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Article
Chemical and sanitary assessment of coal spoil heaps in the south of the Kuznetsk Basin
Ekaterina E. Vorobyeva* , Natalya V. Fotina , Lyudmila K. Asyakina , MariyaA. Osintseva , AlexandrYu. Prosekov
Kemerovo State University, ul. Krasnaya 6, Kemerovo, 650000 Russia *[email protected]
Received: 03.06.2022 Revised: 20.06.2022 Accepted: 25.06.2022 Published online: 29.10.2022
DOI: 10.23859/estr-220603 UDC 631.618
Translated by S.V. Nikolaeva
Abstract. Due to the large amount of pollution at coal spoil heaps, soil reclamation is slow and requires development and use of microbial preparations, selected based on assessments of the biochemical parameters of soil and the extent of its contamination. The material for this study was mine soils sampled in three different zones (Ka, Kb, Kc) of the Korchakol coal spoil heap. The studied sanitary and chemical indicators did not exceed the approximate permissible concentrations (APC) / maximum allowable concentrations (MAC), except for oil products (in the Ka, Kb, Kc zones, the excess averaged 2.2, 1.4, 1.2 times, respectively). The study found a direct correlation between the zinc content and the enzymatic activity of polyphenol oxidase, the level of Ni and peroxidase, as well as an inverse correlation between the As and Cu concentrations with invertase and nitrite reductase, respectively. The index of bacteria of the Escherichia coli group (coliform bacteria) in different zones exceeded the standard values by 61 and 171 times. Even though the sanitary indicators studied do not exceed permissible levels, they can slow down growth and development of plants. Thus, successful reclamation of mine soils requires introduction of biological preparations based on microorganisms that biotransform heavy metals and rhizobacteria.
Keywords: Kemerovo Region, Kuznetsk Basin, enzymatic activity of soils, heavy metals, organic pollutants, sanitary and biological indicators, reclamation of contaminated soils, rhizobacteria, remediation
To cite this article. Vorobyeva, E.E. et al., 2022. Chemical and sanitary assessment of coal spoil heaps in the southof the Kuznetsk Basin. Ecosystem Transformation 5 (4), 7-20. https://doi.org/10.23859/estr-220603
Introduction
The large Kemerovo Region (Kuznetsk Basin) ranks first in Russia for coal production (Vylegzhanin, 2015). Most of the Kuznetsk Basin coal is mined in the Kemerovo, Leninsk-Kuznetsk, Prokopyevsk, Mezhdurechensk, Kiselevsk and Belovo disctricts (Manakov et al., 2018). Coal mining, in particular open-pit coal mining, enrichment, and storage of coal, as well as coal waste disposal, leads to depletion of fertile soils and an increase in the toxicological indicators of soil (Drozdova et al., 2021; Ismagilov et al., 2018). When developing coal heaps, the fertile soil layer is removed, and mine soils become exposed.
Soil enzymes contribute to the breakdown of complex organic and inorganic compounds, and participate in the mineralization of nutrients and their inclusion in the cycle of carbon (invertase, cellulase), nitrogen (nitrite reductase, asparaginase, urease, protease), and phosphorus (phosphatase) (Assemien et al., 2019; Fan et al., 2021; Sobat et al., 2021; Yinping et al., 2018). In addition, enzymes are responsible for detoxification of pollutants (hydrogen peroxide (catalase) and complex organic substances (peroxidase, polyphenol oxidase)), and also contribute to the remediation of polluted soils (Kaushal et al., 2018; Khosrozadeh et al., 2022; Liu et al., 2021).
Coal mining leads to the destruction of the topsoil and the disruption of the flow of subsurface and groundwater, resulting in a decrease in the biodiversity of plants and microorganisms (Fan et al., 2021). Subsequently, soil nutrient content and enzymatic activity decrease, while pathogenic microorganisms and toxic compounds accumulate (Nakayama and Tateno, 2021). In particular, the low enzymatic activity of the soil may indicate high concentrations of various pollutants, including heavy metals and metalloids, which serve as inhibitors for many groups of enzymes. As a result, degradation processes begin in the soil, which lead to the depletion of nutrients, vegetation biodiversity and beneficial microorganisms (Samuel et al., 2017).
