A foraminiferal testimony for the reduced adverse effects of mining in Zuari Estuary, Goa

A FORAMINIFERAL TESTIMONY FOR THE REDUCED ADVERSE

EFFECTS OF MINING IN ZUARI ESTUARY, GOA

*Rajani Panchang†, Rajiv Nigam†, Nasreen Baig‡ and G. N. Nayak‡

†Address: Micropalaeontology Lab,

Geological Oceanography Division,

National Institute of Oceanography Division,

Dona Paula 403 004, Goa, India

Telephone: 091-832-2450340 / 2450489

Fax: 091-832-2450602 / 2450603

‡Address: Marine Sciences Department,

Goa University,

Taliegao Plateau 403 206,

Goa, India

*Corresponding Author

E-mail:[email protected]

Abstract

The present work demonstrates the potentiality of Foraminifera in detecting

mining pollution. Goa’s Mandovi - Zuari Estuarine Complex is most

vulnerable to deterioration due to the mining industry. The objective of the

present study is to estimate the health of the Zuari through foraminiferal

distribution in its surface sediments. The foraminiferal data generated was

compared with the three-decade-old foraminiferal data collected in 1972 (1)

and Total Suspended Matter (TSM) data over the years. It is interesting to note

that there has been a substantial increase in the maximum Total Foraminiferal

Number (TFN), from 1143 specimens in 1972 to 3057 specimens per gram

sand in 2003. Even the Total Species Number (TSN) has increased from 24 in

1972 to 50 in 2003. This is in compliance with the TSM data collected over

the years, which has considerably decreased. The foraminiferal data, TSM

data and reduction in mining activities in the catchment area of the Zuari

Estuary suggest an improvement in the environmental health of the estuary.

This study also strengthens the view that foraminifera can be used as a tool to

monitor marine pollution.

Keywords

Foraminifera, pollution-indicator, Zuari Estuary, mining, total suspended

matter, reworked foraminifera

Introduction

Pollution due to increased anthropogenic influence has adversely affected

almost every habitat within the oceans, land and atmosphere. However, the

hardest-hit habitats are the estuaries, the most productive coastal areas at the

mouths of the rivers where fresh and seawaters meet. Problems of estuarine

pollution, like the ‘Minamata Disaster’ of Japan, are not unique just to

developed countries. Even the densely populated West Coast of India is

characterized by the presence of many such estuaries threatened by

deterioration due to anthropogenic influence.

The Mandovi-Zuari Estuarine Complex of Goa (Fig. 1a) holds a different

significance because it is not only a storehouse of mineral resources

(international supplier of Iron and Manganese ore) but also a major natural

harbour of India. The estuaries are used as cheap waterways to export the

mineral ores. At the same time huge mining rejects also find their way to the

sea, during the monsoons. With such a scenario the health of the estuaries of

Goa need monitoring. Foraminifers, almost entirely marine protists being

highly sensitive to their surroundings have been reliably used world wide and

in India (2, 3, 4)

for the detection of source and extent of marine pollution. The

Fig. 1

relative sensitivity of tolerance of foraminifera is sharply variable and

dependent upon the nature of the pollutants discharged(5, 6)

.

The literature survey revealed the varied aspects of the Mandovi-Zuari

Estuarine Complex studied in the past (Table I). The first two papers have

been published(1, 7)

on the distribution of foraminifera based on samples

collected in 1972. Recently, workers have followed up the environmental

monitoring of the Mandovi Estuary, reporting a reduction in foraminiferal

abundance(8)

; however no such work has been conducted in the Zuari Estuary

over the past three decades.

With such a background, the Zuari River estuary also needs to be monitored

and if any sign of pollution is noticed, the source needs to be checked. This

concern itself forms the basis of the present research. Schafer et al.(9)

and

Nigam et al.(8, 10)

have proved that foraminiferal studies in surface sediments

collected over a considerable time gap can provide reliable clues for any

change in the environment. We attempt to use foraminifers to make a

beginning in the environmental impact assessment of the Zuari estuary, it

being less studied for the quality of its health. Foraminiferal data in the Zuari

estuary based on samples collected in 1972 already exists(1)

. This gives us an

opportunity to compare our recent foraminiferal data (samples collected in

Table I

2003) with Rao’s data. The present work attempts to identify and estimate

alteration in the environment of the estuary if any, over the past three decades.

