-
53
Silva Balcanica, 20(1)/2019 DOI: 10.6084/m9.figshare.8234381
WATER REPELLENCY IN MARITSA-IZTOK OPEN CAST COAL MINE SOILS IN
BULGARIA
Plamen Ivanov, Ivaylo Kirilov, Martin Banov, Biser Hristov, Toma
Shishkov, Irena Atanassova
N. Poushkarov Institute for Soil Science, Agrotechnology and
Plant Protection - Sofia
Abstract
The study presents assessment of water repellency (WR) in
non-humus reclaimed mine soils from the region of Maritsa-Iztok
Mines, Bulgaria. Soil samples from two experimental plots (under
black pine and without vegetation), from depths 0–5 (10) cm and
10–20 cm, in different seasons (spring and summer) were studied.
Soil water repellency (SWR) was assessed by water drop penetration
time (WDPT) before and after laboratory heating at 65°C. Variation
in WDPT of soil samples in both seasons was established before
heating. The longest time was measured in April at the
non-vegetated site. At the pine-vegetated site, these values are
lower, but are typical for most of the samples. After heating, a
decrease of WDPT at both sites was observed. Sub-surface samples
show similar fluctuations between seasons before heating. Unlike in
spring, extremely water repellent samples were found at the
pine-vegetated site in summer. Different WR is typical for most of
the sampling points at the non-vegetation site. WDPT changes
randomly in closer values between seasons. After heating
sub-surface samples, water drop penetration time at both
experimental plots also decreases. The percentage of extremely
water repellent samples increases in summer. After heating, the WR
partially decreases over both seasons, with sharp decline of the
extreme WR in summer. We speculate that the decrease of SWR after
heating is caused by conformational and/or structural and
compositional changes in WR causative agents.
Key words: mine soils, soil water repellency (hydrophobicity),
water drop penetration time
INTRODUCTION
Mining activity is associated with negative impact on soil cover
by creating spoils from deposited waste materials accompanying the
extraction of ores (Petrova et al., 2009). Sometimes the slopes of
spoils or deposition of unsuitable substrates for reclamation on
the surface impede the development of vegetation and cause erosion
(Marinov, 1995; Hristov, Pencheva, 1995; Petrova et al., 2009). On
the other hand, it is possible that the extraction process is
accompanied by loss of humus soil (Petrova, 1989). Thus, the soil
deficiency hinders its subsequent use for reclamation of disturbed
areas (Etov, Slavova, 2011) and necessitates performing non-humus
reclamation (Banov, 1989; Etov, Slavova, 2011). In these cases,
when the deposited geological materials are characterized by heavy
texture, the vertical water flow and the movement of different
compounds in the soil profile are hampered (Hristova, 2013).
Similarly, under these conditions, attention is directed to soil
water repellency (SWR), which depends largely on factors such as
organic matter, soil texture, soil-forming materials, vegetation,
temperature, etc. (DeBano, 1981; Kořenková et al., 2015; Mao et
al., 2016; Simkovic et al., 2008).
-
54
Th e present study aims for fi rst time to undertake a
comprehensive study in the changes in water repellency (WR) in mine
soils in Bulgaria under the infl uence of diff erent factors at
natural conditions in the fi eld (spring and summer period) and
after heating in the laboratory.
MATERIAL AND METHODS
Th e paper presents a continuation of the studies on soil water
repellency (SWR) in mine soils from the area of Obruchishte,
Maritsa-Iztok Mines, Bulgaria carried out in 2017. Overview of the
study site is presented in Fig. 1. Sampling and laboratory studies
were conducted simultaneously with the analytical activity by the
methodology used by Atanassova et al. (2018).