The process of soil remediation makes it possible to restore technogenically disturbed territories, for transfer to forest or agricultural use. To select the method of remediation, a sanitary assessment of the soil is necessary to determine the degree of its contamination, using two groups of sanitary indicators (Mathew et al., 2017):
1. sanitary-chemical: the content of heavy metals and
metalloids, PAHs, phenols, oil products, etc. 1 2;
1 SanPiN 42-128-4433-87. Sanitary standards for permissible concentrations of chemicals in the soil.
2 SanPiN 1.2.3685-21. Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors for humans.
2. sanitary biological3:
a) sanitary-bacteriological: coliform index, enterococci index, content of pathogenic enterobacteria Salmonella and Shigella;
b) sanitary-epidemiological: eggs and larvae of helminths, cysts of intestinal pathogenic protozoa, larvae and pupae of synanthropic flies.
The purpose of this study was to study chemical and sanitary indicators of the quality of mine soils in coal heaps in the south of the Kemerovo Region (Kuznetsk Basin) for further selection of a rational method for the remediation of technogenically disturbed landscapes.
Materials and methods
The objects of the study were mine soil samples taken from the surface layer of the outer spoil heap of the Korchakol Mine (K) (Fig. 1). The total area of the dump is 499000 m2, the height reaches 100 m, and the steepness of the slopes varies from 1°-2° to 35°. The dump is characterized by sandy-argillaceous loose rocks and sparse vegetation; the age of its individual sections is from 5 to 30 years. The heap area is part of the dark coniferous taiga natural zone, located in the continental climate zone. Biological reclamation was partially located at the heap; sites of spontaneous combustion were also observed.
Mine soil samples were taken in autumn (November) 2021 at sub-zero temperatures, before snowfall, in accordance with generally accepted methods4 (sampling depth was 0-20 cm). Sampling was located in three zones of the surface layer of the Korchakol coal heap in five repetitions::
• Zone "Ka" (age - 5 years) is a mixture of waste - rocks from coal enrichment (at least 86%) and overburden rocks (up to 14%), there is no vegetation in this zone. Sampling point coordinates: N 53°42' E 87°25'.
• Zone "Kb" (age -15 years) undergoing technical stage of reclamation (filling with clay); no vegetation recorded. Sampling point coordinates: N 53°41' E 87°25'.
• Zone "Kc" (age - 20 years) is at the biological stage of technogenic land reclamation, including trees planted here (Pinus sylvestris L.), shrubs (Hippophae rhamnoides L.), and herbaceous plants (Trifolium pratense L. and Melilotus albus L); all plants found are characterized by
3 SanPiN 2.1.3684-21. Sanitary and epidemiological requirements for the maintenance of territories of urban and rural settlements, for water bodies, drinking water and drinking water supply, atmospheric air, soils, residential premises, operation of industrial, public premises, organization and implementation of sanitary and anti-epidemic (preventive) measures.
4 GOST 17.4.4.02-2017. Protection of Nature. Soils. Methods
for taking and preparing samples for chemical, bacteriological, helminthological analysis.
Fig. 1. A satellite image from Google Maps of the coal heap of the Korchakol Open-Pit Mine. Ka, Kb, Kc - sampling zones.
a small height. Sampling point coordinates: N 53°41' E 87°24'. N 53°41' E 87°24'. The formation of a fertile soil layer requires a certain content of readily available carbon, as well as the C/N ratio and the redox potential of soils, therefore, at the initial stages of the study, the following enzymes were selected: invertase, nitrite reductase, peroxidase, polyphenol oxidase (Antonov and Chmuzh, 2016; Kochkina, 2016; Li et al., 2020).
Invertase activity was determined using the Sun et al.'s (2021) method. Sucrose solution (Russia, SigmaTek), acetate buffer, copper reagent (5% CuSO4*5H2O (Russia, Yugreaktiv) + solution 25 g Na2CO3 (Russia, LenReaktiv), 25 g Rochelle salt (Russia, SigmaTek), 20 g NaHCO3 (Russia, LenReaktiv), 200 g Na2SO4 (Russia, Yugreaktiv) in 1 liter of distilled water, in a ratio of 1:25), sodium hydrogen phosphate (Russia, "SigmaTek") and a molybdenum reagent (1 l 20% H2SO4 solution (Russia, LenReaktiv) + 5% ammonium molybdate solution (Russia, Yugreaktiv)) were used for the analysis.
Nitrite reductase activity was determined using the method of Liu et al. (2020). Calcium carbonate (Russia, LenReaktiv), sodium nitrite solution (Russia, Yugreaktiv), glucose solution (Russia, SigmaTek), distilled5 water, aluminum alum, Griess reagent (Russia, LenReaktiv).
Peroxidase activity was determined using the method of Sun et al. (2021). The analysis was performed using hydroquinone solution (Russia, SigmaTek),
5 GOST 6709-72. Distilled water. Specifications.
hydrogen peroxide solution (Russia, Ecos-1), ethyl alcohol (Russia, Kemerovo Pharmaceutical Factory).
