f f -gas and f r o m the mixed plume is calculated assuming an emission rate of A= 1 Ci /a . The stack of a 1000 MW(e) nuclear power plant is assumed to be 100 m high, the natural-draught wet cooling tower 150 m. The calculations are per formed using the meteorological data registered at the Karlsruhe Nuclear Research Centre for the year 1969. The dry and wet plume are considered as mixing in the main wind direction sector . Natural precipitation occurs predomi -nantly during the periods when the wind direction l ies within this sector . The precipitation frequency in this sector is about 7%. A prevailing • category D (neutral) is a s s u m e d during rain. Two sets of dispersion para-meters are used; f i rst , the widely-used Pasqui l l /Gi f ford parameters [5] , which are appropriate for a flat, smooth terrain and, second, the parameters measured in the Karlsruhe diffusion experiments [ 6], which are appropriate f o r 'rough' terrain such as forests and dispersed buildings.

Figure 1 shows the calculated deposition of iodine in the dry o f f -gas with and without mixing with the wet cooling tower plume. The dry deposition curves (thin lines) show the influence of surface roughness. Close to the source (x < 800 m), the wet deposition contributes considerably to the dry one, at least in the main wind direction sector with its high precipitation frequency (see the thick-line curves labelled 'total deposition f r o m o f f -gas ' ) .

Iodine deposition f r o m the mixed plume is represented by only one curve, as the diffusion parameters influence the wet deposition very little. The dry deposition is negligibly small due to the strong buoyancy of the mixed plume. It can be seen that, at short distances f r o m the source ( x < 4 0 0 m for rough terrain or < 800 m for smooth), the wash-out f r o m the mixed plume results in a higher iodine deposition and at greater distances a lower deposition than is the case f or dry o f f -gas .


n 3

V .total deposition from N ^ t h e mixed plume

total deposition ^ ^ ^ from o f f -gas ,

——^Cyjrough terrain ^ X ^ ^ smooth terrain

w a s h - o u t \ \ \

^ ^ f r o m oft - g a s / ^ w

from the m i x e d \ ^ plume \ \ \

3

?n-

/ dry deposition / from off -gas

smooth terrain I s rough terrain

•"T ' 1 1 r T 1 T 1 i i i r- i——i— 100 1000 10 000

DISTANCE (m)

FIG.l. Iodine deposition in the main sector downwind, the assumed iodine emission rate being A= 1 C i /a .

4. NOBLE GAS CONCENTRATION NEAR THE GROUND

Radioactive noble gases are re leased by nuclear power plants. However, their radiological effect is small since there is no accumulation mechanism as is the case with radioiodine (the pasture -»• cow -»• milk pathway). As modern l ight-water reactors are equipped with o f f -gas lines containing char-coal beds f or r a r e - g a s retention, only the long-l ived rare gas nuclides such

IAEA-SM-197/20 237

DISTANCE (m)

FIG.2. Equivalent ( 6 + X) dose rate due to xenon-133 emission (A Y , „ , = 10 5Ci/a) .

as 133Xe and 85Kr are re leased. 1 3 3Xe is a ma jor constituent [7] ; 8 5Kr is mainly a j8-emitter (E®ff = 0.27 MeV) and has little b io log ica l ef fect .

There fore only 133Xe is considered here. Xenon-133 is a B and 7 - emi t t e r . As noble gases are adsorbed in the human blood only in very small quantities, only external irradiation needs to be taken into account. The 7 -radiat ion causes a whole-body dose, whereas the.j3-radiation, due to its low ef fect ive energy (E®ff = 0.13 MeV), af fects only the skin.

Normal ly dose equivalents f o r different parts of the body are not added. In this paper, this is done f o r comparison purposes and f o r simplif ication. The skin-dose equivalent, due to the higher permiss ib le dose f o r skin, i s modif ied by a weighting factor of one sixth.

The resulting combined 7 and /3-dose rates as a function of distance are shown in Fig.2. The calculations are per f o rmed using the Karlsruhe m e t e o r o -logical data and two different sets of diffusion parameters . The 133Xe emiss ion rate, Axe-133 i s a s s u m e d t o be 10 5Ci/a.

The upper solid curves r e f e r to the dry stack o f f -gas . Close to the source the 7 -radiat ion is the main contributor to the total dose rate. At these distances the 7 - radiat ion is not sensitive to the diffusion parameters . There fore the di f ference between 'rough' and 'smooth ' terrain is small .

If the o f f - gas mixes with the cooling tower plume it is lifted up to greater heights due to the buoyancy of the latter. As a consequence the dose rates at ground- level decrease . The broken curve in Fig.2 is an estimate rather


than an exact calculation, as the 7 - d o s e rate of a r is ing plume has not yet been evaluated. The dotted curve certainly overest imates the dose rate, and the ameliorating ef fect of plume r i se may even be greater than indicated here .

5. RADIOACTIVE EMISSIONS FROM NUCLEAR POWER PLANTS

Discussing the general e f fec ts of the mixing of the radioactive and the moist p lumes, it has been found that mixing is an important factor if the line joining the stack and cool ing tower is paral le l to the main wind direction. The probabil ity of this occurr ing is greater when severa l r eac to r s are con -centrated at one site. There f o re power plants of modern design should be taken into account here , though there are little emiss ion data available as yet f r o m those power plants that went into operation recently .

The European Community has published data on the radioactive e m i s -sions of European power r eac to r s up to the year 1972 [7] . F r o m these data, a set of actual and l i censed emiss ion rates was compi led , which, it is felt , are representative f o r l i ght -water -moderated power r eac to r s linked to the grid f o r the per iod of the late nineteen sixt ies and early seventies (Table I). The low noble gas emiss ion rates — low as compared with those f r o m ear l i e r plants — are due to the installation of charcoal beds f o r r a r e - g a s retention. Without these devices the emiss ion would be increased by at least a factor of ten.

T A B L E I. RADIOACTIVITY DISCHARGE TO THE ATMOSPHERE FROM EUROPEAN L I G H T - W A T E R -MODERATED POWER REACTORS

Noble gases Iodine Aerosols

Discharge l imit <100 000 C i / a <0.5 C i / a 10 - 2 0 C i / a

Actual discharges <10 000 C i / a <0.4 C i / a <1 C i / a

Predominant nuclide X e - 1 3 3 1-131

The noble gases , in particular 1 3 3Xe, give r i se to skin and whole -body irradiation. An emiss ion rate of even lOOOOOCi 1 3 3 Xeper annum through a 100 m high stack causes equivalent dose rates of l e ss than 1 m r e m / a , if the skin dose rate i s reasonably weighted in relation to the whole -body dose rate. As the permiss ib le dose rates are about one o rder of magnitude higher (30 m r e m / a in the Federa l Republic of Germany at the location of highest dose rate) there would be no prob lem involving the emiss ion of noble gases even if severa l power plants were to be concentrated at one site. This statement impl ies an ef fect ive r a r e - g a s hold-up in the o f f - g a s line. If the o f f - g a s mixes with the cool ing tower plume, the noble gas. dose rate is further reduced (see Fig .2) , so that the environmental burden due to noble gases b e c o m e s almost negligible.

The iodine emiss i on rates , both the permiss ib le and the actual ones, have been sharply reduced since the f i rs t power plants went into operation. The f o r m e r involved consideration of the pasture -»• cow -»• milk pathway in the evaluation of radio log ica l consequences , and the latter involved improvement of iodine retention in the plant.

IAEA-SM-197 /20 239

In most cases the reported iodine discharges have remained well below the discharge l imits . But it will be shown here that the dose rates to the thyroid calculated on the basis of permissible discharge rates can come c lose to the generally accepted dose-rate l imits.

According to R e f . f l ] , a pasture contamination of 1 0 3 p C i / m 2 may cause a thyroid dose rate of up to 30 m r e m per hal f -year grazing period in the thyroid of a child drinking milk as the main diet, this being in the period f r o m a half up to one year old. (This is the most unfavourable age with respect to dose accumulation.) F r o m F i g . l , one can conclude that a constant iodine emission rate of 1 C i /awou lduse up 60% of the dose limit f o r the Federal Republic of Germany, if mixing is excluded (rough terrain, 500 m distance f r o m stack). If the o f f -gas mixes with the cooling tower plume, then at short distances (a few hundred metres f r o m the cooling tower) the iodine deposition can be even higher than for dry o f f -gas .

A comparison with the iodine discharge rates in Table I shows that more effective iodine retention will be necessary if several nuclear power plants are concentrated on one site. This is not just a consequence of the possible mixing of o f f -gas with a cooling tower plume — but we have shown that such mixing certainly does not alleviate the iodine problem.

The aerosol discharge rates are of the same order of magnitude as the iodine discharge rates. The main contributors are activated corros ion products (e.g. cobalt) and some long- l ived f iss ion products (rubidium, caesium and barium). As long as the emission of strontium (90Sr) can be excluded or restr icted to a very low percentage of the aeroso l activity, the radiological ef fect iveness of the aeroso l is lower by several orders of magnitude than that of the iodine. The behaviour of the aeroso l in the mixed plume is s imilar to that of iodine. Therefore the aeroso l activity does not need to be considered separately and may be disregarded here.

6. IODINE FILTER REQUIREMENTS

To avoid major restr ict ions on site use, the environmental burden due to elemental radioiodine must be reduced considerably; this means that elemental iodine must be removed f r o m the exhaust air and o f f -gas . A c c o r d -ingly, modern design concepts will require that: (a) any iodine re lease is controlled; (b) any exhaust air and o f f -gas containing radioiodine passes through

iodine f i l ters ; (c) elemental iodine is adsorbed nearly completely in the f i l ters .

Considering (a), such a requirement can be fulfi l led by having an approp-riate containment concept. Because of the smaller amounts of air to be f i l tered, ventilation concepts providing f o r recirculation of air are to be pre ferred to concepts based on operation with f resh air.

Referr ing to (b), continuous o f f -gas fi ltering for iodine removal is at present either not provided f or at all or is restr icted to the shut-off rooms . There fore additional f i l ter systems will have to be installed to trap the small amounts of elemental radioiodine still escaping. Iodine f i l ters should be required for the exhaust air systems of all r ooms in which components are installed that are susceptible to any considerable release of radioactive coolant or airborne f i ss ion product iodine. These may include the operating rooms of the reactor containment, the annular r ooms between the pressure


containment and the secondary containment and rooms in the auxiliary building. Attention should also be paid to the exhaust air system of the turbine building since, in case of aleak in the PWR steam generator, f i s s ion -product iodine might be present in the secondary loop. In addition, in a BWR, a small amount of iodine is to be expected normally in the steam.

Considering (c) , elemental iodine is removed f r o m the exhaust air or o f f -gas by activated charcoal. Decontamination factors greater than 103 can be attained [ 8] when deep-bed f i l ters of vesse l type are used. A decrease in the removal e f f ic iency of iodine f i l ters over the range of minimum con-centrations discussed in the literature [ 9] might be explained as due to the existence of a certain percentage of iodine compounds that are difficult to remove [10]. Since they are adsorbed to a very low degree only, they are of no significance with regard to deposition on pastures. The deposition rate of methyl iodide is , f o r example, at least two orders of magnitude lower than that of elemental iodine [1]. These compounds may, therefore , be treated like non-depositing gases. Their radiological effect is small in the dry o f f -gas plume and is negligible in the mixed plume. A t rans for -mation of these compounds into elemental iodine during the transport in air need not be taken into account because the transport time of the plume(s) f r o m the stack to the point where potentially the maximum ground contami-nation could exist is too short, being only some minutes.

Provided the above-mentioned requirements are fullfi l led, the re lease of f iss ion product iodine in elemental f o r m could be reduced to an extremely low level which, in turn, is only a small fraction of the total iodine re lease . The remaining iodine compounds that pass through the filtering system need no longer be considered as 'elemental iodine ' , and their deposition and wash-out rates are negligible.

7. CONSEQUENCES FOR FUTURE POWER PLANTS

Review of the possible e f fects due to mixing of radioactive and thermal (cooling tower plume) re leases have shown that the atmospheric dilution factor is improved due to the buoyancy of the moist plume. Aeroso l s and the elemental iodine are partly absorbed by the cloud droplets, which are ef fect ively washed out by^lnatural precipitation. . Close to the source , both ef fects tend to compensate each other. Where a high rainfall probability exists , wash-out may even increase the deposition rate as compared with the case f or dry o f f -gas .

As the present l icensed iodine discharge levels would not permit of ' super -position' of more than afew reactor stack emiss ions , it seems advisable f o r the next generation of nuclear power reactors (and necessary for nuclear energy parks comprising four or more reactors ) to equip the o f f -gas and exhaust air systems with deep-bed charcoal f i l ters in order to remove almost all the elemental radioiodine. Then even a complete mixing of the stack o f f -gas and the cooling tower plume will cause no radiological problems since the rare gases, as well as any residual organic iodine compounds, will not be affected by wash-out or rain-out. The quantity of aeroso ls emitted is , in any case, small enough not to cause any sizable radiation doses.

In considering the radiological impact on the environment, there are arguments that the stack should be integrated into the cooling tower. Ground concentrations and equivalent doses are reduced both by the higher emission

IAEA-SM-197 /20 241

level and the plume rise due to the greater buoyancy of the moist plume. Environmental radioactivity surveillance might turn out to be superfluous, as the activity concentrations would be too low to be detected. (It might also be cheaper to integrate the o f f -gas stack into the cooling tower than to erect a separate stack.) A point to be borne in mind, however, is that the top of the stack would need to protrude beyond the mouth of the cooling tower be sufficiently to ensure that the stack remains effective should the cooling tower be shut down, e.g. during maintenance or in the event of an accident.

R E F E R E N C E S

[ 1 ] HOFFMAN, F.O. , Institut fur Reaktorsicherheit des Techn. Uberwachungsvereins e V , Co logne , Rep. IRS-W-6 (June 1973).

[ 2 ] ENGELMANN. R.J., Nucl. Safety 3 (1966) 354. [ 3 ] Thermal Discharges at Nuclear Power Stations, Technical Reports Series No. 155, IAEA, Vienna (1974). [ 4 ] MARTIN, A . , BARBER, F.R., Atmospheric Environment _8 (1974) 373-81 . [ 5 ] SLADE, D.H., Ed., Meteorology and Atomic Energy 1968, USAEC Rep. TID-24190 (1968). [ 6 ] KONIG, L.A. , e t a l . , "Experiments conducted at Karlsruhe Nuclear Research Centre to determine diffusion

in the atmosphere by means of various tracers", Physical Behaviour of Radioactive Contaminants in the Atmosphere (Proc. Symp. Vienna, 1973), IAEA, Vienna (1974) 67.

[ 7 ] Radioactive Effluents from Nuclear Power Stations in the Community , Commission of the European Communities Rep. (Apr 1974).

[ 8 ] STRAUSS, H.J., STASCHIK, G. , WINTER, K . , Jodfilter fur Kernkraftwerke, Euratom Doc. V / 5 5 9 / 7 4 Vol 1 (Mar 1974) 163.

[ 9 ] PENCE, D . T . , DUCE, F.A. , MAECK, W.J., Developments in the Removal of Airborne Iodine Species with Metal-Substituted Zeo l i tes , USAEC Rep. CONF-720823 (Jan 1973) 417.

[ 1 0 ] WILHELM, J.G., Behaviour of Iodine Sorption Materials, Euratom Doc. V / 5 5 9 / 7 4 , Vol . 2 (Nov 1974) 77.

D I S C U S S I O N

K.G. VOHRA: Your paper, together with the two preceding papers, considers different aspects of the same problem, i .e. the possible ef fects of radioactive, chemical and thermal re leases on atmospheric environments in general. It seems to me that, in order to take into account all the e f fects , it is necessary to adopt an integrated approach to the problem. For example, the effect of mixing of plumes f r o m reactor stacks and cooling towers should also make allowance f or the action of chemical pollutants in the ambient air, possible ion-induced reactions in the plume, and the ef fect of an increased nucleation rate on the rate of deposition of radionuclides through precipitation.

W.G. HUBSCHMANN: Yes, I quite agree. This type of approach may well be necessary in the future.

C. STREFFER: I am very much interested in the data you have reported on iodine. On what basis has the permiss ib le dose to the thyroid that you mentioned — 90 m r e m / a in the Federal Republic of Germany — been ca l -culated? If, as you say, as much as two thirds of this dose may be reached, I would ask whether you have considered combined ef fects , for instance, with some of the drugs which are taken during the f irst few years of child-hood, since a factor of 2 - 3 may be cr it ical at that stage.

Further, you did not say anything about tritium. How high is the increase in the precipitation of tritiated water, which usually finds its way into the atmosphere, during rainy weather?


W.G. HUBSCHMANN: In our calculation of dose rates to the thyroid we only took the energy release due to radioactive decay into account, as is usual up to now. Other ef fects such as those you described earl ier in your own paper at this meeting have not been considered. The curves in Fig . l of our paper are based on an emission rate of 1 Ci of elemental 131I per year. Since two thirds of the permissible dose rate can be reached at this e m i s -sion rate and since discharge rates up to 0.5 C i / a are permitted, nominally three plants of the same design could be set up at a site.

As regards the tritium, our considerations have been confined to light-water-moderated power reactors . With such reactors , tritium emission is of no concern. This nuclide is released mainly f r o m reprocess ing plants or heavy-water-moderated reactors . If at these plants the mixing of trit ium-containing o f f -gas with moist cooling tower plumes occurs , rain-out and wash-out are certainly important factors f o r the deposition of tritium on the ground.

A. BAYER: Assuming that the derived dispersion factors are based on a zero-distance between stack and cooling tower, how would the curves behave if a set distance between these two sources , say a few hundred metres , were taken into account?

W.G. HUBSCHMANN: We assumed complete mixing of both plumes in the prevailing wind direction sector . This might be relevant to distances of up to about 150 m between stack and cooling tower. Once the o f f -gas plume is entrained into the cooling tower plume, the dispersion of the latter is the dominating factor in assessing ground contamination. Hence a greater distance affects the probability of mixing, but not the ground concentration, or deposition below the mixed plume.

IAEA-SM-197 /20

SYNERGISTIC EFFECTS OF AIRBORNE EMISSIONS FROM NUCLEAR POWER PLANTS

H. FUCHS, W. HOFMANN, H.M. von EUW Motor-Columbus Consulting Engineers Inc . , Baden, Switzerland

Abstract

SYNERGISTIC EFFECTS OF AIRBORNE EMISSIONS FROM NUCLEAR POWER PLANTS. The surroundings of a nuclear power plant may be influenced by the way emissions from of f -s i te or on-site

sources interact with natural or arti f ic ial ( coo l ing - tower ) humidity and precipitation. A survey of possible synergistic mechanisms is g iven . The behaviour of SO2 and iodine is reviewed and aerodynamic effects of the cool ing tower on the dispersion of the stack effluents are discussed. Cooling towers may act as turbulence promoters and increase ground- level concentrations of stack emissions, bringing maxima nearer to the source. Measures to reduce this e f fec t are discussed.

1. INTRODUCTION

Emissions f r o m power plants are released into an atmosphere which may be characterized by parameters such as: (a) Weather conditions (wind, turbulence, temperature, humidity,

precipitation, e t c . ) ; (b) Content of foreign matter (dust partic les , acids, gases, etc . ) . Since these parameters , as well as others, e . g . source height and topography, exhibit wide variations, greatly differing interaction processes between emissions and the atmosphere are to be expected.

Special situations ar ise with winds of particular speed and direction, namely, that the dispersion of emissions f r o m the stack may be influenced by turbulence down-wind of high buildings or cooling towers. Following a general survey, the paper discusses this topic in more detail.

2. PROBLEM AREAS

2 .1 . Influence of humidity and precipitation on radioactive emiss ions

Nuclear power plants emit some radioactivity (mainly noble gases and small amounts of iodine and particulate matter) through their stacks. Although total re leases are usually strictly limited, possible radiation doses at ground level must be shown to be within prescr ibed l imits . Scavenging ef fects may dislocate some of the plume material downwards (see Fig. 1) and thus influence the irradiation level at the ground. High humidity and precipitation tend, therefore, to enhance the deposition of iodine and particulate matter emitted by the stack. When discussing interaction effects between the stack plume and the cooling tower plume, the above-mentioned "natural" scavenging should be taken as a re ference . This is also true for the case of SOs gener -ated at the plant or coming f r o m other sources .

243

244 FUCHS et a l .

WASH-OUT

F I G . l . Rain-out and wash-out.

IAEA-SM-197 /14 245

FIG.3 . Interactions with the coo l ing tower plume.

2 .2 . Influence of nearby buildings or structures

It is well known that a high building near the stack may substantially change the dispersion of the airborne effluents. Winds with speeds greater than several metres per second blowing f r o m the stack towards the building may deflect part of the stack plume downwards, leading to higher ground-level concentrations of plume matter near the building.

A rule-of - thumb states that this ef fect becomes negligible if the stack is 2. 5 times higher than the building adjacent to the stack. This rule can hardly be applied, however, to a cooling tower in the vicinity of a stack (Fig .2 ) . Detailed studies to determine an adequate stack height may be necessary (cf. Section 3).

2 . 3 . Influence of cooling tower plumes on various types of emission

Cooling tower plumes are relatively warm and very humid; they may interact with foreign substances in a way s imilar to that of natural clouds.

Data col lected at the Keystone Plant [ 5] have shown that SO2 transported f r o m distant sources interacted with the cooling tower plume (see top of F ig . 3). Whilst there are no means of preventing interaction of the cooling tower plume with airborne materials generated by foreign sources , one should avoid interaction with on-site sources , such as auxiliary bo i lers

246

(Fig. 3 bottom): either the line joining the cooling tower and the boi ler should not be parallel to the main wind direction(s) or the auxiliary boiler should not be in operation when the cooling tower is .

3. INTERACTION BETWEEN THE STACK PLUME AND THE COOLING TOWER PLUME

3 .1 . Parameters influencing the interaction

The degree of interaction is determined by two groups of parameters :

(a) Geometry /design - Type of cooling tower (natural draught/mechanical draught); - Thermal power, height of the cooling tower; - Height of the stack, exit velocity; - Distance between stack and cooling tower; - Orientation of the stack-to -coo l ing tower axis with respect to the main

wind direction(s) .

(b) Meteorology - Wind speed and direction (see Figs 4 and 5); - Temperature, humidity; - Stability c lass .

IAEA-SM-197 /20 247

COOLING TOWER

FIG.5 . Influence of wind direction on p lume interaction.

Interaction between the two plumes can be reduced by taking the following measures : (i) making the stack-to -coo l ing tower axis parallel to the d i r e c -tion of a weak or infrequent wind; (ii) arranging for a substantial distance between the stack and the cooling tower; (iii) providing a stack of such a height that the plumes rare ly mix. Another approach would be to reduce the emissions to a point where interaction between the plumes cannot lead to prob lems.

Investigations descr ibed in subsection 3. 2 have shown, however, that the interaction does not generally present a major problem. It is , therefore, rarely necessary to provide f or all the measures indicated above.

3 .2 . Results of an investigation on the plume interaction problem

During the construction permit licensing for the nuclear power plant Gosgen, Switzerland, the following problem arose . The stack height had to be determined such that col lapse of the stack upon the reactor building would not result in higher loadings than those specif ied f o r an a ircraf t crash and that the radiological impact of the stack emissions at ground level , including possible interaction with the cooling tower plume, would remain within acceptable l imits .

Two restr ict ions had to be observed, namely, conservative estimates of loadings due to a possible stack col lapse were required and stack effluents would be limited to 'as low as practicable ' values.

248 FUCHS et al .

FIG.6 . Stack effluent dispersion (schematic) without and with a cool ing tower ( C . T . ) .

The height of the cooling tower had been fixed as 150 m (natural draught type), and the distance to the stack as 2 70 m.

Wind tunnel experiments were conducted at the Swiss Federal Institute of Technology, Zurich, using N zO as a tracer f o r the stack effluents [ 1 ] . Cooling tower operation was conservatively simulated with air . The height of the stack was varied between a scaled-down 70 and 140 m.

Figure 6 shows, in a somewhat exaggerated form, the effect of inter-action between the stack plume and the cooling tower: with a sufficient wind speed (> 3 m / s ) the ground-level concentration of the substances emitted by the stack becomes notably higher near the cooling tower as compared with the situation without a cooling tower.

The stack plume is, however, not only enlarged in the vertical but also in the horizontal direction. This gives r i se to a lower ground-level concen-tration farther away f r o m the cooling tower. The enhancement of the concentration near the cooling tower is largest if the tower is not in opera -tion (acting mere ly as a 'turbulence promoter ' in a way s imilar to a tall building).

An operating cooling tower lifts part of the stack effluents to a higher level , but the concentration at ground level is still somewhat higher than without the tower.

It should be recal led that this enhancement effect is of importance only for moderate to strong winds parallel to the stack-to -coo l ing tower axis and in that sense; the opposite direction results in a smaller effect, while a .cross-wind has practical ly no effect at all.

Dispersion conditions in the wind tunnel corresponded to Pasquill c lasses C to D. An attempt was made to estimate conservatively the plume behav-iour f or other stability c lasses . Figure 7 depicts the resulting trends.

IAEA-SM-197 /14 249

E X T R E M E L Y U N S T A B L E

log d

FIG.7 . Tendency to modi fy the stack factor due to the presence of a nearby cool ing tower ( C . T . ) .

The presence of a cooling tower relatively near the stack promotes turbulence: the maxima of the curves f o r the stack factor S (=ground concentra tion divided by emission rate) are enhanced and move towards the source . This ef fect is most pronounced for stable conditions, but winds of sufficient speed are not too frequent in these per iods .

The height of the stack proved to exert a great influence on the effects : decreasing the height led to an increased interaction. F o r the special situation at Gosgen, a 100 m stack proved to be acceptable.

4. CALCULATIONS ON INTERACTION OF A COOLING TOWER PLUME WITH S 0 2 , IODINE AND AEROSOLS

The program, SAUNA-S, calculates cooling tower plume behaviour in detail, starting with the parameters of the tower and the results of balloon soundings. The program has been veri f ied with observations and measure -ments taken at various cooling towers in operation.

A subroutine, DROPB, deals with the problem of droplet formation and movement. This subroutine has been modified.to include the interaction of foreign matter with the droplets of the plume also (subroutine DROPG).

DROPG f irst calculates the interaction between the cooling tower and stack plumes. This has been shown to give good results in most cases . In cases with strong winds and irregular topographical character ist ics , the results are checked against wind-tunnel studies.

The subroutine then takes into account the solubility of the substance in water, the absorption (with or without relative movement of droplets), and

250 FUCHS et al .

the time and space reactions within the droplets (diffusion and chemical reactions) ,

Clearly no model can have general validity for all gases, but we found that by using three sub-models , DROPG was able to handle most gases. The sub-models were: (a) no accumulation taken into account; (b) no chemical changes, only diffusion and accumulation; (c) chemical changes, diffusion and accumulation (used for S0 2 ) . DROPG's three sub-models calculate the plume interactions accordingly . Each one of these sub-models has been independently veri f ied using data compiled f rom various experiments.

Results up to now indicate that cooling tower plumes' droplets are, in the main, not very effective c a r r i e r s for iodine. This is probably because natural draught cooling towers with efficient drift eliminators produce very little, if any, artif icial rain. Scavenging due to this arti f ic ial effect is, therefore, very low compared with that due to natural precipitation, which itself is not too eff icient.

The major problem in predicting the rain-out and wash-out resulting f r o m the operation of a cooling tower is the complexity of parameters involved, as well as the reversibi l i ty of some of the reactions. S 0 2 , for example, ionizes almost instantaneously and is absorbed by the water present in the plume (or c loud! ) . This f o rms an aqueous S0 2 which then dissoc iates to become HSOg and H + .

H 2 O + s o 2 ** H 2 S O 3

H 2 S0 3 * H+ + HS03

HSOg * H+ + S03"

It should be noted that, although only 1. 5% to 2. 0% of the S0 2 is oxidized to S 0 3 [2, 3 ] , this should not be taken lightly, since S02 in the presence of moisture f o rms H 2 S0 4 . This can be specially problematical when there is an obstacle in the path of the plume.

Some of the parameters that strongly influence the oxidation of S0 2 are the external partial pressure of the gas in the atmosphere, its concentration, the humidity, the pH of water droplets, the availability of catalysts, the pressure and temperature, the previous concentration of dissolved gas in the droplet and the drop s ize .

The rate of oxidation of S0 2 is greatest at relative humidities just below 100% [ 4 ] . Also , the higher the pH-value of the water, the higher the rate of absorption of the gas [ 5 ] , The absorption of S02 (scavenging) is dependent on the size and acidity of the drops [ 6 ] . The larger drops are less acid and, therefore, are able to absorb greater quantities of S 0 2 . The S02 wash-out increases with the distance f r o m the source while the sulphate wash-out decreases with distance. Since the solubility of S0 2 in water increases as the water acidity decreases , one can immediately see that a cooling tower plume can be a very ferti le breeding ground for H 2 S 0 4 ! This is due to the cooling tower ' s plume continually providing f resh neutral water.

The transport of S0 2 can be quite a problem, due to the reactions which produce H 2 S 0 4 . The concentration of this acid at ground level may become greater under the cooling tower plume, especially with humid weather conditions combined with a strong wind.

IAEA-SM-197 /20 251

Transport of noble gases by droplets is quite inefficient due to the high exchange rates: droplets take up these gases rapidly but give them off just after leaving the gas plume.

The software mentioned above is in the process of being used to investigate scavenging ef fects for various nuclear power plants in Europe.

