Features of the Elemental Composition of Alluvial Soils of the Middle Course of the Bolshaya Kokshaga River

The content of chemical elements in the alluvial soils (Fluvisols) of the middle reaches of the Bolshaya Kokshaga River, inheriting the composition from the lithological basis of two mineralogical-geochemical provinces of Central Russian and Priuralskaya, was estimated, which made it possible to establish the limits of the content of gross forms of elements and their background concentrations, to lay the foundation for monitoring the state of the environment on the territory of the Bolshaya Kokshaga Reserve. The content of 34 chemical elements was found in alluvial soils and sands of coastal shoals, of which the most common are Si, Al, Fe, Ca, K, Mg, Na, Ti, Mn, P, S with a content of >1 g/kg. The concentrations of many elements significantly differ by soil types, the greatest similarity was revealed between meadow and humus-gley. In comparison with alluvial soils, the sands of coastal shoals are characterized by a maximum content of Si and a minimum of all other elements. Turf soils are characterized by the lowest content of elements, with the exception of Si, meadow and humus-gley accumulate more Al, Fe, K, Na, Mg, Ti, Mn, Ba, Cr, Zn, Ni, V and As, silt-peat, which are highly mineralized peat deposits, accumulate more Ca, S, P, Sr, Cl and Rb. It was found that alluvial soils are characterized by a high natural level of content of As, Cu, V, P, Zr, Ni and Zn, exceeding the clarks (Kk = = 1.5–2), and low–Al, K, Mg, Ti, Sr, Rb, Na, Cl and Ca (Kk < 1), the content of the remaining elements are comparable to Clark values.