In summary, two experimental sites located in an area with
geological materials deposited during coal extraction of mine
Troyanovo – 1 in the 1970s were selected for the research. Th e
spoils were formed by mixing geological materials, i.e.
yellowish-green, greyish–green and black clays, containing coal. In
addition, coal ash from incineration of coal in the thermal power
stations had been added to ameliorate soil acidity. Th e fi rst
site is located in a pine-vegetated forest (Pinus nigra) and the
second at a non-vegetated area close to the fi rst site. Point
grids with Δ 2 m, ~ 40 m2 were constructed on the selected sites,
for subsequent sampling. Field studies and soil sampling have been
carried out in during two fi eld trips diminishing in the spring
(beginning of April) and summer (July) seasons.
Soils were classifi ed according to WRB (IUSS Working Group WRB,
2015) as Spolic Technosols (Dystric, Clayic, Laxic). Th e climatic
characteristics of the region are as follows: 5th April, 10.3°C,
83% relative humidity, and 25th July, 27.8°C, 50% relative
humidity.
Fig. 1. Overview of the study site: pine-vegetated and
non-vegetated areas
-
55
In April, soil samples were taken at a depth at 0–5 cm and 10–20
cm for the pine-vegetated site and 0–10 cm, 10–20 cm for the site
without vegetation, because WR was observed on the field at these
depths. Upon arrival in the laboratory, the samples were reduced in
size by coning and quartering to obtain a representative sample,
then dried at room temperature, crushed and sieved through a 2-mm
sieve. Soil samples were later placed in Petri dishes and SWR was
determined by the water drop penetration time (WDPT) test after
Doerr et al. (2002) at 17–18°C and humidity 70–75%. The analysis
was carried out by placing three water drops of distilled water ~
80 μL on the sample surface (in duplicate) and measuring of WDPT of
every water drop. In the next step, the analysis was continued by
heating the samples in a thermostat (NUVE EN500) at a temperature
of 65°C for 24 h to simulate maximum surface soil temperatures in
summer. After equilibration at room temperature, WDPT was measured
again using the same methodology. Median values were determined and
interpreted in the analysis.
In summer (July), a second field trip to the survey sites was
carried out and sampling took place at the same points and depths
at the experimental plots. Samples were processed and tested in the
same way as those in spring at 22-23°C and 67–72% relative
humidity.
The degree of SWR was determined using the scale of classes of
Dekker, Ritsema (1996): wettable or non-water repellent (< 5 s);
slightly (5–60 s); strongly (60–600 s); severely (600–3600 s); and
extremely water repellent (> 3600 s). Currently, the data on
WDPT medians of soil samples before heating was discussed in
connection with microbiological properties of studied Technosols
(Nedyalkova et al., 2018a, b).
RESULTS AND DISCUSSION
The overview of obtained data shows an interesting trend in the
surface 0–5 cm layer of pine-vegetated site associated with
different degrees of variation in WDPT measurements from both field
trips (in April and July) between the individual points of the grid
before heating of samples (Fig.2a, 2c). Only at point 1/2 the WDPT
is almost identical and determines the samples as extremely water
repellent according to the relevant scale (Dekker, Ritsema, 1996).
The variation in measurements (from slightly to extremely water
repellent) before heating is also characteristic of surface samples
(0–10 cm) from the non-vegetated site during the seasons (Fig. 2a,
2c). This specificity may be due to the seasonal weather conditions
already mentioned in other studies (Dekker et al., 1998; Oostindie
et al., 2013) or because of randomly distributed coal particles and
ashes (Atanassova et al., 2018),which are often observed in
open-cast mine spoils (Banov, 1989; Petrova, Gencheva, 1991;
Tsolova, Banov, 2011; Hristova, 2013). Similar variability in WDPT
between different seasons before laboratory heating also
characterizes samples at depth of 10–20 cm. This fact is emphasized
clearly at the pine-vegetated site, where SWR is lacking in spring,
with exception of slightly water repellent point 2/2 with 128
seconds WDPT (Fig. 3a). Two extremely water repellent samples (1/2
and 2/2) are registered in the summer under pine vegetation (Fig.
3c). On the other hand, the WR of slightly to
-
56
extremely WR samples at the non-vegetated site, also changes
randomly but in closer values between seasons (Fig. 3a, 3c).
