Geochemical assessment of ecological state of soils

There was executed the ecological and geochemical assessment of the regional background of heavy metals (HM) and hydrocarbons in the soils of the Komi Republic. There were examined 249 soil samples taken from 15 organic horizons of the main types and subtypes of background soils from Usinsk and Pechora districts of the Komi Republic. The quantitative chemical analysis of HM in the soil samples was carried out by atomic absorption method: Cu, Pb, Zn, Cd, Ni, Mn — on atomic emission spectrometer Spectro Ciros inductively coupled argon plasma, Hg — using the RA-915+ mercury spectrometer on the pyrolytic prefix RP-91C. The concentration of hydrocarbons in the soil samples was determined by the value of the hexane extract of the fluorescence intensity measured on a liquid analyzer Fluorat-02. Background levels of HM and in the soils were found to be determined by characteristics of the particle size distribution of soil-forming rocks, as well as the arrangement of soil geochemical autonomous and subordinate landscapes. The basic amount of HM and hydrocarbons accumulated in the organic horizons: the largest, as a rule, in the soils of river valleys (flood), on flat depressions, poorly drained river ridges and gentle slopes (bog-podzolic and illuvial-ferruginous); the lowest — in the watersheds (podzols). Differentiation between HM and hydrocarbons in genetic horizons is more pronounced in loamy automorphic and less sandy, semi-hydromorphic and hydromorphic soils. For all soils, there is the typical eluvial-illuvial distribution of HM and hydrocarbons in the profile. The revealed pair correlations between the individual elements in the soils give an indication of the similar orientation of biogeochemical processes in the soil formation. The database of the content of HM and hydrocarbons in soils using GIS technology was created. The research results were the basis for the Order of the Ministry of Natural Resources and Environmental Protection of the Komi Republic of November 25, 2009 N 529 «On establishing norms background concentrations of chemical elements and hydrocarbons in the soils of the Komi Republic».