Pre l iminary calculations have shown that f o r special , although rare meteorological conditions the large transfer area of the droplets may result in an appreciable wash-out if the plant has unfavourable design features.

5. CONCLUSIONS

Interactions of on-s i te and o f f - s i te emissions with cooling tower plumes should be investigated on an individual basis . This type of investigation has been facilitated in the last two years by the software discussed in the paper.

Experience [ 7, 8] shows that computer programs like SAUNA-S combined with wind-tunnel experiments are useful tools for obtaining practical solutions.

While radioactive emissions in many cases may not present a major problem in this respect , or can be solved by some modifications of the plant design - even at a late stage - the presence of strong sources of SO2 can lead to serious problems, since detrimental ef fects can be quite noticeable. Detailed investigations should, preferably , be initiated at an early stage of plant design.

R E F E R E N C E S

[ 1] FUCHS, H . , Einfluss von Kiihlturmen auf d ie atmospharische Ausbreitung radioaktiver Abgase; VGB-Kraftwerkstechnik 54 12 ( D e c . 1974) 825.

[ 2 ] SUMMERS, P . W . , "Scavenging of SO2 by convec t ive storms", Proc. Symp. on Precipitation Scavenging (Richland, Washington, 1970), (1970) 293.

[ 3 ] TERRAGLIO, F . P . , MANGANELLI, R . M . , The absorption of atmospheric sulphur d iox ide by water solutions; J. Air Pollut. Control Assoc . 17 6 (1967) 403 .

[ 4 ] JOHNSTONE, H . F . , MOLL, A . J . , Formation of sulphuric acid in fogs, Ind. Eng. C h e m . 52, 10 (1960) 861. [ 5 ] HALES, J . M . , THORP, J . M . , WOLF, M . A . , "Washout of SOz from the p lume of a coa l - f i red power plant" ,

Proc. Symp. on Precipitation Scavenging (Richland, Washington, 1970), (1970) 293 . [ 6 ] HUTCHESON, M . R . , HALL, F . P . , Sulphate washout from a coa l - f i red power plant p lume, Atmos.

Environ. 8 (1974) 23 . [ 7 ] B0GH, P . , "Experience with combined ' w i n d - t u n n e l / p l u m e - m o d e l ' analysis of coo l ing tower environ-

mental i m p a c t " , Proc. Symp. Univ. Maryland, USAEC Rep. CONF-740 302 (1974) . [ 8 ] Vororientierendes meteorologisches Gutachten uber d i e Auswirkungen der Kuhltiirme des KKW Biblis,

Block A and B, Deutscher Wetterdienst, Offenbach (Nov . 1973).

D I S C U S S I O N

E. W. STAUBER: A s you have shown, there is an aerodynamic inter-action between the stack plume and the cooling tower structure. We have calculated that it is negligible in pract ice , because of the height of the stacks, which are much shorter than the cooling tower, e. g. 100 m as compared with 150-180 m for the cooling tower. Because of the Gaussian distribution the cooling tower virtually represents an infinite cylinder, so

252 FUCHS et al .

I don't see why the ground-level concentrations should be any higher than they would be without a cooling tower. Could you comment on this?

A further point is that your Fig . 7 shows that under unstable conditions the ef fect of the cooling tower is negligible. Since the maximum concentra-tion is always found under unstable-neutral conditions, the permiss ib le activity rate at the stack outlet will be about the same without or with consideration of the ef fect of cooling towers. Do you agree?

H. FUCHS: Our wind tunnel tests showed that an increase in ground-level concentration downwind f r o m the cooling tower is most pronounced when the tower is not in operation. We explain this by the fact that the tower acts as a finite cylinder which draws part of the stack plume down-wards. Farther away f r o m the cooling tower, this effect is certainly negligible.

Referr ing to your second point, I agree that if you take the unstable condition as a re ference in order to set emission limits, then the ef fect of the cooling tower is not important, or at least not in the study we have undertaken. I would hesitate to generalize, however, and I think each site should be considered individually.

S. HARTWIG: Do you share Mr. Hiibschmann's view that rain-out is a relatively unimportant process as compared with wash-out, when it is considered that inversions occur quite frequently in r iver valleys?

H. FUCHS: I cannot comment on the relative importance of rain-out and wash-out as natural p r o c e s s e s for the special situation you mention, but I would like to stress that scavenging ef fects due to interaction of the stack plume and cooling tower plume are mostly of relatively minor importance, as compared with the corresponding natural ef fects .

Sessions VI and VII

OTHER FACTORS IN THE ASSESSMENT OF SYNERGISTIC AND COMBINATION EFFECTS

Chairmen: W.G. HUBSCHMANN (Federal Republic of Germany) F. GERA (Italy)

IAEA-SM-197 /20

CHARACTERISTICS OF COASTAL CIRCULATION AFFECTING THE TRANSPORT AND DISPERSION OF MATERIAL RELEASED FROM THE NUCLEAR INDUSTRY

J .O. BLANTON United States Energy Research and Development Administration, Washington D . C . United States of America

Abstract

CHARACTERISTICS OF COASTAL CIRCULATION AFFECTING THE TRANSPORT AND DISPERSION OF MATERIAL RELEASED FROM THE NUCLEAR INDUSTRY.

Our knowledge of circulation in the coastal zones of oceans and inland seas is hindered by lack of detailed observations in these regions. The shallow zone within a few miles of the coast is the region where the impact of nuclear faci l i t ies is l ikely to be fe l t . T h e studies reported here represent an attempt to obtain the spatial and temporal resolution necessary to describe the characteristics of circulation in the coastal z one . These studies were conducted in Lake Ontario, one of the Laurentian Great Lakes, and they are thought to be particularly relevant to most large lakes and inland seas such as the Baltic Sea. Some re levance to shallow continental shelf areas is also noted. Data obtained from moored current meters during thermally stratified conditions indicate the existence of a nearshore region extending some 8 to 10 km from the shore where upwelling and downwelling of the thermocline is conf ined. The root -mean-square(rms) speeds of the wave - l ike currents near the l o ca l inertial period (17 hours) are a small fraction of the ' a l ong -shore ' veloc i ty component in this nearshore zone . Beyond this region, the rms speeds dominate the f low reg ime and are typically 2 to 10 times the mean ve loc i ty . The transition between the nearshore zone is strikingly sudden and is usually completed over a distance of 2 or 3 km. A characteristic of particular importance to dispersion and transport of suspended matter is the large t i m e lag observed in current reversals across the coastal zone . The lags can amount to as much as three days, the results of which are episodes of large lateral shear. These shears can approach the value of 10"4 s"1 , the value of the Coriolis parameter near mid-latitudes. High shear values do not co inc ide with high winds, but are usually related to the inability of the nearshore currents to adjust to a slowly varying wind reg ime . Simple momentum arguments suggest that the t ime for adjustment decreases as water depth nearshore decreases. The most important lesson to be gained by these studies is that current measurements at a single point are often misleading. The characteristics described here cannot be defined without c losely-spaced synoptic current measurements over a coastal region.

INTRODUCTION

As one considers the future increase in the number of nuclear power plants and associated industry throughout the coastal zones of the world, decision makers must objectively assess the capacity of the coastal waters to transport and disperse the wastes from the nuclear industry that are ejected nearshore. This i s an old problem that engineers have considered by looking at single-point current measurements and by calculating the dispersion of turbid or dyed patches of water. However, physical processes responsible for transport and dispersion are not only highly time-dependent, but they can be highly space-dependent as wel l . Thus our knowledge of the circulation in coastal zones of oceans and inland seas i s hindered by a lack of detailed observations that w i l l bring some order to these highly variable processes. The studies reported here represent an attempt to obtain the necessary spatial

255

LEGEND

O CURRENT METER MOORING 1970 • M E T E O R O L O G I C A L S T A T I O N (Plessey "Met Packs "used Offshore) • COASTAL CHAIN FLAG STATION (Univ. of Waterloo)

^ BATHYMETRY: 10 METRE INTERVAL

CO m OJ

> Z H

FIG. 1. Locations where currents and winds were mea -sured during 1970 in Lake Ontario.

IAEA-SM-197 /14 257

and temporal resolution necessary to describe the characteristics of coastal circulation that affect the transport and dispersion of waste material that is dissolved or suspended into the water. This research was conducted in Lake Ontario, one of the Laurentian Great Lakes of North America, and the results described here are thought to be particularly relevant to most large lakes and inland seas such as the Baltic.

Birchfield and Davidson [1] described current measurements in Lake Michigan that clearly delineated between nearshore and mid-lake currents. These measurements confirmed what Charney [2] had already predicted: that under stratified conditions, long interval waves would not respond to the presence of the shoreline until their distance to shore became of the order of the "Rossby radius of deformation." For the Great Lakes under typical conditions of stratification, this radius would be between 5 and 10 km. Within this zone, the rotary circulation associated with long interval waves would be straightened out. The flow within this zone has been observed and interpreted as baroclinic coastal jets [3]. When the Great Lakes are unstratified, the Rossby radius becomes of the order of the Lakes' horizontal dimensions, and theoretically, horizontal motions associated with long waves are everywhere responding to the presence of the shores.

Details of the circulation in the nearshore zone are only now emerging as institutions deploy closely-spaced recording current meters for several weeks at a time [4], [5], [6]. These studies have been complemented in a valuable way by "coastal chain" experiments [7] and by dye diffusion experiments [8]. An array of recording current meters like that shown in Figure 1 offers the means to develop a "climatology" of coastal currents but only after the data base for a particular location extends over several seasons. Such locations are rare even today.

Nevertheless, based on a few such studies, we can divide the regime of currents flowing through a region into three elements [8]:

1) stagnant or sluggish flow 2) alongshore flow accompanied by upwelling and downwelling 3) current reversals accompanied by large values of lateral shear

The comparative magnitude of the dispersive processes during these three regimes have been discussed by Csanady [9], Murthy [8], and Blanton and Murthy [6], but a clear consistent picture has yet to emerge. The purpose of this paper is to summarize some of the complex characteristics of nearshore currents that have come to light recently. These characteristics are all pertinent to the transport of dissolved and suspended material in the nearshore zones of the Great Lakes, other large inland seas, and the continental shelves.

STATISTICAL CHARACTERISTICS

A progressive-vector-diagram (Fig. 2) for currents in Lake Ontario illustrates some essential differences between nearshore currents and those farther from shore. Spectral analyses of these and many more current meter data along the north shore of Lake Ontario [4] revealed that at least 707o of the kinetic energy in the horizontal currents were accounted for, to varying degrees, in two types of motion: (1) motion having a return period in excess of 3 days, (2) rotary

258 BLANTON

NORTH

. t LONGSHORE 1

O

SCALE 0 5 10 20 Km 1 1 I i

F I G . 2 . Simultaneous current meter data at d i f ferent distances f r o m the shore. Data are presented in the f o rm diagrams d e n o t e the day of the month .

or wave-like motion that includes periods betwen 12 and 20 hours. (The theoretical inertial period for Lake Ontario is about 17.5 hours.) One can see those two types of motion in Fig. 2, but the most important fact is that the rotary motion essentially disappears in the record obtained closest to shore. Moreover, the disappearance is rather abrupt, particularly in summer when the lake is stratified. The abruptness has been illustrated by Blanton [4] in which he partitioned the total horizontal kinetic energy into wave-like motions and long-period motions (Fig. 3). Csanady [7] has discussed a "coastal boundary layer" within which adjustments between nearshore and mid-lake motion occurs. Closely-spaced arrays of current meters in Lake Ontario and in Lake Huron show that the adjustment takes place within a narrow zone only 2-3 km wide during stratified conditions. In other seasons, the adjustment appears more subtle. Nevertheless, when we talk of nearshore horizontal currents, we are talking of currents whose principal

I A E A - S M - 1 9 7 /14 2 5 9

DISTANCE FROM SHORE: 11 km DEPTH OF CURRENT METER; 7m 2400 GMT 2 JULY 1970

15

DISTANCE FROM SHORE: 16 km 1200 GMT DEPTH OF CURRENT METER: 6 m 18 JULY 1970

1600 GMT 3 JULY 1970

of a progress ive -vector d iagram compr is ing c o n s e c u t i v e hourly vectors . Numbers a d j a c e n t to the

variations are occurring over a period of 3 days and greater. Thus kinetic energy available nearshore for transport and dispersing dissolved substances is predominantly in lower frequencies less than one cycle per day.

When Lake Ontario is thermally stratified, the zones of upwelling and downwelling are confined within the coastal zone defined for summer in Fig. 3. A typical cycle of upwelling and downwelling is shown in Fig. 4. Note that the lake bottom in the coastal zone is affected greatly by this natural cycling of temperature. Slopes of the thermocline can attain 10~3 within the coastal zone whereas the slope of the main thermocline across Lake Ontario is 10-4 to 10"5 [10].

The vertical decrease of kinetic energy with depth is lower nearshore than the decrease in areas far from shore (Fig. 5). Note

260 BLANTON

1 0 0 - i

80

60

40

> O 20 tr UJ z UJ 0

50 - i

^ 40 HI O DC UJ 0.

30

20

• SPRING : 17MAY- 1 JUNE, 1970

• SUMMER : 3 - 1 7 JULY, 1970

A FALL : 1 - 19 OCTOBER , 1970

ci iWME R_

• SPRING 1970

• SUMMER 1970

A FALL 1970

8AF PA*.

12

DISTANCE OFFSHORE ( k m )

FIG.3. Kinetic energy in motion along the north shore of Lake Ontario having periods (a) exceeding 3 days and (b) between 16 and 18 h. Energy is given as a percent of the total (u2 + v2 = variance u + variance v) . The trend lines are an eye- f i t to near-surface observations. Depth (metres) of observation is given adjacent to each data point ( from Blanton [ 4 ] ) .

IAEA-SM-197 /14 261

FIG.4 . Representative profiles of temperature along the north shore of Lake Ontario. Data were obtained from coastal chain surveys conducted by the University of Waterloo, (a) Upwelling; (b ) downwell ing, f i ve days later.

262 BLANTON

KE ( e r g s / c m 3 ) 10 20 50 100 200 500 800 20

KE ( e r g s / c m 3 )

50 100 200 500 800

STATION 19 STATION 11 KE levels at 10metres

when lake is strat i f ied

FIG.5. Kinetic energy profiles for a mid- lake (left) and nearshore (right) station for various dates in 1972 (IFYGL). Roman numerals on profiles represent the months over which the data were averaged.

particularly the strong vertical decrease in kinetic energy in the middle lake during summer stratification. We have speculated that horizontal momentum is scattered vertically by the presence of a sloping bottom nearshore thus making a more vertically homogeneous profile of kinetic energy nearshore, speculation supported partially by oceanic studies [11]. Studies of chlorophyll a variability in Lake Ontario have suggested that patches of phytoplankton may be broken up or at least inhibited from formation in nearshore zones by the scattering of the horizontal kinetic energy [12] . This all suggests that this process might best be accounted for by increasing the magnitude of the vertical diffusion coefficient in nearshore zones.

Simons [13] pointed out the effect of increasing the vertical diffusion coefficient in numerical models: inertial oscillations decay due to increased coupling of currents in the upper and lower levels. This creates a more vertically homogeneous profile of kinetic energy as observed nearshore as well as create the damping out of wave-like oscillations as also observed. To echo Simons [13] "... further model improvements hinge on a better understanding of the vertical pathways of momentum and energy in the lake."

We have established that most of the variance of currents in the nearshore zones occurs over a period of 3 days or greater. This seems reasonable since weather systems seem to pass over the Great Lakes each 2 to 7 days [14]. Over a weather cycle, we can expect currents to be sluggish, almost stagnant, changing to strong alongshore flow and back

TIME-DEPENDENT CHARACTERISTICS

IAEA-SM-197 /14 263

again. The most important fact from a transport and dispersion point of view is that these changes seldom occur simultaneously across the nearshore zone [4], [6]. The fact that current reversals occur at different times in different places helps explain the observations of Csanady [9] and Murthy [8] in which they documented the accelerated rate of dispersion of dye plumes in shifting or reversing currents. In Fig. 6, a 20-day record of alongshore currents reveals large values of lateral shear that result when currents become unsteady or begin to change their direction. On October 6, currents 6 km offshore reversed about 18 hours after the reversal that occurred 3 km offshore. The time lag was about 30 hours for reversals occurring on October 15-16. After the reversal on October 6, the upwelled thermocline (Fig. 4) became downwelled subjecting the nearshore zone to a great increase in temperature. Blanton and Murthy [6] have analysed similar episodes to show that turbulent parameters such as variance are also high during times when lateral shear is high. Our limited experiments seem to indicate that high frequency fluctuations (greater than 1-2 cycles per day) contain too little energy for effective large-scale dispersion in the nearshore'regions. Dispersion processes are connected with events occurring at frequencies of less than 1 cycle per day.

SUMMARY AND CONCLUSIONS

Boyce [5] has suggested that we may have to consider two coastal zones. We have some evidence of the existence of these two zones (Fig. 7). The first is an outer zone where the effects of upwelling and downwelling are confirmed (8-10 km). Inertial-like oscillations are effectively damped out within this zone (currents marked "L"). Currents measured outside this zone are denoted by "R" for predominantly rotary or wave-like motion. The currents are continually adjusting between wind impulses and friction with the result that large values of lateral shear occur. The latter characteristic occurs essentially year-round with no requirement for a stratified lake to indicate its presence. Blanton [4] observed that the zone of lateral shear propagates offshore over the extent of about 11 km in Lake Ontario. Csanady [16] has discussed the time for frictional adjustment required for water in motion over a sloping bottom, and he places a theoretical offshore limit where the time required for adjustment is longer than the forcing time over which wind impulses are occurring. Thus the first or outer zone seems to be on the order of 10 km in extent. However, we must recognize an inner zone where the flow in the outer zone interacts with shoreline irregularities. The particular example in Fig. 7 shows that these zones coincide with an upwelled thermocline, apparently caused by the interaction of flow with the small cuspate features of the shoreline. The entrapment of plumes of dye and pollutants along the shore [8], [17] might result from the entrainment of the plumes in turbulent eddies shed by the shorelines [8], [19]. Palmer [2] has presented evidence that such a viewpoint is plausible. He compared a kinetic energy spectrum at a nearshore location (depth = 9 m) in Humber Bay, Lake Ontario with a spectrum obtained farther offshore (depth = 22 m) and concluded that the nearshore data indicated that the flow was being affected by bottom or shoreline topography.

What have our recent observations told us about circulation in the nearshore zone? One important thing is that current measurements at a single point are usually misleading. In mathematical models, nonlinear terms representing the correlation of velocity and shear (u ,for example) are often as great i f not greater than the terms containing

5 0 LLI cr o X c (/) - 5 O z O

\ 5 7 , 9 , \ 11 13 \ 19 30 ' 1 2 3

OCTOBER 1970

4 / 6 10 / 12 N / 14 ' 15 16 ' 17 ' 18 \ '

^ \ \

0.5

3 o

< - 0 . 5

\ \

-H 1 V \

3km OFFSHORE •6km OFFSHORE

\ / \

V / \ \

4 0

20 Hi

o o UJ CC o

-20 w O

FIG. 6 . T i m e series o f winds, currents and lateral shear in a nearshore region o f Lake Ontario . T h e curves are produced f r o m hourly averages o f speed and d i r e c t i o n . Currents 3 km o f f shore were measured at a depth of 6 m in water 23 m d e e p . Currents 6 km of fshore were measured at a depth o f 7 m in water 44 m d e e p ( f r o m Blanton and Murthy [ 6 ] ) .

-8 km-

1.5 km FIG.7 . Infra-red mosaic of the coastal zone of Lake Ontario near the Oshawa-Bomanvilie portion of the north shore. Light areas are warmer than dark ones. The associated thermal structure along with currents for that day are in-c luded . Al l measured currents f low out of the page except for the two locations farthest o f f -shore, where there is net motion in the offshore direction.

16 JULY 1970

266 BLANTON

the earth's rotation as a parameter ( f u ) . Here, v i s the alongshore velocity component; u is the cross-shore velocity component in the x-direction; f i s the cor io l i s parameter which i s dependent upon latitude. The very time-dependent nature of lateral shear i l l u s t r a t e s that di f fusion processes are far from constant. Thus one future need points to a new realism required for adequate physical modelling of the nearshore zone.

So long as the lake is stratified, we seem to have a clear conceptual model of the nearshore zone (Figs. 3 and 4). Even in the absence of stratification, the bottom and side frictions that induce strong dispersion processes such as lateral shear have a practical limit that is typically 5 to 10 km depending upon bottom slope. Clearly, the dynamics of the transition between "coastal" and "offshore" is little understood. The width of the coastal zone itself is usually less than the usual grid-size of lake-wide numerical models. Simons [13] acknowledges that the major deficiency confronting numerical models is correct parameterization of interactions between sub-grid-scale and large-scale processes, not more sophisticated analytical and numerical techniques. This is particularly true for the parameterization of the processes that rapidly damp out rotary-type motion in the nearshore zone.

We are s t i l l grasping for ways to quantify the amount of water exchanged offshore during current reversals in the nearshore zone. While we have models that purport to predict the path of pollutants and f loatables through and out of the nearshore zone, these models do not yet incorporate the dynamics of processes that transport and exchange water in this zone. I t i s unlikely that these models would stand the veri f icat ion test with f i e l d data unti l these processes are accurately parameterized.

ACKNOWLEDGMENT

This research was conducted while the author was a research scientist at the Canada Centre for Inland Waters in Burlington, Ontario. I am grateful for their support and for the many helpful discussions with my colleagues there.

REFERENCES

[1] BIRCHFIELD, G. E. and D. R. DAVIDSON, A Case study of coastal currents in Lake Michigan, Proc. 10th Conf. Great Lakes Res. (1967) 264-273.

[2] CHARNEY, J. G., The generation of oceanic currents by wind, J. Mar. Res. 28 (1955) 477-498.

[3] CSANADY, G. T. and J. T. SCOTT, Baroclinic coastal jets in Lake Ontario during IFYGL, J. Phys. Oceanogr. 4 (1974) 524-541.

[4] BLANTON, J. 0., Some characteristics of nearshore currents along the north shore of Lake Ontario, J. Phys. Oceanogr. 4 (1974) 415-424.

[5] BLANTON, J. 0., Nearshore lake currents measured during upwelling and downwelling of the thermocline in Lake Ontario, J. Phys. Oceanogr. 5 (1975) 111-124.

IAEA-SM-197 /14 267

[6] BLANTON, J. 0. and C. R. MURTHY, Observations of lateral shear in the nearshore zone of a Great Lake, J. Phys. Oceanogr. 4 (1974) 660-663.

[7] CSANADY, G. T., The coastal boundary layer in Lake Ontario. Part I: The spring regime, J. Phys. Oceanogr. 2 (1972) 44-53.

[8] MURTHY, C. R., Complex diffusion processes in coastal currents of a lake, J. Phys. Oceanogr. 2 (1972) 80-90.

[9] CSANADY, G. T., Turbulence and diffusion in the Great Lakes, Publ. No. 11, Great Lakes Res. Div., Univ. of Michigan (1964) 326-339.

[10] SWEERS, H. E., Structure, dynamics and chemistry of Lake Ontario, Canadian Dep. Energy Mines and Resources, Marine Sci. Branch, MS Report Series No. 10 (1969) 277.

[11] WUNSCH, C. and R. HENDRY, Array measurements of the bottom boundary layer and the internal wave field on the continental slope, Geophysical Fluid Dynamics 4 (1972) 101-145.

[12] GLOOSCHENKO, W. A..and J. 0. BLANTON, Short-term variability of chlorophyll-a concentrations in Lake Ontario in relation to physical processes, (1974) unpublished manuscript.

[13] SIMONS, T. J., Verification of numerical models of Lake Ontario, Part I: Circulation in spring and early summer, J. Phys. Oceanogr. 4 (1974) 507-523.

[14] OORT, A. H. and A. TAYLOR, On the kinetic energy spectrum near the ground, Mon. Wea. Rev. 97 (1969) 623-636.

[15] BOYCE, F. M., Some aspects of Great Lakes physics of importance to biological and chemical processes, J. Fish. Res. Board. Canada 31 (1974) 689-730.

[16] CSANADY, G. T., Barotropic currents over the continental shelf, J. Phys. Oceanogr. 4 (1974) 357-371.

[17] CSANADY, G. T., Coastal entrapment in Lake Huron, International Assoc. on Water Pollution Res. 1 (1970) 1-7.

[18] OKUBO, A., A mathematical model for the entrapment phenomena, Trans. Amer. Geophys. Union 51 (1970) 319.

[19] 0KUB0, A. , Effect of shoreline irregularities on stream wise dispersion in estuaries and other embayments, Netherlands J. Sea Res. 2 (1973) 213-224.

[20] PALMER, M. V., Some kinetic energy spectra in a nearshore region of Lake Ontario, J..Geophys. Res. 78 (1973) 3585-3596.

D I S C U S S I O N

J. SHAH: As far as I can see, your paper has three important implications. The f i rst relates to the equilibration of the pollutants

268 BLANTON

introduced into Lake Ontario (or the Great Lakes) over a given period of time. Do you really consider it safe to assume that effluents f r o m various point sources would eventually attain equilibrium?

The second concerns thermal standards. What limitations would you suggest on thermal standards in view of the ~15°C variation in the thermo-cline?

The third implication, namely constraints or criteria, prompts me to ask what criteria you would advise for locating cooling water and outfall.

J . O . BLANTON: I cannot really answer any questions about equilibrium, since each substance c learly has its own set of reactions with the receiving waters .

Regarding thermal standards, I feel it is irresponsible to set a 'universal ' standard for all thermal effluents in the coastal zones. You have to know the natural temperature cyc les and variability for a particular region into which heat will be discharged. You have to deal separately with each site, and the 'standard' must be real ist ic for each site.

In reply to your question on criteria, I would say that any well -designed power plant must locate its intake and outfall on the basis of the t ime-variability of the thermal structure and the current reg ime. A good design would assure that the intake is drawing cold water below the thermocline over a maximum period of time. Moreover , a knowledge of the frequency of current reversals (in a cl imatological sense) may help to alert plant operators to the possibil ity of recirculation of warm effluent water into the intake, i . e. indicate the frequency of recirculation that may be crit ical in the eff icient operation of the power plant.

W . G . HUBSCHMANN: Could you say to what extent your findings are speci f ic to Lake Ontario, and what the main criteria are for the applicability of your results to other water bodies?

J . O . BLANTON: There are several p ro cesses (or characterist ics) that can be expected in all water bodies sufficiently large for the rotation of the earth to influence the response of the water body to forc ing. Large volumes of lateral shear would occur in the coastal zones, but the quantitative statistical values may be s i te - spec i f i c , depending upon (1) bottom slope, (2) frequency of storm cyc les , and (3) shoreline roughness. The sudden damping of rotary motion induced in stratified water bodies is also generally applicable in large lakes and inland seas, but the degree of damping and the actual width over which the damping takes place are undoubtedly s i te - spec i f i c . Comparative studies involving other sites of different shoreline roughness, and having different bottom slopes and different shoreline orientations to the prevailing winds, are the next phase required in this type of research .

IAEA-SM-197 /20

A SITE STUDY OF THE MULTIPLE EFFECTS OF THERMAL RELEASES ON THE AQUATIC LIFE IN AN ESTUARINE AREA

D. BORGESE, G. DINELLI, L. GUZZI, E. SMEDILE Ente Nazionale per 1'Energia Elettrica, Milan, Italy

Abstract

A SITE STUDY OF THE MULTIPLE EFFECTS OF THERMAL RELEASES ON THE AQUATIC LIFE IN AN ESTUARINE AREA.

The estuarine area of a river represents a typical site where different factors have to be considered when trying to assess the actual impact on the aquatic l i fe of industrial thermal releases. These factors may be physical (river f l ow, sea currents, tides, residence t ime of waters in marshes and lagoons) , b io logical ( b i o -mass production, mutual organic matter exchange between fresh and sea waters) and e c o n o m i c such as the commerc ia l importance of fishing. In this respect the siting of a large power station in the Po river delta may cause serious problems for the conservation of the existing ecosystem. Thus a multidisciplinary approach with a view to predicting the final thermal impact of a power station on the environment seems fully justified despite its complexi ty . Therefore a detailed research programme has been established in order to study the fol lowing main points: (a) structure of the plant and animal populations; (b) primary production and bacterial activity; ( c ) physical and chemica l characteristics of estuarine waters; (d) coastal characterization; (e) thermal effects on the biocenosis entering the condenser of existing plants operating under similar conditions. Together with conventional experimental techniques, airborne infra-red (IR) and multi-spectra (MS) surveys are planned as, according to preliminary investigations, they provide essential information for the recognition of water flow patterns and aquatic plant growth. The behaviour of the particular ecosystem will be simulated using mathematical models defined on a system theory approach, where the descriptive functions and rate c o n -stants c o m e from experimental studies conducted in situ and with laboratory tests. In fact results of preliminary airborne scanning IR and MS surveys combined with b io log ica l studies confirm the need for systematic research on the Po river delta.

1. INTRODUCTION

New power plants will need to be sited mainly in coastal or estuarine areas since their increasing size puts a heavy demand on cooling water availability. Recently, estuarine areas have been considered to be areas of crit ical environmental concern because of the possible unfavourable con-sequences of heat loads on the aquatic life. In fact in these areas a water temperature increase may give r ise to conspicuous synergist ic e f fects with the other pollutants col lected by the main r iver flow.