Study Area

The entire state of Goa has seven main rivers of which Mandovi and the Zuari

are of great importance. They together have a basin cover of 69% of the state’s

total geographical area. Mandovi and Zuari together with the interconnecting

Cumbarjua Canal form an economically important estuarine complex on the

West Coast of India and are also known as the "Life Lines" of Goa.

The Zuari makes an overbearing presence over the Southern portion of Goa

and is our prime focus in the present study (Fig. 1a). The source of water of

the Zuari River is entirely within Goa. It is fed by the monsoon precipitation

and receives discharge from a catchment area of 550 km3 (11)

. Zuari estuary has

no major tributaries but has a wider mouth. Two important anthropogenic

activities affect the estuarine ecology:

1. The mining activities in the catchment area

2. Transport and handling of ore material and harbour operations within the

estuary

MINING

The estimation of the mineral deposits of Goa conducted by the Geological

Survey of India from 1961-1968, reveals that depending upon the iron

concentration the ore deposits can be broadly divided into three zones; the

Northern, Central and the Southern. From North to South the iron

concentration reduces and in South Goa, the ore is mainly ferruginous

manganese. Exploitation of mines began in South Goa (through which River

Zuari flows) in the 1950’s so as to meet the industrial demands, which

accelerated within a decade(12)

.

During the early days of mining, production was manual and the demand was

for manganese and ferromanganese. Later on the iron ore mining began and

the demand lead to mechanized operations. In 1980 to 1990 mining became a

highly sophisticated, capital-intensive industry where larger quantities of ore

had to be extracted to avail the economies of scale(12)

. Rapid strides in

exploration of mineral resources to cope with the ever-increasing demand

intensified the mining activities in Goa, forming the backbone of the state

economy (Ganihar 1990, Goa Univ. Unpubl. Ph.D. Thesis).

As stated above, South Goa holds the highest grade of Manganese and

Ferromanganese deposits in the state. So mines in South Goa are the best to

satisfy demands for Manganese. With depletion of high-grade ore reserves and

strict ore quality standards demanded by steel mills, processing has also

undergone changes. Thus all major producers have erected washing and

beneficiation plants. Thus exploitation of mineral deposits is the dominant

industry.

Figure 1b illustrates the mining areas of the state of Goa. Until 1980, there

were a total of 129 industries in the Zuari basin and ten large mines, which

generate 1000-4000 tons of reject per day per mine (Qasim et al. 1981, NIO,

Tech. Report,). Directorate of Mines enumerated the general environmental

problems due to the many opencast mines of Goa. In their report, Mining and

Environmental Management they stated that each year some 30 million tonnes

of rejects are generated and stacked in large dumps. Winds and rains erode

these dumps (mainly during monsoons) to the water bodies. Thus, the

tributaries and estuarine waters contain a high concentration of TSM that

mainly comprises iron and manganese due to mining activities (Nayak 1993,

Dept. Environment Tech. Rep.).

MARMUGAO PORT AND HARBOUR OPERATIONS

The Zuari River being perennial and navigable serve as cheap and easy means

of transport of mining ore. During the monsoons when the Mandovi River

faces problems of bar formations, the Cumbarjua Canal provides sheltered

passage to the Marmugao harbour through the Zuari River(13)

. The Marmugao

Port, one of India’s best natural harbours situated on the southern banks of the

Zuari estuary is close to the coastline. 1990, records for the previous decade

for exports through the Marmugao Port show that it handled more than 10

million tons of iron ore for export annually. Ore transport and handling at the

port can also contribute to the suspended load in the estuary.

Materials and Methods

FIELDWORK

The complete sampling route along the Zuari Estuary was divided into 2

stretches: upstream and downstream. Likewise, the pre–monsoon sampling

was conducted in two episodes. First on the 11th

May 2003 seven samples

were collected onboard Coastal Research Vessel, CRV Sagar Sukti. During

the second sampling phase on 4th

June 2003, 12 surface sediment samples

were collected onboard a hired fishing trawler. The collection of a total of 19

surface sediments was done using a Van Veen Grab. Figure 1a shows the

sampling locations and Table II incorporates the sampling details, including

Total Suspended Matter (TSM) and salinity variations recorded during the

fieldwork.

