Introduction. The Black Sea Coast of the Caucasus is one of the most important recreational and tourist regions for Russia. In recent years, it has been subjected to a sharply increased anthropogenic load, due to an increase in the number of tourists, accompanied by an increase in traffic flows and, as a result, an increase in environmental pollution, including oil hydrocarbons. The risks of leakage of oil products during transportation and pumping are increasing. To predict and prevent dangerous consequences of pollution, it is necessary to determine the environmentally safe residual content of oil and oil products in the soil, based on the regional ecological and geochemical characteristics of soils. Materials and methods. Laboratory modelling of contamination with oil and petroleum products (fuel oil, gasoline, diesel fuel) of sod-carbonate typical soil was carried out. To simulate pollution, oil and petroleum products were added to soil samples including fuel oil, gasoline, diesel fuel in a weight concentration of 1% (low pollution), 5% (medium pollution) and 10% (high pollution) of the soil mass. The exposure period lasted 30 days. After the specified period, changes in biological parameters (enzyme activity, radish root length, number of soil bacteria) were determined. Based on the listed parameters, the integral indicator of the biological state IIBS of the soil was calculated . Results. Oil and oil products pollution negatively affected the biological properties of the studied soil. A significant decrease in enzymatic activity, the number of bacteria, and the length of plant roots was recorded. The range of toxicity of the studied substances on biological indicators of soils is as follows: oil > fuel oil > gasoline > diesel fuel. The study made it possible to determine the maximum level of residual content of oil and petroleum products (fuel oil, gasoline, diesel fuel) in the refinery. For oil, it is 0.27%, for gasoline – 0.40%, for fuel oil – 0.30%, for diesel fuel – 0.45%. Limitations. The proposed limit levels of residual oil and petroleum products (fuel oil, gasoline, diesel fuel) in soils are applicable primarily on the territory of the Black Sea coast of the Caucasus. Conclusion. The proposed limit levels of the residual content of oil and petroleum products (fuel oil, gasoline, diesel fuel) in the soils of the refinery area can be used by environmental, agricultural and scientific organizations

Relevance. Operation of solid municipal waste landfills leads to soil degradation and a decrease in its fertility. Studying the impact of heavy metals on the ecology of landfill soils and soils of adjacent territories is important, since the accumulation of high concentrations of heavy metals can lead to disruption of the ecological and agricultural functions of the soil. Aim. To assess the contamination of soils by heavy metals at the solid municipal waste landfill in the city of Rostov-on-Don. Objects. The studied soil samples taken from the center of the landfill were compared to soils of the adjacent territory at different distances and directions relative to the center of the landfill. Methods. Gross contents of heavy metals and metalloids (V, Cr, Co, Ni, Cu, Zn, As, Sr, Pb, Rb, Zr, Ba) were studied using the X-ray fluorescence method. The obtained values were used to calculate the pollution indices: background enrichment coefficient, individual unified pollution index, geoaccumulation index, pollution load index, Nemerov pollution index, potential ecological risk index, pollution protection index, pollution probability index, and general pollution degree index. These indicators were used to determine the pollution degree of the studied territories. Results: The excess of Cr, Ni, Cu, Zn, As and Pb according to the MAC at the landfill from the control was determined. A very high concentration of heavy metals and metalloids compared to the MAC and background was found in the center and close to the center of the landfill, indicating the anthropogenic contribution of these elements. The evaluation of the results showed that the pollution load index is more reliable for assessing the pollution of the landfill and the adjacent territory with heavy metals. When compared, the used indices and pollution coefficients formed the following series: pollution load index>general pollution degree index>Nemerov pollution index>pollution probability index>pollution protection index>potential ecological risk index=background enrichment coefficient. The adjacent territory of the landfill was polluted to a lesser extent. The applied indices and coefficients can be used in environmental assessment, as well as in monitoring and for preventing soil pollution with heavy metals and metalloids. For citation: Kucherova A.V., Minnikova T.V., Kolesnikov S.I., Sherstnev A.K. Assessment of heavy metal pollution of soils of a municipal solid waste landfill of the city of Rostov-on-Don. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 8, pp. 90–101. http://doi.org/10.18799/24131830/2026/8/5062