In such areas the concentration of nutrients and organisms leads to a high biological production that, in some cases , may become of considerable economic value, but as a consequence the particular environment is rather vulnerable to any kind of stress . Moreover these sites are nursery areas for several marine spec ies that are important for the eco log ica l equilibrium of the whole near -shore zone.

269

270 BORGESE et al.

Temperature ef fects are accentuated by the relatively shallow waters usually found in such sites; thus any temperature increase caused by industrial or urban discharges may in some instances cause damage to the animal and plant population.

The additional input of energy flowing through an estuarine zone is governed by the r iver f low, sea currents and wind-induced effect , with the addition of the cycl ical ef fects of tides.

One of the major estuarine areas in the Mediterranean Sea is the delta of the River Po , where a 2 640 MW(e) power station is under construction and is planned to come into operation by 1980.

The operation of this station must be carefully studied in order to avoid any undue effect on the estuarine ecosystem since the delta of the River Po represents a typical environment that has so far developed almost f ree of industrial stress . The circulation pattern of waters and the living organisms is rather complicated due to the interaction of coo ler fresh waters of the r iver with warmer sea water and brackish waters of marshes and lagoons. The marshes and lagoons, as well as the Comacchio lagoon to the south, have rece ived the attention of conservationists.

Hence a research programme has been established in order to: (a) predict the physical, chemical and biological ef fects of the power

station's thermal effluents; (b) contribute to the understanding of the factors which control animal and

plant population activity in estuaries. This programme is to be pursued for three consecutive years , c o m -

bining f ield investigations and laboratory tests as well as in situ campaigns near existing power plants with similar operating conditions.

2. DESCRIPTION OF SITE AND PREVIOUS SURVEYS

2.1. General morphology

The morphology of the Po r iver delta is rather complex due to the presence of several r iver -mouths and lagoons and it is influenced by the combined ef fects of the r i v e r ' s solid transport and the tides. In addition the coastline has advanced at a rate of almost 10 km over the past 200 years. The zone of the delta that will presumably be influenced in the future by the power station at present under construction is delimited by the terminal stretches of the Po -P i la and P o - T o l l e and includes the mouth "Busa Dritta" and two natural lagoons called "Canarin" and "Basson" (F ig . l ) .

The "Busa Dritta" is the most active mouth of the r iver and is charac -terized by high turbidity and a left bank much deeper than the right-hand one. The main physical factors such as temperature and salinity present stratification varying in time.

The "Canarin" lagoon, a relatively large lagoon with a depth varying between 0.5 and 1 metre, is connected on the south-east to the open sea and on the north to the Po -P i la .

The "Basson" lagoon, to the north-east, is a shallow lagoon not directly connected to the r iver .

Both the Basson and Canarin lagoons represent areas f or occasional fishing. The biocenosis structure in each of the above zones is changing under the influence of the combined action of f resh waters and salt waters, as well as because of hydraulic works and drainage.

IAEA-SM-197 /14 271

FIG.l The Po river delta.

BUSA - DRITTA ( 2 4 - 1 0 )

07.15 16.45 hrs

6 7 8 9 10 11 12 13 14 15 16 17 18

m.s.t. 07.15

BASSON (21-10)

TEMPERATURE (°C) 2

16.45 hrs

07.15 16.45hrs m.s . l .

SALINITY ( % ,

A < 5 5 < B < 20

C >20

TIME H 1 1 1 1 1 1 1 1 1 1 1 h 6 7 8 9 10 11 12 13 14 15 16 17 18

07.00

C A N A R I N - N O R T H

(22-10) 18.00 hrs 07.30

m . s . l .

T E M P E R A T U R E ( ° C )

C A N A R I N - S O U T H

(21-10) 16.00 hrs

07 .00 18.00 hrs m . s . l .

S A L I N I T Y ( % o )

A < 5

5 < B <=20

C > 2 0

07.30 16.00 hrs

( m )

0.60

0 .40 -|

0.20

N O R T H

13 13

EAST

10 13 14 15 16 17 18

DIRECTION

W I N D

S P E E D ( m / s )

T IDE

m . s . l .

T I M E

(m) 0.60 H

0.40

0.20 H

SOUTH - WEST

10 11 12 13 14 15 16

FIG.2 Temperature and salinity stratifications as a function of the tide (m.s. l . = mean sea level ) .

274 BORGESE et al.

2.2. Hydrological conditions

F r o m the hydrological standpoint many independent variables are involved. First of all the r iver f low, which is rather irregular even within a reference month period [1 , 2).

During high flow the coo ler r iver water f loods the lagoons, whereas during low flow periods warmer sea water penetrates into the lagoons and the terminal section of the Po -P i la . This last phenomenon is greatly accentuated when coincident with strong on-shore winds.

As a consequence natural thermal s tresses occur , since the r iver temperature varies on the average f r o m about 5°C in winter to about 25°C in summer — while the sea surface temperature ranges f r o m 10°C to 25°C.

At the main mouth of the r iver , the Busa Dritta, a transition mixing zone of f resh water f r o m the r iver with sea water subsists f o r a distance f r o m the shore varying f r o m a few hundred metres to several ki lometres.

The tidal cyc le , although usually of weak amplitude, determines a rather complex circulation of waters in the lagoons. As a consequence water inside the lagoon undergoes changes in temperature with diurnal periodicity, due to solar heating, that may exceed several degrees centigrade [ 3].

Some examples of temperature and salinity stratifications are given in Fig.2. In the Busa Dritta the thermal stratification depends on the salt wedge penetration which, in turn, is regulated by two main factors , the r iver flow and the tide amplitude. The temperature variation with depth may be as high as 5°C with a spatial displacement of several ki lometres depending upon with the tidal period.

In the Basson and Canarin lagoons the temperature pattern fol lows the salt stratification, which depends on the amount of mixing of f resh r iver water with sea water. Of the two lagoons, the water conditions in the Canarin lagoon fol low a more dynamic pattern as a consequence of the r iver flow through it and temperature variations with time. The Basson lagoon, being connected to the sea only, has more uniform salinity and temperature. However, under certain conditions of the sea currents and wind velocity a circulation of f resh water subsists either f r o m the Busa Dritta to the NE or f r o m the mouths of the near Canarin lagoon to the SW. This phenomenon is evidenced in Fig.2 by the presence of coo ler waters at the surface.

A prel iminary airborne in f ra - red survey to observe the ef fects of the alongshore drift (i .e. drift parallel to the shore line) and tides upon the natur-ally (solar) heated waters in the shallow lagoons to the north and the south of the Busa Dritta has shown that on the f lood tide stagnation of sun-warmed waters occurs along the barr ier sand bars north and south of the mouth. However, even near slack water the alongshore drift, although of low velocity (10 c m / s on the average), is effective in dispelling this stagnation pattern — hence overcoming the back-eddy ef fects of the r iver discharges [4].

2.3. Biological information

Some experimental studies, sponsored by ENEL, have recently been undertaken on the terminal region of the delta most exposed to future con-sequences of the thermal re leases f r o m the power station under construction. F r o m the preliminary surveys it has been possible to draw up a check list of the f l ora and fauna, as well as a f irst eco log ica l description of the region.

IAEA-SM-197 /14 275

These investigations have shown a different distribution of animal population in the northern and southern areas. In fact in the southern region, speci f ical ly in the Basson and Canarin lagoons, there exists a poorer popu-lation with weaker marine contributions.

The f l ora consists mainly of benthic algae (Enteromorpha sp., Ulva sp.) that f o r m rather intensive and widespread beds; these algae represent a frequent component of food chains in such brackish waters. Among the macrophytes spec ies the Phragmites sp., that f o rms almost continuous barr i e rs , prevails [5]. Zooplankton f o r m s undergo a significant variation during the year both in quantity and composition [ 6].

The f ish population consists of several spec ies , having a well -def ined structure in each zone according to the local variations in water temperature and salinity. For instance, in the Canarin lagoon there were freshwater and brackish-water spec ies , with a high density of Gambusia sp. during.the summer period [7] .

Most significant was the presence of Merc iere l la enigmatica, an exotic and thermophylic spec ies , and Argnlus giordani, an ectoparasite for the eel whose activity increases with temperature and reaches a maximum at over 35°C [8].

Pre l iminary bacterial activity analysis, based on 1 4C-glucose labelled uptake, has shown a limited amount of mineralization activity in the sediments and pelagic waters [9].

3. THE PORTO TOLLE POWER STATION COOLING SYSTEM

The Porto Tolle thermal power station is located at the terminal region of the delta on the right bank of the P o - P i l a where on the average the water f low amounts to 60% of the total flow of the r iver just before the delta. Four 660 MW(e) units should be completed by 1980 and four additional units are planned for the next decade.

The cooling system is a direct one with a cooling water flow of some 20 m 3 / s for each unit and a water temperature increase through the con-denser of about 8°C. The peculiar character of the site allows the use of both r iver and sea water for cooling; thus a flexible operating scheme was selected, as shown schematically in Fig.3.

During a f irst phase of operation the cooling water will be drawn only f r o m the r iver (Point A) and will be discharged by means of sluice gates either downstream into the r iver (Point B) or into the Canarin lagoon (Point C). The latter operational scheme will be adopted during periods of drought (low r iver flow) in order to avoid recirculation problems. This procedure appears adequate to satisfy a need f or a cooling water f low as high as 80 m 3 / s , i .e . f o r the operation of four 660 MW(e) units.

When the installed capacity is further increased, it might become necessary to draw some water directly f r o m the sea. In fact during the months of July and August and January and February, cr it ical situations may develop due to the extremely low flow conditions in the River Po.

As a re ference , the frequency of occurrence of 5-day low f lows and daily average f lows is reported in Fig.4 f o r the months of August and February, which were deduced f r o m measurements made at Pontelagoscuro, some 50 ki lometres upstream of the delta. In particular during August and July, the average flow for five consecutive days may be lower than 500 m 3 / s , giving a r iver flow at Po Pila of 250 to 300 m 3 / s during drought periods.

IAEA-SM-197 /14 277

FLOW (m3 /s)

FIG.4. Cumulative frequency of daily average flow ( ) and 5-day minimum flows ( ) at Pontelagoscuro.

Thus in a second phase, with an increased cooling water demand at the power station, an artif icial canal and a second intake in the Canarin lagoon will have to be constructed (Point D). It will then be possible to draw, through a system of sluice gates, any ratio of f resh - to - sa l t water to match the speci f ic hydrological conditions of the River Po.

4. RESEARCH PROGRAMME TO EVALUATE THE MULTIPLE THERMAL EFFECTS

The research programme that is planned is divided into two phases, as shown in Fig.5. In an initial phase (Phase A), f ield work will be comprehen-sive enough to allow the formulation of indices characterizing the community structure and function and, more generally, the trophic state of the zones of interest in the Po r iver delta.

In a second phase (Phase B), investigations will be devoted to obtaining information f or the prediction of the multiple e f fects of the heated effluents f r o m the power station. During this phase laboratory test analysis will be implemented with in situ investigations at existing power plants operating under similar conditions. At the same time an environmental assessment programme will be established including pre-operational and operational surveys.

4.1. Pre l iminary ecosys tem studies

Pre l iminary biological investigations are planned with the purpose of evaluating the spatial and temporal distributions, density, b iomass , p r o -duction and trophic relations of the main biological groups as indicated in Table I. Also the location of f ish spawning and nursery areas, their migratory patterns and population dynamics will be studied.

278 BORGESE et al.

FIG.5. Combined thermal effects research scheme.

TABLE I. PRELIMINARY ECOSYSTEM SURVEY

BIOLOGICAL: PHYSICAL:

Phytoplankton Temperature

Macrophytes Salinity

Zooplankton Dissolved oxygen

Microbenthos pH-value

Macrobenthos Turbidity

Fish Redox

Bacterial activity

CHEMICAL: WATER CIRCULATION PATTERNS AND ENERGY BUDGETS:

Nutrients ( P - P 0 4 ; P-total ; Dynamic pattern recognition of : N-Org. ; N-NO3; N - N 0 2 ; N -NH 3 ; S i - S i 0 4 ) Temperature

Organic matter (C .O.D. ; Sea currents

T . I .C . ; T .O .C . ) Wind veloc i ty

Air temperature

Relative humidity

Solar radiation

IAEA-SM-197 /14 279

The following zones of the delta will be examined: Po -P i la , Biisa Dritta, Basson and Canarin lagoons and the nearshore sea.

Due to the strong interrelations between the biotic and abiotic properties of the ecosystem, some physical and chemical investigations, concurrent with the biological studies, are also planned, taking into consideration the parameters listed in order of priority given in Table I. In the f irst surveys the sampling frequency f or the above analysis will be chosen on a flexible basis and will be updated according to the results obtained. Also the number and/or kind of measured parameters may be revised as the interrelations between water physics , chemistry and biology are better understood.

4.2. Predictive studies

4.2.1. In situ cooling ef fects investigations

The purpose of such studies is to evaluate the effect of the intake and the entrainment through the condenser on living organisms as well as the discharge impact. The investigations will be carr ied out at an existing power plant c lose to the Po delta area.

(a) Intake stress . The fish behaviour in the intake area will be studied and the ef fects of the power plant on the key fish species will be deter-mined. Damage to f ish due to the intake screens will be recorded. The sampling frequency will be selected according to migration patterns as well as f ish local movements. (b) Entrainment stress . The mechanical, chemical and thermal damage on phytoplankton organisms will be determined by evaluating the meta-bol ic changes with 1 4 C fixation. Similar fi ltering techniques will be used to determine if there is a significant difference in susceptibility to damage between large ( > 1 0 micron) and small ( < 1 0 micron) phytoplankton.

Zooplankton samples will also be analysed and the mechanical, thermal and chlorine ef fects evaluated by noting survival rates. Bottle samples taken at the intake will be suspended in the discharge canal to deter-mine survival rates as a function of temperature and time of exposure.

Similar investigations will be pursued on entrained fish eggs and larvae of the benthic organisms. (c)__Discharge impact. The ef fects induced by heat and chemical shock on species trapped in the discharge canal and in the near-field thermal plume will be evaluated by means of three 'live boxes ' anchored in the discharge canal, just upstream of the intake and downstream of the point of discharge (Fig.6). The growth rate of some spec ies can also be studied in these cages in order to evaluate the possibil ity of under-taking fish farming in connection with the power plant operation.

4.2.2. Laboratory tests

Laboratory tests f o r the evaluation of the acute ef fects of temperature will be conducted on the most significant species of f ish f r o m an eco log ica l and economic point of view. These studies will be pursued using a wel l -established methodology f r o m previous, investigations on r iver f ishes.

2 8 0 BORGESE et a l .

FIG.6. Live boxes (cages) for external impact studies.

The following points need to be clarified: the temperature/survival time relationship, and critical chlorine levels, for different temperatures, for physiological functions such as swimming, branchial gaseous exchanges, etc.

In addition, the combined effects of temperature and antifouling com-pounds on the attachment of sessile invertebrates on natural and/or artificial aquatic substrata will be investigated in order to evaluate the possible modi-fications in the colonization capacity of benthic organisms.

IAEA-SM-197 /14

4.3. Investigations of water circulation patterns and energy budgets

281

The eco log ica l implications of the power plant will depend greatly on the dynamics of the water circulation patterns in the delta area as well as on the amount of heat that is exchanged directly to the atmosphere at the water surface. Both these phenomena need to be studied under the different conditions of the Po r iver f low, sea currents, tides and meteorological factors in order to establish their relative influences on the local e cosystem and their possible e f fects on the general circulation of waters in the northern Adriatic sea once the power plant comes into operation.

The geographical amplitude and complexity of such investigations suggest the use of remote sensing techniques f o r the detection of the energy ref lected and/or emitted in the electromagnetic spectrum f r o m the water body. In previous surveys, such techniques have proved very useful for mapping the surface characterist ics of a water body over large areas in a time short enough to fair ly represent almost instantaneous conditions [10]. As an example, in Fig.7 an in f ra - red thermal image of the Po delta is shown f r o m which the zones of interaction of f resh, brackish and salt waters can be easily identified. By repeating the survey at different t imes of the day, the residence t imes and water volumes in the lagoons may be inferred f r o m the derived surface temperature maps. Also the zone of influence of a thermal effluent and the water /atmosphere heat exchange coef f ic ients may be assessed. With the prel iminary surveys this last factor was found to vary on the average between 30 and 50 W'm" 2 « °C~1.

More generally, in f ra - red and mult i -spectral surveys are planned with the following objectives: (a) To map the water surface temperature and quantify its diurnal and

seasonal variations; (b) To examine the macrophytes and phytoplankton and compare their modi -

fications subsequent to the operation of the power station; (c) To control the morphology of the delta as defined by hydrological and

meteorological events. Information col lected with remote sensing surveys will be supplemented

with in situ measurements of selected parameters..

5. CONCLUSIONS

The results of the planned eco log ica l r esearch will serve as a basis f o r discovering the main mechanisms and the ' cr i t i ca l zones ' of the delta ecosystem. Also the species of crit ical importance in the food chain and the synergistic e f fects of heat, chlorine, oxygen and salinity s t resses will be established.

The experimental data will be used to develop cause-and-e f fect modelling techniques f or relating the loca l e f fects of a thermal discharge to their regional consequences. The formulation of predictive impact models will be validated by experiments to provide empir ical correct ions as required.

These simulation models will also provide prel iminary information f or the siting of new power plants by providing the characterization of a ser ies of typical b iocenos is , known in their composition, dynamics and external s tress response. As a consequence new eco log ica l impact studies will

FIG.7. Infra-red survey mosaic .

IAEA-SM-197 /14 283

require further in situ measurements only in order to investigate local di f ferences in the typical b iocenosis ; thus it is hoped that the whole environ-mental impact work will be speeded up considerably in the future.

R E F E R E N C E S

[ 1 ] MINISTERO DEI LAVORI PUBBLICI, Uf f i c io Idrografico del Po: "Hydrological Annals" , Parma (1956-1967) . [ 2 ] DINELLI, G. , "Regional management of thermal effluents along the Po river" , 16th IAHR Symp.

(Sao Paulo, 1975). [ 3 ] DINELLI, G. , et a l . , "Airborne infra-red scanning; surveys of thermal alterations of water bodies" ,

AEI-75 Annual Meeting (Rome, 1975) in Italian. [ 4 ] BORGESE, D. , et al. : "Isothermal mapping of temperature patterns from thermal discharges in Italian

coastal waters", Proc. 8th Int. Symp. on Remote Sensing of Environment (Ann Arbor, 1972). [ 5 ] PARISI, V . , Status of knowledge o f the bio logical population of Po Delta Region, Ann. Univ. Ferrara

(N.S.) , Sez. I, Ecol . , Suppl. 1 (1973) , 79 -93 : in Italian. [ 6 ] FERRARI, I . , Seasonal succession of zooplanktonic population in the thermal region of the Po river,

Ateneo Parmense 9 4 (1973) 393-407: in Italian. [ 7 ] GANDOLFI, G. , The fish population on the Po river delta. First data, Ateneo Parmense 9 4 (1973) 409 -17 :

in Italian. [ 8 ] PARISI, V . , On the b io log ica l population in the Po river, Ateneo Parmense 9 4 (1973) , 363-75 : in Italian. [ 9 ] MELCHIORRI SANTOLINI, U. , BERTONI, R . , Methodology for the study of the microb io log i ca l eco logy

of the delta of the Po river, Ateneo Parmense 9 4 (1973) 439 -48 : in Italian. [ 1 0 ] DINELLI, G. , et a l . , "Use of thermal infra-red scanning in evaluating predictive models for power plant

thermal plume mixing in Italian coastal waters", Remote Sensing and Water Resources Management, Am. Water Resources Assoc. Proc. No. 17 (1973).

D I S C U S S I O N

F. GERA: I don't quite understand the question of the plant inlets and outlets. You showed us in your presentation that sea water can be discharged into the Canarin lagoon and that the lagoon ecosystem will thereby be exposed to increased temperatures and salinities. Could you tell us if this discharge into the lagoon will take place continuously or only in special situations?

G. DINELLI: Sea water will be drawn f r o m the lagoon for cooling purposes only when there are very poor flow conditions in the River Po. This water will be returned to the Canarin lagoon. The temperature and salinity variations induced thereby in the lagoon are expected to be c ompar -able to those which occur under natural conditions. In fact, as shown by the in f ra - red images, during low flow periods in the River Po the sea water periodical ly f loods the lagoon through tidal movement, thus inducing tempera-ture variations as high as 5°C and different salinities ranging f r o m f resh water to almost sea-water conditions.

P.G. ROLLIN: In your paper you describe an eco logical research project for the Porto Tol le power plant, and point out that there will be a study made of the ef fects of temperature on the survival capacity of aquatic organisms. But it has already been decided to build this plant, and it may even have been begun. The layout plans you showed us provide for very long discharge canals, although these are disadvantageous f r o m the standpoint of the 'thermal dose ' (At X time) rece ived by the organisms. What are you going to do if the project studies turn out to be negative?

284 BORGESE et al.

G. DINELLI: I quite agree that long discharge canals may worsen the eco log ica l impact of a heated effluent. The point is that we envisage at Porto Tolle a long canal f o r drawing cooling water directly f r o m the sea, whereas the actual discharge canal is relatively short and the heated water is discharged into the Canarin lagoon, where we have experienced large natural fluctuations both in temperature and salinity. These two canals are supposed to be used only when the power station is operating at full capacity; in any case, some modifications may still be made in the actual layout and position of these additional intake and outfall systems.

IAEA-SM-197 /17

COST EFFECTIVENESS OF RELEASE PREVENTION CONTROLS FOR TRITIUM AND KRYPTON-85

J .J . C O H E N

Joint IAEA/IIASA Research Project, International Atomic Energy Agency, Vienna

Abstract

COST EFFECTIVENESS OF RELEASE PREVENTION CONTROLS FOR TRITIUM AND KRYPTON-85. This paper reviews the consequences of releases of tritium and krypton-85 to the environment. The

ob jec t ive is to p la ce these consequences in perspective so that costs for release prevention may be made commensurate with the potential hazard. Evidence is presented indicating that projected levels of krypton-85 may pose a more serious health problem than those of tritium while significantly more past effort has been devoted to tritium control . It is suggested that application of cost /benef i t analysis might result in a more ef f ic ient al location of priorities.

1. INTRODUCTION

Expanding application of nuclear energy has caused a growing concern with regard to potential environmental re leases of tritium and krypton-85. Both of these nuclides have widespread distributions in the biosphere and extended environmental residence t imes. Another characterist ic that both nuclides share is that their ultimate ef fects to man (in terms of population dose) can be predicted with a minimum of conjecture. F o r this reason they readily lend themselves to evaluation by cost /benef i t analysis. This study evaluates and compares potential ef fects of environmental re leases of these nuclides f r o m various sources , including nuclear power reactors , peaceful uses of nuclear explosives and potential application of controlled thermo-nuclear (fusion) energy. The objective is to place exposure risks in perspective so that costs f o r re lease prevention may be related to and made commensurate with the potential hazard, and so that cost ef fect iveness f or controls may be established on an objective basis .

2. THE COST EFFECTIVENESS CONCEPT

It is generally the case in major industrial or governmental enterprises that the availability of financial r esources is not sufficient to satisfy all desired object ives . This is a lso true in health and safety ef forts where the extent of these ef forts is limited by the resources available.

This situation requires the establishment of some system of pr ior i t ies whereby health and safety funds are allocated to competing programmes according to both the availability of such funds and the respect ive needs and benefits of the programme.

285

286 COHEN

F I G . l . Cost effectiveness of health and safety expenditures.

In limiting the release of harmful materials to the environment, there-fore , a balance or trade-of f must be determined between expenditure and degree of restrict ion of the release, the objective being to maximize the effective use of financial resources . Such trade-of fs are modelled in Fig . 1. This curve relates cost of an environmental health programme to the resultant level of hazard. It fol lows the well-known economic law of diminishing returns. It should be noted that in expenditures to reduce a particular hazard (either radiation or some other) at some given cost (C), the return per unit expenditure decreases as the total expenditure increases . It may also be noted that no matter how much money is expended, a further reduction could be attained by additional spending. Beyond a certain point, however, money might be more efficiently spent to reduce a different hazard where the benefit per unit investment would be greater. This point would be at the intersection of the cost -e f fec t iveness guideline and the diminishing-returns curve.

F o r radioactivity, a suggested cost -e f fect iveness guideline is approximately $200 per man • rem avoided [ 1 ] . This f igure can be derived f r o m guidance suggested by the BEIR Committee [ 2 ] .

As a case in point, this paper will discuss ef forts f o r the prevention of re lease of tritium and krypton-85.

IAEA-SM-197 /14 287

Year

FIG.2 . Estimated world inventory of tritium in the atmosphere and in surface waters (taken from Ref. [ 3 ] ) .

3. PRODUCTION OF TRITIUM AND KRYPTON-85

3 .1 . Trit ium

Environmental tritium is produced naturally by cosmic rays and arti f ic ial ly as a result of thermonuclear explosive detonations and nuclear reactor operation. Figure 2, taken f r o m Ref. [ 3 ] , gives a breakdown of projected world-wide tritium accumulation resulting f r o m these sources . It may be noted that present environmental levels are due almost entirely to residual tritium f r o m atmospheric testing of thermonuclear explosives . Reactor produced tritium constitutes only a small fraction of the total at present and this level will not become substantial until the end of the century.

3 .2 . Krypton-8 5

As there is essentially no natural background of this nuclide, environ-mental levels are entirely due to man's activities (anthropic) [ 4 ] . Pro jected world-wide production and accumulation is given in Fig . 3 [ 5 ] . The p r e -dominant source of krypton-85 re lease is the nuclear fuel reprocess ing plant.

288 COHEN

YEAR

FIG.3. Projected world-wide production of krypton-85 to the year 2000.

TABLE I. SOURCE TERM ESTIMATES FOR 3H AND 8 5Kr PER UNIT OF POWER PRODUCTION

Estimated potential release

Application 3H 85Kr

( C i ) ( C i )

Fission powered reactors 1 f LWR 24 475

(per M W ( e ) - a ) a J LMFBR 35 430

Peaceful nuclear explosives f Fission 33 c 25

(per kt y i e l d ) b J I Fusion 2 x 104 0

Controlled thermonuclear reactors [ 1 8 ] 3 0

(per MW(e) • a)

a per megawatt (electrical) -year = 32 TJ. b 1 kt yield is defined as an energy release of 1012 gram-calories — 4 . 2 TJ. c Assumed upper l imit based on announced values from the Rio Blanco event [ 1 4 ] .

IAEA-SM-197 /14 289

TABLE II. EXPOSURE-DOSE DATA FOR WORLDWIDE TRITIUM AND KRYPTON-85

Tritium Krypton-85

Whole-body Whole-body Skin

Total worldwide population d o s e a / man • rem\

I Ci J 4 . 0 x 10 ' 4 1 .8 x 10"4 0.027

Maximum permissible dose ( r e m / a ) 0 . 5 0 . 5 3 . 0

Total worldwide population d ose (WBE) ^

I man*rem\

\ C i / 4 . 0 x 10"4 4 . 5 x 10" 3

Cost effectiveness guidel ine for release c o n t r o l 0

( $ / C i ) 0 . 1 1. 0

a Dose per curie released to biosphere, assuming a constant world population of 3 . 5 x 10®. b Whole -body equivalent. c Based on cost effectiveness guidel ine of $200 per man - r e m averted.

3 .3 . General

Table I gives source term estimates for both nuclides per unit of power production. Barring the unlikely possibility of a significant increase in the use of thermonuclear explosives, it would appear that production of krypton-85, on the basis of radioactivity measured in curies , will greatly exceed that of tritium.

4. EXPOSURE/DOSE RELATIONSHIP

The consequences of re lease of radioactivity to the environment may be c lassi f ied into two basic categories . The f irst is high-level local ef fects , whereby maximum permiss ib le concentrations [ 6] for individual exposure might be exceeded. The second is l ow- leve l widespread ef fects , whereby there is no danger of any single individual receiving a dose in excess of standards; however the total aggregate population dose summed to infinite time might be significant. In the cases of both tritium and krypton-85, the possibil it ies of re leases of the f i rst category are unlikely. This discussion will, therefore, concentrate on overall population dose e f fects .

4 . 1 . Trit ium

Trit ium released to the environment partitions itself between the atmosphere and hydrosphere. Dose effects are dependent on the relative exposure to these components. Since tritium is uniformly incorporated within body tissues, the dose to all organ systems is essentially uniform and only whole-body doses need be considered. Cohen and Higgins [ 7] per formed calculations based upon data of Jacobs [ 8 ] , indicating that the

290 COHEN

YEAR

FIG.4. World-wide dose effect due to accumulated nuclides.

overall population dose due to world-wide environmental tritium was 4 x 10'4 man • rem per curie released. F r o m this a cost -e f fect iveness guide of approximately US $0. 10 per curie for tritium release prevention was determined.

