Distribution of Cu, Ni, Zn, Mn, Cr, Cd, Pb, Co, Mo, As in alluvial soils of floodplain landscapes of the Sozh river basin

The studies were carried out in the western part of the Bryansk Region in the landscapes of the Sozh River basin (Iput’ River, tributary of the 1st order, south of the village of Perevoz; River Besed', tributary of the 1st order, northwest of the village of Baturovka; River Unecha, tributary 2nd order, west of the village of Lopatny). The aim of this work is to study the features of the vertical and horizontal distribution of the gross content of Cu, Ni, Zn, Mn, Cr, Cd, Pb, Co, Mo, As in the alluvial soils of floodplain landscapes. The selection of soil samples for the determination of the gross content of trace elements was carried out in subsystems of the floodplain landscape, different in geomorphology and hydrology, by the method of soil springs. Each key soil plot was a full-profile soil pit and four reconnaissance pits. Samples were taken from the walls of the cuts every 5 cm, mixed and averaged by the quartering method. The gross content of trace elements was determined by the atomic absorption method, after preliminary decomposition of the samples with a mixture of concentrated nitric and hydrofluoric acids using a microwave system. Variations in the content of trace elements in the layers of alluvial soils were assessed using the coefficient of variation. To characterize the degree of concentration or dispersion of trace elements in soils, the concentration clarke was calculated. As a result of the research, it was found that the vertical distribution of trace elements in the 0–20 cm layer is determined by their chemical properties and the genesis of the soils of the floodplain subsystems, and can be uniform, decreasing/increasing with depth or with concentration in separate layers. Clarke concentrations of microelements and their content increase in the direction from the riverbed to the near-terrace subsystem of the floodplain. Concentrations of elements in the soils of floodplain landscapes do not exceed the clarke value. The exceptions are Cr, Zn and Cu in the soil of the near-terrace subsystem of the river Unecha, Cd – in the soil of the central subsystem of the river Besed’, as well as Cu and Cd – in the soil of the near-terrace subsystem of the river Besed’. An excess of the clarke value for some elements may indicate their anthropogenic origin.