Ecological and Toxicological Assessment of the Soil and Vegetation Cover at the Site “Streletskaya Steppe” of the Central Chernozem Reserve Named after V.V. Alekhin

The ecological and toxicological assessment of the of the soil and vegetation cover at the Streletskaya Steppe site of the V.V. Alekhin Central Chernozem Reserve is presented. The contents of a number of heavy metals (HM) and radionuclides in the typical chernozem are determined. The values of concentration clarks of HM (Cc), geoaccumulation indices (Igeo) for As, Cd, Co, Cs, Cu, K, Pb, Sr, Zn, 232Th, 238U and pollution indices (PI) for individual HM in chernozem were calculated. It is shown that increased values of the pedogeochemical background in comparison with clark values in the lithosphere are observed only with respect to Cd and As. At the same time, for the studied HM (As, Cd, Cu, Pb, Zn), it can be argued that they do not pollute the soil. The content of radionuclides (40K, 137Cs, 232Th, 238U), HM and potassium in various types of natural steppe vegetation was determined. Based on the plant accumulation coefficients of HM and radionuclides, the degree of biophilicity of radionuclides and HM was estimated. The values of the aggregated transfer factors (Cag) 137Cs and 40K from soil to plants were also determined and a comparative analysis of the bioavailability of cesium and potassium during root uptake was carried out. The vertical distribution of 137Cs and 40K radionuclides in the root-inhabited soil layer of 0–20 cm was studied. It was established that 40K is evenly distributed in the root layer of the soil The features of the vertical distribution of 137Cs in the soil profile are noted, consisting in the displacement of the maximum from a depth of 0–5 to 5–10 cm. Based on the data obtained, the value of the migration coefficient 137Cs is calculated, taking into account the convective and diffusion components of the radionuclide translocation process in a typical chernozem.