4 .2 . Krypton-8 5

Since environmental krypton-85 resides entirely in the atmosphere, determination of dose ef fects are somewhat more straight-forward than is the case with tritium. However, for exposure to krypton-85, the dose to the skin is a more serious consideration than is whole-body dose [9, 10] . Cohen and Peters on [ 11 ] calculated that atmospheric krypton-85 release would cause world-wide population doses of 1. 8 x 10 ' 4 man* r e m / C i whole-body dose and 0.02 7 man* r e m / C i skin dose. To compare the seriousness of skin dose with that of whole-body dose the Whole-Body Equivalent (WBE) concept is used. This is roughly based on the ratio (a factor of 6) between the ICRP [6 ] maximum permiss ib le dose (MPD) cr iter ia f o r whole-body and skin. This implies that approximately equivalent damage is done to an individual by exposure to MPD levels of either 0. 5 r e m / a to the whole body or 3 .0 r e m / a to the skin. Using this ' f a c t o r - o f - s i x ' , the dose conversion factor for whole-body equivalent (WBE) dose due to atmospheric krypton-85

I A E A - S M - 1 9 7 /14 291

10"J -i

10-*-

2 10'7 -

1 0 " B -

10"

^ — TOTAL TRITIUM /

/

/ /

s

NATURAL TRITIUM —

1970 1980 1990

YEAR

2000

F I G . 5 . W h o l e - b o d y dose f r o m biospheric a c c u m u l a t i o n .

is 4. 5 x 10"3 m a n - r e m / C i . F r o m this figure a cost -e f fec t iveness guideline can be estimated to be $ 1. 00 per curie for krypton-85 release prevention.

A summary of pertinent exposure-dose relationships on tritium and krypton-85 is given in Table II.

PREDICTED DOSE EFFECTS

Based on predicted environmental levels f r o m nuclear power reactors f o r both nuclides, the dose rate (in r em/a ) is shown in Fig . 4. The total combined effect is essentially the same as the krypton-85 WBE curve. By the year 2000, this value is expected to reach approximately 0. 1 man - r e m / a , o r about 0.1% of the total radiation background. It is assumed that in this period nuclear explosives and controlled thermonuclear fusion will not make a significant contribution and that nuclear power reactors will be the p r e -dominant source .

Population dose ef fects are summarized in Fig . 5 for all sources , both natural and anthropic. It can be seen that in the case of tritium the dose effects will be almost entirely due to natural sources and the residual tritium f r o m atmospheric explosive testing. Reactor-produced tritium will constitute

292 COHEN

FIG. 6 . Number of publications on health implications of tritium and krypton-85 exposure based on references in Nuclear Science Abstracts.

only a small fraction of the total. Since man will have no control over either the natural or the residual tritium levels , any ef fort to minimize tritium exposure would have to be aimed at reducing tritium effluent resulting f r o m nuclear power production activities, pr imari ly nuclear fuel reprocess ing .

Since environmental krypton-85 is entirely anthropic, proper control measures to minimize its re lease might produce substantially lower future population dose levels due to this nuclide over the next several decades.

IAEA-SM-197 /14 293

6. A REVIEW OF SOME PRACTICES

In the light of this information, it is interesting to review some past pract ices - both in control measures and research relating to krypton-85 and tritium. Figure 6 compares the numbers of technical publications related to the health implications of population exposure due to tritium and krypton-85 as a measure of the research ef fort invested on each. It can be seen that the preponderance of the work has been done to tritium. F r o m these data, one might suspect that the relative attention, work and concern regarding these nuclides has not been commensurate with the relative seriousness of their environmental ef fects and that perhaps there has been undue concern over tritium, and/or indifference toward krypton-85.

Certain pract ices evident in the nuclear industry and in government tend to conf irm this suspicion. To cite a few examples: A. Proposed United States of Amer i ca " . . . numerical guides for design

and objectives and limiting conditions for operation to meet the cr iterion f or 'as low as pract icable ' f o r l ight-water reactor effluents. . . " would require liquid wastes to have a tritium concentration approximately three orders of magnitude below MPC standards pr ior to dilution in a natural body of water [ 12, 13 ] .

B. At the Rio Blanco experiment f o r nuclear gas stimulation in Colorado, the tritium release control cost ef fect iveness was in excess of $ 100 000 per man • rem of exposure averted [14, 15] .

C. At the Savannah River Plant, the cost ef fect iveness of tritium release control measures exceeds $67 000 per man • rem of exposure averted [ 1 6 ] ,

D. At the Mound Laboratory, the programme for tritium emission control has as its goal to 'approach z e r o emission ' [ 1 7 ] . The extent to which economics is considered in such a programme is uncertain; however, at the lower portion of the cost -e f fec t iveness curve (Fig. 1), marginal costs become very high. On the other hand, at fuel reprocess ing plants, the major source of

krypton-85 release , it has been estimated that krypton-85 re lease control could be accomplished at a cost of about 4 cents per curie or $ 10 per man • rem averted [ 1 1 ] . Implementation of such controls is not at present required.

7. DISCUSSION

F r o m the information presented it would appear that perhaps undue emphasis has been placed on control of tritium re leases to the environment while krypton-85 control may not have been receiving the attention it warrants.

T o understand how such a situation might evolve is difficult since it has most probably resulted f r o m the interaction of several intrinsic as well as extrinsic factors . One explanation might lie in the fact that the ratio of level of detectability to that of the hazard is much higher in the case of tritium. One may hypothesize that the ability to measure minute quantities of a hazardous material in the environment can significantly contribute to the degree of concern over its presence . There sometimes appears to be a tendency on the part of many to equate detectability with hazard. F o r example, it may be noted f r o m Fig . 6 that a marked increase in the publica-tions dealing with research on tritium occured in the early 1960s. Although

294 COHEN

there were doubtless many factors contributing to this increase , the wide-spread application of liquid scintillation analysis for tritium, a relatively l ow- cos t high-sensitivity method, may have been a major contributory factor . The desire of scientists to utilize this rather elegant research tool may have encouraged a proliferation of research on tritium. Noting this proliferation, policy administrators and the public may have inferred that it ref lected an increasing concern on the part of the scientif ic community over the hazard of environmental tritium. This, in turn, stimulated the sponsor -ship of further research and further concern resulting in a self-perpetuating phenomenon having little regard for the actual severity of the environmental problem.

A similar phenomenon may have been observed in the last decade with the introduction of atomic absorbtion analysis and mass spectroscopy, which allowed for the relatively simple detection of extremely low levels of environmental mercury . Widespread application of such analytical techniques may have contributed significantly to excess ive concern over this pollutant.

At this time the 'detectabi l i ty-awareness-concern ' hypothesis is conjectural, but it certainly merits further investigation.

8. CONCLUSION

Evidence has been presented indicating that predicted environmental levels of krypton-85 resulting f rom the growth of the nuclear power industry may pose a more serious health problem than will predicted tritium levels . Despite this, significantly more effort and expense has been directed toward technology f o r tritium control.

A hypothesis has been advanced postulating that the availability of equipment for detection of extremely low levels of environmental tritium may have contributed to this misallocation of priorit ies .

Application of cost/benefit analysis could perhaps result in more efficient allocation of resources .

R E F E R E N C E S

[ 1 ] COHEN, J .J . , On determining the cost of radiation exposure to populations for purposes of cost -benef i t analysis, Health Phys. 25 (1973) 527.

[ 2 ] NATIONAL ACADEMY OF SCIENCES, USA, The Effects on Populations of Exposure to Low Levels of Ionizing Radiation, Report of Advisory Committee on the Biological Effects of Ionizing Radiation, US National Academy of Sciences, Washington, D C (1972) .

[ 3 ] UNITED STATES ENVIRONMENTAL PROTECTION AGENCY, Estimates of Ionizing Radiation Doses in the United States ( o f Amer i ca ) , USEPA, Rockvil le , Md. (1972) .

[ 4 ] KIRK, W . P . , Krypton-85: A Review of the Literature and an Analysis of Radiation Hazards, USEPA O f f i c e of Monitoring and Research (1972) .

[ 5 ] OAK RIDGE NATIONAL LABORATORY, Siting of Fuel Reprocessing Plants and Waste Management Facilities, Rep. ORNL-4451 (1970) .

[ 6 ] 1CRP, Recommendations of the International Commission on Radiological Protection, ICRP Publication 9, Pergamon Press, London(1966) .

[ 7 ] COHEN, J .J . , HIGGINS, G . H . , The Soc i o -Economic Impact of Low-Level Tritium Releases to the Environment, University of California Rep. UCRL-73182 (1972) .

[ 8 ] JACOBS, D . G . , Sources of Tritium and its Behaviour upon Release to the Environment, USAEC Rep. TID-24635 , USAEC Crit ical Review Series (1968) .

IAEA-SM-197 /14 295

[ 9 ] DUNSTER, H . J . , WARNER, B . F . , Disposal of Noble Gas Fission Products from the Reprocessing of Nuclear Fuel, UKAEA Rep. AHSB(RP)R-101 (1970) .

[ 1 0 ] SOLDAT, K . J . , BRAMSON, P . E . , PARKER, H . M . , The Dosimetry of the Radioactive Noble Gases, Battelle Pac i f i c Northwest Rep. BNWL-4813 (1973) .

[ 1 1 ] COHEN, J .J . , PETERSON, K . R . , Considerations in Siting Long-Term Radioactive Noble Gas Storage Facil ities, University of California Rep. UCRL-75234 (1973) .

[ 1 2 ] UNITED STATES ATOMIC ENERGY COMMISSION, Proposed Amendments to 10 Code of Federal Regulation (CFR) Part 50, Fed. Reg. 36 : 111, 9 June 1971.

[ 1 3 ] HULL, A . P . , Reactor effluents: As low as practicable or as low as reasonable?, Power ( N o v . 1972). [ 1 4 ] UNITED STATES ATOMIC ENERGY COMMISSION, Rio Blanco Gas Stimulation Project: Environmental

Statement, USAEC Rep. WASH-1519, (Jan. 1972). [ 1 5 ] TOMAN, J . , private communicat ion to author, 1973. [ 1 6 ] JACOBSEN, W . R . , "Trit ium effluent reduction programs at the Savannah River Plant", paper at USAEC

Pollution Control Conference , Oak Ridge, Tenn. Oct. 1972. [ 1 7 ] KERSHNER, C . J . , BIX EL, J . C . , "Trit ium Effluent Control Laboratory", presented at 13th Air Cleaning

Conference , San Francisco, C a l i f . , August, 1974. [ 1 8 ] KULCINSKI, G . L . , Fusion Power - An Assessment of its Potential Impact in the USA, Energy Policy

(Jun. 1974).

D I S C U S S I O N

D. LARRE: The methods of economic analysis described by you seem to apply to the biological ef fects of other f o rms of contamination than just radioactive materials . Is there any similar work on chemically toxic substances, f o r instance?

A further question I have is, how would the problem of the combined ef fects of several contaminants be dealt with in your methodology?

J. J. COHEN: Ef forts towards systematic economic analysis of environmental re lease prevention are, of course , still in their very early stages where the pr imary work concerns the development of methodology for performing such analyses. I selected tritium and krypton-85 for analysis in this paper simply because their environmental ef fects could be predicted with minimum equivocation. Other radionuclides would have been far more difficult to evaluate, since various release mechanisms and biological pathways would have had to be considered in detail and the results would have been based to a large extent on assumptions.

In the case of chemical pollutants, such problems are much more complicated, since we do not know their environmental ef fects as well as we do in the case of radioactivity. Nonetheless, I certainly would agree that comparable analyses on chemically toxic pollutants should be made. Such evaluations would be at least as important as those for radioactivity, since chemical pollutants probably pose a more serious environmental threat.

In addition to our joint IAEA/IIASA project , there are at least two programmes in the USA relating to such activities under the sponsorship of the US Energy Research and Development Agency (USERDA). The results have been published.1

In answer to your second question, I would say that because of the diff iculties I have just discussed regarding evaluation of individual pollutants, little, if any, ef fort has gone into economic analysis of possible combined or synergistic e f fects . We must learn to walk before we can run.

1 USERDA report WASH-1224 (1975) .

296 COHEN

C. STREFFER: I agree with a number of your concluding statements.' However, with respect to tritium released f r o m the nuclear industry, including research laboratories , we have to consider local concentrations, participation of tritium in metabolism, and biological hal f - l ives . With respect to the number of publications you re fer to in your Fig . 6, we have to realize that tritium is one of the most frequently used radionuclides in research , including medical research, where it is usually found in organic compounds which can be taken up by the organism; hence the risk to persons occupationally exposed to it might also be of interest.

J. J. COHEN: Let me discuss the points you raise in reverse order . F irs t , I realize that tritium is very valuable as a tracer and has found widespread application in medical work. Publications on such applications, however, were not considered in our summary of publications; only those pertaining to the health implications of environmental exposure were included. Of course , it is difficult to determine whether the study on health effects is motivated by concern for occupational or environmental exposure, so judge-ment had to be exerc ised in several cases . I do believe, however, that the summary given in Fig . 6, although it may not be prec i se , does provide a reasonable index of the relative level of concern regarding environmental tritium and krypton-85.

With regard to the special metabolic and biological half - l i fe ef fects of tritium, I cannot really comment, since I am not well versed in radiation biology. We merely assumed that the ICRP took all such factors into consideration in determining a suitable maximum permiss ib le concentration (MPC) for tritium. We used this MPC in deriving our concentration-to-dose conversion factor . If the ICRP values are in error , then, of course , our conversion factor would have to be altered accordingly.

My statement that possible high-level local ef fects were highly unlikely, and therefore of little concern, may sound somewhat off-hand, but it has a basis . If you take a nuclear installation releasing tritium to the atmosphere then, f o r example, assuming a dose conversion factor of 106 ( R - m 3 / C i - a ) and a reasonable average diffusion factor (x/Q) of 1CT6 s / m 3 between the source and an offsite receptor , the installation would have to re lease more than 107 Ci of tritium per year in order to cause an offsite exposure of 500 m R / a . I believe re leases of this magnitude are at best improbable, particularly at nuclear reactors which produce a total of only ~ 2 5 kCi per 1000 MW(e) /a .

Finally, your comment on tritiated organic compounds is well taken, since their ef fects are indeed far more serious than those of HTO or HT gas. But since such organic compounds do not exist in man's general environment, they are not relevant to a discussion on environmental e f fects . They should be considered as a special case of occupational exposure. Perhaps a special MPC value for occupational exposure to tritiated thymidine and similar compounds would be a good idea.

Y. J. SOUSSELIER: One of the reasons why the problem of tritium is so much more studied is that it ar ises at many more sites, for instance, reactor plants, where 5-10%, or even as much as 20%, is released, as opposed to 1% krypton-85 at the same site. It would be more difficult to build a reactor with a n e a r - z e r o release because of the tritium rather than the krypton.

Another reason is that the problem of krypton retention has been virtually solved. In France , for instance, we have developed a procedure

IAEA-SM-197 /14 297

which could be applied immediately, if necessary . Trit ium elimination techniques, on the other hand, are less developed, especial ly as it is so difficult to concentrate it in an effluent of small volume.

J . J . COHEN: I would certainly agree with you that prevention of tritium release poses a far more difficult problem than does that of krypton-85. However, this fact, in itself, would justify a high level research ef fort only if the need for preventing tritium release were f i rs t established. I have seen no convincing evidence that tritium could pose a significant environmental problem under any reasonable conditions — and that is the point I have tried to bring out.

Another point I wish to make is that the concept of ' z e ro re lease ' or ' n e a r - z e r o re lease ' is economical ly absurd and I doubt if such a policy was the intent of ICRP in their " low as pract icable" guidance. In my opinion, too much money has already been squandered in pursuit of this aim. This is money which could have been spent far more beneficially in other areas of health and safety.

I would also agree that the technology for economic prevention of 85 Kr re lease is now available, and I regret the fact that this technology is not being implemented. Where it is demonstrable that controls can be applied at an acceptably low cost per man- rem of exposure averted, I would think that this fact, in itself , would provide sufficient justification f or their implementation regardless of "standards" or "background radiation l eve l s " . I believe this approach would be more in keeping with the " low as practicable" guidance.

F . GERA: Your Table I shows the predicted release rate of 3H f r o m nuclear reactors to be about one tenth of the f igure for f iss ion powered reactors on a per MW(e) /y basis . Could you describe the assumptions on which this estimate is based?

J. J. COHEN: The figure of 3. 0 Ci /MW(e) • a for tritium release f r o m controlled thermonuclear reactors (CTR) is based upon data contained in Ref . [ 18] of mypaper . I do not know the assumptions underlying these estimates.

H. G. EDELHAUSER: You have talked about the classif ication of radia-tion ef fects into 'high-level local e f fects ' and ' low- level widespread e f fects ' , and pointed out that there is often no optimal limitation of discharge rates with respect to cos t -e f fec t iveness analysis.

It strikes me that this results f r o m the fact that in most countries environmental protection is based on legislation, guidelines or recommenda-tions — which only consider local e f fects . Even in the USA the relatively recent Appendix I to 10 CFR 50, which stipulates cost -e f fec t iveness analysis f o r limitation of radioactive discharges, only requires integration of col lect ive doses up to a distance of 50 miles f r o m the plant. Perhaps an international organization, such as the IAEA, could recommend a discharge limitation for the long- l ived nuclides you talked about that result in an exposure to the global population. What would you propose f or such a guideline?

J . J . COHEN: Thank you for that question. It gives me the opportunity to express a personal opinion I have long held. I do not agree with the pract ice of considering dose ef fects only outside some arbitrari ly determined distance f r o m the source , such as the 50-mile l imit. The reason should be apparent f r o m today's discussions, in which it has been brought out that the largest population doses f r o m krypton-85, f o r example, occurred to the

298 COHEN

largest population groups regardless of their geographic location or that of the source of re lease . I would recommend, therefore, that all population dose ef fects be considered primari ly on a global basis .

It might also be of interest to note that the new Appendix I to which you re f e r recommends a cost -e f fect iveness guideline of $ 1000/man • rem. This f igure di f fers by a factor of 5 f r o m that suggested in this paper. I don't think it would change the conclusions material ly , but if one wishes to do so, the , ef fective values given in this paper could easily be altered to conf irm with the USNRC suggestion.

I A E A - S M - 1 9 7 / 1 7

THE EFFECT OF TEMPERATURE ON THE BEHAVIOUR OF MARINE FISHES* A comparison among Atlantic mackerel , Scomber scombrus, bluefish, Pomatomus saltatrix, and tautog, Tautoga onitis

B.L. OLLA, A. L. STUDHOLME, A . J . BEJDA, C. SAMET, A . D . MARTIN National Marine Fisheries Service, United States Department o f Commerce , Sandy Hook Laboratory, Highlands, New Jersey United States of America

Abstract

THE EFFECT OF TEMPERATURE ON THE BEHAVIOUR OF MARINE FISHES: A COMPARISON AMONG ATLANTIC MACKEREL, Scomber scombrus, BLUEFISH, Pomatomus saltatrix, AND TAUTOG, Tautoga onitis.

A comparison was m a d e o f the behavioural responses to temperature o f Atlantic mackerel , Scomber scombrus, bluefish, Pomatomus saltatrix, and tautog, Tautoga onitis, held under controlled laboratory conditions. When the temperature was either raised or lowered from normal levels , juvenile and adult bluefish and adult Atlantic mackere l , all pe lag i c species, responded similarly by increasing swimming speed as much as 61-190%. This response was interpreted as a manifestation o f behavioural avoidance o f a particular leve l o f temperature, indicative o f capabi l i ty for directive movements relative to ambient thermal conditions. Comparing the response o f pe lag i c species to earlier work on tautog, a demersal species, it was clear that avoidance capabil i ty is dependent upon the behavioural repertoire o f the individual species. The s igni f icance o f the results, regarding distribution o f fish and response potential under thermal stress, is discussed.

INTRODUCTION

A small but significant number of marine ecosystems are being increas-ingly subjected to abnormally high temperatures resulting from the heated effluents of electrical generating plants. Since there is limited understand-ing of the influence of normal levels of temperature on the life habits of marine organisms, it is not surprising that so little is known about the ef-fects of abnormally high thermal levels. The aim of this work was to explore the role of various temperatures on selected behaviors of several marine fish species.

While certain physiological and biochemical responses to temperature may transcend species lines, the external manifestation of these responses, i.e., how the animal may act when confronted with a potentially lethal or stressful thermal regime, cannot he generalized. Aside from temperature which may cause almost immediate debilitation or death because of the level or rate of change, the way in which the animal will respond will depend upon its behav-ioral capabilities or what might be termed its scope of behavioral responsive-ness. Defining and understanding the behavior of the animal, first under

* This work was supported in part b y a grant from the USAEC, No. AT ( 4 9 - 7 ) 3 0 4 5 .

299

300 JONES et al .

normal conditions and then, when subjected to potentially stressful condi-tions, is the approach we have adopted for providing at least one aspect for predicting survival potential.

We have integrated published data with previously unpublished mater-ial and compared behavioral responses in adult Atlantic mackerel, Scomber scombrus, adult and juvenile bluefish, Pomatomus saltatrix, and young tautog, Tautoga onitis. From these studies we have drawn certain conclusions, in some cases tentatively, as to the response capabilities of these animals when subjected to thermal stress.

MATERIALS AND METHODS

Juvenile bluefish

Juvenile bluefish, 14.0-27.0 cm TL, were captured by seine nets in Sandy Hook Bay, New Jersey. Following acclimation periods of 10-40 days at temperatures ranging from 19.5-23.5°C, and a photoperiod of 14.5 h, we subjected 4 groups of 4 fish each to a rise in temperature.

The experiments were conducted in an elliptical fiberglass aquarium, 1.78 x 1.22 x 0.86 m with a volume of 1.4 kl. In this system, temperature was raised by thermostatically-controlled immersion heaters located in an external filter box. Water quality was maintained by filtration through sand, gravel and oyster shell. The fish were fed pieces of clam once each day until satiated during both acclimation and test periods.

Activity was measured on the hour by taking 5 stopwatch readings of the time for the leading fish of the group to swim 65 cm (cm/s), with the median of the readings used for analysis. In one experiment, readings were made each hour for 48 h preceding the temperature rise. In the other 3. experiments, hourly readings were made as follows: 48 h preceding the rise from 0800-1500 and from 2000-0300; 24 h preceding the rise from 0800-1500 and continually beginning 2000 until completion of each test. At light onset of the day of the rise (about 0423) the temperature was raised from 20.0 1 0.7°C at a mean rate of 1.38°C/h until 2 of 4 fish in each test lost equilibrium.

Atlantic mackerel

Studies were conducted on 6 separate groups (8-14 fish/group) of adult Atlantic mackerel, with mean total length and weight for each group ranging from 35-40 cm and 385-623 g, respectively. All fish were captured by hook and line at temperatures ranging from 7.5-10.8°C during the northerly spring or southerly fall migration off the coast of Sandy Hook, New Jersey.

The experiments were conducted in a large 121-kl aquarium located in a temperature-controlled room in which natural diurnal changes in light intensity were simulated • Water temperature was controlled primarily by room temperature, although for the low temperature experiment, a thermal ex-changer and associated refrigeration unit were utilized. The aquarium was operated as a semi-closed system, with water quality maintained primarily by filtration through sand and gravel. Salinity ranged from 21-25 °/oo; oxygen from 6.2-8.7 ppm; pH from 7.2-7.8. Photoperiods were held at 15.3 + 0.2 h for Studies I and II; at 10.6 ! 0.2 h for Studies III through VI. Initial acclimation temperatures for each group are presented in Table I.

Measurements of swimming speed consisted of 5 successive stopwatch readings made hourly of the time taken for the lead fish in the school to swim a distance of 335 cm (cm/s) with the median of each set of measurements used for analysis. Activity measurements were begun during acclimation, 8-22 days prior to a change in temperature, which was initiated in each case after the fish had achieved stability as reflected in activity and feeding.

I A E A - S M - 1 9 7 /14 301

T A B L E I . S U M M A R Y OF E X P E R I M E N T A L C O N D I T I O N S F O R A T L A N T I C M A C K E R E L S T U D I E S R E L A T E D T O

T E M P E R A T U R E - S W I M M I N G S P E E D M E A S U R E M E N T S

Study No. days at prior temp

+/- Temp A mean rat;e/h

( ° c )

Mean holding temp

( ° C ) Days used for

activity measurements * following acclimation or ^ '

I Initial acclimation - 13.3 9 - 1 3

II Initial acclimation 7.9 37 - 4 1

III Initial acclimation _ 12.8 20 - 24 24 +0.02 15.8 12 - 16 19 +0.02 17.9 12 - 16 31 +0.02 19.9 12 - 16 16 +0.02 21.9 12 - 16

IV Initial acclimation _ 18.6 - 19.6 104 - 108 108 +0.02 21.6 7 - 1 1 11 +0.02 23.6 12 - 16

V Initial acclimation _ 1 1 . 0 42 - 46 46 -0.02 7.3 7 - 1 1 11 +0.02 10.8 12 - 16 24 +0.02 14.8 12 - 16

VI Initial acclimation _ 12.8 43 - 46 47 +0.09 15.8 12 - 16 35 -0.10 12 . 8 12 - 16 19 +0.09 15.8 12 - 16

Mean day and night swimming speeds for each 5-day period are plotted in Fig. 3.

In Studies I, III, IV and V, readings were taken each hour (24 h/d); in Studies II and VI readings were made in separate 8-h periods each day, from 0800-1500 during the light period, at light levels ranging from 1 000-3 000 lux, and from 2000-0300 during the dark period at 0.5 lux. Estimates of day-night swimming speed were derived by using the mean of the 8 highest consecutive readings from light onset to offset and the mean of the 8 lowest consecutive readings from light offset to onset for all studies.

The fish were fed live grass shrimp, Palaemonetes vulgaris, every 5th day with shrimp introduced 20 at a time in all Studies (with the exception of I and III) until the fish reduced ingestion to 20-30% of the amount intro-duced.

In one study (Study I) the temperature rose over a 37-day period until 4 of the group of 8 fish had lost equilibrium. Beginning at an acclimation temperature of 13.3°C, the temperature was raised (mean rate 0.02°C/h) over 4-day periods, with one day between periods in which the temperature was held constant and the-fish fed. In another study (Study II) the temperature was gradually lowered over an 8-day period from the initial acclimation level of 7.9°C (mean rate 0.03°C/h) until 8 of the group of 13 lost equilibrium.

In the remaining studies, III through VI, data were gathered on swimming speeds at various temperatures. Following initial acclimation periods of 24-108 days, at temperatures ranging from 11.0-19.6°C, the temperature was changed in steps of 2-4°C (mean rates ranged from 0.02-0.10°C/h) and held at a constant level until swimming speeds stabilized, reflective of activity at the particular temperature. Successive step changes for these studies are summarized in Table I. Although activity measurements were made con-tinually in each study, to reflect the relation between temperature and activity, mean swimming speeds were averaged either for the last 5 days of each initial acclimation period (i.e., following capture) or for days 12-16 after a new temperature was reached following a step change. In the two instances where the fish were held only 11 days following a step change, speeds were averaged for days 7-11. Irt Studies I and II, only initial acclimation periods are included in Table I.

302 JONES et al.

TEMPERATURE (°C)

FIG. 1. Mean swimming speeds o f four groups o f juvenile bluefish plotted at 2°C intervals during temperature rise.

RESULTS AND DISCUSSION

Juvenile bluefish increased swimming speed significantly (P<_0.05, Runs Test) as the temperature rose above 27°C, approximately 7°C above initial starting temperature. Swimming speed continued to increase reaching maxi-mum levels at about 32-33°C (Fig. 1). Loss of equilibrium occurred between 34.5-35.6°C for 8 of the 16 fish tested.

In a previous study adult bluefish increased swimming speed at sim-ilar temperature levels even though the rate of rise was much more gradual (0.021°C/h). While maximum speeds were attained at 29.8-30.4°C for adults, juveniles reached maximum levels at slightly higher temperatures. The re-sults reflect the fact that the juveniles respond in a similar fashion to the adults (Fig. 2), possessing what we interpret to be a similar capabil-ity for temperature avoidance (see below for further discussion).

A series of swimming speed measurements were made both day and night on 6 different groups of Atlantic mackerel at temperatures ranging from 7.3-23.6°C (Table I). ,The fish swam continually day and night at all temper-atures, with speed higher during the day. Based on 18 mean nighttime speeds, a count of runs above and below the median indicates a positive correlation between speed and temperature (P <0.01; Runs Test; Fig. 3). A similar cor-relation exists during daytime (Fig. 3). Since, with only two exceptions (7.9°C and 13.3°C), all speeds were measured at photoperiods <11.0 h, it may be presumed that any photoperiod effect has been negated and that the speeds are attributable primarily to temperature.

When a group of mackerel was subjected to a continual rise in tempera-ture from an initial acclimation level of 13.3°C, both day and night speeds increased significantly (P<0.01; Runs Test; Fig. 4B). As the temperature rose above 14-15°C, daytime swimming speed began to increase (approximately

I A E A - S M - 1 9 7 / 9 303

100

60

40

20

PELAGIC FISH M E A N S W I M M I N G SPEED ( C M / S )

DEMERSAL FISH MEAN DAYTIME ACTIV ITY(%)

ADULT

BLUEFISH

ADULT

TAUTOG YOUNG TAUTOG

FIG.2. Comparison o f activity at normal and stress temperature for adult Atlantic mackere l , adult and juvenile bluefish, and adult and young tautog. (Adult bluefish data as modi f ied from Olla and Studholme [ 2 ] young tautog data as modi f ied from Olla and Studholme [ 1 3 ] ).