There are unique types and subtypes of soils on the Crimean Peninsula. The growing tourist load on the region requires an increase in the productivity of all industries, including oil refining. All of this increases risks of spills and leaks of oil and petroleum products during their transportation and pumping. There is a large gap in the field of regulation of soil pollution with petroleum products (gross content), which consists in the absence of maximum permissible concentrations in the regulatory framework of the Russian Federation. To predict the possible negative consequences of environmental pollution with oil and oil products, it is necessary to develop regional environmentally safe concentrations of oil and oil products that will take into account the local regional ecological and geochemical characteristics of soil types. The purpose of this study is to conduct laboratory modelling of environmentally safe oil concentrations in the soils of Crimea. Fuel oil contamination (1, 5, and 10

Remediation is an important area of oil-contaminated soil restoration in Russia, since oil refining industry is the major one for Russia and neighbouring countries, and the issues of environmentally effective and economically profitable remediation of oil contamination have not yet been solved. Soils under various economic uses have different surface areas and degrees of soil particles envelopment with oil due to the presence or absence of cultivation, the amount of precipitation and plant litter. The introduction of various substances for remediation into oil-contaminated soils of steppes (arable land), forests, and semi-deserts, considering their differences, gives different results. Biochar is coal obtained by pyrolysis at high temperatures and in the absence of oxygen. The uniqueness of this coal lies in the combination of biostimulating and adsorbing properties. The purpose of the study is to conduct an environmental assessment of biochar application for remediation of oil-contaminated soils under various economic uses. The article compares the environmental assessments of biochar application in oil-contaminated soils with different particle size fraction. The following indicators of soil bioactivity were determined: enzymes, indicators of initial growth and development intensity of radish, microbiological indicators. We found that the most informative bioindicator correlating with residual oil content is the total bacteria count, and the most sensitive ones are the roots length (ordinary chernozem and brown forest soil) and the shoots length (brown semi-desert soil). The use of biochar on arable land and in forest soil (ordinary chernozem and brown forest soil) is less environmentally efficient than in semi-desert soil (brown semi-desert soil). The study results can serve to develop measures and managerial and technical solutions for remediation of oil-contaminated soils under various economic uses.

Introduction. Germanium (Ge) is a valuable chemical element for the technological sphere. In recent years, Ge has been increasingly used in various branches of high-tech industry: in the creation of fiber and infrared optics, as well as as polymerization catalysts in the production of polyethylene terephthalate (PET). In soils contaminated with mining waste, the Ge content ranges from 1.45 to 7.91 mg/kg. The maximum permissible concentrations (MPC) of Ge in the soil have not been developed, accordingly, it seems relevant to conduct a comprehensive assessment of the effect of Ge on biological indicators of soil condition and establish an environmentally safe concentration of Ge in the soil. Materials and methods. In a laboratory experiment, the ecotoxicity of 3, 30, and 300 Ge background concentrations (BC) on 10th, 30th, and 90th day was evaluated using biodiagnostic methods. All the studied indicators were included in the calculation of the integral indicator of the biological state (IIBS) of the soil. In case of contamination with Ge there was diagnosed the sequence of violations of the ecosystem functions of the soil according to the degree of decrease in IIBS. The dose of the element, under the influence of which there is a violation of the integral functions of the soil, characterizing the degree of the soil fertility, is defined as an environmentally safe concentration of Ge in this soil. Results. With an increase in the Ge dose in the soil, the ecotoxic effect of the impact of the mineral on catalase and dehydrogenases activity, the abundance of bacteria of the genus Azotobacter, cellulolytic activity, germination and length of radish roots increased. After Ge contamination of the soil, the maximum toxicity was revealed for the indicators studied on the 10th and 30th das. The radish root length index showed the greatest sensitivity to Ge soil contamination compared with the indicator of dehydrogenases activity. The strongest correlation was noted between the Ge content in the soil and catalase activity. An environmentally safe concentration of Ge in the soil has been established – 6.5 mg/kg. The obtained results on the assessment of ecotoxicity of soils contaminated with Ge can be used to diagnose the ecological state of soils. Limitations. The proposed environmentally safe concentrations in Ge soils are applicable, first, for ordinary chernozem. Conclusion. An increase in background concentrations of Ge in the soil inhibited the biological parameters of ordinary chernozem. The maximum ecotoxic effect of Ge on the studied parameters was demonstrated on 10th and 30th days. The length of radish roots is most sensitive to Ge soil contamination compared to the indicator of dehydrogenase activity. The strongest correlation was noted between the Ge content in the soil and catalase activity. An environmentally safe Ge concentration in the soil has been established – 6.5 mg/kg. The obtained results on the assessment of ecotoxicity of soils contaminated with Ge can be used for diagnostics and as an indicator of the ecological state of soils.