Polyphenol oxidase activity was determined using Qianxi. et al.'s (2022) method using hydroquinone solution (Russia, SigmaTek).
The optical density of all samples after thermostatting was measured using a UNICO spectrophotometer (Model 1201) (Russia, ProPribory).
Recent publications show that the main pollutants present in the coal of the Kemerovo Region are zinc, copper, nickel, arsenic, and mercury (Fotina et al., 2021; Osipova et al., 2015; Zhuravleva et al., 2015). Therefore, these heavy metals were selected to control the sanitary and chemical state of the study area. Content of these substances was determined according to standard methods6, 7 8. In addition, in accordance with regulatory documents, the presence
6 M-MVI-80-2008. Method for performing measurements of the mass fraction of elements in samples of soils, soils and bottom sediments using atomic emission and atomic absorption spectrometry methods.
7 MU 31-11/05. Quantitative chemical analysis of soil samples, greenhouse soils, sapropels, silts, bottom sediments, solid wastes. Method for performing measurements of mass concentrations of zinc, cadmium, lead, copper, manganese, arsenic, mercury by inverse voltammetry (stripping analysis) using analyzers of the TA type.
8 PND F 16.1:2:2.2.80-2013. Quantitative chemical analysis of soils. Method for measuring the mass fraction of total mercury in samples of soils, grounds, including greenhouse soils, clays and bottom sediments using an atomic absorption method using a RA-915M mercury analyzer.
of benzo(a)pyrene, phenols and oil products was analyzed9, 10 11, as well as sanitary-bacteriological and epidemiological indicators12.
All sanitary-chemical and sanitary-biological parameters were determined in triplicate. For statistical processing was the Statistica for Windows v. 12.0 ("StatSoft, Inc.") software was used.
Results and discussion
The results of granulometric and physico-chemical analyzes of the studied soils of rocks are presented in Tables 1 and 2. It was found that according to the granulometric composition, the soils of rocks of the Ka, Kb, Kc zones belong to light loam, medium clay, and heavy loam, respectively. The soils of the Kb zone have a slightly alkaline reaction of the medium (8.6), while the soils of the Ka and Kc zones have a pH close to neutral (7.4 and 7.5, respectively). The studied samples are characterized by a low level of humidity, which may indicate an insufficient ability of coal heaps to retain water. The studied samples were characterized by a high degree of saturation with bases, so the restored soils do not need liming. In all samples, a low content of organic matter is observed, therefore, in order to improve fertility during reclamation, additional sources of humic acids will be required. In addition, a low content of total nitrogen, calcium and magnesium was found, suggesting the need for mineral fertilizers.
Since inorganic and organic pollutants seriously affect the biochemical parameters of the soil, the assessment of enzyme activity makes it possible to assess the state of the soil (Dadenko et al., 2013). The results of determining the enzymatic activity of the studied rock soil samples are presented in Table 3; the average values of these indicators are shown in Figs. 2-4.
Figure 2 shows that invertase activity increases as the reclamation works progress: its average value for rock soils taken from the surface layer of the Korchakol coal heap in the Kc zone is almost twice as high as
9 FR.1.31.2008.01725. Method for measuring the mass fraction of benzo(a)pyrene in soils, soils and sewage sludge using high performance chromatography.
10 PND F 16.1:2.3:3.44-05. Quantitative chemical analysis of soils. Method for performing measurements of the mass fraction of volatile phenols in soil samples, sewage sludge and waste using the photometric method after stripping with water vapor.
11 PND F 16.1:2.2.22-98. Quantitative chemical analysis of soils. Methodology for measuring the mass fraction of oil products in mineral, organogenic, organo-mineral soils and bottom sediments using IR spectrometry.
12 SanPiN 2.1.3684-21. Sanitary and epidemiological requirements for the maintenance of territories of urban and rural settlements, for water bodies, drinking water and drinking water supply, atmospheric air, soils, residential premises, operation of industrial, public premises, organization and implementation of sanitary and anti-epidemic (preventive) measures.
the same indicator for the Ka zone. This could result from the mine soils of the Ka zone containing a small amount of polysaccharides, while the root systems of vegetation in the Kc zone contributes to an increase in their concentration. Thus, it can be concluded that the native microflora of this area mainly uses polysaccharides as a carbon source.
The study of the nitrite reductase activity of the soils of the Korchakol coal heap showed that in the Kc zone this parameter is 1.5 times higher than in the Ka zone (Fig. 3). This may indicate an increased need for nitrogen caused by the biological processes of microorganisms and plants.