1.7 cm/s per day) over a 16-18 day period with the fish reaching a mean day speed of 64.1 cm/s at 20.6°C. Speeds at night increased more gradually (0.37 cm/s per day) during the initial 11 nights after the temperature began to rise. At 18-19°C, speeds at night began to increase consistently, rising at a rate of about 2.7 cm/s per day until the fish reached a peak night speed of 61.4 cm/s at 22.5°C. The difference in swimming speed between day and night increased significantly (P<_0.01; Runs Test) after the temperature reached 16°C, reflecting the faster rise in day speeds. These differences appeared to lessen as the temperature rose from 21°C to 24°C. As the tem-perature increased to 28.6°C, the mean speed of the fish appeared to make an oscillatory approach to a saturation level of activity (about 58 cm/s during the day; 50 cm/s at night). This oscillation tended to mask any con-sistent differences in day-night activity but it would appear that this dif-ference is quite small. These speeds represent activity increases of 57% and 68% for day and night, respectively, above speeds at initial acclimation. Evidently these were the fastest speeds the animals could swim over a pro-longed period at these high, stressful temperatures. By the time the temper-ature reached 28.6°C, 4 of the animals had died.

Another group of Atlantic mackerel was subjected to gradually decreas-ing temperature from an initial acclimation level of 7.9°C (Fig. 4B). Com-parison of the mean day activity during the temperature decrease with that preceding the decrease indicated a significant increase in swimming speed (P<_0.01; Runs Test). A similar increase was observed at night. Peak day speed (x = 55.0 cm/s) was reached at about 3.0°C; peak night speed (x = 50 cm/s) at 1.9°C. Comparison of mean activity recorded at 7.9°C with speeds between 2.7-1.9°C showed day speeds had increased 47%; night speeds,

3 0 4 JONES et al.

FIG.3, Mean day (•) and night (•) swimming speeds o f adult Atlantic mackerel measured over 5 -day periods at temperatures from 7 . 3 to 23. 6°C.

80%. Day-night differences increased significantly (P-£0.05; Runs Test) as the temperature began to drop below 7.9 C but then decreased significant-ly (P<0.05; Runs Test) below 3.0°C, as the fish swam at high speed both day and night. At 1.9°C there was a reversal of the rhythm with night speeds greater than day speeds. At this level 8 of the fish had died.

The difference in peak speeds attained at high and low temperatures may be due to lower activity during acclimation at 7.9°C in the low temper-ature test. Although both groups of fish were caught during spring migra-tion at a similar photoperiod, higher acclimation temperature (13.3°C) than capture temperature (8.9°C) may have accounted for higher activity levels in the high temperature test.

The increase in swimming speed observed in Atlantic mackerel in re-sponse to either a rise or fall in temperature, and of juvenile bluefish to a rise, is similar to what was previously observed in adult bluefish to both a temperature rise and fall (Figs. 2, 4) (2). Since an increase in speed occurred when temperature was either raised or lowered, we interpret-ed the response to be, at least in part, a manifestation of avoidance be-havior to thermal regimes which departed significantly from preferred ranges. The fact that some fish species have the ability to regulate body temperature behaviorally bv the selection of water temperature been demonstrated both in situ v^) and under laboratory conditions (4,5,6).

Our conclusions about preferred temperature ranges agree to a large ex-tent with what is known about the distribution of adult Atlantic mackerel and adult bluefish with respect to temperature. Regarding Atlantic mackerel, Sette's ("^conclusion that temperatures of 7-8°C may form a barrier to both vertical and horizontal movements of these fish is supported by our labora-tory results. When temperature dropped below 6-7°C in our experiment, there

IAEA-SM-197 /14 305

TEMPERATURE(°C)

FIG. 4 . Activity recorded during low and high temperature experiments for (A) adult bluefish and (B) adult Atlantic mackerel . Points represent the high and low mean swimming speeds for 4 or 5 -day periods at the mean temperature for each period. Relation between activity and temperature is indicated by a median curve. (Bluefish data as modif ied from Olla and Studholme [ 2 ] ).

was a significant increase in swimming speed. The upper limit for distribu^ tion is not as clear, but from what is known, must be placed about 18-20°C with peak abundance of the species occurring at temperatures somewhere between these upper and lower limits. It would appear from our laboratory data, that the preferred range for Atlantic mackerel is between 7°C and 16°C which over-laps the optimal range of 12-14° cited by Dannevig (9) for Scomber scombrus in the eastern North Atlantic.

Regarding adult bluefish, a preliminary analysis comparing commercial catch with temperature showed peak abundance at about 18-22°C (Walford, un-published). Within this range of temperature, adult bluefish in the labora-tory showed lowest swimming speeds (speed values relative to the seasonal influence of photoperiod (ior. These temperatures are similar to those re-ported by Lund and Maltezos (11) when adult bluefish appear in inshore waters in mid-summer along the Middle Atlantic and New England coast. The authors also point out that the appearance of bluefish in these areas in the spring occurs between 12-15°C and departures in the fall at about 13-15°C which would not be very different from laboratory findings showing increased acti-vity as temperatures dropped below 15°C.

It is not so surprising that what was observed in the laboratory re-flected what has been generally accepted: that temperature plays an impor-tant role in the movement and distribution of certain species of fish. The extent of the relation between temperature and movements is dependent upon the specific environmental requirements of the individual species (see below for further discussion).

306 JONES et al.

Negating the advantage of capability to choose a thermal regime and thereby regulate body temperature, is the possibility of attraction to zones which may be potentially lethal for a variety of reasons.

In contrast to these pelagic species, are fish that are much more re-stricted in their movements. For example, the tautog, an inshore demersal inhabitant of temperate waters of the western Atlantic, is tied to a parti-cular locus with a very limited home range for at least part of its life (12). This animal lives in close association with objects which provide cover, e.g., rocks, pilings and docks. While tautog of all ages spend the night quiescent in association with shelter, this association is most pronounced in young immature fish which spend their first 3-4 years within several meters of some shelter. From this, we hypothesized that these animals would be especially limited in their capability to respond to stress by moving away from such a zone. Subjecting young tautog to thermal stress in the laboratory, we found that the fish reduced activity (13) in con-trast with the responses of the pelagic species we had tested (Fig. 2).

Along with the reduction in activity, the fish also showed an increased association with shelter. While the pelagic species, not tied to a parti-cular place, moved in response to changing temperature and escaped stress by avoidance, the young tautog sought shelter, whether the stress was tem-perature or predation It appears that these shelter-oriented animals do not have within their behavioral repertoire the capability to regulate body temperature by moving when the ambient temperature changes even to the level of lethality.

In preliminary studies on adult tautog subjected to high, sublethal temperature, the fish also reduced activity (Fig. 2) although they did not increase their association with shelter (011a, unpublished).

Although our studies to date have concentrated on a small number of species, our results showing opposite responses to thermal stress support the view that it is most important to define, species by species, the basic behavioral repertoire of each as related to their particular environmental requirements. This is the first step in attempting to predict particular effects on animals that may, or may not, have the capability to avoid poten-tially lethal stresses. It is likely that other species of fish which show association with shelter, e.g., reef species, or even invertebrates with similar habits, e.g., American lobster, Homarus americanus, (Atema, pers. commun.) may be limited in their escape or avoidance capability. To test such animals for avoidance reactions in the laboratory when the require-ment of the animal in the natural situation is one in which avoidance would not be a part of its behavioral repertoire, does not seem reasonable.

ACKNOWLEDGEMENT

We express our grateful appreciation to E. B. Ferrell for his assis-tance in analysis of the data.

R E F E R E N C E S

(1) OLLA, B. L., MARCHIONI, W. W., KATZ, H. M., A large experimen-tal aquarium system for marine pelagic .'fishes, Trans. Am. Fish. Soc. 96 (1967) 143.

(2) OLLA, B. L., STUDHOLME, A. L., The effect of temperature on the activity of bluefish, Pomatomus saltatrix L., Biol. Bull. mar. biol. Lab., Woods Hole 141 (1971) 337.

(3) STEVENS, E. D., The evolution of endothermy, J. theor. Biol. 38 (1973) 597. —

IAEA-SM-197 /14 307

NEILL, W. H., MAGNUSON, J. J., Distributional ecology and behavior-al thermoregulation of fishes in relation to heated effluent from a power plant at Lake Monona, Wisconsin, Trans. Am. Fish. Soc. 103 (1974) 663. .;. ' ROZIN, P. N., MAYER, J., Thermal reinforcement and thermoregula-tory behavior in the goldfish, Carassius auratus, Science, N. Y. 134 (1961) 942. NEILL, W. H., MAGNUSON, J. J., CHIPMAN, G. G., Behavioral thermo-regulation by fishes: a new experimental approach, Science, N. Y. 176 (1972) 1443. SETTE, 0. E., Biology of the Atlantic mackerel (Scomber scombrus) of North America. II. Migrations and habits. Fishery Bull. Fish. Wildl. Serv. U. S. 51 (1950) 251. RECKSIEK, C. W., McCLEAVE, J. D., Distribution of pelagic fishes in Sheepscot River-Black River estuary, Wiscasset, Maine. Trans. Am. Fish. Soc. 102 (1973) 541. DANNEVIG, A., Mackerel and sea temperature. Measurements - 21 April to 15 May, 1952. Praktiske Fiskeforsjzfc, 1952, Arsber. Norges of Fisk. (1955): 64. Cited p. 21 in HELA, I., LAEVASTU, T., Fisheries Hydrography. Fishing News (Books) Ltd., London (1961). 0LLA, B. L., STUDH0LME, A. L., "Daily and seasonal rhythms of activ-ity in the bluefish (Pomatomus saltatrix)", Ch. 8, The Behavior of Marine Animals Vol. 2 (WINN, H. E., 0LLA, B. L., Eds.) Plenum, New York (1972) 303. LUND, W. A., Jr., MALTEZ0S, G. C., Movements and migrations of the bluefish, Pomatomus saltatrix, tagged in waters of New York and southern New England, Trans. Am. Fish. Soc. _99 (1970) 719. 0LLA, B. L., BEJDA, A. J., MARTIN, A. D., Daily activity, move-ments, feeding, and seasonal occurrence in the tautog, Tautoga onitis, Fishery Bull. U. S. 72 (1974) 27. 0LLA, B. L., STUDH0LME, A. L. The effect of temperature on the behavior of young tautog, Tautoga onitis (L.), in press in Proc. 9th Europ. mar. biol. Symp. (1975) 75.

D I S C U S S I O N

B. B ^ H L E : In Norway we have carried out experiments on behavioural thermoregulation with cod, using the same technique as W.H. Neill, w h o m you quoted in your presentation. In contrast to your results for mackerel, cod exhibited less activity when the temperature decreased. The questions I wish to ask are, first, could you comment on the relationship between the two terms 'avoidance temperature' and 'preferred temperature' . Second, the temperature increase in your experiments seems to be very slow. Could it be that the animals had time to adapt to the increased temperatures? And, third, do you think that an abundance of food in areas with unfavourable temperature could of itself extend the temperature range of the fish, more especially the mackerel?

B.L. O L L A : The word 'avoidance'in the strictest sense is perhaps more correct than 'preferred'. However, I personally see no problem with either word.

As regards the slow temperature increase, if you are referring to the pelagic species, they were probably adapting, except when the temperature deviated sufficiently from the acclimation point, i.e. the temperature at which they were under stress. In the case of the mackerel, this ultimately resulted in death at both the upper and lower thermal levels.

308 JONES et al.

Within a certain range of temperature abundance of food may play a role in distribution. But there are limits to this. I think transient movements into stress ful temperature regimes are highly likely when conditioned by the motivation to feed.

E. SMEDILE: The feeding rates of fish depend directly on their activity. Did you measure the feeding rates of the fish be fore , during and after the experiments ?

B .L . OLLA: Although I have not included feeding data as part of my presentation, we have made such measurements with each spec ies . In all cases there was a reduction of feeding under thermal s t ress .

O.J. VAN DER BORGHT: Would tautog exhibit the same behaviour habit of keeping to the same shelter when under high-temperature s tress in field conditions, or would they try to find other shelter? In other words , can your laboratory observations be extrapolated to field conditions?

B .L . OLLA: Our hypothesis on the c lose shelter association of young f ish, reducing their capability of avoiding s t ress , was based on the normal habits in their natural surroundings. The laboratory experiments carr ied out so far have confirmed this. There are many examples of species showing the same c lose relationship with shelter. Thus it is my opinion that in terms of behaviour one can extrapolate f rom laboratory to field conditions with a high degree of confidence.

E . - A . HAMPE: Did you carry out any experiments under other physical conditions? I am thinking more particularly of reduced atmospheric pressure above the water, which, like a r ise in temperature, also decreases the oxygen content of the water.

B .L . OLLA: At this point in our research I can only say that the water was saturated at each temperature studied. There is , of course , the possibility that the tautog may have been responding to a combination of oxygen and temperature s t ress .

M. NIETO GARCIA: If the acclimation temperature is increased, will the thermal limit for the f ish, as measured by their swimming speed, be higher '

B .L . OLLA: Our measurements fol low the c lass ic response described by other investigators, i .e . as the acclimation temperature r i s e s , the thermal limit increases . But this only o c curs , of course , up to a speci f ic point, beyond which the animal can no longer accl imate.

P.G. ROLLIN: Were the animals studied in any way exceptions f r o m the normal run of f ish? I ask this since in the case of other species a lower swimming speed is often taken as a sign of weakening, and, furthermore , it is often indicated that the fish are able to move about in search of more favourable temperatures.

B .L . OLLA: There are other species of f ish, for example, many of the cora l reef f ishes , which normally show a high degree of shelter association and are probably limited in their ability to leave an area when exposed to stress

J.O. BLANTON: Since the fish you have studied remain in the same habitat over long periods of t ime, what is their behaviour likely to be under conditions where the environmental temperature may complete a natural cyc le of , let us say, 10°C in a matter of hours?

B .L . OLLA: I imagine that if the temperature rose as much as that and attained levels which were stressful — I am thinking of transient short - term changes o f , say, the length of a tidal cyc le — the fish would probably swim into shelter until the temperature fell below the levels which originally induced the s t ress .

IAEA-SM-197 /17

CYCLING OF 55Fe AND 65Zn IN COLUMBIA RIVER CARP FOLLOWING REACTOR SHUTDOWN*

W.M. JONES, C.D. JENNINGS Oregon College of Education, Monmouth, Oregon

N.H. CUTSHALL Oregon State University Corvallis, Oregon United States of America

Abstract

CYCLING OF 55Fe AND 6 5Zn IN COLUMBIA RIVER CARP FOLLOWING REACTOR SHUTDOWN. The dec l ine o f 55Fe and 6 5Zn has been observed in the tissues of Columbia River carp fol lowing shutdown

o f the plutonium production reactors at Hanford, Washington. A mode l for the decrease in spec i f i c activity (activity per gram total e lement) is tested for carp flesh. The predictions o f the model are slightly higher than the speci f ic activities observed, probably because o f stable element dilution. Rate o f loss o f 6 5Zn appears to fol low the order skin > flesh > l iver, eggs > heart, whi le the rate o f loss o f 55Fe follows the order heart > eggs > flesh > l iver , underscoring the fact that each tissue may treat each element in a characteristic manner. Therefore the ability o f an organism to free itself o f radionuclide contamination wil l depend on what portion o f the organism and what radionuclide is involved.

Introduction

The Columbia River served as a source of coolant water for single pass plutonium production reactors at Hanford, Washington, from 1944 to 1971. Neutron activation of stable trace elements contained in the river water resulted in many radionuclides, including 5 5 F e and 6 5 Z n . The coolant water, following a brief holding time to allow for decay of shortlived radionuclides, was returned to the river resulting in concentrations of radio activity in the river ecosystem below Hanford [1] and in the Pacific Ocean off Oregon and Washington [2, 3, 4]. Since the shutdown of the last production reactor in January 1971, however, radio-activity in the Columbia River and adjacent Pacific Ocean has been declining. It is in this environment of declining radioactivity that our study of the cycling of " F e a n c| 652 n -jn -j.^ C Ommon carp, Cyprinius carpio, was undertaken.

In the absence of reactor effluents most of the radioactivity in the Colum-bia River system is found in bottom sediments and 5 5 F e and 5Zn make up most of the photon-emitting radioactivity. Robertson et^ al_. [1] reported 64 percent of the photon-emittipg radioactivity of the sediments to be from 5 5 F e and 14 per-cent to be from °5Zn with and 155[:Uj the o n ] y other major radionuclides, contributing 7 percent each. The radioactivity that enters the water column does so through resuspension of radioactive sediments or through desorption of radionuclides from sediments. The radioactivity was 70 to 90 percent in particulate form when the reactors were discharging effluent into the river and this tendency is enhanced now that reactor operation has ceased [1].

'•'Research supported by USAEC contracts A T ( 4 5 - 1 ) - 2 2 3 1 and A T ( 4 5 - l ) - 2 2 2 7 .

309

310 JONES et al .

FIG. 1. Geographical relationship o f the Columbia River to the Hanford Works.

Carp are well suited for studying the decline of radioactivity in the Columbia River because they live and feed in the sediments, the primary site of radioactivity. The diet of carp consists of up to 85 percent algae and detritus [5] which they get by rooting around in soft bottoms [6], sucking up mud and other materials from the bottom, ejecting it, and then selecting food when it is suspended in the water [7]. Small silt- and clay-sized particles contain a much greater concentration of radionuclides than do coarser particles [8], so carp ingest the most highly-radioactive material. Also, carp do not appear to migrate so that a series of samples from the same location should result in fish that reflect the changes in radioactivity at that location.

1. Sampling Program and Procedures

Carp collected for this study were taken from the reservoir behind McNary Dam, the first slack water downstream from Hanford (Figure 1) which contains the largest sediment deposits to have been contaminated by Hanford reactors. Collection began on July 17, 1970 and continued to May 18, 1973 with a total of seven samplings being made. After collection, the fish were placed in plas-tic bags and kept in a cooler with dry ice until they could be put into a freez-er. Methods of collection included beach seine, gill net, and bow and arrow.

Prior to dissection, the fish were thawed overnight, washed with deionized water, and weighed. Stainless steel surgical instruments were used for dissec-tion; new knife blades were used with each group. Separate samples of flesh and gonads were collected from each fish, while each of the remaining tissues samples was a composite of all the fish caught on the same day in order to have large enough samples for analysis.

IAEA-SM-197 /14 311

GROUND CONNECTOR

DETECTOR HIGH VOLTAGE WIRE

MYLAR WINDOW ,

ELECTRONIC SHIELD WIRE

GUARD HIGH VOLTAGE WIRES

PLEXIGLASS CASE HIGH VOLTAGE INSULATORS

FIG. 2. Anticoincidence-shielded gas-f low proportional counter.

Samples were dried, ashed and then analyzed for Zn on a gamma ray spec-trometer. The ashed samples were dissolved in 6 M hydrochloric acid; an aliquot was removed for stable element analysis and the remainder of the sample was used to measure

Iron-55 was measured by first extracting iron from the dissolved sample with 20% Alamine-336 in xylene, electroplating the iron by the method of Maletskos and Irvine [9], and counting the k x rays of the 5 5Mn daughter of S^Fe in an anticoincidence-shielded, gas-flow proportional counter (Figure 2). This method has been described in detail elsewhere [10].

Stable iron and zinc were measured by atomic absorption spectrophotometry.

2. A Model for Loss of Radioactivity

As a first estimate of the cycling of ^ F e and ^ Z n in carp, we considered that a carp in steady state would have its blood in isotopic equilibrium with the environment through contact with the intestine, the site of uptake and loss of radionuclides from the environment (see Figure 3). The exchange of radio-nuclide with each body tissue occurs by exchange from the blood and the change in activity with time is just the uptake rate less the excretion and decay rates.

If the specific activity (activity of radionuclide (pCi)/total amount of element g) of the source is changing, as was the case in this study, the equa-tion predicting radioactivity in carp can be found by first deriving an equa-tion for no uptake and then modifying the equation to account for uptake from a changing source. For the condition of no uptake the change in activity for a tissue would equal losses by excretion and physical decay or symbolically:

( 1 )

(2)

dAy + „ A

- fAy.o A A T j 0

= - t t + p ) A T f 0

312 JONES et al .

Intake

FIG. 3 . Proposed mode l for the uptake and loss o f a radionuclide from carp.

where Ay t = activity of tissue at time t, turnover constant, and X = decay constant giving

A T > t = A T ) 0 e - ( ^ + P )t, or (3)

in terms of specific activity

S r . f S t . o - H W 1 ( 4 )

To this specific activity we must add the increment of specific activity that the tissue will gain from uptake from an environment with declining activity.

Tissue Activity from Uptake

Original Source x Rate of radio-specific activity nuclide uptake

Biological Turnover

Physical decay Interaction of biological of radionuclide " and physical decay rates

Or symbolically:

AT,t = R S ^ 0 e" t - e - ^ + t (5) f

But since the concentration of stable element Cy = R/p,

S T j t = S s > 0 ( e - X t - e - ( X + * H ) (6 )

Adding equations (4) and (6) we have the specific activity of a tissue from an environment with declining activity:

S T,t = S s , o ( e - X t - e - < X + ? >t) + S T ) 0 e - ( W > t ( 7 )

IAEA-SM-197 /14 313

T A B L E I. CALCULATED FLESH SPECIFIC ACTIVITIES FROM PREDICTION MODEL

Ss,0

(pCi/g)

St,0

(pCi/g)

B i o l t l / 2

(days)

Elapsed

Time

(days)

Calculated

S t f t(pC1/g)

Observed

S t / t (pCi/g)

6 5 Z n

1.26X10 5 1.22X10 5 519 644 2.01X10 4 3.79X10 3

5 5 F e

1.50X10 5 1.50X10 5 516 644 9.37X10 3

5.39X10 3

In order to test whether the model can predict what actually happened in the ecosystem* the model was tested for carp flesh over a 644 day period and in the case of " Z n sediment specific activity was used as the source (sediments were assumed to be the source of radionuclides for carp). No information on the specific activity of ^ F e -jn sediments was available, but since the specific activity of was nearly the same in flesh and sediments, it was assumed that the similarity would hold for a s Well.

A comparison of the calculated and observed specific activities (Table I) shows that the predictions of the model are slightly higher than the observed specific activities, about two times higher for " F e a n c| f-jVe times higher for 6 5 Z n . It is not surprising that the predictions of the model are slightly high because no consideration is given to the addition of stable elements through sedimentation which has the effect of diluting the radionuclides. Nevertheless, the model predicts reasonably well the specific activities of carp flesh even though errors occur because of stable element dilution, difficulties in choosing time zero, and difficulty in estimating biological turnover rates.

Loss Rates of 6 5 Z n and 5 5 F e

Loss rates of Zn from flesh, eggs, liver, heart, and skin are recorded in Figure 4. The order of declining specific activities suggested is:

skin > flesh > liver, eggs > heart

However, the similarity in loss rates amongst the tissues is readily apparent and, indeed, when an "F" test was performed, no significant differences were 1

found for the loss rates (F = .6347, Fo y/jO*) = 4.04 at 95 percent confidence). Because of the lack of statistical differences amongst the loss rates of the individual tissues, a common loss rate was derived with an ecological half-life of 177 days.

Furthermore, since the ecological half-lives were not significantly dif-ferent from each other, a "t" test was performed to see if any of the tissue loss rates differed from the physical decay rate of Only flesh differed significantly (t=5.32, t,5(<*/2) = 3.59 at 99 percent confidence).

2 Small num-bers of samples and large variations in the activities of the samples may have masked significant differences for the other tissues.

1 F = calculated F-value; F^f (a) = tabulated F-value [ 1 1 ] ; df = degrees o f freedom. 2 t = calculated t-value; t^^ (a /2 ) = tabulated t -value , two-tailed [ 11] .

314 JONES et al .

0 500 1000

FIG. 4 . Loss rates o f 6 6Zn spec i f i c activity from several tissues o f carp in the Columbia River. The lines were fitted to the data b y least-squares analysis.

IAEA-SM-197 /19 315

104

104

I RANGE OF SPECIFIC A C T I V I T Y

0 500 1000 D A Y S

FIG. 5. Loss rates o f 55Fe spec i f i c activity from several tissues o f carp in the Columbia River. T h e lines were fitted to the data by least-squares analysis.

Although no differences were noted in the loss rates of Zp in individual tissues, differences were apparent for ^ F e . The loss rates of ^ F e from flesh, eggs, livers and hearts are recorded in Figure 5. The loss rates were shown to be different from each other in an "F" test (F=4.80, F 3 ) = 4.16 at 95 per-cent confidence). The data suggest the rate of decline'of " F e specific activities to follow the order:

heart > eggs >• flesh > liver

The suggested order seems logical if one assumes that the liver is a storage center for iron and that the heart (which had not been drained of blood) may be rich in blood which may contain up to 60 percent of the body's iron [12]. Since blood was assumed earlier to be in isotopic equilibrium with the environment,

316 JONES et al .

it is reasonable to assume that the blood would respond most rapidly to an en-vironmental change in radioactivity. The eggs would also tend to respond rapidly to an environmental change because they are produced yearly while the flesh is probably not renewed at that rate.

None of the tissues showed their ecological half-lives to be significantly different from the physical decay rate of 5 % e when subjected to a "t" test. Small numbers of samples and large variances may again have masked significant differences. However, if the lack of a difference is accepted, one might con-clude that the body either basically conserves and recycles iron or that the source of iron-55 was declining at the same rate as the tissues. Furthermore, there may be a storage pool, such as the liver where iron is stored but at any given time an atom of iron (stable or radioactive) may be transported to any given tissue of the body, dependent on the body needs at that moment [12, 13].

Conclusions

It is evident from this study that each tissue may treat each radionuclide apd, hence, each element, in a characteristic manner, i.e., the loss rate of ^ F e from carp hearts was faster than the other tissues while the loss rate of

from hearts appeared slowest (see Figures 4 and 5). Therefore the ability of an organism to free itself of radionuclide contamination will depend on what portion of the organism and what radionuclide is involved.

Statistical tests for significant differences in tissue ecological half-lives indicate that:

1) The loss rates of ^ F e do vary from one tissue to another. The fol-lowing order is suggested:

heart ^ eggs > flesh Oliver

The order seems reasonable when it is recalled that the hearts contained un-drained blood which reacts to ecological changes most rapidly (the body fluids being in isotopic equilibrium with the source of radioactivity). Eggs, being reproduced once a season, would also be expected to react rapidly. The liver, considered to be a storage center and not subject to removal or renewal as in the case of eggs, should have the longest turnover time.

2) Zinc-65, on the other hand, showed no statistically significant dif-ference in rates of loss between tissues. A trend, however, was suggested fol-lowing the order:

skin > flesh >• eggs-liver > heart

The suggested trend differs markedly from that of 5 5 F e which points up the fact that zinc's role as an enzyme activator allows it a different mode of body usage than iron, perhaps a more general mode. On the other hand, the nonsignificance of loss rates between the tissues may have been primarily due to small numbers of samples and large variations in the observed activities, and/or radionuclide uptake by tissues with rapid turnover may have caused their ecological half-lives to appear longer and approach the half-lives of those which would have picked up smaller amounts of the element.

The model developed in the study can be used as a tool for estimating tissue radioactivity in an environment of declining radioactivity. However, complicating factors, such as radionuclide dilution by stable element addition as in sedimentation and the history of the environmental contamination itself

IAEA-SM-197 /14 317

are known to influence its reliability. Furthermore, computation of biological half-lives are necessary for the working of the model. This is a real limita-tion because a no-uptake situation must be assumed in the face of knowledge that uptake from a declining environment, such as the carp/sediment relation-ship in the Columbia River, is probably a major factor in the amount of radionuclides present in the carp.

Finally, in spite of the movement of carp which present the possibility of sampling more than one population, the carp appear to be very useful in fresh water ecological studies of this type because of their size and ease of capture and abundance.

References

1. Robertson, D. E., W. B. Silker, J. C. Langford, M. R. Peterson and R. W. Perkins. 1972. Transport and depletion of radionuclides in the Columbia River. Proceedings of the IAEA Symposium on the Interaction of Radioactive Contaminants with Constituents of the Marine Environment, 1972. Seattle, Washington, pp. 141-155.

2. Osterberg, C. L., N. Cutshall, V. Johnson, J. Cronin, D. Jennings and L. Fredrick. 1966. Some non-biological aspects of Columbia River radioactiv-ity. Disposal of radioactivity wastes into seas, oceans, and surface waters. International Atomic Energy Agency (Vienna J. p. 321-325. RL0-1750-4).

3. Perkins, R. W., J. L. Nelson, and W. L. Haushild. 1966. Behavior and transport of radionuclides in the Columbia River between Hanford and Vancouver, Washington. Limnol. Oceanogr. 11(2)-.235-248.

4. Gross, M. G., C. Barnes, and G. Riel, 1965. Radioactivity of the Columbia River effluent, Science 3 1 0 0 8 .

5. Kevern, N. R. 1966. Feeding Rate of Carp Estimated by a Radioisotopic Method. Transactions of American Fish Society. #95. pp. 363-371.

6. Miller, H. J., C. L. Brydnildson, and C. W. Threinen. 1959. Rough fish control. Wisconsin Conserv. Dept. Publ. No. 229. p. 15.

7. Black, J. D. 1946. Nature's own weed killer, the German carp. Wisconsin Conserv. Bull. II No. 4.

8. Nelson, J. L., R. W. Perkins, and J. M. Nielsen. 1964. Progress in studies of radionuclides in Columbia River sediments. A summary of Hanford achieve-ments in this program under General Electric 19630 1964. HW-83614.

9. Maletskos, C. J. and J. W. Irvine, Jr. 1956. Quantitative electro-deposi-tion of radiocobalt, zinc and iron. Nucleonics 14(4):84-93.