The scale of lithium mining and environmental pollution has increased dramatically in recent years, due to the production of automotive lithium batteries. In a model experiment, changes in the alkaline-acid properties of three types of soils of different buffers (common chernozem, brown forest acid soil, and sulfur sands) were studied when contaminated with various compounds of lithium chloride (LiCl), hydroxide (LiOH), sulfate (Li2SO4), and carbonate (Li2CO3) at concentrations of 15, 30, 50, 100, 125, 250 and 500 mg of Li per 1 kg of soil. According to the results of the study, it was revealed that the alkaline-acid properties of soils vary depending on the chemical form of lithium, the concentration of lithium compounds and the buffering of contaminated soil. When lithium chloride and sulfate are introduced, soil acidification occurs, and when lithium hydroxide and carbonate are introduced, alkalinization occurs.

Introduction. Chromium (Cr) is one of the most toxic heavy metals. The pulp of the Urup Mining and Processing Plant (MPP) contains a high concentration of Cr up to 1370 mg/kg. At the same time, the maximum permissible concentration of Cr in the soil (0.05 mg/kg) is not consistent with its natural content in the soil (up to 130 mg/kg). To assess the impact of the Urup MPP tailing dump on the adjacent mountain-meadow chernozem-likes soils, it is advisable to determine the environmentally safe Cr content. Materials and methods. Cr (VI) contamination of mountain meadow chernozem soil was simulated in laboratory conditions. Chromium was introduced into the soil in concentrations 10, 25, 50, 100, 250, 500 mg/kg. The exposure period of the model experiment was 30 days while maintaining constant humidity and temperature. At the end of this period, in all samples of mountain meadow chernozem soil there were determined biological indicators: the number of soil bacteria, indicators of enzyme activity, root length and germination of radishes. Results. Cr contamination of mountain-meadow chernozem-likes soil was found to lead to inhibition of biological parameters. An inverse relationship has been established between the Cr concentration and the biological parameters of the soil. In the vicinity of a mining enterprise in a mountain-meadow chernozem-likes soil, a concentration of 125 mg/kg should be taken as an environmentally safe Cr concentration. Limitations. Environmentally safe concentrations can be used primarily as a local environmental standard for the Cr content in the soil in the area of the mining and processing plant. Conclusion. The proposed environmentally safe concentration of Cr around a copper mining enterprise can be recommended for use by institutions in the field of environmental protection, agricultural and scientific activities.

Under the influence of pollution by petroleum hydrocarbons, soils from different natural zones have different physical, chemical, and biological indicators of the soil condition. Biological indicators are the most sensitive to soil pollution and changes in the ecological state. Arid zone soils, compared to other types of soils, due to the soil formation conditions and the physical and biological properties, are very unstable to pollution by petroleum hydrocarbons. In this regard, it is important to standardize the content of petroleum hydrocarbons taking into account the response of enzyme activity and microbiological indicators, and an assessment of soil phytotoxicity. Such standards serve as parameters for the health of soils in a region when contaminated with oil and oil products. The aim of this study is to assess the environmental health standards of arid soils in southern Russia when contaminated with oil and oil products. It has been established that, with an increase in the concentration of oil and oil products, the biological indicators of soils are suppressed. The ecological standard for oil in brown semi-desert soil (0.1

In the field, the effect of liquid mineral fertilizers and carbamide ammonium nitrate (LMF and CAN) in the agrocenoses of peas, chickpeas, coriander and flax on the biological activity of chernozems treated for a long time using null technology was studied. Among the biological parameters, the activity of enzymes involved in the carbon cycle (invertases, dehydrogenases), the intensity of soil respiration, the number of microorganisms, and the content of active carbon were evaluated. There is a difference in the effects of fertilizers on crops and different parameters of biological activity. The biological activity of the studied soils varied depending on the type of mineral fertilizer, as well as the cultivated crop.

The processes of extraction and enrichment of metal ores are accompanied by the formation of waste containing pollutants, including heavy metals. To reduce the impact on the environment, after decommissioning of the tailings dump, in which enterprises store waste, reclamation is carried out. In this study, the phytotoxic properties of the soil of the reclaimed tailings pond of the Urup mining and processing plant, using radish seeds (Raphanus sativus L. var. Radicula). As a result, it was found that the soils of the reclaimed tailing dump have a satisfactory level of phytotoxic indicators, from which it can be concluded that high-quality reclamation.