LAB TECHNIQUES

In order to undertake foraminiferal investigations the sediment samples were

initially washed thoroughly through a 63-micron sieve using a slow shower to

Table II

prevent foraminiferal test breakage. The samples were then subjected to 10ml

of 10% sodium hexa-meta-phosphate and kept over night to dissociate

clumped aggregates of sediments if any. Similarly 5ml of 10% hydrogen

peroxide was added to remove any traces of remaining organic matter and kept

overnight. The samples were washed 5-6 times repeatedly till they became

clean. The sand fractions were then collected over Whatman filter papers and

were oven dried at 60oC. Dried sand was spread on a glass plate, coned and

quartered to obtain a representative fraction of each sample. Later, each of the

small fractions was weighed and spread over a gridded picking tray. Total

foraminiferal specimens (a minimum of 300 specimens) were picked using a

moist brush. All the specimens picked were mounted on gridded faunal slides,

identified up to the species level, and finally counted under a stereo binocular

microscope. The Total Foraminiferal Number (TFN) in each sample were

computed and standardized to 1g dry sediment.

Results

Some unusual specimens that look older than the normal foraminifera have

been encountered at three stations, SASU-11, -13 and -14. These foraminifera

have been named as ‘reworked’, counted separately. Of the 19 surface

sediment samples collected in the Zuari Estuary, SASU-12 and GU-3 to GU-

12 did not yield any foraminifers. Remaining 8 samples have yielded recent

benthic foraminifera, both calcareous and agglutinated forms. None of them

Table III

contained any planktonic specimens. The results of the foraminiferal picking

are tabulated as Table III.

RECENT BENTHICS

The total recent benthic foraminifera show a declining trend towards the head

of the Zuari River, leading to complete absence beyond station GU-2. The

TFN is very high in SASU-1 and SASU–2 and relatively lowers at SASU-11,

13 and 14. The stations at and around the confluence of Cumabarjua Canal and

Zuari River show low or no foraminifera at all. Eg. Stations GU-1 and SASU-

13 (low), where as SASU-12 (Nil). Though the TFN falls drastically at GU-1,

still head-wards GU-2 shows TFN prevalence to be high.

REWORKED FORAMINIFERA

Samples collected at SASU-11, 13 and 14 show the presence of specimens

different in appearance than the normal Recent benthics. They are black to

brown in colour. Silica or Fe- or Mn- oxide has replaced the calcareous test.

They have undergone transport, which is evident by their rounding, polishing,

fracturing and at times absence of test with only the sutures resistant to

abrasion standing out. They appear to be older in age and dull in luster than

the recent benthic foraminifera. This suggests that they have been eroded from

an older deposit and have been re-deposited in the present environment and

thus the nomenclature ‘reworked foraminifera’.

Stations SASU-11 and SASU-13 are located on either sides of station SASU-

14 within the Marmugao Bay. At the central station the number of reworked

specimens are high with a decrease in numbers on either locations.

Discussion

Based on the results, the discussion has been divided in to two parts:

RECENT BENTHIC FORAMINIFERA

Depending upon the quantitative distribution of foraminifera the Zuari estuary

can be divided into three parts: the lower reaches of the estuary marked by a

gradual decrease in TFN away from the sea head wards, the middle reaches by

low TFN and the upper reaches characterized by absence of foraminifera.

The declining trend in the TFN from the sea upstream follows the normal

estuarine distribution pattern; just near the mouth the TFN is very high, and it

falls drastically at GU-1. The absolute absence of Foraminifera beyond station

GU-2 indicates the truncation of the estuarine environment within the Zuari

River Basin and weakening of tidal ingress of seawater. The salinity data

collected during sampling shows that the salinity drops below 32 ppm

upstream beyond station GU-3, which is the beginning of hypo-saline

conditions(14)

. The absence of foraminifera beyond station GU-2 can be

attributed to the fall in salinity causing hindrance to their growth in the study

area.