From the analysis for determination of SWR in April we found
that, after heating in the thermostat, WDPT decreases in the
surface samples (0–5 cm and 0–10 cm) from both experimental sites
(Fig. 2a, 2b). Th is downward trend in WDPT is maintained for all
surface samples from the same points under pine vegetation and
without vegetation taken during the second fi eld trip (Fig. 2c,
2d).
Th e comparison of WDPTs for the surface spring samples before
heating indicates that the highest value of WDPT is measured at
point 2/2 from the grid at the non-vegetated site. At the
pine-vegetated site, these values, although extreme, are lower and
are typical for two points (1/2 and 2/1) from the sampling area
(Fig. 2a).
Subsequently, after heating in a thermostat, the samples with
registered extreme water repellency in April kept their ratio to
each other, although with lower WDPT values (Fig. 2b). In this
case, the surface layer of pine-vegetated experimental site
contains more extremely hydrophobic samples than those at the
non-vegetated site. However, when comparing the samples from both
sites taken in diff erent seasons before heating (Fig. 2a, 2c), we
can conclude that, unlike in spring, three samples in July at the
non-vegetated area (points 1/2, 2/2, 2/3) are extremely water
repellent, despite of the lower values for sample 2/2 at the same
site from April. Regarding pine-vegetated site, the samples with
the longest measured WDPT from spring (samples 1/2, 2/1) maintain
comparatively similar and even higher values in summer, while
others (samples 1/1, 1/3) vary considerably in the measured
indicator (WDPT) (Fig. 2a, 2c).
Fig. 2. Water Drop Penetration Time in surface layer of
experimental sites (median values)
-
57
Atanassova et al. (2018) assume that SWR in the soils from the
pine-vegetated site can be a result from the presence of lignite
particles and wax compounds from vegetation. In addition, the
authors establish signifi cant correlation of WDPT with soil
organic carbon (SOC) (RSOC = 0.699* p< 0.05), and its fractions
(humic organic carbon (HOC) RHOC = 0.499*) and fulvic organic
carbon (FOC) RFOC = 0.442*). Similarly, the data show that SOC, HOC
and FOC correlate signifi cantly with cation exchange capacity
(Atanassova et al., 2018). Kořenková et al. (2015) also observe
correlation between SWR and organic carbon and consider that this
is due to accumulation of raw organic matter. Regarding the
non-vegetated site, Atanassova et al. (2018) suggest that the
hydrophobic lignite compounds are most likely to cause greasiness
of clays and increase of SWR.
DeBano (1981) notes that when a soil contains several percent
organic matter it can show some WR, in the context of heating and
fi re eff ect. In our study, during the next stage of laboratory
measurements, the surface layer samples taken in July were
characterized by drastically shorter WDPT after heating at 65°C for
24 h (Fig. 2d). Similarly extreme water repellent values between
seasons after heating retain only samples from point 2/1 in the
pine-vegetated site (Fig. 2b, 2d). Th e observed trend is typical
without exception also for the summer samples at depth of 10–20 cm
in both experimental sites – the pine-vegetated site and the
non-vegetated site (Fig. 3d). However, samples from the
pine-vegetated site from the second fi eld trip with a strong
pre-heating WR (samples 1/2 and 2/2) (Fig. 3c), stand out after
heating, although with drastically reduced time values (sample 1/2,
113 s; sample 2/2, 100 s) (Fig. 3d).
Dekker et al. (1998) also measured decline in WR after heating
of samples from two sites with sandy soils at 65°C. A decrease of
SWR after heating at 105°C for 14 days
Fig. 3. Water Drop Penetration Time in subsurface layer of
experimental sites (median values)
-
58
or heating at 200°C for 24 h was also recorded by Roy, McGill
(1998). In our case, the shortened WDPT after heating is inherent
for July samples (Fig. 2d, 3d). However, partial deviation from
established trend was observed in spring samples at non-vegetation
site, where two points (1/2 and 1/3), at a depth of 10–20 cm,
slightly increased their higher values of WDPT after heating,
against of two others (2/1 and 2/3), which accelerate the
absorption of water drops (Fig. 3a, 3b). In this regard, Lichner et
al. (2002) reported for inconsistencies in the data of several
studies on the effect of heating temperature on SWR.