10. Palmer, H. E. and T. M. Beasley. 1967. Iron-55 in man and the biosphere. Health Phys. 13:889-95.

11. Snedecor, G. W. 1956. Statistical methods. The Iowa State University Press, Ames, Iowa. 593 pp.

12. Jones, L. M. 1959. Veterinary Pharmacology and Therapeutics. The Iowa State University Press. Ames, Iowa. 944 pp.

13. Goodman, L. S. and A. Gilman. 1960. The Pharmacological Basics of Therapeutics. The Macmillan Company, New York, 1831 pp.

318 JONES et al .

D I S C U S S I O N

A. BAYER: Referring to Eq.(6) in your paper, I see that the influence of the 'declining environment' is described by A, the radioactivity decay constant. The 'declining environment' might also be influenced by the entrainment of resuspended particles containing radioactive material . In such a case it should be replaced by a which is a larger number than A. You might find that the discrepancies in your results were then somewhat reduced.

C.D. JENNINGS: Thank you for your comment. We shall certainly look into that possibil ity.

O.J. VAN DER BORGHT: Perhaps I could just comment that the relative extent of Zn+Fe uptake f rom the water, on one hand, and f rom the sediments, on the other, could provide a sound physiological basis for assessing the exchanges of Zn+Fe.

C.D. JENNINGS: I agree that studies using a physiological rather than mathematical model would be very useful.

IAEA-SM- 294/91

EFECTO DE LA TEMPERATURA DE ACLIMATACION SOBRE LA PROLIFERACION DE PRECURSORES ERITROPOYETICOS EN Carassius auratus así como sobre la incorporación de timidina tritiada en tejido hematopoyêtico e intestinal

M. NIETO GARCIA, Marfa José BENGOECHEA PERE, J. G. MAGANTO FERNANDEZ División Química y Medio Ambiente, Junta Energía Nuclear, Madrid, España

Abstract-Resumen

THE EFFECT OF ACCLIMATION TEMPERATURE ON PROLIFERATION OF ERYTHROPOIETIC PRECURSORS IN Carassius auratus AND ON THE UPTAKE OF TRITIATED THYMIDINE IN HAEMATOPOIETIC AND INTESTINAL TISSUE.

The authors studied the cellular proliferation o f undifferentiated erythropoietic precursors in the goldfish Carassius auratus acc l imated at various temperatures: 5, 10, 20 , 30 and 35°C, The combined use o f h igh-resolution autoradiography and DNA labelling with 3 H-TdR made it possible to study the duration o f the cellular c y c l e from the decrease in the number o f grains/nucleus with t ime. A shortening o f the mitot ic c y c l e was found for high acc l imat ion temperatures, together with an increase in the label led ce l l fraction and in the number o f grains/nucleus in the four erythropoietic cellular precursors. The authors also studied the uptake o f 3 H-TdR in intestinal and haematopoiet ic tissue, observing increased uptake in the haematopoiet i c tissue with temperature over the range considered, and a decrease in uptake by the intestine between 25 and 35°C. The number o f cells per gram of fish decreases at high acc l imation temperatures.

EFECTO DE LA TEMPERATURA DE ACLIMATACION SOBRE LA PROLIFERACION DE PRECURSORES ERITROPOYETICOS EN Carassius auratus, ASI COMO SOBRE LA INCORPORACION DE TIMIDINA TRITIADA EN TEJIDO HEMATOPOYETICO E INTESTINAL.

Se ha estudiado la proli feración celular de los precursores indiferenciados eritropoyêticos en el pez dorado, Carassius auratus, acl imatados a diferentes temperaturas: 5°C, 10°C, 20°C, 30°C y 35°C. La uti l ización combinada de la autorradiograffa de alta resolución y el marcado del DNA con 3 H-TdR ha permitido estudiar la duración del c i c lo celular a partir de la disminución del número de granos/núcleo con el t iempo. Se encuentra un acortamiento del t iempo del c i c l o mitót ico para las temperaturas elevadas de ac l imatación y un aumento en la fracción de células marcadas y número de granos/núcleo en los cuatro precursores celulares eritropoyêticos. También se ha estudiado la incorporación de 3 H-TdR en tej ido intestinal y hematopoyêt i co , encontrándose un aumento de esta incorporación con la temperatura dentro del intervalo estudiado en el tej ido hematopoyêt ico y una disminución en la incorporación, para el intervalo 2 5 ° C - 3 5 ° C , en el intestino. El número de cé lu las /g de pez disminuye para las temperaturas elevadas de ac l imatac ión .

I n t r o d u c c i ó n

La c r e c i e n t e e x p a n s i ó n de e n e r g i a e l é c t r i c a de o r i g e n n u c l e a r da como s u b p r o d u c t o grandes c a n t i d a d e s de c a l o r y a l uti_ l i z a r s e e l agua como r e f r i g e r a n t e t i e n e l u g a r un aumento de l a t e m p e r a t u r a de l a misma. En e s t e t r a b a j o e s t u d i a m o s e l e f e c t o d e l aumento de l a t e m p e r a t u r a d e l agua s o b r e un organ ismo poiqui_

319

320 NIETO GARCIA et al .

l o termo t í p i c o de l a s b i o c e n o s i s a c u á t i c a s , e l p e z . Como i n d i c a dor de cambios de temperatura en e l pez u t i l i z a m o s l o s t e j i d o s hematopoyé t i c o e i n t e s t i n a l , que c o n s t i t u y e n s i s temas de r e n o v a -c i ó n c e l u l a r , es d e c i r , su f u n c i ó n depende de l a r e n o v a c i ó n cons t a n t e de sus componentes c e l u l a r e s , y para compensar e s t a p é r d i -da han de mantener una p r o l i f e r a c i ó n c o n s t a n t e a t r a v é s de l a v i da d e l organismo. Estas c é l u l a s en p r o l i f e r a c i ó n son s e n s i b l e s a cambios t é r m i c o s .

Los t r a b a j o s s o b r e c i n é t i c a c e l u l a r en po iqui lo te i rmos son poco numerosos . Es tud ios p r e v i o s en e l pez d o r a d o , Carass ius auratus , f u e r o n l l e v a d o s a cabo por Etoh [ l ] quien e n c o n t r ó de 3 - 5 v e c e s más e l e v a d a l a v e l o c i d a d de p r o l i f e r a c i ó n cuando l a tem p e r a t u r a d e l agua de a c l i m a t a c i ó n pasaba de 152c a 252C. l o r i o [ 2 ] , e s t u d i ó l a m o r f o l o g í a y d e s c r i p c i ó n de l o s p r e c u r s o r e s i n d i -f e r e n c i a d o s de l a s e r i e e r i t r o p o y é t i c a después de una i n y e c c i ó n de t i m i d i n a t r i t i a d a . Nie to y Johnson [3] e s t u d i a r o n l a r e n o v a -c i ó n c e l u l a r d e l t e j i d o hematopoyé t i co u t i l i z a n d o e l p r e c u r s o r marcado d e l DNA 1 2 5 l - 5 - i o d o - 2 ' - d e o x y u r i d i n a ( 1 2 5 i - U d R ) y Зн-TdR. Al e s t a r compuesto el t e j i d o hematopoyé t i c o por una mezc la h e t e -r o g é n e a de t i p o s c e l u l a r e s pueden s o l a p a r s e l o s e f e c t o s de l a temperatura , es por l o que hemos c o n s i d e r a d o ú t i l e l e s t u d i a r l o s e f e c t o s de l a misma sobre l o s p r e c u r s o r e s i n d i f e r e n c i a d o s er i tro -p o y é t i c o s . Asi e s t e t r a b a j o se r e f i e r e al e s t u d i o de l o s cambios i n d u c i d o s en l a p r o l i f e r a c i ó n de l o s p r e c u r s o r e s e r i t r o p o y é t i c o s cuando e l pez se mantiene a. temperatura c o n s t a n t e , a c l i m a t a c i ó n , durante un p e r i o d o de 30 d i a s , antes de i n i c i a r s e l a exper imen-t a c i ó n . Las temperaturas de a c l i m a t a c i ó n e s t á n comprendidas den -t r o d e l i n t e r v a l o de t o l e r a n c i a t é r m i c a d e l pez dorado ( 4 5 C - 3 ^ C ) .

El recuento se r e a l i z ó mediante un contador de c ente -l l e o en fase l i q u i d a modelo Intertechnique SL 30. Se empleó como l í q u i d o cente l l eador un luminóforo a. base de dioxano, PPO y P0P0P. Aplicando e l método de r e l a c i ó n de canales se normalizaron todas las muestras y se comprobó que l a co r recc i ón de l a ex t inc i ón en 1a. mayoría de l o s casos era desprec iab le .

M a t e r i a l y métodos

En e s t e t r a b a j o hemos u t i l i z a d o p e c e s dorados comunes, Carass ius auratus , p r o c e d e n t e s de c a s a c o m e r c i a l , de peso e n t r e 15 a 20 g. La a c l i m a t a c i ó n se l l e v a a cabo v a r i a n d o l a tempera tura del acfua en З^C por d í a y una vez a l canzada l a temperatura deseada de a c l i m a t a c i ó n se mantiene e l pez durante 30 d í a s antes de exper imentar .

El agua es f i l t r a d a , a i r e a d a y s i n c l o r o . La d i e t a a l i mentar ía e s de o r i g e n c o m e r c i a l , tomándolo dos v e c e s por d í a . El f o t o p e r i o d o ha s i d o de 9 horas d i a r i a s . La dens idad de p o b l a c i ó n e r a un pez por 4 l i t r o s de agua.

IAEA-S M-197/9

Autorradiografía y numeración de células

321

Las p r e p a r a c i o n e s de t e j i d o h e m a t o p o y é t i c o l a s hemos ob t e n i d o d e l r i ñ ó n d o r s a l d e l p e z . Se se can a l c a l o r y se f i j a n con metanol a b s o l u t o durante 15 m i n u t o s . La e m u l s i ó n u t i l i z a d a en l a s r a d i o g r a f í a s e s l a NTB-2 de Kodak, d i l u i d a 1:1 con agua d e s t i l a d a . La t i m i d i n a empleada p r o c e d e de Amersham, 2 Ci/mM y l a s d o s i s i n y e c t a d a s de 0 ,1 ,¡u C i / g de p e z . Esta d o s i s se e l i g i ó con o b j e t o de e v i t a r p o s i b l e s e f e c t o s s e c u n d a r i o s en l o s p e c e s a c l i m a t a d o s a e l e v a d a s t e m p e r a t u r a s . l o r i o [2] e n c o n t r ó que l a f r a c c i ó n de c é l u l a s marcadas no cambiaba p a r a d o s i s comprendidas e n t r e 0 , 5 - 6 ц C i / g , p a r a t e m p e r a t u r a de a c l i m a t a c i ó n e n t r e - 2 4 ^ С . El número de c é l u l a s numeradas e s de 50 p o r c l a s e . El número de p e c e s p a r a cada punto de l a c u r v a e s de 5 - 1 0 . Para l a numerac ión de l a s c é l u l a s e x i s t e n t e s en e l r i ñ ó n d o r s a l obtenemos s u s p e n s i ó n en Hanks pasando e l t e j i d o a t r a v é s de m a l l a de n y l o n de media . Se h i z o l a numerac ión con h e m a t o c i m e t r o . Las autorra-d i o g r a f í a s , después de un t iempo de e x p o s i c i ó n de 12 d i a s , a 4?-C, se t i ñ e n con Giemsa. La c l a s i f i c a c i ó n de l o s p r e c u r s o r e s i n d i f e r e n c i a d o s e r i t r o p o y é t i c o s e s l a de l o r i o [ 2 ] , que i n c o r p o r a n Зн-TdR inmediatamente después de l a i n y e c c i ó n i n t r a p e r i t o n e a l a l p e z .

Ensayo d e l DNA

El a i s l a m i e n t o d e l DNA p r o c e d e n t e d e l t e j i d o hematopo -y é t i c o e i n t e s t i n a l s e hace por e l método de Schmidt -Tannhauser [4]. Los p e c e s son i n y e c t a d o s i . p . con una d o s i s de 2 ¡л Ci/mM y e l t i empo de i n c o r p o r a c i ó n e s de una h o r a .

R e s u l t a d o s y d i s c u s i ó n

La i n c o r p o r a c i ó n de 3 H-TdR en l o s p r e c u r s o r e s i n d i f e r e n c i a d o s e r i t r o p o y é t i c o s y su d i s m i n u c i ó n con e l t i empo después de una i n y e c c i ó n e s e x p o n e n c i a l . Si seguimos e s t e p r o c e s o autorradio-g r â f i c a m e n t e , número de g r a n o s / n ú c l e o y se r e p r e s e n t a n l o s v a l o -r e s medios en c o o r d e n a d a s s e m i l o g a r i t m i c a s obtenemos una r e c t a , cuya p e n d i e n t e k , r e p r e s e n t a l a c o n s t a n t e de v e l o c i d a d . En un t e j i d o en e s t a d o e s t a c i o n a r i o , e l t i empo mit ad ( т 1 / 2 = In 2 / k ) , e s e q u i v a l e n t e al v a l o r medio d e l c i c l o m i t ó t i c o de l a s c é l u l a s en p r o l i f e r a c i ó n en d i c h o t e j i d o , e s d e c i r , en un c i c l o c e l u l a r cada c é l u l a marcada p a s a r á una vez a t r a v é s de l a f a s e S, s u s t i t u y e n d o l a mitad de su DNA marcado, con DNA no r a d i a c t i v o . Hay que s e ñ a -l a r que l a p e n d i e n t e к depende so lamente d e l c i c l o c e l u l a r y no de l a i n c o r p o r a c i ó n i n i c i a l d e l p r e c u r s o r . Se han o b t e n i d o l a s l i n e a s de r e g r e s i ó n u t i l i z a n d o e l método de mínimos c u a d r a d o s . Para e l c á l c u l o de k , s e ha u t i l i z a d o l a p a r t e l i n e a l de l a c u r v a , p r e s c i n d i e n d o d e l tramo en que no d isminuye con e l t i e m p o , p o r r e u t i l i z a c i ó n de l a t i m i d i n a . Los v a l o r e s o b t e n i d o s p o r e s t e mé t o d o p a r a l o s c i c l o s m i t ó t i c o s son aprox imados .

322 NIETO GARCIA et al .

TABLA I. EFECTO DE LA TEMPERATURA DE ACLIMATACION SOBRE LOS PRECURSORES ERITROPOYETICOS: k, PENDIENTES (CONSTANTES DE VELOCIDAD) DE LA CURVA DE DISMINUCION DEL NUMERO DE GRANOS/NUCLEO

C l a s e c e l u l a r 1 0 °c 20 °C 30 °C 35 °C

I 0 , 0 0 2 6 0 , 0 0 2 8 0 , 0 0 7 4 0 , 0 1 8

I I 0 , 0 0 1 3 0 , 0 0 4 0 0 , 0 0 6 0 0 , 0 1 3

I I I 0 , 0 0 1 9 0 , 0 0 3 4 0 , 0 0 7 2 0 , 0 1 7

IV 0 , 0 0 2 4 0 , 0 0 2 3 0 , 0 0 7 2 0 , 0 1 2

1 2 3 4 5 di as

FIG. 1. Efectos de la temperatura de ac l imatac ión sobre la disminución del valor medio del número de granos/núcleo después de una inyecc ión de timidina tritiada. V , 4°C; • , 10°C; Д , 20°C; + , 30°C; O , 35°C.

IAEA-SM-197 /14 323

TABLA II. CARACTERISTICAS CINETICAS DE PRECURSORES ERITROPOYETICOS CON TEMPERATURAS DE ACLIMATACION: k, PENDIENTES (CONSTANTES DE VELOCIDAD) DE LA DISMINUCION DEL NUMERO DE GRANOS/NUCLEO Y T 1/2 + CICLO MITOTICO

Temperatura 35 °C 30 °C 20 °C 10 °C 4 °C

к x 10 3 14 6 , 6 3 , 3 9 1 ,6 0 , 4 3

T 1 / 2 días 2 ,1 4 , 4 8 , 5 1 8 67

En la Tabla I , están dispuestos l os valores de k, c o -rrespondientes a. las cliases ce lulares I - IV , consideradas i n d i v i -dualmente dentro de cada temperatura de aclimatación. Se aprecia, dentro de l a var iac ión inter animal de este material , que e l valor de к es prácticamente igual para las d i ferentes c lases ce lulares dentro de cada temperatura y sensiblemente d i f erente para las dis_ t intas temperaturas de aclimatación. El va lor de k, aumenta para temperaturas elevadas de aclimatación.

En la f i gura número 1, están representadas las curvas de disminución del va lor medio del número de granos/núcleo c o n s i -derando las 4 c lases ce lu lares en conjunto y para cada temperatu-ra. Se aprecia claramente l a dependencia de к con la temperatura de acl imatación.

En l a Tabla I I están dispuestos l os valores de к y los tiempos mitad que corresponderi an al va lor del c i c l o c e lu lar . Se observa fáci lmente l a dependencia del c i c l o ce lu lar con la tempe-ratura de acl imatación.

En l a Tabla I I I , están dispuestos los valores c o r r e s -pondientes a l a f r a c c i ó n de cé lulas marcadas y al número de gra nos /núc leo , para sesenta, minutos de incorporación. Ambos pará-metros aumentan con 1a. temperatura de aclimatación.

De l o hasta aquí expuesto se deduce la ex i s t enc ia de una mayor renovación ce lu lar ( turnover) , para temperaturas elevadas de aclimatación viniendo r e f l e j a d a por un acortamiento del tiempo de c i c l o mi tó t i c o , valores más a l tos en l a f r a c c i ó n de cé lu las marca-das y número de granos/núcleo. En e l mismo sentido se interpreta e l aumento de l a actividad e s p e c i f i c a del DNA, f i g u r a número 2 en e l t e j i d o hematopoyético.

324 NIETO GARCIA et al.

TABLA III. EFECTO DE LA TEMPERATURA DE ACLIMATACION SOBRE LA FRACCION DE CELULAS MARCADAS Y NUMERO DE GRANOS/NUCLEO EN PRECURSORES ERITROPOYETICOS

Temperatura 4 °C 10 °C 30 °C 35 °C 37 °C

Fracción de c é l u l a s mar cadas

4 , 6 3 + 3 , 6 1 * 8,1+1 ,52 3 0 , 7 7 + 7 , 3 9 3 9 , 5 6 + 9 , 4 2 51 ,32 + 6 , 4 9

№granos /nú c l e o 9 , 7 9 + 2 , 1 2 1 1 , 3 6 + 3 , 4 3 4 , 6 9 + 4 , 2 5 4 6 , 7 7 + 5 , 3 0 61 ,28 + 6 , 9 4

* Error standard

No sucede l o mismo en e l t e j i d o in tes t ina l en e l que se observa un amento de l a actividad e s p e c i f i c a del DNA dentro del intervalo de temperatura de 52C-255C, y una disminución de l a mis-ma en e l intervalo comprendido entre 25^C-35^C, f i gura número 3. Este comportamiento viene avalado por los datos publicados por Nieto y Johnson [3], en e l estudio de l a f racc i ón de cé lulas mar-cadas que disminuía sensiblemente para temperaturas elevadas de aclimatación, en tanto que las pocas cé lulas marcadas aumentaban e l número de granos. De aqui se i n f e r i a que para temperaturas elevadas de aclimatación disminuía e l número absoluto de cé lulas en p r o l i f e r a c i ó n en e l in tes t ino . Una imagen parecidá la propor-ciona e l trabajo de Clark y Diamond [6], al estudiar l a p r o l i f é r a ción " in v i t r o " con una l ínea ce lu lar procedente de S. gairdneri , en que ex i s te un óptimo térmico de p r o l i f e r a c i ó n y a par t i r de é l disminuye hasta alcanzar e l mínimo para las temperaturas máximas de t o l e ranc ia de dicha espec ie . No sucede l o mismo en e l trabajo de Johnson, T.S. y co l . [5], que estudian l a i n f l u e n c i a de l a tempe-ratura de aclimatación sobre l a renovación ce lu lar en t e j i d o intes t ina l de individuos jóvenes de 0. Kisutch, mediante l a incorpora-ción de 3H -TdR. Las actividades e s p e c i f i c a s eran dependientes de l a temperatura, mayores para temperaturas más elevadas de aclima-tac ión . En e l pez dorado C. auratus, dotado de una amplia toleran c i a térmica, se acl imataría a temperaturas elevadas a costa de disminuir e l número de cé lulas en p r o l i f e r a c i ó n en e l i n -tes t ino .

En la Tabla IV están dispuestos valores ponderales del t e j i d o hematopoyêtico e in tes t ina l relacionados con l a temperatu-ra de aclimatación. Se aprecia que l a re lac ión mg r iñón/g de pez y su expresión equivalente ^ c é l u l a s / g de pez, disminuyen pa

IAEA-SM-197 /9 325

1 0 0

T 1

_ i I • 1 i L

5 10 15 20 25 30 35 ^c

FIG. 2. Efectos de la temperatura de aclimatacifin sobre la incorporation de timidina tritiada en el tej ido hematopoyet ico (rinfin dorsal). Desviaci6n standard.

FIG. 3. Efectos de la temperatura de aclimatacifin sobre la incorporacifin .de timidina tritiada en el tejido intestinal. Desviacifin standard.

326 NIETO GARCIA et al.

TABLA IV. EFECTO DE LA TEMPERATURA DE ACLIMATACION SOBRE LAS RELACIONES m g ORGANO/g PEZ Y NUMERO DE CELULAS POR GRAMO DE PEZ.

Temperatura 4 °C 8 °C 10 °C 20 °C 30 °C 35 °C

mg riñón/gr pez 6,92+0,39* 4,8 7+1,12 5,37 + 1 ,23 4,29 + 1 ,04 3,26+0,75 2,56+0,53

Número células /gr pez x 106 5,64+0,44 4,17+0,28 5,5 2+0,39 4,49+0,41 '3,30+0,21 2,55+0,10

mg intestino/ gr pez 25,58+5,03 20, 73 + 1 , 39 18,99+1,54 16,38+0,77 12,81+0,93 12,12+0,72

* Error standard

ra temperaturas elevadas de aclimatación aunque dentro del i n t e r -valo considerado 42C-352C l a var iac ión es muy pequeña. Asimismo sucede con la re lac ión mg intestino/g pez, que var ía en e l mismo sentido también. Por e l contrario l a variac ión para la duración del c i c l o mitót ico en dicho intervalo térmico es de 30.

Conclusiones

En los peces dorados, C. auratus, aclimatados a 52C, 10°C, 20°C, 30°C y 359C, se observa un acortamiento de l a dura-ción del c i c l o mi tó t i co , como compensación al incremento de tem peratura en los precursores indi ferenc iados e r i t r o p o y é t i c o s , a través del proceso de aclimatación. Esto vendría respaldado por las variaciones en e l mismo sentido de la f r a c c i ó n de cé lu las marcadas, número de granos/núcleo y l a incorporación de precurso res marcados ^H-TdR en e l t e j i d o hematopoyético.

R E F E R E N C I A S

[ 1 ] ETOH, H . , Dobutsugaku Zasshi (Zoological Magazine) 77 (1968) 213. [ 2 ] IORIO, R.J. , Cell Tissue Kinet. 2 (1969) 319. [ 3 ] NIETO GARCIA, M . , JOHNSON, H. A . , Cell Tissue Kinet. 5 (1972) 331. [ 4 ] SCHMIDT, G . , THANNHAUSER, S.J. , J. Biol. Chem. 161 (1945) 83. [ 5 ] JOHNSON, T . S . , NAKATAMI, R. E. , CONTE, F. P. , Radiat. Res. 42 (1970) 129. [ 6 ] CLARK, F .J . , Cell Physiol. T7_ (1971) 385.

IAEA-SM-197 /14 327

D I S C U S S I O N

C. STREFFER: Did you try to establish the radiosensitivity of the proli ferating ce l ls at the various temperatures?

A lso , you mentioned that the number of colony forming units (CFU) increased with increasing temperatures. Did you measure the number of CFU?

M. NIETO GARCIA: No. we do not have any data on radiosensitivity as a function of temperature.

In reply to your second question, I would re fer you to the paper by Baker et al . , which deals with that point.

Session VIII

PANEL DISCUSSION

Chairman: B. LINDELL (Sweden)

PANEL DISCUSSION ON THE SIGNIFICANCE OF SYNERGISTIC AND COMBINATION EFFECTS IN THE FUTURE DEVELOPMENT OF NUCLEAR POWER PROGRAMMES, AND THE NEED FOR FURTHER STUDIES

PANEL MEMBERS

Chairman: B. Lindell (Sweden & ICRP)

R.J . KIRCHMANN (Belgium), J . ANCELLIN (France), C. STREFFER (Germany, Fed. Rep. of), K . G . VOHRA (India), H. FUCHS (Switzerland)

B. LINDELL (Chairman): The Panel Members had a discussion to-day, before this Panel, regarding the various questions that we would discuss, and we reached agreement that our aim would be to initiate an exchange of opinion with the audience and not to try to give all the answers ourselves , which we might not be able to do, anyway. The questions we rece ived seem to cover the whole range of topics touched on at the Symposium. We shall start with one asking for the definition of a synergism, and we shall end with a question directed to all of us, namely, whether we understand the synergist ic ef fects of radiation, heat and toxic chemicals well enough to be able to f o resee their effects on nuclear power development.

Before handing over the f i rs t question to the Panel, I would like to make a general comment. I have read comments in the Swedish newspapers to the effect that yet another phenomenon has now been found - suggesting that radiation is even more dangerous, that it is becoming more and more hazardous every day, and that the idea of synergism is something which those working with radiation, particularly in radiological protection, only r e l u c -tantly admit. I think this is a basic misconception. Indeed, it is the International Atomic Energy Agency and the Nuclear Energy Agency of the OECD which have taken the initiative in holding this Symposium, and the interest in synergism, as ref lected here, has largely come f r o m within the radiation field, where there is a very definite desire to know more about synergist ic e f fects . But this should not be taken to mean that the synergistic ef fects of radiation are the most important synergistic e f fects . I am certain that if we had not limited ourselves to synergistic ef fects as applied to ionizing radiation, we would have had an enormous field to work with.

Our f i rs t question calls f o r a definition of synergistic e f fects , and I think that Mr. Vohra has promised to say something on this point.

K. G. VOHRA: It is very difficult to give an exact definition of the term 'synergist ic ef fect ' in the present context, but I shall try to say something about it 's usage in the environmental sc iences . F irs t of all, I think that the idea expressed in the title of this Symposium, namely 'combined e f fec ts ' ,

331

332 PANEL DISCUSSION ON THE SIGNIFICANCE

is very apt, because synergistic ef fects represent a special case in the study of combined ef fects . To define a synergism very brief ly , in the way it has been defined in most publications and papers so far, one may say that whenever the combined effect produced by two agencies is more than the sum total of the effects of each of individually, the ef fect can be called a 'synergistic e f fec t ' . F o r example, if we consider the combined ef fect of heat and a chemical on the mortality rate of f ish and note that in one particular case the increase in the mortality rate is 10% for a certain r ise in temperature, and, in a second case, that in the presence of a certain concentration of a chemical the increase in mortality rate is again 10%, but when the same r ise in temperature and the same chemical concentration occur together, the mortality rate is, say, 100%, then this combined effect represents a true 'synergist ic e f fect ' .

Let me take a further example - the synergistic effect of ionizing radiation and photochemistry in the case of atmospheric re leases . If we consider the photochemical effect in the formation of certain chemical spec ies in the atmosphere as a result of the action of light on a chemical substance released, we may find, f o r example, 100 part ic les of this species formed per cubic centimetre. If we now consider the ef fect of ionizing radiation, we find that the effect on spec ies formation is negligible. But, if we have both sources acting together, that is the sources of the photochemical ef fect and the radiation chemical effect, and find that they lead to the formation of a million partic les of the species per cubic centimetre, then we have here an outstanding case of a synergistic ef fect .

B. LINDELL (Chairman): I hope the definition will suf f ice . The synergistic ef fects we have seen relate to the cellular level, to the physio logi -cal level of the body as a whole, to cr it ical pathways in the environment, and even to meteorological conditions, c learly a very broad area of activity. We have arranged the questions submitted so as to start at the cellular level in man and to finish with considerations of the nuclear reactor site, attempting, en route, to survey the synergistic e f fects involved. Continuing with the fundamental problems of cellular biology, we have been asked three questions relating to biological e f fects . One questioner asks, with regard to the ef fects that have been studied under laboratory conditions at high-dose levels , whether they can really be extrapolated down to the lower dose levels that one is likely to find in the environment? Another c losely related question is whether synergistic ef fects have really been observed in the environment, that is outside the laboratory, and whether there is evidence of synergist ic ef fects at lower levels of radiation exposure? And a third question, directed specif ical ly to Mr . Streffer , asks about the synergistic ef fects of antibiotics and radiation; is there a genetically significant dose equivalent for antibiotics, and, if so, what is its combined effect with a radiation dose of 0. 3 rem per generation (based on 10 mi l l i rem per year)?

C. STREFFER: Any answer to these questions can only be based, of course , on certain assumptions. As you know, we have to use comparatively high radiation doses in radiobiological research in order to establish carcinogenesis or mutagenic ef fects , since otherwise it would be difficult to have statistically significant results . I would only remind you that although Russell , for instance, delivered high doses in his work, he had to use one to two million mice in order to establish significant dose -e f f e c t relationships f or mutagenesis due to ionizing radiation. Well , can we now extrapolate to

OF SYNERGISTIC AND COMBINATION EFFECTS 333

low radiation doses? Considering combined effects or synergistic ef fects , it has been the general concept so far, in the evaluation of r isk due to radiation, to extrapolate f r o m high to low radiation doses, on the basis of a linear d o s e / e f f e c t relationship since this gives a figure representing the 'highest possible r i sk ' . The ICRP, especial ly, has evaluated this concept.

