Ecological State Assessment of the Coastline Soil Cover of Small Rivers in St. Petersburg

The study was conducted to determine the degree of contamination of soils along the coastline of the Black River (right tributary of the Neva River). Gross and mobile forms of heavy metals were determined in the soil samples. It was found that industrial activity in areas along the river contributes to an increase in the concentrations of heavy metals in the soil cover. The ecological condition of the soils was studied using bioassay methods, and the selection of sensitive bioassays for the detection of contaminants was tested. The bioassays on the mortality of Daphnia magna Straus , on the chemotaxis of Paramecium caudatum ciliates , on the change in optical density of Chlorella vulgaris Beijer algae , and a contact bioassay on the seeds of Triticum vulgare L. were conducted. A "block" of bioassay systems was formed, which allows assessing the ecological state of these soils. Zones of increased ecological risk associated with the impact of highways, as well as the construction of residential complexes located along the river, were identified. The information obtained is recommended for use in applied purposes for managing the risks of technogenically contaminated soils.