The data presented in Fig. 4 show a significant decrease in the peroxidase and polyphenol oxidase activities of the soil in the Kc zone compared to the Ka and Kb zones (by 3.5 and 3.2 times, respectively). This can be because the content of organic pollutants decreases in the mine soils from the Ka zone to the Kc zone (Table 4), which, in turn, affects the production of the above enzymes. However, these pollutants were not completely degraded; this can be established by the fact that enzyme activity is still observed in the area of the biological stage of reclamation.
Inorganic and organic pollutants in high concentrations have a toxic effect on plants and microorganisms. Therefore, to determine a consortium of microorganisms that remediate contaminated sites, it is necessary to assess the degree of contamination. The results of the study of the soils of the Korchakol coal dump in terms of sanitary and chemical indicators are presented in Table 4. APC/MAC and average values of pollutant concentrations in the studied areas are shown in Figs. 5 and 6.
We found that high concentrations of zinc, copper, nickel, arsenic are observed in the soils of the Korchakol heap (Fig. 5), which is consistent with the data of other studies (Akinina et al., 2017; Fotina et al., 2021). It is known that an increased content of zinc can lead to slower plant growth and cause leaf chlorosis (Jain et al., 2020), because of Zn-chlorophyll derivatives, which cannot perform photosynthesis (Küpper and Andresen, 2016). A high copper concentration negatively affects photosynthesis, the absorption of phosphorus from the soil, and also promotes the synthesis of reactive oxygen and lipid peroxidation in plants. This leads to high oxidative stress, which can cause plant death (Angulo-Bejarano et al., 2021). Excessive nickel concentrations can provoke a decrease in biomass growth, inhibit the formation of lateral roots, disrupt the nutrient balance in the plant, and lead to leaf chlorosis (Hassan et al., 2019). Finally, an increased content of arsenic can lead to a decrease in germination and yield of plants, growth of shoots, roots and leaves, slow down the process of photosynthesis, and also cause plant death due to oxidative stress (Martins et al., 2019; Zhang et al.,
Table 1. Granulometric analysis of soils of the surface layer of the Korchakol coal heap.
Size of mechanical particles, mm Zone Ka % of total particles Zone Kb Zone Kc
Over 10.0 0 0 0
10.0-5.0 0 0 0
5.0-2.0 0 0 0
2.0-1.0 0 0 0
1.0-0.5 0.4 1.9 0.1
0.5-0.25 0.2 0.2 0.2
0.25-0.1 0.3 0.1 0.3
0.1-0.05 55.4 14.6 10.4
0.05-0.01 22.7 38.7 39.3
0.01-0.002 15.8 27.6 28.4
Less than 0.002 5.2 16.9 21.3
Table 2. Physico-chemical parameters of soils of the surface layer of the Korchakol coal heap.
Indicator
Ka
Zone Kb
Kc
pH of water extract 7.4 ± 0.1 8.6 ± 0.1
Hygroscopic humidity, % 2.10 ± 0.09 5.16 ± 0.23
Organic matter, % 1.15 ± 0.04 3.48 ± 0.15
Degree of saturation with bases, % 98.40 ± 4.52 99.14 ± 4.85
Total nitrogen, % 0.17 ± 0.01 0.21 ± 0.01
Calcium, mmol/100 g 0.45 ± 0.02 0.58 ± 0.02
Magnesium, mmol/100 g 0.55 ± 0.02 0.64 ± 0.03
7.5 ± 0.01 4.34 ± 0.21 4.08 ± 0.20 99.66 ± 4.73 1.2 ± 0.04 0.79 ± 0.02 0.99 ± 0.04
2021). Also note that zinc and arsenic belong to the first hazard class, while copper and nickel to the second13.
The MAC of benzo(a)pyrene was not exceeded in any of the studied samples (Fig. 6). The content of oil products in the studied soil of the Ka sample (mean value 160.872 mg/kg) was more than double the background value, but, for the heap of the Kc zone subject to biological reclamation, this parameter is almost equal to the background content (86.544 mg/kg) (Fig. 5).
The content of phenols in the studied samples did not exceed 1 mg/kg (Fig. 6). Phenolic pollution of soils can be caused by both biogenic and technogenic factors. The complex nature of this type of pollution, as well as the chemical and typological diversity of soils inhibits
using fixed MAC for the total content of phenols. Based on the published data, at a concentration of phenolic substances from 1 to 5 mg/kg, the pollution level is interpreted as medium (Ieronova and Bezukhova, 2014). Thus, the studied mine soils in all zones have a low level of contamination with phenolic substances.