In the present study, we compare the WDPT of soil samples by the
median, which is determined between three water drops for each
sample (Doerr et al., 2002; Papierowska et.al., 2018). In this
regard, we have to note, that in spite of sample averaging and
collecting a representative soil sample, in some samples we found a
significant difference in the measured WDPT between the three water
drops that fall into two or even three levels of Dekker, Ritsema
(1996) scale. Such examples are the two subsurface samples from the
non-vegetated site before heating for sample 2/1 (61 s, 5738 s,
1090 s) in April and sample 1/2 (405 s, 7320 s, 795 s) in July. On
the same site WDPT of sample (1/2, 10 – 20 cm), increased slightly
after heating (Fig. 3a, 3b), but the maximum time interval differs
significantly (2500 s before heating and 10 800 s after heating).
We assume that one of the reasons for such variation is the
heterogeneity in composition of the geological materials
constituting the reclaimed mine soils, which was attributed by
Bachmann et al. (2013) to be due to either organic matter covering
the mineral grains as coatings or existing as adsorbed nano-sized
microaggregates, therefore causing high spatial variability of
SWR.
SWR can be expected at small scales. In this regard, Secu et al.
(2015) describe the human impact on soils as one of the factors
determining the high spatial variability of the degree of
infiltration in urban soils. Earlier, Orfánus et al. (2008) also
found spatial variability in water impermeability of Regosols in a
pine forest, suggesting that the reason for this lies in soil biota
and vegetation. The authors add that this variability is high even
at soil sample level with area of 22 cm2. On the other hand,
Lichner et al. (2007) suggest for influence of soil biota and
vegetation on soil physical properties, which may be related to
hydrophobic coating of soil particles.
When comparing the distribution of samples from experimental
sites between different levels of WR, we found that before heating
the surface layer (0–5 cm) from spring for the pine-vegetated site,
33% of the samples were extremely, 17% severely and 50% slightly
water repellent. After heating, regardless of the lower WDPT
values, the extremely water repellent samples were still 33%. The
same percentage are also the strongly water repellent samples.
However, the observed decline in WDPT after heating has led to the
presence of 17% wettable samples in the pine-vegetated site
surveyed in spring (Fig. 4a). Compared to the April field trip, the
proportion between the different levels of water repellency in
summer before heating changes in the direction of increasing the
extremely water repellent samples to 50%, reduction of slightly
water repellent samples to 33% and establishment of 17% wettable
samples. Here we will note that the share of wettable samples in
summer before heating is equal to that established in spring but
after heating (Fig. 4a).
-
59
Compared to the pine-vegetated site, in April, the samples with
extreme SWR in the surface layer (0–10 cm) of the non-vegetated
site before heating are less (17%). Similar is the distribution of
slightly and severely water repellent samples (Fig. 4c). Th e
highest is the share of the strongly water repellent samples (50%).
In this case, wettable samples are not registered. Here, we observe
equal proportions of the extremely water repellent samples after
heating. However, measurements from the spring fi eld trip have
shown a clear tendency for increase in samples with lower SWR as
well as lack of such after heating (17% – strongly water repellent,
33% – slightly water repellent, 33% – wettable) (Fig. 4c).
During the second fi eld trip, extremely water repellent samples
in the surface of the non-vegetated site increase up to 50% before
heating. Wettable samples are not registered, just like in April.
However, after heating of summer samples, extremely water repellent
samples in the non-vegetated site are not detected. In this case,
samples exhibit proportionality in their distribution among the
other levels of water permeability with a clear tendency for a
decrease in SWR (17% – severely water repellent, 17% – strongly
water repellent, 33% – slightly water repellent, 33% – wettable)
(Fig. 4c).