The ‘low to no’ situation of foraminiferal abundance in areas close to the

confluence of Cumbarjua is supported by the high TSM values. SASU-12 at

the confluence of the Zuari and Cumbarjua is the only station where

foraminifers are absent within the favourable zone. The turbulent hydrography

because of the confluence compliments the extremely high local TSM values

(43.80 to 477.40 mg l-1

) leading to increased turbidity and mechanical

abrasion. This explains the absence of foraminifers at this location and low

TFN at SASU-13 and GU1.

The abrupt rise in TFN at GU-2 could be attributed to favourable salinity and

low values of suspended load.

Though the trend of change in TSM values shows a decreasing trend from

upper reaches to lower reaches (Table II), the relatively low TFN in the bay

(stretch between Cumbarjua and the harbour) needs to be explained.

Considering the repeated reports of ore transport to Marmugao harbour from

the Mandovi basin being redirected through the Cumbarjua, relatively high

TSM values obtained in the bay, especially at the Cumbarjua-Zuari

confluence, are also obvious.

Comparison with previous report: environmental impact assessment

Rao(1)

, based on sediment samples collected in 1972, studied the foraminifera

from the two estuaries and reported a total of 23 species in the Zuari Estuary

(Table IV).

Estimating whether the health of the Zuari estuary has deteriorated or

improved over the past, we compared the present data with the pre-existing

data(1)

. The TSM and the TFN data collected over the years at one particular

station in the bay was plotted (Fig.2). Our sampling station SaSu-11 coincided

with the TSM sampling stations; the absolute TFN (337) at this station was

thus used. 2 stations of Rao (11 and 12) fall on either sides of the TSM

sampling station; thus the average TFN of these stations (356/2 = 178) was

used.

Turbidity has been known to affect foraminiferal populations, since light

penetration is inversely proportional to turbidity. High total suspended matter

(TSM), thus high turbidity inhibits photosynthetic activity, reducing nutrient

material. In different parts of the world, anomalous foraminiferal populations

have been attributed to increase in the amount of suspended material in the

Table IV

Fig.2

water(15, 16, 17)

. Reduced benthic foraminiferal populations have been reported

from areas of high suspended matter(18, 19, 20)

. TSM acts as a limiting factor

along coastal zones, particularly where there are river mouths(21)

. Studies have

also shown that the concentration of TSM in bottom waters is always higher

than that of surface waters in the estuarine regions (Nayak 2004, Personal

communication).

Even in the present context, a similar relationship between TSM and TFN is

seen. The TSM data over three decades (Fig.2) shows a gradual reduction in

values. Inversely the TFN shows a significant increase. It is interesting to note

that the maximum TFN recorded by Rao was 1143 while the present study

records a maximum of 3057 specimens within the estuary. There also has been

an increase in the Total Species Number (TSN). Rao reported 23 species

whereas the present study records 50 species of foraminifera (Table IV).

This indicates that the health of the estuary has possibly improved. In order to

support the present findings we need to look for the reason responsible for the

improvement in the environment.

As the manganese mining has lost demand, ore handling, barging and

transport of ore within the Zuari basin has apparently come down, thereby

suggesting lowered contribution of its share to TSM in the estuary. Reduction

in TSM over the years seems to have led to decrease in the turbidity thereby

improving the penetration of light in the estuarine waters and creating

favourable conditions for the growth of foraminifers.

Demand for Iron ore has been on a gradual rise since the beginning (Fig.3a).

In the mid 70’s it reached a high and then stabilized to more or less the same.

However Manganese (Fig.3b) and Ferromanganese (Fig.3c) show decreasing

trend in production.

So over the past three decades, the mining in South Goa has lost priority as it

is houses mostly manganese and ferromanganese mines. Out of 581 leases,

which were in force only 211 were reported working during 1980. (Figure 1b

illustrates the mining areas of the state of Goa). To begin with, intense mining

operations were carried out in South Goa (Sanguem and Quepem talukas)

when there was demand for manganese ore, in the early 50’s. Later on with

increasing demand for iron ore since the early 70’s, mining activities shifted to

North Goa (Bicholim taluka). In Sanguem and Quepem talukas the mining has

now been greatly reduced (Table V) and most of the mines have remained

inactive for long(13)

. It should also be noted that approximately half of the

mining areas in Sanguem and Ponda talukas fall under the watershed of

Mandovi Estuary. The reduction in the washing of mining rejects into the

Zuari due to reduction in mining operations in the adjoining areas is evident

Fig. 3

by the reduction in the values of TSM collected over the time and enumerated

in Figure 3.