The amount of mercury in the soils of the Korchakol coal dumps did not exceed MAC14 (Fig. 6), which does not contradict published data (Zhuravleva et al., 2015). This is due to the impact of reclamation measures that contribute to the purification of soils from pollutants.
Correlation coefficients (r) and significance coefficients (p) were calculated to reveal the relationship between metal content and enzyme activity. The sig-
13 MU 2.1.7.730-99. Guidelines. Soil, cleaning of populated areas,
household and industrial waste, sanitary protection of the soil. Hygienic assessment of soil quality in populated areas.
14 SanPiN 1.2.3685-21. Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors for humans.
Table 3. Enzymatic activity of soils of the surface layer of the Korchakol coal heap (mean ± SE).
Indicator
Ka
Zone Kb
Kc
Ka1 2.197 ± 0.062 Kb1 3.865 ± 0.102 KC1 4.295 ± 0.164
Ka2 2.284 ± 0.074 Kb2 4.253 ± 0.115 Kc2 5.218 ± 0.231
Invertase activity, mg of sucrose, split 1 g of soil for 1 hour Ka23 2.140 ± 0.063 Kb23 4.154 ± 0.123 Kc3 4.124 ± 0.185
Ka4 2.161 ± 0.085 Kb4 4.647 ± 0.098 Kc4 5.081 ± 0.193
Ka5 2.185 ± 0.053 Kb5 3.846 ± 0.075 KC5 4.768 ± 0.205
Ka1 0.380 ± 0.012 Kb1 1.536 ± 0.086 KC1 2.378 ± 0.063
Nitrate reductase activity, Ka2 0.316 ± 0.007 Kb2 1.974 ± 0.092 Kc2 2.643 ± 0.086
mg reduced NO" per 1 g of soil in 24 hours Ka23 Ka4 0.410 ± 0.018 Kb23 Kb4 1.246 ± 0.066 Kc3 Kc4 2.014 ± 0.051
0.597 ± 0.025 2.211 ± 0.094 2.936 ± 0.069
Ka5 0.451 ± 0.021 Kb5 2.675 ± 0.083 XC5 3.476 ± 0.094
Ka1 1.545 ± 0.068 Kb1 0.856 ± 0.035 KC1 0.568 ± 0.014
Peroxidase activity, mg of formed Ka2 1.427 ± 0.053 Kb2 0.921 ± 0.029 Kc2 0.294 ± 0.006
1.4-p-benzoquinone per 1 g of soil Ka3 1.638 ± 0.077 Kb3 1.058 ± 0.051 Kc3 0.316 ± 0.011
in 30 min Ka4 1.402 ± 0.061 Kb4 0.716 ± 0.026 Kc4 0.842 ± 0.023
Ka5 1.430 ± 0.064 Kb5 0.693 ± 0.034 XC5 0.169 ± 0.004
Polyphenol oxidase activity, mg of formed 1.4-p-benzoquinone per 1 g of soil in 30 min
Ka1 Ka2 Ka3
Ka4 Ka
1.101 1.213 1.167 1.054 1.182
± 0.031 ± 0.048 ± 0.056 ± 0.025 ± 0.057
Kb1
Kb2 Kb23
Kb4
Kb
1.145 ± 0.046 0.956 ± 0.032 0.843 ± 0.028 1.058 ± 0.041 0.732 ± 0.036
Kc1
Kc2 Kc23
Kc4 Kc
.564 ± 0.009 .429 ± 0.016 .683 ± 0.017 .267 ± 0.003 Kc
nificance coefficient in all cases was less than 0.05. Samples of soils of the surface layer of the Korchakol coal heap showed a high direct relationship between zinc content and polyphenol oxidase activity (r = 0.84), as well as nickel content and peroxidase activity (r = 0.83). The obtained direct dependence contradicts previously published data (Pleshakova et al., 2010; Rusyaeva et al., 2019; Tang et al., 2022) and indicates the possible presence of other factors that reduce the effect of metals. These factors may include the following: amount of substrate, C/N ratio in soil, soil pH, microbiome composition, mass fraction of humus, amount of mineral compounds, humidity (Dadenko et al., 2013; Soldatov et al., 2020; Tovstik and Olkova, 2021; Xu et al., 2020). High inverse correlation was observed between the contents of copper and nitrite reductase (r = -0.92), as well as arsenic and invertase (r = -0.84). This dependence is consistent with the data of other studies (Black et al., 2019; Dadenko et al., 2013; Govarthanan et al., 2018).