Notably diff erent trends are observed with SWR in the
subsurface layers (10–20 cm) of sampled sites. Th is fact is well
expressed at the pine-vegetated site, where the samples without
registered SWR predominate. Th e observed specifi city is most
pronounced during the spring fi eld trip where only 17% of
subsurface samples are strongly water repellent before heating and
the remaining 83% are wettable. After heating, the water repellency
of the samples disappears completely (at a depth of 10–20 cm).
On the other
Fig. 4. Water repellency ratio in sample points from
experimental sites (median values)
-
60
hand, 33% of the samples from July field trip possess extreme
SWR before heating. However, 17% of the other subsurface samples
are slightly water repellent and 50% wettable. After heating, the
WDPT declines again in these samples, 33% of which are strongly
water repellent and 67% wettable (Fig. 4b).
Not so extreme is the change in the degree of SWR in subsurface
layer (10–20 cm) of the non-vegetated site. However, there is again
variation in WR in the downward direction of WDPT after controlled
heating. From the field trip in April, the highest percentage of
samples have severe WR (50%), 17% are strongly and 33% – slightly
water repellent. After heating, severely water repellent samples
decline to 17%. The same percentage are the wettable ones (Fig.
4d). In summer, before heating, WDPT measurements for the
subsurface samples from the non-vegetated site show distribution
among all classes of Dekker, Ritsema (1996). Strongly water
repellent samples (33%) predominate. The rest have the same ratio
in the other levels (17%). After heating, a change in this
distribution occurs. Wettable samples remain, and all the others
(83%) are characterized with slight SWR (Fig. 4d).
So far, we presented the share distribution of samples from the
experimental sites between different SWR classes, by comparing the
percentages of samples from each site and depth separately. Thus,
we have found the trends in changing distribution over the seasons,
at different depths, with different vegetation, and before and
after controlled laboratory heating.
However, in order to obtain more complete and generalised
picture of the changes in SWR of the studied areas, we have
calculated the proportional variations between all tested samples.
Thus, the comparison between different seasons, as well as before
and after heating, was performed on all samples from every field
study (48 in total).
First, we will pay attention to the spring samples before
heating in the thermostat, which are characterized by slight
predominance of strong to extreme SWR classes over the slightly
water repellent and wettable samples (Fig. 5а).
After the second field trip in July, the share of slightly water
repellent (25%) and wettable samples (21%) remains, but the
extremely water repellent samples increase significantly (38%),
unlike of severely (4%) and strongly water repellent (13%) (Fig.
5b). We believe that the cause for this change are the seasonal
weather conditions, which has been already noted in other studies
(Dekker et al., 1998; Oostindie et al. 2013). At the same time,
during April laboratory heating there was no significant change in
the percentage of the extremely water repellent samples, but it was
clearly observed that the wettable samples increase twice to 42%,
in contrast to the slightly to severely WR (Fig. 5a). Therefore, we
assume that the controlled sample heating influences the SWR, but
in direction of its partial reduction, with maintaining the ratio
of extremely water repellent samples (13%). In addition, we will
note the similar increase in wettable samples up to 38% after
heating summer samples (Fig. 5b). In this case, the share of
slightly and strongly water repellent samples also increases, but
this increase is connected with drastic decline of samples with
extreme WR to 4%. This further confirms the observed influence of
laboratory heating on the partial reduction of SWR in the samples
from the studied
-
61
sites (Fig. 5b). It has been found that there exist seasonal
variations of SWR which is associated more with hot (warm) and dry
periods and decreases during colder and wet conditions (Doerr et
al, 2000; Leighton-Boyce et al., 2005).
Putative mechanisms of SWR reduction during heating at 65°C.Th
ere are several possible mechanisms that may function during
heating of
water repellent soils in the thermostat. One possibility is
conformational changes in organic compounds during heating, leading
to liberation of hydrophilic sites on the soil surface as
speculated by Hallet (2007). Another reason could be partial
destruction or transformation of hydrophobic compounds into
compounds of higher polarity, which will also decrease WR. Chemical
changes in organic compound composition have been found after
heating water repellent soils at 300°C resulting in an increase of
SWR (Atanassova, Doerr, 2011). A third possibility could be
production of hydrophilic compounds due to microbial lysis or
changes in microbial diversity and production of polar metabolite
products during heating (Norris et al., 2002).