Comparison between the two Goan Estuaries

Monitoring the Mandovi River estuary, using foraminifera in surface

sediments shows that within 18 years, the TFN came down considerably from

10-139 (1972) to 2-42 (1990) specimens per gram sediments. The Total

Species Number (TSN) also fell, from 18 in 1972 to 5 in 1990. These had

been reported to indicate adverse effects of continued increase in the

suspended load due to mining activities in its catchment area(10)

.

The present study clearly indicates a considerable rise in the numbers as well

as the diversity of foraminifera in the Zuari estuary, exactly in contrast to the

adjoining Mandovi Estuary, in its north. These results corroborate with

progressive fall in the values of TSM and status of mining activities within the

basin.

The major shift in mining area from South to North over the past three decades

seems to explain the simultaneous but opposite situations in two adjoining

estuaries. Thus it can be said that foraminifera can reliably be used as an

Table V

indicator of progressive and retrogressive mining pollution, as demonstrated in

this study.

REWORKED FORAMINIFERA

All the locations of SASU-11, -13 and –14 lie within the bay, with SASU-14

occupying the central location and the other two on either side. The central

location also shows maximum number of reworked specimens (406 g-1

sand).

Occurrences of reworked specimens were reported earlier from the shelf

region of Daman(22)

and also in the vicinity of the Zuari River Estuary (8, 23)

.

Recently based on the distribution of reworked foraminifera in the Mandovi

estuary, Nigam et al.(8)

have postulated the possibility of finding a shelly layer

along the banks of River Mapusa (Fig.1a), deposited during a high sea stand in

the past.

Finding reworked fauna in the Zuari Estuary exhibits the possibility of a

similar situation in the study area. Two shelly layers deposited during a higher

sea-stand in the geological past ~6,000 years ago, have already been reported

(Fig.1a) along the Northern (24)

and Southern(23)

banks of Zuari. These

sampling locations with reworked foraminifers lie within the stretch of the

estuary right between the two shelly layers. Thus, it can be concluded that

reworked foraminifera have been eroded from those shelly layers and are

being re-deposited within the estuary.

Away from the location SASU-14, the number of reworked foraminifers goes

down on account of dilution away from the source.

Conclusions

1. The surface sediments in the middle and lower reaches of Zuari estuary

have yielded a Total Foraminiferal Number (TFN) ranging from 16 to

3057 per gram sediment in the estuary, whereas upper reaches shows

total absence of fauna.

2. There is a normal inverse relationship between the TSM values and the

foraminiferal distribution in the estuary; higher TFN in the areas with

lower TSM and vice-versa.

3. The direct relationship of foraminifera with salinity is also clearly

evident. The foraminifera are absent in lower salinity conditions in the

upper estuary.

4. Samples SASU-11, -13 and -14 collected within the stretch between

Cortalim and Vasco yielded reworked foraminifera. The reworked

foraminifera are being derived from 2 already reported elevated shelly

layers on either banks of the Zuari estuary.

5. A comparison with a previous report (Rao 1974) shows a substantial

increase in the Total Foraminiferal Number (TFN) as well as Total

Species Number (TSN) within the Zuari Estuary over the past three

decades.

6. Increase in TFN and corresponding decrease in TSM values over the

years seems to indicate a possible reduction in the mining activities in

the catchment area of Zuari. This could be suggestive of an

improvement in the environmental health of the Zuari Estuary, which

needs further confirmation.

7. Foraminifera can be used as proxies to indicate mining pollution of

both kinds- progressive and retrogressive.

ACKNOWLEDGEMENTS

The authors are thankful to Dr. Satish R. Shetye, Director of National Institute

of Oceanography for their encouragement and kind permission to publish this

report. We are also grateful to all the cruise members on board the two vessels,

CRV Sagar Sukti and fish trawler Datta Ravalnath, as well as Mr. Abhijit

Mazumder and Mr. Rajiv Saraswat for their help in sample collection. We

thank Dr. P.D. Naidu, Scientist, NIO, for reviewing this manuscript and his

suggestions.