Growth and development of plants and useful microflora are affected not only by the concentration of heavy metals and organic pollutants, but also by the
sanitary and biological indicators of the soil15, data on which for the surface layer of the Korchakol coal dump are presented in Table 5. According to the results of the research, there are no enterococci, pathogenic enterobacteria, eggs and larvae of helminths (viable), cysts of pathogenic protozoa, larvae and pupae of synanthropic flies in the samples. Bacteria of the Escherichia coli group (ECG) were also not found in soil samples from the Ka zone; at the same time, in zones Kb and Kc, the ECG (coliform) index exceeds the norm16 by about 61 and 171 times, respectively. Apparently, the Kb and Kc zones have optimal conditions for the growth of microorganisms; at the same
15 MU 2.1.7.730-99. Guidelines. Soil, cleaning of populated areas, household and industrial waste, sanitary protection of the soil. Hygienic assessment of soil quality in populated areas.
16 SanPiN 2.1.3684-21. Sanitary and epidemiological requirements for the maintenance of territories of urban and rural settlements, for water bodies, drinking water and drinking water supply, atmospheric air, soils, residential premises, operation of industrial, public premises, organization and implementation of sanitary and anti-epidemic (preventive) measures.
■ Zone Ka Zone Kb ■ Zone Kc Fig. 2. Invertase activity of soils in the surface layer of the Korchakol coal heap (mean ± SE).
-o
<u
u ,
S
2 I
s ^
H CN
c c
<u °
52 60
TO
-4-1 '—I
a K .3 "->
73 a
n i —m
« O
2 z;
o
1.08
0.83
0.72
■ Zone Ka Zone Kb ■ Zone Kc Fig. 3. Nitrite reductase activity of soils in the surface layer of the Korchakol coal heap (mean ± SE).
Zone Kc
i Peroxidase activity Polyphenol oxidase activity Fig. 4. Peroxidase and polyphenol oxidase activity of soils of the surface layer of the Korchakol coal heap (mean ± SE).
Table 4. Sanitary and chemical indicators of soils of the surface layer of the Korchakol coal heap; "n/n" - the indicator is not standardized.
Indicator MAC17/ APC18/ Ka Zone Kb Kc
Ka1 60.187 ± 2.759 Kb1 53.452 ± 2.156 Kc1 48.556 ± 1.956
Ka2 61.234 ± 3.015 Kb2 52.363 ± 2.349 Kc2 47.234 ± 1.894
Zinc (gross content), mg/kg 11018 Ka3 60.568 ± 2.963 Kb3 52.951 ± 2.448 Kc3 48.191 ± 2.056
Ka4 59.894 ± 2.565 Kb4 54.184 ± 2.128 Kc4 49.352 ± 2.148
Ka5 60.819 ± 3.003 Kb5 53.079 ± 2.356 Kc5 47.848 ± 1.920
Ka1 22.341 ± 0.987 Kb1 15.906 ± 0.623 Kc1 10.740 ± 0.415
Ka2 22.644 ± 1.004 Kb2 15.231 ± 0.587 Kc2 10.327 ± 0.276
Copper (gross content), mg/kg 6618 Ka3 23.104 ± 1.216 Kb3 16.361 ± 0.713 Kc3 11.167 ± 0.348
Ka4 22.377 ± 0.855 Kb4 14.815 ± 0.346 Kc4 10.078 ± 0.500
Ka5 5 22.185 ± 0.783 Kb5 14.557 ± 0.469 Kc5 9.856 ± 0.281
Ka1 24.128 ± 1.005 Kb1 18.751 ± 0.865 Kc1 13.841 ± 0.516
Ka2 24.896 ± 1.225 Kb2 19.141 ± 0.921 Kc2 14.026 ± 0.631
Nickel (gross content), mg/kg 4018 Ka3 24.314 ± 1.119 Kb3 19.759 ± 0.934 Kc3 14.338 ± 0.522
Ka4 25.373 ± 1.342 Kb4 20.239 ± 0.756 Kc4 15.124 ± 0.684
Ka5 24.184 ± 0.989 Kb5 20.016 ± 1.005 Kc5 14.959 ± 0.348
Ka1 4.313 ± 0.121 Kb1 3.043 ± 0.124 Kc1 1.995 ± 0.085
Ka2 Ka3 4.658 ± 0.203 (M ro .a .a 3.531 ± 0.110 Kc2 Kc3 2.262 ± 0.114
Arsenic (gross content), mg/kg 518 4.066 ± 0.043 3.919 ± 0.098 2.738 ± 0.099