The effect of silver nanoparticles (AgNPs) in concentrations was evaluated 0.1; 0.5; 1; 5; 10; 50 and 100 mg/kg for the germination and root length of ordinary black earth radish 30 days after contamination. It was found that the degree of ecotoxic effect of AgNPs on the germination and length of radish roots is directly dependent on their dose in the soil. The content of AgNPs 1, 5, 10, 50, 100 mg/kg in ordinary chernozem caused a decrease in the germination of radish by 11, 13, 15, 18 and 38 % compared with the values in uncontaminated soil. Doses of AgNPs 0.5, 1, 5, 10, 50 and 100 mg/kg inhibited the length of radish roots by 19, 20, 25, 30, 37 and 43 % compared with the values obtained in uncontaminated soil. The radish root length index showed the greatest sensitivity to soil contamination by AgNPs compared to the germination index. The obtained results on the assessment of phytotoxicity of soils contaminated with AgNPs can be used for diagnostics and as an indicator of the ecological state of soils.

Enzymatic activity of soils is the most important diagnostic indicator of the ecological state of soils affected by various types of anthropogenic impact. The aim of the study was to evaluate the enzymatic activity of ordinary chernozem (Haplic Chernozem) contaminated with Ag, Bi, Te, and Tl. Ten enzymes (catalase, dehydrogenase, peroxidase, polyphenol oxidase, ascorbate oxidase, ferrireductase, protease, phosphatase, invertase, and urease) were analyzed. According to the degree of inhibition of enzymes, heavy metals formed the following sequence: Tl > Ag > Bi > Te. With an increase in the concentration of heavy metals, the toxic effect on the activity of enzymes increased. The oxidoreductases showed greater sensitivity to Ag, Bi, Te, and Tl contamination than hydrolases. Among oxidoreductases, the highest sensitivity was found for ferrireductase, and the lowest one for ascorbate oxidase. According to the activity of enzymes of the hydrolase class, invertase was the most sensitive, and urease was the least sensitive. When contaminated with Ag, Bi, and Te, invertase had the highest informative value, and when contaminated with Tl, urease and polyphenol oxidase were the most informative. Among the enzymes of the oxidoreductase class, the highest information value was found for peroxidase, and the lowest one for ascorbate oxidase. Among the enzymes of the hydrolase class, invertase was the most sensitive, and phosphatase was the least sensitive. The results of the study can be used to assess the ecological state of soils contaminated with Ag, Bi, Te and Tl.

The dynamics of phytotoxicity indicators (germination and length of radish roots) of ordinary chernozem when contaminated with silver nanoparticles was studied. In laboratory conditions, ordinary chernozem was contaminated with silver nanoparticles (1, 10 and 100 mg/kg) for 3, 10, 30, 90 and 180 days. It was found that the more silver nanoparticles were introduced into the soil, the greater the decrease in germination and length of radish roots. There was no restoration of germination and length of radish roots with an increase in the period from the moment of contamination. In this study, the maximum toxic period from the moment of contamination for each indicator was identified by its sensitivity to silver nanoparticles and informativeness. The maximum toxicity of silver nanoparticles in relation to the root length and germination of radishes was noted on the 10th and 30th days, respectively. The results can be used to assess the phytotoxicity of soils contaminated with silver nanoparticles.

Wildfires result in the emission of large volumes of toxic smoke, which is transported hundreds of kilometers away from the fires and can have an adverse impact on soil, biota, and humans. A series of modelling experiments on pyrogenic fumigation of soil has been carried out to assess the effects of gaseous products of wildfires on soil biochemical parameters. The effects of continuous exposure to gaseous substances and periodical, repetitive effects of smoke exposure on soil have been determined. The results have been compared with a single intense smoke exposure. It was found that pyrogenic impact significantly affected the enzymatic activity of ordinary chernozem. The degree of influence depended on the duration and periodicity of smoke exposure. In all experiments, enzymes of oxidoreductase class (catalase, peroxidase, polyphenol oxidase) were more sensitive to fumigation than invertase from hydrolase class. High concentrations of toxic gases were the cause of suppressed enzymatic activity of soils. The following concentrations exceeded the maximum permissible concentrations for atmospheric air: CO 714 times, phenol (hydroxybenzene) 441 times, acetaldehyde 24100 times, formaldehyde 190 times. Accumulation of polycyclic aromatic hydrocarbons (PAHs) in soil after fumigation was revealed, the total content of PAHs was 377 ng/g. The highest values were recorded for naphthalene, where the concentration was 4.4 times higher than the maximum permissible concentration and phenanthrene, 2.8 times higher than the maximum permissible concentration. It has been found that 60-min intensive smoke affects the soil to a lesser extent than continuous and periodical ones. Indices of enzymatic activity of chernozem after such fumigation decreased by 15–33