LITERATURE CITED

1. K.K. Rao, “Ecology of Mandovi and Zuari estuaries, Goa: distribution

of foraminiferal assemblages” Indian J. Mar. Sci. 3, 61-66 (1974).

2. V. Yanko, A.J. Arnold and W.C. Parker, “Effects of marine pollution

on benthic Foraminifera” Modern Foraminifera (ed. B.K. Sen Gupta,

Kluwer Academic Publishers, Great Britain, 1999) pp.217-235.

3. E. Alve, “Benthic foraminiferal responses to estuarine pollution: a

review” J. Foram. Res. 25, 190-203 (1995).

4. R. Nigam, R. Saraswat and R. Panchang, “Application of Foraminifers

in ecotoxicology: retrospect, perspect and prospect” Environment

Intern. (In press, 2005).

5. M. G. A. P. Setty, “Pollution effects monitoring with foraminifera as

indices in the Thana Creek, Bombay Area” Intern. J. Environmental

Studies 18, 205-209 (1982).

6. M.G.A.P. Setty and R. Nigam “Benthic foraminifera as pollution

indices in the marine environment of west coast of India” Rev. Ital. de

Paleontol. de Stratigrafi. 89, 421-436 (1984).

7. S.G. Dalal, “Relationship between environmental parameters and

foraminiferal species in Mandovi and Zuari estuaries” Mahasagar Bull.

9, 9-13 (National Institute of Oceanography, India, 1976).

8. R. Nigam, R. Panchang, and P. Banerjee, “Foraminifera in surface

sediments of Mandovi River Estuary: indicators of mining pollution

and high sea stand in Goa” J. Coast. Res. 21(4) (In press, 2005).

9. C.T. Schafer, E.S. Collins and J.N. Smith, “Relationship of

foraminifera and thecamoebian distributions to sediments

contaminated by pulp mill effluent; saguency fiord, Quebec, Canada”.

Mar. Micropalaeontol. 17, 255-283 (1991).

10. R., Nigam, G.N. Nayak, and S. Naik, “Does Mining Pollution affect

the foraminiferal distribution in Mandovi estuary, Goa, India?” Rev.

Paleobiol. 21(2), 673-677 (2002).

11. S. Z. Qasim, and R. Sen Gupta, “Environmental characteristics of the

Mandovi-Zuari estuarine system in Goa” Estuar. Coast. Shelf Sci. 13,

557-578, (1981).

12. S.V. Salgaokar, “Goan iron ore industry, historical background and

present status” A Report- Seminar on mining and environmental

preservation- The Goan mineral ore industry, mining and the

environment (Goa Mineral Ore Exporter’s Association- GMOEA,

1991) pp. 32.

13. G.N. Nayak, “Impact of mining on environment in Goa, India”

(International Publishers New Delhi, 2002) pp.112.

14. J.W. Murray, “Ecology and Palaeoecology of Benthic Foraminifera”

(Longman Scientific and Technical, New York, 1991) pp. 397.

15. L. Berthois, Y. Le Calvez and A. Crosnier “Repartition des

foraminiferes dans les sediments du plateau continental camerounais;

essai d’ecologie” Acad. Sci. 266(7), 660-662 (1968).

16. T. Uchio “Influence of the River Shinano on foraminifera and

sediment grain-size distributions” Pap. Mar. Geol. 411-428 (Univ.

South Calif. Press, 1964).

17. D. Vedantam and M.S. Rao “Recent foraminifera from off Pentakata,

east coast of India” Micropalaeontol. 16(3), 325-344 (1970).

18. E.H. Myers “Ecologic relationship of some recent and fossil

foraminifera” Nat. Res. Counc. (Div. Geol. Geogr., Ann. Rept., Appen.

2, 1942).

19. W.E. Frerichs “Distribution and ecology of benthonic foraminifera in

the sediments of the Andaman Sea” Contr. Cushman Found. Foram.

Res. 21(4), 123-147 (1970).

20. R. Nigam “Living benthonic foraminifera in a tidal environment: Gulf

of Khambat (India)” Mar. Geol. 58, 415-425 (1984).