Prom the scientif ic point of view, we know that a number of repair and recovery p r o c e s s e s do exist, and in the low dose range there is no doubt that these r e c o v e r y and repair p r o c e s s e s would serve to decrease the radiation damage. So the ef fects may be l ess at lower doses if we use low LET radiation and deliver the dose over a longer period. I think, however, that f o r practical purposes it is necessary to stick to the concept of linearity. I twouldbe very difficult to consider variations in such factors as time or L E T . As I have stressed in my paper, with increasing LET the recovery processes decrease , and at high LET we do not seem to find any recovery p r o c e s s e s . With regard to the threshold dose, I consider that, for the sake of p rac t i ca -bility, we should neglect the threshold dose, again applying the concept of obtaining the 'highest possible r isk ' value. With dose-modi fy ing factors we have the same situation, as I have already mentioned. Dose-modi fy ing factors and sensitizing substances generally affect the r e covery p r o c e s s e s . This means they inhibit recovery , and we are justified in extrapolating these data, as a general rule, f r o m higher dose ranges to lower dose ranges on a l inear basis .

As far as antibiotics and genetic ef fects are concerned, you all know that during the last years there has been a great-deal of public concern about genetic e f fects , not only those due to radiation but also to various chemical and other substances. Since then a number of faci l it ies have been set up in various countries, including the Federal Republic of Germany, where a broad so - ca l l ed 'screening programme ' has been drawn up for studying genetic e f fects of potentially hazardous substances such as antibiotics. It has been shown that there are a number of substances used in medicine which exhibit genetic e f fects . Whether we can compare such genetic ef fects with radiation mutagenesis is not really c lear . I showed you some data which I was given by Dr . Ehling, of the Deutsche Gesellschaft fttr Strahlen- und Umweltforschung in Munich, whose aim has been to compare the genetic ef fects of radiation and of various antibiotics. But the mechanisms of mutagenesis due to substances or to radiation may be different, and this must be borne in mind.

As far as I know, we have up to now no c lear indication whether there are synergistic e f fects between radiation and radiosensitizing substances in mutagenesis. The data which we possess on cel l killing and other rad io -biological e f fects suggest that such combined ef fects do, in fact, exist. But whether we can speak of synergistic ef fects between radiation and substances down to doses as low as 10 mi l l i rem per year, or 0. 3 rem for the whole population per generation, is questionable, and I can only remind you of my ear l ier remarks on linearity. Nevertheless, I should point out that the genetic r isk of radiation has certainly been better evaluated up to now than is the case for a number of substances which we commonly use in medicine and in everyday l i fe .

B. LINDELL (Chairman): Are there any comments or questions? J . J . COHEN: How do you determine 'maximum possible r isk ' values? C. STREFFER: Since we have data on radiation-induced mutagenesis,

and we know that recovery p r o c e s s e s take place in mutagenesis - f o r instance,


this has been established by experiments — we can expect that, under certain conditions and at lower doses, there might be a l e s ser ef fect than that determined with a linear extrapolation. Thus obtaining a 'highest possible r isk ' value would involve taking a l inear extrapolation.

J. J. COHEN: In other words, it is an estimate based on the data that one happens to have available.

C. STREFFER: Yes , of course . We have to use this approach or else we cannot extrapolate at all. I don't believe there is any other possibil ity.

H. EDELHAUSER: I 'm sorry , but I don't think the term 'highest possible r isk ' is acceptable since it could be understood as referr ing to 'death'.

B. LINDELL (Chairman): We should bear in mind that death is not a risk; death is an indication of the severity of an effect, while the risk is the probability of somebody dying. The product of the risk and the severity of the effect is what the ICRP calls a detriment. Perhaps we are inclined to confuse ef fects and risks of ef fects .

E . W . STAUBER: Your argument is not entirely c lear to me, Mr .St re f f e r . You say that we do not yet know anything definite about the combined ef fects , o r if such exist or not, but, on the other hand, you state that one must assume that they do.

C. STREFFER: I said that up till now we have not obtained any c lear -cut experimental data on the combined ef fects of radiation and substances in mutagenesis. But, as I pointed out in my paper, we have some experimental data on the synergistic effects between substances and other radiobiological e f fects . F o r instance, cell killing, protein synthesis, DNA synthesis - these are all e f fects which modify the action of radiation on DNA and its metabol ism. On the other hand, DNA and its metabolism are certainly involved in muta-genesis. We can therefore assume that such combined ef fects also exist f o r mutagenesis.

B . L I N D E L L : W e h a v e j u s t t i m e f o r o n e m o r e q u e s t i o n o n t h i s p o i n t .

P. G. ROLLIN: By applying the principle of a linear dose relationship you accept the fact, without any proof, that very low doses may cause cancer. Do you think that this is psychologically useful?

C. STREFFER: I 'm afraid I 'm not a psychologist . All I can say is that, if we accept the fact that we can modify recovery processes , f o r instance by increasing LET radiation or by combining radiation with substances, we have then to accept that linear extrapolation is the only way open to us at the present time. A further consideration is that we don't yet know whether there is actually a threshold dose . We have had no proof of it up to now, and so until we get the proof , it is our responsibil ity to the public to assume linear dose -e f fec t relationship.

B. LINDELL (Chairman): The next two questions relate to the impact of possible synergistic ef fects on standards and norms. One questioner asks whether the ICRP has considered synergistic e f fects in its latest review of the dose l imits? Another question, in the same vein, is: Should synergistic e f fects be permitted to influence radiological standards already at the present stage? I think I can answer these. The ICRP is not con-sidering synergistic e f fects in its present review of dose limits, although this fact should not be misconstrued. We have examined synergistic ef fects over the whole sphere of applicability and the only ones that would be of relevance to dose limits would be those at cellular level. These are not


considered and there is no possible way of considering them at present. After all, there is implicit in any system of dose limitation a statistical assessment-of radiation r isks at low doses. For a human population with a normal variability of individual habits and physiology etc. , all data on radiation r isk would inevitably include any possible synergisms as well. There is no c lear-cut experimental laboratory data, however, which could be used f or extrapolation purposes. Synergistic ef fects which do apply at the cellular level, f o r example the crit ical pathways by which radioactive nuclides are transported in the environment, e f fects on meteorological con-ditions, and so forth, are surely outside the basic system of dose limits but still within the sphere of application of the system. When one is trying to assess the radiation dose f r o m radioactive material re leased f r o m a stack, for example, one should try to include any knowledge available on any type of meteorological synergistic e f fects likely to affect the irradiation pattern.

We now have four questions which all relate to the combined action of heat and other ef fects . For example, one questioner asks: How would the combined ef fects of heat and chemicals influence the crit ical pathways of radionuclides in the environment? Another related question is: What kind of environmental surveys would be meaningful for the combined heat-chemical-radiation situation? A third question is (we have already mentioned it): Have synergistic e f fects actually been observed in the environment? And another questioner ra ises the point, might not the mobilization of radio -nuclides due to chemical pollutants be a favourable phenomenon in that by spreading them around it reduces local concentrations of nuclides? All these questions concern, by and large, the pathways by which radionuclides are transported f r o m a release site into the human organism. Mr. Kirchmann could perhaps say something on this point.

R.J. KIRCHMANN: With regard to the influence — and I say influence because I hesitate to use the term synergism — of chemical pollutants and heat discharged to a receiving stream of water on the behaviour of radio -active re leases , I will limit myself to two examples provided by studies made under natural conditions downstream of a 300 MW(e) nuclear power plant which has been operating f or several years . The study has shown us, among other things, that the availability of cobalt-60, i .e. its fixation on sediments and by aquatic mosses , has decreased by a factor of 5 downstream of an industrialized and urbanized area, as compared with upstream. There may be two reasons for this: it is either due to the action of the iron salts discharged by a steel works, or else to the complexing by organic material discharged f r o m the town. No s imilar effect has been observed for manganese-54, which is also released by this nuclear plant. I think that the high-speed technique f or evaluating mobility potential, which has been dealt with this week at the Symposium, could be used to clear up points of this type. Another example is provided by the use of b io - indicators (such as aquatic mosses ) sampled at different dams, situated on the River Meuse downstream of the same nuclear power plant; the study has shown that the cobalt-60 and manganese-54 concentration is higher in the samples recovered f r o m a dam situated downstream of conventional power plants, the condensers of which are cooled by r iver water containing radionuclides stemming f r o m the nuclear power plant located upstream. Furthermore , laboratory exper i -ments have conf irmed the effect of temperature on the fixation of manganese-54 and cobalt-60 by these aquatic mosses ; for a temperature dif ference of 10°C (5 15°C). the increase observed was a factor of less than 2. It is c lear


that there is some combination effect , but it is still not extensive. Interactions or combination ef fects of liquid radioactive re leases and chemical pollutants are therefore ef fects which it is important to evaluate at the level of p r e -dictive radiological studies, so as to use them in interpreting the results obtained f r o m radiological monitoring programmes. It is also necessary , I think, to press for a periodic reappraisal of eco logical situations at nuclear sites. This is a problem associated with speci f ic features of a site and changes with time in the environment of the actual plant. The influence of chemical pollutants in rendering radioisotopes more mobile can certainly be considered as a favourable phenomenon at t imes, since it reduces the r isk of the accumulation of radioactivity, for example, in sediments, and also cuts down any subsequent r isk at the time of dredging, flooding, and so on. Nevertheless, it is also c lear that it could be a disadvantage, since mobility may lead to contamination of ground water used, among other pur-poses , as a source of drinking water. Hence, what is required is an examination of each particular case and a weighing up of the risks. With regard to the monitoring programme, which we agree may be complicated if a simultaneous study is provided for , one should at least measure the different parameters , that is to say not only the radiological ones, but also the thermal and chemical characterist ics ; I think that any radiological monitoring programme could be supplemented by continuous temperature measurement and an evaluation of some of the chemical parameters of the receiving waters as well.

B. LINDELL (Chairman): That is perhaps one of the more interesting studies that could be made. Since the crit ical pathways f r o m release points could be affected thereby, the results would be of great practical importance.

G. BOERI: The combined ef fects of heat and chemicals can affect cr i t ical pathways not only in the sense that they change the physico -chemical properties of, say, a water environment, but also, through their ability to change or induce changes in an aquatic habitat (or even terrestr ia l habitat), they might displace a species f r o m the habitat, affecting an existing pathway.

B. LINDELL (Chairman): The displacement of some species is a secondary fact that may not be so obvious when considering the direct e f fects , but it might well be of great importance if it happened.

O.J. VAN DER BORGHT: I agree with a statement Mr. Kirchmann had previously made that in most of the studies that have been per formed to see if there is any metabolic influence on the biological fixation of isotopes, the temperature has been used as the normal and obvious means of detecting such ef fects . Rise in temperature will result in an increase in the metabolic uptake of some isotopes. Provided the increase of temperature is limited to 7°C, we ourselves have observed in our experiments that the increase in uptake of isotopes is never more than a factor of 2; I believe that the safety of our standards is well beyond a factor of 2.

R.J. KIRCHMANN: I should add, furthermore, that the thermal effect is much more important in itself than its repercussions at the level of fixation by the aquatic organisms involved.

C. HOEDE: I gather that the Swedes are making measurements in cold water and the Indians are making measurements in hot water, but I 'm wondering whether there is any definite programme for making s imilar experiments at these various temperatures? It strikes me as the obvious thing to do.


B. LINDELL (Chairman): Perhaps Mr. Grimas might wish to comment on that. o

U. GRIMAS: I think the organisms of interest are those that are very-useful or abundant in the waters we in Sweden are working with. We have very special fauna and f lora in the Swedish waters and it is those organisms which bring us into contact with radioactive waste products. So it is quite obvious that we are experimenting with our own spec ies , and over the temperature range which is of interest to us. But if there is a spec ies which can be found all over the world, it would certainly be of very great value to carry out experiments with that particular species ; certain mussels , for instance, might be interesting in that respect .

B. LINDELL (Chairman): So it is not just temperature that makes a dif ference between Sweden and India. Mr. Vohra, would you like to comment?

K.G. VOHRA: I have nothing much to add to what has been said. For each particular country or region of the globe there are certain species which have adapted to a particular environment and particular temperature range, hence it is necessary to study each environment within the range of interest. As I pointed out ear l ier , for some of the species being studied in India, the ambient temperatures achieved are near the upper survival limit for these species and even a few degrees change in the temperature above that limit could lead to an increase in mortality. F r o m these considerations it is clear that the study should be conducted in each individual situation, and we should make different studies at different temperatures.

B. LINDELL (Chairman): This brings us round to the questions that have been submitted on thermal ef fects . They can very roughly be summarized as fol lows. Since thermal equilibrium varies f r o m winter to summer, how can we maintain an eco log ica l equilibrium? Another question relates to the ef fects of cycling temperature: is a short - term cycling temperature in an environment even more important, perhaps, than di f ferences in temperatures between environments. One questioner wonders whether we should not be more concerned with waste heat in view of the r isk of eventually causing too much global thermal pollution. Although we have tended to discuss here only local thermal pollution, we should perhaps think about the global thermal pollution of the future. This point as such is not real ly related to synergistic e f fects but might nevertheless be interpreted in the light of such ef fects . Another question deals with thermal pollution causing oxygen def ic iency and, therefore , the resulting mortality in fish. Mr. Ancellin, I believe you would like to answer the questions relating to thermal impact.

J. ANCELLIN: The problem is to ascertain to what extent a r ise in temperature disturbs the biological medium. One can say, as a generalization, that when they reach a certain point temperature changes lead to changes in the biological sense. We can try to c lassi fy these changes in two main groups: the f irst group concerns changes in the distribution of spec ies , and the second group changes in the physiology of species . The f o r m e r effect — change in distribution — is observed particularly whenever the r ise in temperature is fair ly high; for example it has been found at sea that there is replacement of some of the cold-water fauna and f lora by a number of warmer-water spec ies , and that a new balance is thereby established. At any rate, nature responds by replacing one balance by another, and that is the problem that we always come back to. The possibility of replacing cold-water by hot-water spec ies has also been shown in certain areas of


the USA coast, where c lose to one or more power plants there has been a certain depletion in brown algae, which have been replaced by green algae and ulva, the latter being considered more heat-resistant. As regards change in the distribution of species , we have observed that this phenomenon occurs in certain media, and sometimes in a rather sudden manner; it relates, primari ly , to tropical waters and, secondly, to enclosed or semi -enc losed waters, and, of course , to the r iver situation. In tropical environments, the spec ies normally found there already have a higher ambient temperature, and are almost at the upper limit of their thermal tolerance potential; hence a thermal contribution, even a relatively low one, might cause a major e c o -logical imbalance. With regard to the r iver situation, it is clear that the ef fects of temperature may be more marked, since in that environment there is less thermal dilution than in the marine environment, and there may unfortunately be greater temperature r ises . So among the problems created is the need to find out whether action should be taken to limit the thermal load not only f r o m one facility, but a set of faci l it ies, or to envisage certain regulations that could be applied to one country, or a number of countries, sharing a coast or a r iver basin. It is clear that when the thermal load exceeds a certain level , some sort of action will certainly have to be taken.

The second aspect of biological change created by temperature concerns modification of the physiology of species . Such changes may take place in regions where the temperature increase is relatively low and does not induce changes in the fauna in the true sense, but simply means that the spec ies present in the environment remain there and adapt physiologically to the higher temperature, showing, for example, increased growth rate and accelerated sexual maturity. Hence physiological changes of this type are observed most often in regions where the temperature increase is relatively moderate, f o r example, of the order of two or three degrees. It can be con-sidered that for up to two or three degrees the biological ef fects are fair ly limited, except in cases such as the tropical situation. There is also the problem of the relationship that may exist between radioactive contamination and temperature, as has been discussed. If we accept that temperature exerts an effect on the contamination level of species , then normally we have to take into account the natural temperature changes, and include them in experiments relating to radioactive contamination.

B. LINDELL (Chairman): It makes me wonder whether we should try not just to limit local thermal pollution, but to aim at reducing it on a global scale. Of course, any energy, even if it is not waste energy, will cause thermal pollution in the long run, so if we wish to limit global pollution, we will be f o rced to limit the production of energy as such, and not just the release of waste heat.

K.G. VOHRA: I think the answer to the question of the global ef fects of using nuclear power in a big way in the coming years , and the associated effect of an increased heat output into the atmosphere is that the total amount of heat input f r o m whatever is possible in another 100 or 2 00 years is never going to be anywhere near the heat energy involved in the atmospheric processes . At the same time, meteorologists are very much concerned today about the heat balance of the atmosphere. What I said earl ier related to direct heat; but we are also faced with the question of indirect ef fects on the heat balance of the atmosphere. We are actually concerned with two major problems at present and, if you consider both of them together, in comparison the effect of the direct heat output f r o m the nuclear power


stations probably becomes negligible. The f irst is the effect of a carbon dioxide increase f r o m the burning of f oss i l fuels on a major scale, which is a problem that will escalate during the next 100 - 200 years — as long as the foss i l fuels last — because the increased release of carbon dioxide into the atmosphere will lead to a r ise in temperature due to absorption of in f ra - red radiation f r o m the earth. The other area where nuclear energy, or its indirect ef fect , becomes more important than its direct impact is the effect on the albedo,, that is the back ref lection of solar energy by clouds and particles in the atmosphere. Now, if the increased heat f r o m the cooling towers, as has been mentioned at this meeting, gives r ise to increased fog formation and if particulate matter is also f ormed by ion-induced reactions, then the overal l effect of this input would be increased particulate matter, and the latter certainly gives r ise to increased albedo. So the amount of heat energy f r o m nuclear power stations that might contribute to the heating of the atmosphere would be negligible compared to the cooling effect p r o -duced by the back ref lection of the solar energy due to the partic les or clouds f o rmed by the operation of a large number of nuclear power stations. This, on the whole, is a highly specialized problem, and I have only given a brief outline of it.

E. IOANNILLI: Mr. Ancellin pointed out some of the possible e f fects of a thermal input into the natural environment, but what he did not mention was the practical importance of, say, a replacement of a certain species by another within a local context. I would be interested to know, for example, the significance of a change in physiology f r o m the practical point of view? It is easy to see that if the breeding season could be anticipated, a certain spec ies might die out, and this could, of course , result in economic loss . The practical consequences of such changes are an important consideration. I think that in this sense we should consider the local impact and not so much the global impact, since the f o r m e r is of greater economic and practical importance.

B. LINDELL (Chairman): Well , of course, there are two ef fects involved in the displacement of species . One is the economic ef fect , namely that a species may disappear, although it might conceivably be replaced by another one of greater economic value. The second effect is that the displacement of a species could alter the radioecological transport chains. The new species , f o r example, may take up more radioactivity and thereby pass on higher doses to man.

C. STREFFER: One of the things we have to do is to try to see whether we can estimate the r isk between the different sources of energy that we have available today.

But I want to ask Mr. Ancellin what he thinks about the increase in growth rate, for instance in the case of fish, when the temperature r i ses by 1 or 2°C. Does he consider it a favourable situation f r o m the eco log ica l standpoint?

J. ANCELLIN: I don't think one could say categorical ly yes or no, since it would depend basical ly on the local conditions and the fauna and f lora affected. As far as the growth rate increase is concerned, there have been observations of this in the natural environment; I am thinking, for example, of the Hunterston power plant in Scotland, where some mol luscs have been seen to grow more quickly and attain maturity sooner than normal. I do not believe this fact has been exploited on a commerc ia l scale, that is in the consumption of mol luscs as food. At other places the ef fect may be of


no consequence — it may be irrelevant whether one species of algae is replaced by another. And, in yet other cases , the effect that occurs is more in the nature of damage, for example, depletion of the fauna through the disappearance of species that are not completely replaced in terms of the b iomass , or , for example, cases in which one sees large algae disappearing and being replaced by microscop i c algae. I wouldn't say that was n e c e s -sarily an advantage.

B. LINDELL (Chairman): I think we should move on. We started out. at the human level and discussed the environment, and we are now approaching problems connected with the nuclear power station site. We have been asked three questions, which are all quite s imi lar , namely whether power plants should be located in industrialized areas? One questioner suggests that the siting of a nuclear power station at a particular point will tend to attract industry, and that there could be cases where the environment would be changed and where re leases of various products f r o m industry could create different conditions through the resulting combined ef fects , that is radiation effects different f r o m those originally envisaged. Mr. Fuchs is going to comment on this problem.

H. FUCHS: If one expects strong combination effects between a nuclear power plant and all the pollutants present in an industrialized area, one should certainly be careful about siting a nuclear power plant there. But f r o m what I knew be fore this Symposium and f r o m what I have heard here , I must admit I am not alarmed by what seems to be our present knowledge of the combination effects of a ir -borne materials . Let me c lari fy this with an example. Measurements have been made at the Keystone plant in the USA, which is a coa l - f i red power station employing cooling towers. It has been observed that near the cooling towers sulphur dioxide coming f r o m strong outside sources may be deflected down towards the ground and that the cooling tower plume may convert a small fraction of it into sulphuric acid. This is a local effect which has, of course , disadvantages f o r the region adjacent to the cooling tower. One should not forget , however, that such mechanisms also have positive aspects: the air gets rid of some of its pollutants, so that areas outside the industrialized region will have a cleaner atmosphere. I must say, though, that in highly industrialized areas with a lot of a ir -borne pollutants one should take special care in siting a nuclear power plant, but with proper planning right f r o m the beginning, based on the location and strength of all the relevant pollutant sources , a plant could be set up without any undue negative e f fects . It seems to me that over the last few years the prel iminary safety analysis reports for nuclear power plants have, in fact , not only taken account of the industry already located in the neighbourhood of the proposed plant, but have also tended to make p r o j e c -tions of future industrial development. Provided we continue along these lines and try to improve our planning — not only for the nuclear power plant itself but also f o r what might be expected in its immediate environs — we should be able to avoid any undue negative ef fects .

Further, I think there is at least one good reason why one should site nuclear power plants in industrialized areas . And that is the advantage to be gained by industry in terms of the possibility of having clean process heat or e lectr ical energy f r o m the nuclear power plant and thereby burning up much less pollutant-producing coal or oil . I 'm afraid that a little legal pressure may be necessary , however, to promote this kind of long-range planning and collaboration.


B. LINDELL (Chairman): Are there any other comments on the possible combined ef fects of industrial and nuclear power plant discharges?

B. P E L L E T R A T DE BORDE: During this Symposium we have discussed the combined effects of chemical pollutants in the atmosphere or pollutants in liquid effluents f r o m nuclear power plants. I think the important point is not so much to ascertain whether or not we should set up nuclear power plants in urban or industrial areas but, more than anything e lse , to work out how we can perfect systems f o r the retention of radionuclides. Important research has been done in this area. For example, the retention of xenon and krypton is a relatively easy matter, though still rather cost ly . I think that the research efforts should be aimed at improving the retention of nuclides, in the same way as we are trying to reduce thermal re l eases , and, thereby, the combined thermal ef fects . But it is essential , of course , to direct one's ef forts at the same time to maintaining an improved atmosphere in urban areas , which depends on industries other than the nuclear industry.

G. BOERI: I should like to add a further comment. In my opinion, what is emerging f r o m our discussions at this Symposium and, in e f fect , f r o m public discussions all over the world, is that the siting of a nuclear power plant or any other plant that re leases effluents into the environment is being increasingly recognized as a problem of the capacity of a given environment to rece ive those effluents, account being taken of all the pollutants that are , or might be, present in that environment. It is a s imilar problem to the radiological capacity of a site , except that in this case we should consider all , or at least the principal, combining and/or synergistic ef fects of other pollutants to the extent that an environment, already compromised by re leases f r o m other industries, is much less able to rece ive the effluents of a nuclear plant, even if its radiological capacity alone were considered suitable.

B. LINDELL (Chairman): Well , that seems a reasonable suggestion, though rather difficult to apply in pract ice . It i s , of course , what we try to do in various quarters , without always knowing what is coming in the future.

P . KAYSER: I don't think we need be unduly pess imist ic regarding the importance of exposure to radiation associated with the nuclear industry in the course of normal operation of nuclear power plants. I am quite certain that the overal l exposure to radiation will be reduced in the future. We should not forget that by virtue of the medical application of radiation we are receiving an exposure seven times higher than is actually necessary , or in other words , we could reduce medical irradiation, f o r example, by 70%, and still carry out the same medical examinations. I mean by this that we have here a possible reserve f or reduction, and it would be useful to study a bit m o r e the ways in which we could reduce useless radiation of this kind.

B. LINDELL (Chairman): We have two more questions, which are of a m o r e general nature. The f i rst is as fol lows: Could the Panel comment on the feasibil ity of a research programme aimed at assessing the influence, if any, of the occurrence and levels of radionuclides in the environment, f i rs t , on the toxicity or environmental significance of various chemical pollutants, and, second, on the sensitivity of human and non-human targets to bacterial or v iral contamination. We are in fact being asked whether radiation and/or radionuclides in the environment make us more sensitive to toxic substances, bacteria and v iruses . Personal ly , I fee l it is very unlikely that low radiation levels in the environment could affect our sens i -tivity in that respect .


C. STREFFER: I don't think we have data on this point, and it would be risky to speculate on it. It would certainly only be the higher doses that could lead to such effects with respect to toxicity. Whereas the susceptibility of cel ls to viral intoxication might well be changed by radiation, I think we do not know this at present and to accept this could be mere speculation. I agree that at the low radiation doses with which we are dealing here it is highly improbable that such effects occur .

B. LINDELL (Chairman): Our last question can be summed up as fol lows: Do we understand the combined synergistic effects of radiation, thermal pollution and chemical pollution well enough to f o resee the effects of nuclear power? Should what we have heard here this week make us m o r e pessimist ic with regard to the effects of nuclear power? And will it be of practical relevance or only of academic interest?

E . -A . HAMPE: As a patient who sometimes has to undergo medical treatment, I often have cause to wonder what is likely to happen to me when I am exposed to radiation and at the same time given medication. It is abundantly clear f r o m what Mr. Streffer has told us that we do not have sufficient data on the human organism. I am therefore wondering whether there is any chance of activating the experience which must surely exist, but which is not yet available, in the medical f ield. It we could obtain more information f r o m this source , we could extrapolate to man with better under-standing and confidence.

C. STREFFER: Well , once again, we only have experimental data f or high radiation dose levels . But a number of you perhaps know that the substances I have talked about have been used in radiotherapy in combination with radiation. The aim was to develop substances which sensitize tumour cells against ionizing radiation. There exists certain information on this which could be evaluated, or at least we could draw conclusions f r o m it by analogy. However, the problem is whether we can extrapolate such data to low radiation doses — this is still uncertain. We definitely need further information on low radiation doses , more especial ly when delivered in c o m -bination with substances. As I have said, the modifying effect may increase at low radiation doses , and likewise at low dose rates. But if we keep to the linear concept, we thereby give consideration to most of these effects in a quantitative sense. I did, in fact , point out in my paper that the modifying effect of substances is represented by a factor in the range of 2-3 in the high dose range, and at a high dose rate, let us say f r o m about 10 to 100 rad/min; this means the dose should be multiplied by this factor so as to calculate the biological effect. We can thus estimate f r o m these data what might be expected at least over this range.

B. LINDELL (Chairman): With regard to other as yet undetected c o m -bination effects that might have a bearing on the impact of nuclear power, most of what has been discussed here concerns effects outside of man in the environment, which, as they become known, can be allowed for in what-ever system of control is applied to re leases of radioactive substances. If such effects are found, it does not automatically mean that nuclear power becomes more hazardous, but it might certainly mean that nuclear power would become somewhat m o r e expensive, since we would need to impose further restr ict ions. But the basic tenets would not be affected thereby. If it were found, however, that there were combination effects at cellular level , then it would mean that the risk assessment based on radiation dose would have to be revised. The situation would then have a number of impl i -


cations — not just f o r nuclear power, but f o r the whole field of use of radiation, and not least, of course , f o r hospitals, where the risk of combination effects must logically be very much higher. In this connection it is important to real ize that we do not really know why at low radiation levels some people develop cancer or a genetic injury which others do not. Is it just a physical -mathematical target ef fect , or is it that some people are more sensitive f o r some reason? The latter case would imply some kind of combination effect in the people concerned. Cases of this kind are known. For example, evidence of radiation ef fects includes women who underwent f luoroscopic X - r a y examinations f or tuberculosis in Nova Scotia, during which the doses were very high because the technique used at the time was so poor . Some of them developed breast cancer , which seems to be related to the radiation exposure. If one looks at the r isk , one sees that it was essentially women between the ages of 15-30 who developed cancer . Consequently, it was a selected group of women, rather than all women, who were at r isk. Women with a certain hormonal state seemed to develop cancer , while the others did not. As radiation effect research continues, it is very likely that we shall establish more and more groups at r isk related to their physiological state or perhaps eating habits, f o r example, if they eat certain foods or take certain drugs, or if they already have certain d iseases . Before we have established these facts , it will be very difficult to say what an additional combination effect with other r isk factors really means.

Are there any other questions that any participant would like to put to the Panel?

H.G. EDELHAUSER: I would like amplification on a point already d i s -cussed: Do you believe that any results presented on synergistic or c o m -bined effects should be taken into account at the present stage in licensing procedures f o r nuclear plants, or even in setting standards for radiological protection purposes , m o r e especially re lease rates f o r nuclear plants? I ask this on the assumption that the dose limits might not be changed at all.