The effect of contamination of ordinary black earth with platinum oxide (PtO2) on biological properties: root length and germination of radish, total number of bacteria, abundance of bacteria of the genus Azotobacter, activity of catalase and dehydrogenases have been studied. The concentrations studied were 0.01, 0.1, 1, 10 and 100 mg/kg in 10, 30 and 90 days after contamination. A stimulating effect (hormesis) of platinum oxide at a concentration of 0.01 mg/kg on the biological properties of ordinary black earth was recorded. It was found that in other cases, platinum oxide has a negative effect on the studied parameters, and exhibits the greatest toxicity after 30 days after contamination, followed by restoration of soil properties after 90 days. It was concluded that the most sensitive (highest degree of reduction) indicators to platinum oxide contamination were the total number of bacteria, germination and length of radish roots. Early diagnosis of the degree of soil contamination with platinum compounds is recommended in order to obtain a prompt assessment of the impact and prevent possible negative consequences.

Thallium ecotoxicity was assessed in laboratory model experiments by changing in microbiological, biochemical, and phytotoxic properties of soils in the South of Russia: ordinary chernozem (Haplic Chernozem (Loamic)), seropesok (Eutric Arenosol), and slightly unsaturated brown forest soil (Eutric Cambisol), differing in texture, pH, and organic matter content. There was usually a direct relationship between Tl concentration and the deterioration rate of the studied soil properties. The ecotoxicity of Tl nitrate was higher as compared to Tl oxide. The ecotoxic effect of Tl was the strongest for chernozem and seropesok within 10 days and for brown forest soil within 30 days after contamination. Restoration of biological soil properties was recorded on the 90th day. The resistance to Tl contamination was the greatest for ordinary chernozem and the smallest for seropesok. The results obtained indicate a high ecotoxicity of Tl.

The automotive industry is the main source of environmental pollution with platinum group metals, which increases the concentration of platinum in road dust, soil, and plants. This can lead to the achievement of toxic levels of this metal in the environment, and consequently, an imbalance of the ecosystem, a reduction in the microbial population, and a decrease in soil fertility. The effects of platinum on the activity of oxidoreductases of ordinary chernozem have been studied: the activity of catalase and dehydrogenase. Platinum was introduced into the soil in the form of chloride. Platinum concentrations were studied – 0.01; 0.1; 1; 10 and 100 mg/kg. The change in the indicators of ordinary chernozem was assessed 10, 30 and 90 days after contamination. The absence of a stimulating effect of platinum chloride on catalase activity, the effect of hormesis on the activity of dehydrogenases of ordinary chernozem has been established. The dependence of the degree of decrease in indicators on the concentration of the pollutant in the soil and the time from the moment of contamination is shown. The study shows the negative effect of even a small concentration (0.1 mg/kg) of platinum chloride on the enzymatic activity of the soil. Early diagnosis of the degree of soil contamination with platinum compounds can be successfully used to promptly assess their impact on soil condition and prevent possible negative consequences.

The results of studying the effect of fires on the biological properties of brown soils of xerophytic forests (Skeletic Leptic Cambisol) of the Utrish State Nature Reserve, Krasnodar Territory (crown fire of 2020), and burozem of mesophytic forests (Haplic Cambisol (Loamic)) of the Khamyshinsky forestry, Republic of Adygea (ground fire of 2018) are presented. Changes in the reaction of the soil environment, the content of organic carbon, and the activity of such enzymes as catalase, urease, phosphatase, and invertase involved in the cycle of carbon, phosphorus, and nitrogen have been studied. The reaction of enzymes to pyrogenic effects depends on the type of enzyme and the type of soil. A factor analysis was also carried out. The activity of catalase and invertase for two types of soils in a layer of 0–3 cm decreased by an average of 47%, while the reaction of phosphatase and urease differed depending on the soil type. Two years after the fire, the phosphatase activity of the surface layer of post-pyrogenic brown soils approached the control values; urease activity recovered more slowly compared to other enzymes. Four years after the fire, in the 0–3 cm layer, for the post-pyrogenic acid burozem, on the contrary, the values of urease activity approached the control values. An increase in pH values by an average of 30% and a decrease in the content of Corg by an average of 12% were also established for two types of soils. In the 3–10 cm layer, for brown soils, an average increase in the activity of all the studied enzymes was noted, while for acid burozem, on the contrary, a decrease. Factor analysis showed the presence of a relationship between the reaction of the soil environment, the content of organic carbon and the activity of enzymes, while the tightness and nature of the relationship differed depending on the type of soil. The results obtained indicate the influence of the edaphic features of the studied soils on the response of enzymatic activity to pyrogenic exposure.