Th e diff erent behaviour of water absorption by the studied
soils in the fi eld (increase of SWR in the summer period and
decrease after heating at 65°C in the laboratory) is a result of
diff erent chemical and physico-chemical mechanisms acting on soil
particles leading to variations in the critical soil water contents
for WR increase and reduction.
CONCLUSIONS
Th e measurements of WDPT from both fi eld trips (in April and
July) vary in diff erent degrees between the individual samples in
the surface layer of the experimental sites before laboratory
heating. Th e highest value of WDPT is measured in April at the
non-vegetated site. At the pine-vegetated site, these extreme
values are lower, but they characterize a higher percentage of
samples. After heating soil samples from the surface layers at 65°C
in a thermostat, WDPT is reduced. Th is is typical of both
experimental sites and samples from the two sampling seasons. Th e
total percentage of all samples included in the study shows that
during the two seasons, before heating, the samples with extreme
SWR increase in summer. After laboratory heating of samples at
65°C, the degree of WR
Fig.e 5. Water repellency ratio in all sample points from
experimental sites (median values)
-
62
partially decreases in both seasons, with more drastic decline
of extreme WR in summer. We speculate that the decrease of SWR
after heating is caused by conformational and/or structural and
compositional changes in SWR causative agents.
Acknowledgements: The present study was supported by the
National Science Fund (NSF), Ministry of Education and Science,
Bulgaria, Project DN 06/1 (2016-2019).
REFERENCES
Atanassova, I., S. H. Doerr. 2011. Changes in Soil Organic
Compound Composition Associated with Heat-Induced Increases in Soil
Water Repellency. European J. of Soil Science, doi:
10.1111/j.1365-2389.2011.01350.x.
Atanassova, I., M. Banov, T. Shishkov, Z. Petkova, B. Hristov,
P. Ivanov, E. Markov, I. Kirilov, M. Harizanova. 2018.
Relationships between Soil Water Repellency, Physical and Chemical
Properties in Hydrophobic Technogenic Soils from the Region of
Maritsa-Iztok Coal Mine in Bulgaria. Bulgarian J. of Agricultural
Science, 24 (Suppl. 2), 10-17.
Bachmann, J., M. O. Goebel, S. K. Woche. 2013. Small-scale
contact angle mapping on undisturbed soil surfaces. J. of Hydrology
and Hydromechanics, 61, 3-8.
Banov, M. 1989. Studies of Some Soil Genetic Changes in
Non-humus Reclaimed Lands from Maritsa-iztok Region. PhD Thesis.
Agricultural Academy, N. Poushkarov Soil Science and Yield
Programming Institute, Sofia, 188 (In Bulgarian).
DeBano L. F., 1981. Water Repellent Soils: a state of the art. -
USDA, Forest Service, Pacific Southwest Forest and Range Experiment
Station, General Technical Report PSW-46, Berkeley, California,
21.
Dekker, L. W., C. J. Ritsema. 1996. Variation in Water Content
and Wetting Patterns in Dutch Water Repellent Peaty Clay and Clayey
Peat Soils. CATENA, 28, 1-2, 89-105. ISSN 0341-8162,
https://doi.org/10.1016/S0341-8162(96)00047-1.
Dekker, L. W., C. J. Ritsema, K. Oostindie, O. H. Boersma. 1998.
Effect of Drying Temperature on the Severity of Soil Water
Repellency. Soil Science, 163, 10, 780-796. ISSN: 0038-075X. DOI:
10.1097/00010694-199810000-00002.
Doerr, S. H., R. A. Shakesby, R. P. D. Walsh. 2000. Soil Water
Repellency: its Causes, Characteristics and Hydrogeomorphological
Significance. Earth-Science Reviews, 51, 33-65,
https://doi.org/10.1016/S0012-8252(00)00011-8.