21. E. Boltovoskoy and R. Wright, ‘Recent Foraminifera’ (Dr. W. Junk

Publishers, The Hague, 1976) pp.515.

22. R. Nigam, and M.G.A.P. Setty “Palaeogene reworked foraminifera in

the recent sediments of Daman, western India” Proc. 3rd

Indian Geol.

Cong. 273-280 (1980).

23. R. Nigam, “Potentiality of Foraminifera in deciphering palaeosea

levels” India’s Exclusive Economic Zone (ed. S.Z. Qasim and G.S.

Roonwal, 1996) pp.225-232

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Times 1& 8 (30 Nov. 2002).

Table I: Existing literature on the foraminifera from the Estuaries of Goa

No. Author & Year Remarks

1 Rao 1974 Living population poor in the lower reaches of Mandovi-

Zuari Estuary, areas of high organic carbon exhibited low

diversity assemblages

2 Dalal 1976 Statistical analysis of Rao’s 1974 data

3 Naik 1997

Distribution, ecology and environmental significance of

foraminifera in sediments of Mandovi Estuary (Goa),

with special reference to mining pollution (M.Sc.

Dissertation at NIO, Goa, India)

4 Nigam et al. 2002 Reduction in diversity and TFN due to mining pollution.

5 Banerjee 2002 Environmental Monitoring of Mandovi River Estuary

with Reference to Mining pollution, using Foraminifera

as a tool (Project Report at NIO, Goa, India)

6 Nigam et al. 2005 Reduction in diversity and total foraminiferal number

due to consistent increase in TSM. Reworked

foraminifera suggesting presence of shelly layer along

banks of River Mapusa.

Table II: Sampling locations and related details

Sample

Number§

Location Water

Depth

TSM

(mg/l)

Salinity

(ppm)

Latitude Longitude S$ B

# S

$ B

#

GU-12 15016`16`` 74

006`58`` 4 7.20 20.00 2.5 1.5

GU-11 15015`99`` 74

006`19`` 5 6.00 24.00 2.5 3

GU-10 15016`42`` 74

005`22`` 3 13.90 31.1 5 5

GU-9 15016`55`` 74

004`41`` 5 24.1 18.2 9 10

GU-8 15017`87`` 74

003`73`` 4 36.8 39.4 12.5 15

GU-7 15018`34`` 74

001`11`` 3.5 50.9 96.7 18 18.5

GU-6 15019`40`` 74

000`49`` 4 60.3 115.70 22.5 22

GU-5 15020`62`` 74

000`49`` 7 73.4 142.10 25 25

GU-4 15022`10`` 73

058`57`` 9.5 136.8 259.30 32.5 30.5

GU-3 15022`59`` 73

057`51`` 10 69.2 74.9 33.5 33

GU-2 15024`37`` 73

056`82`` 8 130.8 139.4 35 36

GU-1 15024`42`` 73

054`88`` 4 398.10 477.40 35 35

SASU -12 15024`21`` 73

055`14`` 4 43.80 60.90 33 33

SASU -13 15024`46`` 73

053`47`` 5 23.5 31.00 36 37

SASU -14 15024`49`` 73

051`56`` 3 41.8 -- 36 --

SASU -11 15024`56`` 73

050`24`` 3 31.1 35.60 34 35

SASU –10 15025`04`` 73

042`41`` 12 21.3 66.40 32 33

SASU -2 15025`00’ 73

046`00’ 11 -- -- 37 35

SASU -1 15025`00’ 73

045`30`` 11 -- -- 35 38

§Locations arranged from upper to lower reaches of Zuari Estuary

$S= Surface;

#B= Bottom

Table III: TFN per gram sediment

Sample Number§ TFN/gm sample

Recent Benthics

Reworked

G U-2 1233 Absent

G U-1 16 Absent

Sasu –12 Nil Absent

Sasu –13 22 15

Sasu –14 203 406

Sasu –11 337 27

Sasu –10 3057 Absent

Sasu –2 7135 Absent

Sasu –1 3174 Absent

§Locations arranged from head to mouth of Zuari Estuary

Table IV: Comparison of Foraminiferal distribution in Zuari River

Estuary in 1972 and 2003

Samples (K.K. Rao 1974) (Present Study)

