THE GROUP COMPOSITION OF METAL COMPOUNDS IN SOIL AS AN INDEX OF SOIL ECOLOGICAL STATE

A system of indices for assessing the soil ecological state as based upon the group composition of heavy metal compounds in soils is proposed. The group composition of heavy metal were determined using combined fractionation including sequential and parallel extractions (1 N NH4Ac, pH 8; 1% EDTA in NH4Ac and 1 N HCl). It was shown that strongly bound compounds of Zn and Pb prevail in the original chernozem, mainly in silicates. Among mobile metal compounds, those specifically sorbed forms are predominant. At the additional input of Zn and Pb into the soil, the equilibrium in the system of metal compounds is shifted toward an increase in metal mobility. The analysis of the group composition of metal compounds was allowed to identify mechanisms of amendments effects on the metals mobility in soil and assess their efficiency. Application of chalk and glauconite leads to decreasing the Pb and Zn mobility.