Trace Elements in Soils and Vegetation of Natural Steppe and Semidesert Pastures of the Stavropol Region

Comprehensive ecological, toxicological, and biogeochemical studies were conducted at two test sites (TS) in the northeast of Stavropol region, within the Chograi–Caspian and Chograi–Raguli landscapes. The aim was to study the background content of trace elements belonging to the group of heavy metals (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and metalloids (As) and also to evaluate a number of biogeochemical parameters of migration of these elements in the soil–plant system. Using a using a Supec 7000 ICP-MS spectrometer (China), the content of trace elements was measured in pasture silt loamy soils with slightly alkaline and alkaline reaction (a layer of 0–20 cm), as well as in various herb species. The individual and complex soil pollution indices showed either no contamination of soil with the studied elements or low/acceptable contamination. Using the transfer factor, a comparative analysis of bioavailability (biophilic properties) of the studied elements was performed, which permitted us to arrange them in the following order of ascending bioavailability: As ≈ Cr < Co < Pb < Ni < Cu < Zn ≈ Сd.