Biodiagnostics of stability of soils of southern Russia to silver pollution

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