Ka4 4.237 ± 0.109 Kb4 3.235 ± 0.086 Kc4 2.515 ± 0.054
Ka5 5 4.210 ± 0.098 Kb5 4.149 ± 0.146 Kc5 3.127 ± 0.123
Ka1 0.052 ± 0.003 Kb1 0.036 ± 0.002 Kc1 0.015 ± 0.001
Ka2 0.059 ± 0.002 Kb2 0.024 ± 0.001 Kc2 0.023 ± 0.001
Mercury (gross form), mg/kg 2.117 Ka3 Ka4 0.065 ± 0.004 0.054 ± 0.002 Kb3 Kb4 0.041 ± 0.002 0.034 ± 0.001 Kc3 Kc4 0.018 ± 0.001 0.023 ± 0.001
Ka5 0.045 ± 0.002 Kb5 0.046 ± 0.001 Kc5 0.031 ± 0.002
Ka1 0.020 ± 0.005 Kb1 0.014 ± 0.001 Kc1
Ka2 Ka3 0.019 ± 0.006 (M ro .a .a 0.013 ± 0.001 Kc2 Kc3
Benz(a)pyrene, mg/kg 0.0217 0.018 ± 0.002 0.013 ± 0.001 <0.010
Ka4 0.019 ± 0.007 Kb4 0.015 ± 0.001 Kc4
Ka5 0.017 ± 0.005 Kb5 0.011 ± 0.001 Kc5
Ka1 161.234 ± 8.012 Kb1 105.349 ± 5.107 Kc1 86.348 ± 4.210
Ka2 160.319 ± 7.942 Kb2 106.217 ± 4.234 Kc2 88.102 ± 3.861
Oil products, mg/kg 73.619 Ka3 Ka4 161.075 ± 8.105 161.237 ± 7.346 Kb3 Kb4 104.315 ± 4.751 105.284 ± 5.106 Kc3 Kc4 86.318 ± 4.105 85.294 ± 3.756
Ka5 160.496 ±7.812 Kb5 106.101 ± 5.245 Kc5 86.657 ± 4.208
Ka1 0.915 ± 0.041 Kb1 0.759 ± 0.027 Kc1 0.218 ± 0.015
Ka2 0.751 ± 0.036 Kb2 0.613 ± 0.021 Kc2 0.134 ± 0.009
Phenol, mg/kg h/h Ka3 0.824 ± 0.042 Kb3 0.598 ± 0.019 Kc3 0.259 ± 0.013
Ka4 0.917 ± 0.046 Kb4 0.716 ± 0.025 Kc4 0.187 ± 0.008
Ka5 0.862 ± 0.035 Kb5 0.653 ± 0.026 Kc5 0.210 ± 0.016
17, 18 SanPiN 1.2.3685-21. Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors for humans.
19 The background content of oil products for the city of Novokuznetsk is presented (Zagryaznenie..., 2021).
Zinc (gross Copper (gross Nickel (gross Arsenic (gross Oil products content) content) content) content)
■ MAC/APC Zone Ka " Zone Kb ■ Zone Kc
Fig. 5. The content of heavy metals/metaloids and oil products in the rock soils of the surface layer of the Korchakol coal heap (mean ± SE).
2.1
Mercury (gross Benz(a)pyrene Phenol
form)
■ MAC/APC Zone Ka ■ Zone Kb ■ Zone Kc
Fig. 6. The content of mercury, benzo(a)pyrene, phenols in the soils of rocks of the surface layer of the Korchakol coal heap (mean ± SE).
Table 5. Sanitary and biological indicators of soils of the surface layer of the Korchakol coal heap; "n/a" - not allowed; "n/d" - not detected.
Zone
Indicator Norm20
Ka Kb Kc
Ka1 Kb1 643.98 ± 31.50 KC1 1598.54 ± 63.23
Ka2 Kb2 453.21 ± 20.28 Kc2 1456.29 ± 65.29
ECG Index 1-9 Ka3 n/d Kb23 567.30 ± 28.18 Kc23 1673.67 ± 82.51
Ka4 Kb4 482.49 ± 21.02 Kc4 1435.83 ± 69.37
Ka5 Kb5 631.25 ± 30.65 KC5 1549.11 ± 65.67
Ka1 Kb1 KC1
Ka2 Kb2 Kc2
Enterococci Index 1-9 Ka3 n/d Kb23 n/d Kc3 n/d
Ka4 Kb4 Kc4
Ka5 Kb5 KC5
Ka1 Kb1 KC1
Ka2 Kb2 Kc2
Pathogenic enterobacteria Salmonella sp. and Shigella sp. n/a Ka3 n/d Kb23 n/d Kc3 n/d
Ka4 Kb4 Kc4
Ka5 Kb5 KC5
Ka1 Kb KC1
Ka2 Kb2 Kc2
Viable eggs and larvae of helminths 1-9 Ka3 n/d Kb23 n/d Kc23 n/d
Ka4 Kb4 Kc4
Ka5 Kb5 KC5
Ka1 Kb1 KC1
Ka2 Kb2 Kc2
Cysts of pathogenic protozoans 1-9 Ka3 n/d Kb23 n/d Kc3 n/d
Ka4 Kb4 Kc4
Ka5 Kb5 XC5
Ka1 Kb1 KC1
Ka2 Kb2 Kc2
Larvae and pupae of synanthropic flies n/a Ka3 n/d Kb23 n/d Kc3 n/d
Ka4 Kb4 Kc4
Ka5 Kb5 KC5
20 SanPiN 2.1.3684-21. Sanitary and epidemiological requirements for the maintenance of territories of urban and rural settlements,
for water bodies, drinking water and drinking water supply, atmospheric air, soils, residential premises, operation of industrial, public premises, organization and implementation of sanitary and anti-epidemic (preventive) measures.