Doerr, S. H., L. W. Dekker, C. J. Ritsema, R. A. Shakesby, R.
Bryant. 2002. Water Repellency of Soils: The Influence of Ambient
Relative Humidity. Soil Science Society of America J., 66,
401-405.
Etov, V., D. Slavova. 2011. Technologies for No Humus
Reclamation of Coal Mining Disturbed Lands in the Mini Maritza
Iztok Region. Soil Science, Agrochemistry and Ecology, XLV,
Supplement 1-4, 111-116 (In Bulgarian, English summary).
Hallett, P. D. 2007. An Introduction to Soil Water Repellency. -
In: R. E. Gaskin (Ed.). Proceedings of the 8th International
Symposium on Adjuvants for Agrochemicals (ISAA 2007) (Vol. 6, p.
9). Wageningen: International Society for Agrochemical
Adjuvants.
Hristov, B., V. Pencheva. 1995. On Some Erosion Problems in
Spoils Built With Sulfide Containing Materials. - In: I. Marinov
(Ed.). Proceedings from the Scientific Conference with
Participation of Foreign Specialists ‘90 Years of Soil Erosion
Control in Bulgaria’, 16 - 20 October 1995, Sofia. Print: SD
‘Lotus’ IS. 58-62 (In Bulgarian, English summary).
Hristova, M. 2013. Content and Availability of
Microelements-Metals in Technogenic Soils. Ph.D. Thesis.
Agricultural Academy, ISSAPP ‘N. Poushkarov’, Sofia, 140 (In
Bulgarian).
IUSS Working Group WRB. 2015. World Reference Base for Soil
Resources 2014, update 2015. International Soil Classification
System for Naming Soils and Creating Legends for Soil Maps. World
Soil Resources Reports No. 106. FAO, Rome.
Kořenková, L., I. Šimkovic, P. Dlapa, B. Juráni, P. Matúš. 2015.
Identifying the Origin of Soil Water
-
63
Repellency at Regional Level Using Multiple Soil
Characteristics: The White Carpathians and Myjavska Pahorkatina
Upland Case Study. Soil and Water Res., 10, 78-89. doi:
10.17221/28/2014-SWR.
Leighton-Boyce, G., S. H. Doerr, R. A. Shakesby, R. P. D. Walsh,
A. J. D. Ferreira, A. Boulet, C. O. A. Coelho. 2005. Temporal
Dynamics of Water Repellency and Soil Moisture in Eucalypt
Plantations, Portugal. Australian J. of Soil Research, 43, 269-280,
https://doi.org/10.1071/SR04082.
Lichner, Ľ., N. Babejová, L.W. Dekker. 2002. Effects of
Kaolinite and Drying Temperature on the Persistence of Soil Water
Repellency Induced by Humic Acids. Plant Soil Environment, 48,
203-207. https://doi.org/10.17221/4225-PSE.
Lichner Ľ., T. Orfánus, K. Novákova, M. Šír, M. Tesař. 2007. The
Impact of Vegetation on Hydraulic Conductivity of Sandy Soil. Soil
and Water Res., 2, 59-66. https://doi.org/10.17221/2115-SWR.
Mao, J., K. G. J. Nierop, M. Rietkerk, J. S. Sinninghe Damsté,
S. C. Dekker. 2016. The Influence of Vegetation on Soil Water
Repellency-Markers and Soil Hydrophobicity. Science of the Total
Environment, Volumes 566-567, 608-620, ISSN 0048-9697,
https://doi.org/10.1016/j.scitotenv.2016.05.077.
Marinov, I. 1995. Development of Erosion Processes in the
Recultivated Spoil Heaps. - In: I. Marinov (Ed.). Proceedings from
Scientific Conference with Participation of Foreign Specialists ‘90
Years of Soil Erosion Control in Bulgaria’, 16 - 20 October 1995,
Sofia. Print: SD ‘Lotus’ IS. 55-57.
Nedyalkova, K., G. Petkova, I. Atanassova, M. Banov, P. Ivanov.
