Arsenic and selenium in shore soils and bottom sediments of Samara city ponds

Arsenic and selenium are included in the group of chemical elements of the first hazard class, which confirms the need to analyze their content in natural environments of natural and man-made ecosystems during ecological and biogeochemical monitoring. By their chemical properties, arsenic and selenium are metalloids or semimetals. In very low concentrations, they are necessary for the normal functioning of the organisms, but with increasing concentrations in the habitat or food they show high toxicity. Particularly dangerous is the accumulation of arsenic and selenium in accumulative environments and landscapes, which include soils and confined water bodies. For the urban ecosystems of the Samara Region, earlier monitoring of the content of arsenic and selenium in the components of their accumulative landscapes was not carried out, which confirms the relevance and practical significance of the presented materials. The authors carried out ecological and geochemical studies of the accumulation of arsenic and selenium in coastal soils and bottom sediments of twenty ponds located in the Samara city within the coastal slope of the Saratov reservoir (Volga slope) and on the watershed between the Saratov reservoir and the Samara River. The results analysis showed a relatively low level of arsenic accumulation in the analyzed substrates of the studied ponds. Compared with the level of regional background for the Middle Volga, the studied accumulative aqual landscapes are noticeably enriched in selenium (2-15 times). The technogenic influx of arsenic and selenium into the accumulative landscapes of the Samara city may be associated with the activities of metalworking and machine-building enterprises, as well as thermal power plants. The materials presented in the paper concerning the content of arsenic and selenium in coastal soils and bottom sediments of urban ponds in the Samara city can be considered as pioneering for the region and subsequently used in the ecological and geochemical monitoring of regional urban ecosystems.