Total Species No. 23 50

Ammonia beccarii

Bolivina nobilis

Discorbis vilardedoana

Elphidium articulatum

Elphidium crispum

Elphidium incertum

Fissurina lueida

Lagena laevis

Lagena semistriata

Miliammina fusca

Nonion boueanum

Nonion scapha

var. parkinsoniana

Quiqueloculina costata

Quiqueloculina

dimidiata

Quiqueloculina

lamarekiana

Quiqueloculina

seminulum

Quiqueloculina

vulgaris

Spiroloculina costifer

Ammobacculites periscus

Ammobaculites agglutinans

Ammobaculites americanus

Ammobaculites subcatenulatus

Ammonia parkinsonia

Ammonia sobrina

Ammonia tepida

Ammotium sp.

Asterorotalia dentata

Asterorotalia inflata

Bolivina exilis

Bolivina limbata

Bolivina striatula

Bulimina marginata

Cuneata Arctica

Elphidium advenum

Elphidium craticulatum

Elphidium indicum

Elphidium sp.

Spiroloculina

planissima

Triloculina

trigonula

Trochammina

globigeriniformis

Trochammina

inflata

Eponides sp.

Glabratella patelliformis

Globigerina bulloides

Hauerinidae

Nonion asterizans

Nonion depressula

Nonion pacifacum

Nonion scaphum

Nonionides elongatum

Nonion sp.

Pararotalia minuta

nipponica

Poroeponides

cribrorepandus

Poroeponides lateralis

Quinqueloculina costata

Quinqueloculina

schlumbergeri

Quinqueloculina

seminulum

Quinqueloculina tropicalis

Quinqueloculina polygona

Quinqueloculina sp.

Spiroloculina communis

Spiroloculina affixa

Spiroloculina exima

Spiroloculina indica

Spiroloculina sp.

Textularia agglutinans

Textularia conica

Textularia earlandii

Thurammina albicans

Triloculina sp.

Triloculina rupertina

Trochammina

globigeriniformis

var. pygmaea

Table V: Area under mining lease (area in hectares) in South Goa

Taluka

Area under

mining lease

as in 1973

Area under

mining lease as

in 1993

Percentage

reduction in

mining area

Marmugao 11 ---- 100%

Quepem 5,026 2,123 42.24%

Salcete 1,610 867 53.85%

Sanguem 31,481 16,690 53.01%

Ponda 4,614 1,140 24.70%

Total area 42,742 20,820 48.71%

FIGURE LEGENDS

Fig.1: a. Study Area; b. Mining areas and political boundaries of Goa

Fig. 2: Variation in TFN with reference to TSM and mining

production over the years, within the catchment area of the

Zuari estuary

Fig. 3: Mining Production in Goa till 998 (a) Iron (b) Manganese

(c) Ferromanganese

Fig.2: Variation in TFN with reference to TSM and mining production over the years, within the catchment area of the

Zuari Estuary

0

20

40

60

80

100

120

140

160

180

200

1970 1972 1980 1981 1983 1990 1998 2002

To

tal

Su

sp

en

ded

Matt

er

(TS

M)

mg

/l

-50

0

50

100

150

200

250

300

350

400Legend

Pre-monsoon

Monsoon

Post-monsoon

TFN

Production of

Manganese and

Ferro-manganese in

tonnes (x103) in the

catchment area of

the Zuari Estuary

Fig. 3: Mining production in Goa till 998 (a) Iron (b) Manganese

(c) Ferromanganese

0

50000

100000

150000

200000

250000

1951

1953

1955

1957

1959

1961

1963

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

Ton

ne

s

T o nnes

0

2000000

4000000

6000000

8000000

10000000

12000000

14000000

16000000

18000000

20000000

1951

1955

1959

1963

1967

1971

1975

1979

1983

1987

1991

1995

Ton

ne

s

T o nnes

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

195119

5319

5519

5719

5919

6119

6319

6519

6719

6919

7119

7319

7519

7719

7919

8119

8319

8519

8719

8919

9119

9319

9519

97

Ton

ne

s

T o nnes

a

b

c