2018а. Microbiological Properties of Hydrophobic and Hydrophilic
Technosols from the Region of Maritza-Iztok Coal Mines. Comptes
rendus de l’Académie Bulgare des Sciences (C. R. Acad. Bulg. Sci.),
71, 4, 577-584. DOI:10.7546/CRABS.2018.04.18
Nedyalkova, K., G. Petkova, I. Atanassova, M. Banov, P. Ivanov.
2018b. Microbiological Parameters of Technosols Monitored for
Hydrophobicity. Acta Microbiologica Bulgarica, 34, 2, 121-125.
Norris, T. B., J. M. Wraith, R. W. Castenholz, T. R. McDermott.
2002. Soil Microbial Community Structure across a Thermal Gradient
following a Geothermal Heating Event. - Applied and Environmental
Microbiology, 68 (12), 6300-6309.
DOI: 10.1128/AEM.68.12.6300-6309.2002.
Oostindie, K., L. W. Dekker, J. G. Wesseling, C. J. Ritsema, V.
Geissen. 2013. Development of Actual Water Repellency in a
Grass-covered Dune Sand during a Dehydration Experiment. Geoderma,
Volumes 204-205, 23-30, ISSN 0016-7061,
https://doi.org/10.1016/j.geoderma.2013.04.006.
Orfánus, T., Z. Bedrna, Ľ. Lichner, P. D. Hallett, K. Kňava, M.
Sebíň. 2008. Spatial Variability of Water Repellency in Pine Forest
Soil. Soil and Water Res., 3, 123-129.
https://doi.org/10.17221/11/2008-SWR.
Papierowska, E., W. Matysiak, J. Szatyłowicz, G. Debaene, E.
Urbanek, B. Kalisz, A. Łachacz. 2018. Compatibility of Methods Used
for Soil Water Repellency Determination for Organic and
Organo-mineral Soils. Geoderma, 314, 221-231.
https://doi.org/10.1016/j.geoderma.2017.11.012.
Petrova, R. 1989. Loss of Humus Soil in the Process of
Reclamation of Damaged Terrains. - In: N. Sherbanova, R. Nacheva
(Eds.). Proceedings from Fourth National Conference on Soil Science
‘Problems of Soil Science in Intensive Agriculture’. BSSS, N.
Poushkarov Soil Science and Yield Programming Institute, Sofia,
203-206 (In Bulgarian).
Petrova, R., S. Gencheva. 1991. Soil Fertility of Different
Industrial Embankments in Pernik Coal Basin. Forestry, 3, 10-11 (In
Bulgarian).
Petrovа, R., L. Totev, L. Tsotsorkov. 2009. Mining, Reclamation
and Sustainable Management of Degraded Lands in Bulgaria. - In: L.
Totev, P. Pavlov (Eds.). Proceedings of the International
Scientific Conference on Mining Science and Geotechnics - European
Challenge. 1-3 Oct 2009. ISSN 1314-0469. Lux Print, Sofia, 78-83
(In Bulgarian).
Roy, J. L., W. B. McGill. 2000. Flexible Conformation in Organic
Matter Coatings: A Hypothesis about Soil Water Repellency. Canadian
J. of Soil Science, 80(1), 143-152.
Secu, C. V., I. Minea, I. Stoleriu. 2015. Geostatistical
Modeling of Water Infiltration in Urban Soils. Carpathian J. of
Earth and Environmental Sciences, 10 (4), 95-104.
Simkovic, I., P. Dlapa, S. H. Doerr, J. Mataix-Solera, V.
Sasinkova. 2008. Thermal Destruction of Soil Water Repellency and
Associated Changes to Soil Organic Matter as Observed by FTIR
Spectroscopy.
-
64
CATENA, 74, 3,205-211. ISSN 0341-8162,
https://doi.org/10.1016/j.catena.2008.03.003.Tsolova, V., M. Banov.
2011. Organic Matter Status in Reclaimed Technosols of Bulgaria.
Agricultural
Science and Technology, 3, No 2, 155-159.
E-mail: [email protected]