Distribution of risk elements in Slovakian soils

Risk elements are important in several ways. Many are used industrially in technologically advanced countries, some are physiologically essential for plants and animals (and thus have a direct bearing on human health and agricultural productivity) and many are significant as pollutants of ecosystems throughout the world. The natural concentrations of risk elements in soil depend upon the amounts present in the parent rock from which the soil forms and upon soil forming processes closely related to climatic conditions. Thus, the natural budget of risk elements in the soil should be an effect of those factors as well as of geochemical properties of an element. Anthropogenic global changes in soils are reflected mainly by: - metal enrichment in surface soil layers; acidification, penetrating deep in the soil profile; decrease in soil buffer capacity; mobilization of most metals; migration of the risk elements to ground waters; general losses in soil fertility; degradation in quality and quantity of crop plants. The accumulation of the risk elements in soils posses many risks to human and ecosystem health. Total content of the risk elements in soils is an important indicator of soil contamination. This paper is based on the results of geochemical soil mapping. In the territory of the Slovak Republic was connected with two projects - Geochemical atlas of the Slovak Republic and Set of Regional Maps of Geological Factors of the Environment. Analytical results (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, Zn) from 7189 soil samples were completed into relation databases of the regions and the whole Slovakia. The objectives of the statistical analysis, of the pedogeochemical database, were to characterize the risk elements distribution variability within soil units (Lithosols, Regosols, Rankers, Rendzinas, Pararendzinas, Chernozems, Fluvic Phaeozems, Orthic Luvisols, Luvisols, Cambisols, Podzols, Planosols, Gleysols, Fluvisols). The purposes of this paper are to present the current information on background and anomalous values of the risk elements in soil units, all Slovakian soils. From statistical point of view, median was taken as background value, anomalous values were calculated according to formula AV = 1.5 x (UQ - LQ) + UQ and interquartile range according to formula IR = UQ – LQ. Obtained data have served for the preparation of environmental soil quality criteria and background values for soil units, and the basis for correlation studies also European context.