The use of silver in various spheres of life and production leads to an increase in environmental pollution, including soil. At the same time, the environmental consequences of silver pollution of soils have been studied to a much lesser extent than those of other heavy metals. The aim of this study is to estimate silver ecotoxicity using the soil state biological indicators. We studied soils that are significantly different in resistance to heavy metal pollution: ordinary chernozem (Haplic Chernozems, Loamic), sierosands (Haplic Arenosols, Eutric), and brown forest acidic soil (Haplic Cambisols, Eutric). Contamination was simulated in the laboratory. Silver was introduced into the soil in the form of nitrate in doses of 1, 10, and 100 mg/kg. Changes in biological parameters were assessed 10, 30, and 90 days after contamination. Silver pollution of soils in most cases leads to deterioration of their biological properties: the total number of bacteria, the abundance of bacteria of the genus Azotobacter, the activity of enzymes (catalase and dehydrogenases), and the phytotoxicity indicators decrease. The degree of reduction in biological properties depends on the silver concentration in the soil and the period from the contamination moment. In most cases, there is a direct relationship between the silver concentration and the degree of deterioration of the studied soil properties. The silver toxic effect was most pronounced on the 30th day after contamination. In terms of their resistance to silver pollution, the studied soils are in the following order: ordinary chernozem > sierosands ≥ brown forest soil. The light granulometric composition of sierosands and the acidic reaction of the environment of brown forest soils, as well as the low content of organic matter, contribute to high mobility and, consequently, high ecotoxicity of silver in these soils. The regional maximum permissible concentration (rMPC) of silver in ordinary chernozem (Haplic Chernozems, Loamic) is 4.4 mg/kg, in sierosands (Haplic Arenosols, Eutric) 0.9 mg/kg, and in brown forest soils (Haplic Cambisols, Eutric) 0.8 mg/kg.

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Aim. To assess the resistance of soils in the south of Russia to silver pollution using biological indicators.Methods. The contamination of soils in southern Russia (ordinary chernozem, grey sandy and brown forest soils) was simulated with silver under laboratory conditions. Soils were contaminated with water‐soluble silver nitrate in order to reveal the maximum ecotoxicity of silver. Soil stability was assessed according to the most sensitive and informative biological parameters in dynamics of 10, 30 and 90 days after pollution. Results. Silver contamination inhibits the activity of oxidoreductases (catalase and dehydrogenases), reduces the total number of bacteria and the growth and development of radish. For all soils, a direct relationship was noted between silver concentration and the degree of deterioration of soil properties. The toxic effect of silver was most pronounced on the 30th day after contamination. According to their resistance to silver pollution, the soils investigated form the following sequence: ordinary chernozem> grey sandy soil ≥ brown forest soil. Conclusion. The light granulometric composition of grey sandy soils and the acidic reaction of the environment of brown forest soils, as well as the low organic matter content, contribute to the high mobility and high ecotoxicity of silver in these soils. Regional maximum permissible concentrations (MPCs) of silver content in ordinary chernozems, grey sandy and brown forest soils have been determined as ‐ 4.4, 0.9 and 0.8 mg/kg, respectively.

The results of the study of the ecotoxicity of bismuth on ordinary chernozem, brown forest soils and sierosands along the length of radish roots are presented. Small doses of 1.5-3 mg/kg of bismuth stimulated the growth of radish roots on ordinary chernozem. The maximum toxicity of bismuth carbonate and nitrate at a dose of 300 mg / kg was established on sierosands (reduction in the length of radish roots by 43% of the control). Bismuth carbonate 300 mg/kg showed the greatest toxicity when applied to ordinary chernozem and brown forest soil and reduced the length of radish roots by 31 and 44% of control, respectively. The series of toxicity ((on radish’s root length) of chemical forms of bismuth for soils forms the following sequence: bismuth carbonate (84) ≥ bismuth nitrate (86) > bismuth oxide (90). The toxic effect of bismuth depends on the form and concentration of bismuth in the soil,the particle-size composition, the reaction of the soil environment and the content of organic matter in the soil.

AIM: To qualitatively assess the impact of some anthropogenic factors (construction of industrial facilities, transport networks, intensification of agriculture) on natural foci of tularemia in the Rostov agglomeration. MATERIALS AND METHODS: The official data and reports of the Federal State Budgetary Institution Rosselkhoznadzor, the data of the Department of Rospotrebnadzor for the Rostov region, the Federal State Budgetary Institution Center of Hygiene and Epidemiology in the Rostov Region of Rospotrebnadzor were analyzed. Zoological and parasitological studies were carried out in accordance with modern regulatory documents in force. The detection of F. tularensis markers in field samples was carried out using serological and molecular genetic methods. RESULTS: It was found that the existing territories under natural protection of the Russian agglomeration restrict degradation processes, while maintaining the simultaneous coexistence of native species and synanthropic animals that make up the parasitic circulation system of the tularemia pathogen. CONCLUSION: The qualitative assessment of anthropogenic pressure/action can probably be interpreted as conditionally neutral. This could lead to potential risks of infection of the unvaccinated population of the Rostov agglomeration in natural foci of tularemia. The dynamism of the processes of anthropogenic action requires constant monitoring of the changes in the species diversity of carriers and vectors, their abundance, and infection in the natural foci of tularemia in the Rostov agglomeration.

The results of studies of changes in the activity of catalase in ordinary chernozem, brown forest soil and sierosands under pollution with different of the bismuth chemical compounds: bismuth oxide, carbonate and nitrate are presented. It has been established that bismuth contamination of different types of soils reduces catalase activity, regardless of the chemical compounds. The toxicity of bismuth increases with an increase in the dose applied to the soil. Based on the chemical bismuth compounds, the average toxicity series for soils by catalase activity is as follows: bismuth nitrate (86)> bismuth carbonate (90) ≥ bismuth oxide (93). The greatest ecotoxicity is shown by bismuth nitrate due to its good solubility and greater mobility in the soil solution of Bi3+. The bismuth oxide showed slightly less negative effects. The series of soil sensitivity to bismuth pollution has the following sequence: ordinary chernozem (95) > sierosands (89) ≥ brown forest soil (86). The most resistant to contamination with bismuth soil is ordinary chernozem, and the most sensitive soil is brown forest soil.