B. LINDELL (Chairman): Perhaps my previous comment was, in a way, a reply to your question also. Clearly, in setting re lease l imits , we cannot introduce f o r consideration effects that are not yet known. We could try to set re lease l imits , as recommended by the ICRP, at the lowest level; it would be reasonably easy to do so , considering social and economic fac tors . But, of course , that kind of differential cost /benef i t analysis would depend on what one knew about the effects of the r isks . Risks that are not known cannot easily be introduced. As I said, when combination ef fects become better known, they can certainly be taken into account. One would then have to revise limits or recommendations on operational procedures , though not the basic dose l imits , unless, of course , the problem related to basic cellular problems affecting the r isk of cancer or genetic e f fects .

G.J. VAN DER BORGHT: It seems to me that one of the biggest challenges to organizations s imi lar to the IAEA is to try to ensure that the same safety standards and regulations that are applied to nuclear energy are applied also to the other industries. How much better our environment would become if we could apply the lowest practicable limits to the release of chemical effluents f r o m these industries into the environment. We might then not have any environmental problem at al l !

B. LINDELL (Chairman): One would f irst have to ascertain whether society could afford to do so.

3 4 4 PANEL DISCUSSION ON THE SIGNIFICANCE OF SYNERGISTIC AND COMBINATION EFFECTS

C. STREFFER: I would agree with you, but it would not rel ieve us of the responsibility of being careful about radiation, too.

B. LINDELL (Chairman): On that note I would like to c lose the d i s cus -sion and to thank all those who have taken part.

CHAIRMEN OF SESSIONS

Session I R. GRADIN Sweden

Session II R.J. KIRCHMANN Belgium

Session III F.B. HAWES United Kingdom

Session IV J. WEBER The Netherlands

Session V Y.J. SOUSSELIER France

Session VI W.G. HUBSCHMANN Federal Republic of Germany

Session VII F. GERA Italy

Session VIII B. LINDELL Sweden

SECRETARIAT

Scientific Secretaries :

Administrative Secretary:

Editor:

Records Off icer :

Liaison Of f i cer , Government of Sweden:

P.J. WEST

R.E. CRAWFORD

Caroline H. de MOL van OTTERLOO

E.R.A. BECK

J.H. RICHARDSON

P.O. AGNEDAL

Division of Nuclear Safety and Environmental Protection, IAEA

Division of Radiation Protection and Waste Management, OECD Nuclear Energy Agency

Division of External Relations, IAEA

Division of Publications, IAEA

Division of Languages and Pol icy Making Organs, IAEA

AB Atomenergi , Studsvik, Sweden

345

LIST OF PARTICIPANTS

AUSTRIA

Mtlhlberger, F. Bundesministerium fflr Gesundheit und Umweltschutz, Stubenring 1, A -1011 Vienna

BELGIUM

Van Der Borght, O .J .

Glibert, R . C .

Kirchmann, R.J.

Lambotte, J . - M .

Lievens, F.

Van De Voorde, N.L .

CEN/SCK, Boeretang 200, B-2400 Mol

Belgonucléaire,

25, rue du Champ de Mars, B-1050 Brussels

CEN/SCK,

Département de Radiobiologie, Boeretang 200, B-2400 Mol Institut Hygiène et Epidemiologic , 14, rue Juliette Wytsman, B-1050 Brussels

Administration de la Recherche Agronomique, Ministère de l 'Agriculture , 2 9 - 3 1 , Chaussée d ' Ixe l les , B-1050 Brussels

CEN/SCK, Boeretang 200, B-2400 Mol

CANADA

Shah, J.

Winmil l , A . E.

Environment Canada, Ottawa, Ontario K1A 0H3

Ecological Impact Control Division, Environmental Protection Service, Environment Canada, Ottawa, Ontario K1A 0H3

CZECHOSLOVAKIA

Kasák, F.

Neuman, F.

Nuclear Research Institute, CS-25068 Rez near Prague

Czechoslovak Atomic Energy Commission, Slezská 9, CS-12020 Prague

DENMARK

GjSrup, H.L . Danish Atomic Energy Commission, Research Establishment Risfi, DK-4000 Roskilde

347

348 LIST OF PARTICIPANTS - 348

Hannibal, L . G .

Jiirgensen, C . I

State Institute of Radiation Hygiene, Frederikssundsvej 378, DK-2700 Brtfnshtfj

University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen

Lassen, U . V . University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen

FINLAND

Akesson, T .E . Institute of Radiation Protection, PO Box 268, SF-00101 Helsinki

Ilus,- E.H. Institute of Radiation Protection, PO Box 268, SF-00101 Helsinki

JSrvi, J.S. National Water Board, PO Box 250, SF-00101 Helsinki

Kekkonen, I . E . O . National Water Board, PO Box 250, SF-00101 Helsinki

Koskelo, M.J .

Niininen, H.P.

Department of Technical Physics, Helsinki University of Technology, SF-02150 Espoo

Imatran Voima O y . , PO Box 138, SF-00101 Helsinki

Riekkinen, Anna-Liisa Meteorological Institute, PO Box 503, SF-00101 Helsinki

Salo, Anneli L. Institute of Radiation Protection, PO Box 268, SF-00101 Helsinki

Taipalinen, A. Irmeli

Vuori, S.J.

National Water Board, Water District of Kuopio, PO Box 49, SF-70101 Kuopio 10

Technical Research Centre of Finland, SF-02150 Espoo 15

FRANCE

Ancellin, J.

Bernier, J .M.

Laboratoire de radioecologie marine, Centre de la Hague, B.P. N° 209, F-50107 Cherbourg

Electricite de France, Direction etudes et recherche, 6,quai Watier, F-78400 Chatou

Bourdeau, FrancineC. Electricite de France, 3, rue de Messine, F-75008 Paris

LIST OF PARTICIPANTS 349

Bovard, P.

Edouard, L . M .

Formé, C . R .

Commissariat à l ' énerg ie atomique, CEN de Fontenay-aux-Roses, В.P. № 6, F-92260 Fontenay-aux-Roses

Electricité de France, 3 , rue de Messine, F-75008 Paris

Electricité de France, 2, rue Louis Murat, F-75008 Paris

Fraizier, A.

Lec lerc , J .G .

Massin, J . - M . E .

Pelletrat de Borde, В.

Roche, L.

Rollin, P . G .

Saas, A .

Laboratoire de radioéco logie marine, Centre de la Hague, В.P. № 209, F-50107 Cherbourg

Techn i ca tome , B.P. № 18, F-91190 Gif -sur-Yvette (Essonne)

Ministère de la qualité de la v ie , Direction de la prévention des pollutions et nuisances, Service des problèmes de la mer et des océans, 14, boulevard du Général Lec lerc , F-92200 Neuilly

Service National de la Protection C iv i l e , 14, rue J. Lemercier, F-78000 Versailles

Electricité de France, Direction études et recherches, 6, quai Watier, F-78400 Chatou

Electricité de France, Direction études et recherches, 6, quai Watier, F-78400 Chatou

Commissariat â l ' énerg i e atomique, CEN de Cadarache, B.P. № 1, F-13115 St. Paul - lez -Durance

Schaeffer, R.

Siméon, С . G .

Sousselier, Y .J .

Vilquin, A .

Ministère de l ' industrie et de la recherche, 13, rue de Bourgogne, F-75007 Paris

Commissariat á l ' énerg ie atomique, 63, rue de la Fédération, F-75015 Paris

Commissariat â l ' énerg i e atomique, CEN de Fontenay-aux-Roses, B.P. № 6, F-92260 Fontenay-aux-Roses

Commissariat à Г énergie atomique, CEN de Fontenay-aux-Roses, B.P. № 6, F-92260 Fontenay-aux-Roses

GERMAN DEMOCRATIC REPUBLIC

Wetzel , К . G . Zentralinstitut fïïr Isotopen- und Strahlenforschung, Permoserstr. 15, D -705 Leipzig

350 LIST OF PARTICIPANTS 350

GERMANY, FEDERAL REPUBLIC OF

Bayer, A . Gesellschaft ffir Kernforschung, Kernforschungszentrum Karlsruhe, Postfach 3640, D-7500 Karlsruhe

EdelhSuser, H . G .

Grupe, H.

Hartwig, S.

Heise, F.

Hil le, R.

Hoffmann, G.

Hflbel, K.

Hübschmann, W . G .

Jaek, W.

Meurin, G .R .

Meyer-Jungnick, W.

Muszynski, G . L .

Papp, R.

Schlesinger, H.J.

Schultz, H.

Bundesministerium des Innern, Rheindorferstr. 198, D-5300 Bonn

Gesellschaft fur Kernforschung, Kernforschungszentrum Karlsruhe, Postfach 3640, D-7500 Karlsruhe

Battelle-Institut, Am RSmerhof 35, D-6000 Frankfurt/Main

Gesellschaft fflr Kernenergieverwertung in Schiffbau und Schiffahrt mbH,

Postfach, D-2057 Geesthacht-Tesperhude

Nukem GmbH, Postfach, D-6450 Hanau

Gesellschaft fflr Kernforschung, Kernforschungszentrum Karlsruhe, Postfach 3640, D-7500 Karlsruhe

Bayerische Biologische Versuchsanstalt, Kaulbachstr. 37, D-8000 Mflnchen 22


Kernforschungsanlage JOlich GmbH, Postfach 1913, D-5170 Jttlich

Institut fflr Reaktorsicherheit eV des Technischen Uberwachungsvereins,

Glockengasse 2, D-5000 K51n 1

Systec Systemplanung und Industrieberatung, Wildenbruchstr. 28, D-4000 Düsseldorf 11

Technischer Oberwachungsverein Baden eV, Richard Wagner Str.2, Postfach 2420, D-6800 Mannheim


Interatom, Postfach, D-5060 Bensberg

Arbeitsgruppe fflr Technischen Strahlenschutz, Technische UniversitSt Hannover, Callinstr. 15, D-3000 Hanover

Schwarz, G. Institut fflr Reaktortechnik, Rheinisch-WestfSlische Technische Hochschule Aachen, D-5100 Aachen

LIST OF PARTICIPANTS 351

Stauber, E .W. (see also under ISO)

Streffer, C .

Vogt , K.J .

Wahsweiler, H . G .

Kraftwerk Union AG, Berliner Str. 695-699, D-6050 Of fenbach /Main

Institut fOr Medizinische Strahlenphysik und Strahlenbiologie, UniversitSts-Klinikum Essen, Hflfelandstr. 55, D-4300 Essen

Kernforschungsanlage Jfllich GmbH, Postfach 1913, D-5170 ja i i ch

Hochtemperatur-Reaktorbau GmbH, D-6800 Mannheim

INDIA

Vohra, K . G . Division o f Radiological Protection, Bhabha Atomic Research Centre, Trombay , Bombay 400 085

IRELAND

Newbould, P.J. New University of Ulster, Coleraine, C o . Derry

ITALY

Amato , A .

Bazzano, Eisa

Boeri, G.

Dinell i , G .

Di Donfrancesco, V.

Géra, F.

Ghersini, G.

Ioannilli , E.

Marena, F.

Smedi le , E.

Strobino, G . C .

Centro Studi Nucleari,

Via Val Maira 115, 1-00141 Rome

CISE, C . P . 3986, 1-20100 Milan

CNEN, Viale Regina Margherita 125, 1-00198 Rome

ENEL-CRTN, Via Bastioni di Porta Volta 10, 1-20121 Milano

ENPI, Via Alessandria 220E, Rome

Radioactive Waste Laboratory, CNEN, Centro Studi Nucleari Casacc ia , C . P . 2400, 1-00100 Rome

CISE, Via Redecesio 12, C . P . 3986, 1-20100 Segrate/Milan

ENEL, Laboratorio Centrale, Via Bixio 39, 1-29100 Piacenza.

ENPI, Via Alessandria 220, Rome

ENEL-CRTN, Via Bastioni di Porte Volta 10, 1-20121 Milan

CISE, Via Redecesio 12, C . P . 3986, 1-20100 Segrate/Milan


JAPAN

Hiyama, Y.

Kishimoto, Y .

Kurabayashi, M.

University Museum, University of Tokyo, Hongo, 2 - 1 4 - 6 Honkoma Chome, Bunkyo-ku, Tokyo

Power Reactor and Nuclear Fuel Development Corp. , Tokai Works, Tokai-mura, Ibaraki-ken

Power Reactor and Nuclear Fuel Department Corp . , Tokai Works, Tokai-mura, Ibaraki-ken

LUXEMBOURG

Kayser, P. Direction de la Sante Publique, 37, rue Glesener, Luxembourg

MOROCCO

Aziz i , A. Ministere de la Sante Publique, Boulevard Mohamed V, Rabat

THE NETHERLANDS

Hoede, C .

Weber, J.

van Weers, A . W .

Twente University of Technology, P .O. Box 217, Enschede

Ministry of Public Health and Environmental Hygiene, Dokter Reijersstraat 10, Leidschendam

Stichting Reactor Centrum Nederland, Petten, N.H.

NIGERIA

Babalola, O. Agronomy Department, University of Ibadan

NORWAY

BjzShle, B.

Garder, Karen

Haugen, I .N .

Statens Biologiske Stasjon FISdevigen, N-4800 Arendal

Institutt for Atomenergi, PO Box 40, N-2007 Kjeller

Norwegian Institute for Water Research, PO Box 333, Blindern, Oslo

SPAIN

Nieto Garcia, M. Junta de Energia Nuclear, Ciudad Universitaria, Madrid 3

LIST OF PARTICIPANTS - 5 3

SWEDEN

Agnedal , P . O . AB Atomenergi , Studsvik, Fack, S - 6 1 1 0 1 NykSping

Bergman, R .O . AB Atomenergi , Studsvik, Fack, S - 6 1 1 0 1 NykSping

BergstrSm, S . O . W . Swedish Board for Reactor Safety Research, (see also under ISO) Fack, S -61101 NykSping

Boge, R. National Institute o f Radiation Protection, Fack, S -10401 Stockholm 60

Borgne, K . G . Swedish Environment Protection Board, Fack, S-17120 Solna 1

Christensen, J.

Edgren, M.

Ehlin, U.

Ekendahl, Ann-Mari

Gradin, R.

Grimas, U. (see also ICSU)

Kumlin, B . R . V .

Lindell, B. (see also under ICRP)

Lindgren, L.

Pipersgatan 3B, S-11224 Stockholm K

Swedish Environment Protection Board, S -17011 Drottningholm

Swedish Meteoro log ica l and Hydrological Institute, Fack, S-60101 NorrkSping

Oskarshamnsverkets Kraftgrupp AB, PO Box 1746, S-11187 Stockholm

Ministry o f Industry, Stockholm

Swedish Environment Protection Board, S -17011 Solna

Joint Organization o f Swedish Power Companies (CDL), Fack, S-10240 Stockholm 5

National Institute o f Radiation Protection, Fack, S-10401 Stockholm 60

Ministry of Agriculture, Fack, S-10320 Stockholm

Norrby, S . U . National Institute o f Radiation Protection, Fack, S -10401 Stockholm 60

Nyman, L . O . Swedish Environment Protection Board, Research Secretariat, Fack, S-17120 Solna

papp, T . Statens Vattenfallsverk, Fack, S-16287 VSllingby

Rolandson, S .E .R . A B A S E A - A T O M , PO Box 53, S-72101 VSsteras

Schelin, P.E. Swedish Environment Protection Board, Research Laboratories, S -17011 Drottningholm

StenstrSm, T . Swedish Environment Protection Board, Department of Environmental Hygiene, Fack, S -10401 Stockholm 60


Swedjemark, Gun Astti National Institute of Radiation Protection, Fack, S-10401 Stockholm 60

Thunell , J. South Swedish Power Company,

Fack, S -20070 Malm5 5

Wahlberg, B.I. Statens Vattenfallsverk, Fack, S-16287 VSllingby

Willner, H. Swedish Environment Protection Board, S -17011 Drottningholm

SWITZERLAND

Fuchs, H. Motor-Columbus Consulting Engineers I n c . , Parkstr. 27, CH-5401 Baden

UNITED KINGDOM

Carmichael , R.J. Naval Nuclear Technical Safety Panel, Ministry of Defence , Room 1512A , Empress State Building, Lil l ie Road, London SW6 1TR

Hawes, F.B. Central Electricity Generating Board, Sudbury House, 15 Newgate Street, London EC1A 7AU

UNITED STATES OF AMERICA

Blanton, J .O. Division of Biomedical and Environmental Research, US Energy Research and Development Administration, Washington, DC 20545

Eiler, H . O . Nalco Environmental Sciences, 1810 Frontage Road, Northbrook, IL 60062

Jennings, C . D . Oregon Co l l ege , Department o f Natural Sciences, Monmouth, OR 97361

Lanza, G .R . New York University, Laboratory for Environmental Studies, Long Meadow Rd. , Tuxedo, NY 10989

Olla, B. N . O . A . A . , National Marine Fisheries Service, Middle Atlantic Coastal Fisheries Center, Sandy Hook Laboratory, Highlands, NJ 0773.2

Siddiqui, T . A . Indiana University, School o f Public and Environmental Affairs,

400 East Seventh S t . , Bloomington, IN 47401

Wol fe , D. A . N . O . A . A . , National Marine Fisheries Service, Atlantic Estuarine Fisheries Center, Beaufort, NC 28516

YUGOSLAVIA

Gavri lovic , M . D . Energoprojekt, Zeleni Venae 18, YU-11000 Belgrade

Tomas", P. Ruder Boskovic Institute, Zagreb

LIST OF PARTICIPANTS - 3 5 5

ORGANIZATIONS

COMMISSION OF EUROPEAN COMMUNITIES (CEC)

Braun, H . W . M . CCREuratom, 1-21020 Ispra (Varese), Italy

Hampe, E. - A . Directorate for Sanitary Protection, 29, RueAldrigen, Luxembourg

FORATOM

Sandstrom, S .G . Swedish Atomic Forum, PO Box 5506, S-11485 Stockholm, Sweden

INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)

Servant, J. Division of Nuclear Safety and Environmental Protection, PO Box 590, A-1011 Vienna, Austria

INTERNATIONAL ATOMIC ENERGY AGENCY/INTERNATIONAL INSTITUTE FOR APPLIED SYSTEM ANALYSIS (IAEA/IIASA)

Cohen, J.J. International Atomic Energy Agency, PO Box 590, A -1011 Vienna, Austria

INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION (ICRP)

Lindell, B.. National Institute of Radiation Protection, (see also under SWEDEN) Pack, S-10401 Stockholm 60, Sweden

INTERNATIONAL COUNCIL OF SCIENTIFIC UNIONS/SCIENTIFIC COMMITTEE ON PROBLEMS OF THE ENVIRONMENT (ICSU/SCOPE)

Grimas, U. National Environment Protection Board, (see also under SWEDEN) S-17011 Solna, Sweden

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO)

BergstrSm, S . O . W . (see also under SWEDEN)

Stauber, E.W. (see also under GERMANY, Fed. Rep. of)

Swedish Board for Reactor Safety Research, Fack, S-61101 NykSping, Sweden

Kraftwerk Union AG, Berliner Str. 695-699, D-6050 Offenbach/Main, Federal Republic o f Germany

ORGANIZATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT/ NUCLEAR ENERGY AGENCY (OECD/NEA)

Wallauschek, E. Division of Radiation Protection and Waste Management, 38, boulevard Sachet, F-75016 Paris, France

LIST OF PARTICIPANTS - 356

UNITED NATIONS ENVIRONMENT PROGRAMME (UNEP)

Larre, D. Division o f Geophysics, Global Pollution and Health, PO Box 30552, Nairobi, Kenya

AUTHOR INDEX

Ancellin, J . : 51 , 64, 65, 337, 339 Balani, M . C . : Г7 Bayer , A . : 189, 205, 242, 318 Bejda, A . J. : 299 Bengoechea P e r é , María José: 319 Blanton, J . O . : 255, 268, 308 Boer i , G . : 336, 341 B^hle, В . : 307 Bonka, H . : 193 Borde , В . Pel letrat de

(see under Pel letrat de Borde) Borgese , D . : 269 Borght, O . J . Van Der

(see under Van Der Borght) Bovard, P . : 179, 189, 190 Brenk, D. : 193 Briissermann, K. : 193 Carmichael , R . J . : 48 Christensen, J . : 221 Cohen, J. J. : 12, 49, 125, 206,

285, 295, 296, 297, 333, 334 Cutshall, N . H . : 3_09 De Borde , В. Pel letrat

(see under Pel letrat de Borde) Dinelli , G . : 93, 269, 283, 284 Edelhàuser, H . G . : 297, 334, 343 Ehlin, U . : 69 Euw, H . M . von (see under

von Euw) Fernández, J . G . Maganto (see

under Maganto Fernández) Fonne, C . R . : 93 Fors ter , W . O . : 155 Fra iz ier , A . : 51 Fuchs, H . : 125, 243, 252, 340 García, M. Nieto (see under

Nieto García) Géra, F . : 283, 297 Ghersini, G . : 177 G inn, T . C . : 95

Grimas , U . : 69, 80, 81, 33 7 Grouby, A . : 145, 179 Guzzi, L . : 269 Hampe, E . - A . : 206, 308, 342 Hartwig, S . : 13, 80, 125, 220,

232, 252 H awes, F . В . : 91, 124 Heise, F . : 13, 93 Hoede, С . : 48, 65, 94, 232, 336 Hofmann, W . : 243 Hübel, К . : 12, 81, 93 Hübschmann, W . G . : 11, 48, 153,

207, 233, 241, 242, 268 Ioannilli, E . : 83_, 92, 93, 94,

177, 339 Jennings, C . D . : 64, 309, 318 Jones, W. M. : 309 J^rgensen, C . B . : 34, 65, 92 Kayser, P . : 12, 341 Kirchmann, R . J . : 12, 65, 92,

335, 336 Koskelo, M. J. : 92 Lambotte, J . - M . : 93 Lanza, G . R . : £5, 124, 125, 126, Larré , D . : 295 Lauer, G. J. : 95 Lievens, F . : 34 Lindell, В . : 207, 331-344 Lowman, F . G . : 155 Maganto Fernández, J . G . : 319 Martin, A . D . : 299 McClin, R . : 155 Nester, K. : 233 Nieto Garcia, M . : 308, 319, 327 Olla, В. L . : 92, 299, 307, 308 Panday, V . K . : _17 Par is i , V . : _127 Patel , В . : _17 Patel , Shakunt: _17 Pel letrat de Borde , B . : 341

357

358 AUTHOR INDEX

P e r é , María José Bengoechea (see under Bengoechea P e r é )

Rollin, P . G . : 94, 125, 283, 308, 334

Saas, A . : 34, 145, 153, 154, 1_79 Samet, С. : 299 Schaeffer , R . : 179 Schultz, H . : 223, 232 Schwarz, G . : 193, 206, 207 Shah, J . : 125, 153, 190, 267 Shakunt Patel (see under Patel) Smedile, E . : 83, 127, 142, 269,

308 Soman, S . D . : 17 Soussel ier , Y . J . : 92, 142, 152,

190, 296 Stauber, E . W . : 251, 334 Storm, Patr ic ia С . : 95

Stref fer , C . : 3, 12, 13, 48, 65, 241, 296, 327, 332-34, 339, 342, 344

Studholme, A . L . : 299 T o m a s , P . : 206 Van Der Borght, O . J . : 34, 65,

81, 308, 318, 336, 343 Van W e e r s , A . W . (see under Weers ) Voelz , E . : 223 Vohra, К. G . : 13, 34, 209, 220,

221, 241, 331, 337, 338 von Euw, H. M. : 243 Weber , J . : 154, 206, 220 W e e r s , A . W . van: 35, 48, 49 Wilhelm, J . G . : 233 Wolfe , D. A . : 155, 177 Wüneke, C . D . : 223 Zubarik, Lo is : 95

The following conversion table is provided for the convenience of readers and to encourage the use of SI units.

FACTORS FOR CONVERTING UNITS TO SI SYSTEM EQUIVALENTS* SI base units are the metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd) and mole (mol). [For further information, see International Standards ISO 1000 (1973), and ISO 31/0 (1974) and its several parts]

Multiply by to obtain

Mass

pound mass (avoirdupois) 1 Ibm = 4.536 X 10"1 kg ounce mass (avoirdupois) 1 ozm = 2.835 X 101 g ton (long) (= 2240 Ibm) 1 ton = 1.016 X 103 kg ton (short) (= 2000 Ibm) 1 short ton = 9.072 X 102 kg tonne (= metric ton) 1 t = 1.00 X 103 kg

Length

statute mile 1 mile = 1.609 X 10° km yard 1 yd = 9.144 X 10_1 m foot 1 ft = 3.048 X 10"1 m inch 1 in = 2.54 X 10~2 m mil (= 10~3 in) 1 mil = 2.54 X 10~2 mm

Area

hectare 1 ha = 1.00 X 104 m2

(statute mile)2 1 mile2 = 2.590 X 10° km2

acre 1 acre = 4.047 X 103 m2

yard2 1 yd2 = 8.361 X 10_1 m2

foot2 1 ft2 = 9.290 X 10"2 m2

inch2 1 in2 = 6.452 X 102 mm2

Volume

yard3 1 yd3 = 7.646 X 10"1 m3

foot3 1 ft3 = 2.832 X 10"2 m3

inch3 1 in3 = 1.639 X 104 mm3

gallon (Brit, or Imp.) 1 gal (Brit) = 4.546 X 1CT3 m3

gallon (US liquid) 1 gal (US) = 3.785 X 10"3 m3

litre 1 I = 1.00 X 10"3 m3

Force

dyne 1 dyn = 1.00 X 10"5 N kilogram force 1 kgf = 9.807 X 10° N poundal 1 pdl = 1.383 X 1CT1 N pound force (avoirdupois) 1 Ibf = 4.448 X 10° N ounce force (avoirdupois) 1 ozf = 2.780 X 1CT1 N

Power

British thermal unit/second 1 Btu/s = 1.054 X 103 W calorie/second 1 cal/s = 4.184 X 10° W foot-pound force/second 1 ft . Ibf/s = 1.356 X 10° W horsepower (electric) 1 hp = 7.46 X 102 W horsepower (metric) (= ps) 1 ps = 7.355 X 102 W horsepower (550 ft-Ibf/s) 1 hp = 7.457 X 102 W

* Factors are given exactly or to a maximum of 4 significant figures

Multiply by to obtain

Density

pound mass/inch3

pound mass/foot3

Energy

British thermal unit calorie electron-volt erg foot-pound force kilowatt-hour

Pressure

newtons/metre2

atmosphere* bar centimetres of mercury (0°C) dyne/centimetre2

feet of water (4°C) inches of mercury (0°C) inches of water (4°C) kilogram force/centimetre2

pound force/foot2

pound force/inch2 (= psi)** torr (0°C) (= mmHg)

Velocity, acceleration

inch/second foot/second (= fps) foot/minute

mile/hour (= mph)

knot free fall, standard (= g) foot/second2

Temperature, thermal conductivity, energy/area - time

Fahrenheit, degrees —32 Rankine 1 Btu-in/ft2-s- °F 1 Btu/ft-s- °F 1 cal/cm-s-°C 1 Btu/ft2 s 1 cal/cm2-min

Miscellaneous

foot3 /second foot3 /minute rad roentgen curie

1 lbm/in3 = 2.768 X 104 kg/m3

1 lbm/ft3 = 1.602 X 101 kg/m3

1 Btu = 1.054 X 103 J 1 cal = 4.184 X 10° J 1 eV 1.602 X 10~19 J 1 erg = 1.00 X 10"7 J 1 ft-lbf = 1.356 X 10° J 1 kW-h = 3.60 X 106 J

1 N/m2 = 1.00 Pa 1 atm = 1.013 X 105 Pa 1 bar = 1.00 X 105 Pa 1 cmHg = 1.333 X 103 Pa 1 dyn/cm2 = 1.00 X 10-' Pa 1 f t H 2 0 = 2.989 X 103 Pa 1 inHg = 3.386 X 103 Pa 1 inH20 = 2.491 X 102 Pa 1 kgf/cm2 = 9.807 X 104 Pa 1 Ibf/ft2 = 4.788 X 101 Pa 1 lbf/in2 = 6.895 X 103 Pa 1 torr = 1.333 X 102 Pa

1 in/s = 2.54 X 101 mm/s 1 ft/s = 3.048 X 10-1 m/s 1 ft/mi n = 5.08 X 10"3 m/s t m rin /u [4.470 X 10"1 m/s 1 miie/n [1.609 X 10° km/h 1 knot = 1.852 X 10° km/h

= 9.807 X 10° m/s2

1 ft/s2 = 3.048 X 10"1 m/s2

°F - 3 2 l 5 °R \ 9 1 K

= 5.189 X 102 W/rn-K = 6.226 X 101 W/m-K = 4.184 X 102 W / m K = 1.135 X 104 W/m2

= 6.973 X 102 W/m2

1 ft3 /s = 2.832 X 10"2 m3 /s 1 f t3 /min = 4.719 X 10~4 m3 /s

rad = 1.00 X 10-2 J/kg R = 2.580 X 10"4 C/kg Ci = 3.70 X 1010 disintegration/s

3 atm abs: atmospheres absolute; atm (g): atmospheres gauge.

*>lbf/in2 (g) (= psig): gauge pressure; lbf/in2 abs (= psia): absolute pressure.

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SUBJECT GROUP: II Nuclear Safety and Environmental Protection/Waste Management

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