Ecological-Geochemical Studies of Technogenic Soils in the Flood Plain Landscapes of the Seversky Donets, Lower Don Basin

The paper presents the ecological-geochemical studies of soils confined to the impact zone of industrial waste water storage and sludge reservoirs of former Lake Atamanskoe in the Seversky Donets River flood plain. These soils show hundreds time increase of Zn, tens times increase of Cu and Pb, and few times increase of Cu, Ni, and Cr as compared to the average lithosphere values. The coefficients of technogenic concentration of elements (Kc) and the total indicator of soil pollution (Zc) are calculated. In terms of Zc, the studied soils are ascribed to the extremely dangerous category of pollution. Using predominant pollutant metal, Zn, as an example, it is shown that an increase in the metal pollution level of soil leads to a change of interaction mechanism with organic matter and Fe oxides, and, subsequently, to the prevalence of Zn forms loosely bound with the given components. The metal is mainly confined to the silicate-related fraction, which is confirmed by the mineralogical study and chemical fractionation. Owing to the limitation period and long duration of pollution, the mineral phase of technogenically polluted soils revealed the high degree of transformation changes, which led to the formation of authigenic minerals, mainly sulfates.