time, the general sanitary-chemical state of the Ka zone inhibits the development of the natural microbiome.
Conclusion
In the direction from the Ka zone to the Kc zone, the activity of invertase and nitrite reductase increased; peroxidase and polyphenoloxidase activities, on the contrary, decreased. This may indicate that the technical and biological stages of reclamation have a positive effect on the enzymatic activity of rock soils, but it remains small. Also, in these territories, the values of all studied sanitary and chemical indicators are consistently decreasing; the content of pollutants does not exceed the established APC. Thus, it can be assumed that the ongoing reclamation contributes to the restoration of anthropogenically disturbed soils. At the same time, the concentration of pollutants remains significant, and they can negatively affect the vital activity of plants growing in the vicinity of the coal spoil heap, so in the future additional measures will be required to clean the soil from heavy metals.
Statistical analysis of biochemical and sanitary-chemical parameters of rock soils of the Korchakol coal heap revealed a significant negative correlation between copper content and nitrite reductase activity; between arsenic levels and invertase activity. At the same time, zinc and polyphenol oxidase, as well as nickel and peroxidase, show a direct correlation with each other. In the future, it is planned to study the dependence of the enzymatic activity of these territories on the amount of the substrate (phenol, aromatic compounds, PAHs and alcohols), the composition of the microbiome, humus, and the amount of mineral compounds. In addition, it is necessary to assess the impact of heavy metals on the microbiome of rock soils. In this case, it will be necessary to take into account their duration of exposure to pollutants, since the negative impact of these elements manifests itself in the long term (Ivanova et al., 2020).
In the study of sanitary and bacteriological indicators of the surface layer of the coal dump, it was found that the coliform index in the Kb and Kc zones exceeds the established norm for the permissible level of soil contamination by more than 60 times. Probably, these zones have more favorable conditions for the development and vital activity of the microbiota compared to the Ka zone. It is also planned to take samples in the spring to monitor the state of the heap21.
At the moment, soil samples of the surface layer of the Korchakol coal heap have been analyzed for agrophysical, agrochemical, biochemical and sanitary indicators; in addition, microorganisms were isolated
from the soils. Based on the results obtained and further research, it is planned to select certain types of plants and microorganisms for the remediation of technogenically disturbed lands. When developing a microbial preparation, first of all, it is necessary to select the most promising strains that biotransform heavy metals. This is necessary to increase the survival of plant cultures used in the biological stage of recultivation (Saha et al., 2021). Particular attention should be paid to strains capable of neutralizing zinc and arsenic, which pose the greatest threat in contaminated areas22. Also, for better plant survival, it is necessary to introduce rhizobacteria (Saha et al., 2021) and bacterial producers of substances with antimicrobial activity that can suppress the metabolism of ECG to reduce the risk of infection of agricultural products (Lukin and Marchuk, 2011). Thus, conducted and planned studies will be used in the future to develop a biological product that is best suited for the remediation of the studied area (Tretyakova, 2018).
Funding
The work was carried out within the framework of the state assignment on the topic "Development of approaches to phytoremediation of post-technogenic landscapes using plant growth-stimulating rhizobacteria (PGPB) and "Omic" technologies", additional agreement no. 075-03-2021-189/4 dated September 30, 2021 (internal no. 075-GZ/X4140/679/4).
ORCID
E.E. Vorobyeva 0000-0001-6362-7589 N.V. Fotina 0000-0002-7655-0258 L.K. Asyakina 0000-0003-4988-8197 M.A. Osintseva 0000-0002-4045-8054 A.Yu. Prosekov 0000-0002-5630-3196
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