Introduction. Тhe municipal solid waste of pollution negatively affects on the state of the environment, since during their storage on the territory of landfills and the adjacent territory, accumulation of heavy metals (HM) can change the biological indicators of soil conditions: microbiological, biochemical, and phytotoxic. The aim of the study was to assess the influence of the toxic effect of the municipal waste landfill “Azov” in the Rostov region on the ecological state of the soil. Materials and methods. It was explored the influence of municipal solid waste landfill “Azov” of the Rostov region on the ecological condition of the ordinary chernozem in the landfill and adjacent territory (140, 260, 380, and 540 m). The content of heavy metals in the soil, such as chromium (Cr), strontium (Sr), zinc (Zn), vanadium (V), copper (Cu), nickel (Ni), cobalt (Co), lead (Pb), and arsenic (As) were defined. The ecological state is assessed by sensitive and informative-biological indicators of soil pollution: the abundance of bacteria of the genus Azotobacter, the total prevalence of soil bacteria, the activity of catalase, dehydrogenases. Results. Soils were found to contaminate with arsenic by MAC / TAC (exceeding the MAC by 7 times at the landfill and exceeding the MAC by 4 to 6 times in the territory). Pollution with heavy metals according to German MACs with chromium exceeded by 1.4 times). The highest concentration of heavy metals prevailed in the body of the landfill. Depending on distance from the landfill the concentration of heavy metals in the soil decreased. HM contamination leads to negative consequences for the ecological state of ordinary chernozem: the total number of bacteria decreases (until to 95% of the control), the number of the genus Azotobacter decreases (up to 95% of the control), the activity of catalase (up to 25% of the control) and dehydrogenase decreases (up to 30% of control) and increased soil phytotoxicity (up to 60% of control). It can be concluded that the exploitation of the landfill leads to a deterioration of the environmental situation on the territory of the landfill and beyond. Limitations. The ecotoxic effect of HMs on soils less buffered to pollution will be higher than on the chernozems studied in the article. Conclusion. The Landfill “Azov” was found to impact on the microbiological, biochemical, and phytotoxic parameters of the soil negatively. This problem connects with influence of heavy metals which get into the soil of during the operation of the landfill. The most sensitive and informative biological indicators are total number of bacteria and length of radish roots.

The ecotoxicity of Ag particles of different size has been assessed by microbiological, biochemical, and phytotoxic indicators for the upper layer (0–20 cm) of ordinary chernozem (Haplic Chernozem) in a laboratory model experiment. The effect has been studied of nano- (10 and 100 nm) and microparticles (1000 nm) of Ag at concentrations of 1, 10, and 100 mg/kg on the biological parameters of ordinary chernozem 30 days after contamination: the activity of catalase, dehydrogenases, ferrireductase, urease, peroxidase, polyphenol oxidase, invertase, phosphatase, the total number of bacteria, the abundance of bacteria of Azotobacter genus, the number of germinated seeds and the length of radish roots. It was found that the ecotoxicity of Ag particles depended on their size: in most cases, Ag particles 10 nm in size had a stronger ecotoxic effect on the biological parameters than particles 100 and 1000 nm in size. There were no significant differences in the ecotoxicity of 100 and 1000 nm Ag particles. The difference in the effects of Ag particles of different sizes increased with increasing Ag concentration in the soil: the higher the Ag concentration was in the soil (from 1 to 100 mg/kg), the more pronounced the difference was in ecotoxicity between 10 nm Ag particles and 100 and 1000 nm Ag particles. Phytotoxic indicators were more sensitive to contamination by Ag nanoparticles at all concentrations studied (1, 10 and 100 mg/kg); the total number of bacteria, invertase and phosphatase activity at 10 and 100 mg/kg; the abundance of bacteria of Azotobacter genus and the activity of dehydrogenases at 100 mg/kg. It is advisable to use these indicators in biodiagnostics of the ecotoxicity of Ag nanoparticles.