Fractional Composition of Nickel, Copper, Zinc, and Lead Compounds in Soils Polluted by Oxides and Soluble Metal Salts

The transformation of technogenic compounds of nickel, copper, zinc, and lead entering the soil as nitrates and oxides has been studied in a model experiment. It has been shown that the results of the determination of the fractional composition of the heavy metals strongly depend on the fractionating method used. The fractional composition of heavy metals that entered the soil as the readily soluble compounds mainly depends on the affinity of ions with the reaction centers of the soil components. When soils are polluted by such weakly soluble compounds of heavy metals as oxides, their transformation and, consequently, the fractional composition formed are determined, in the first place, by the solubility of these compounds and only afterwards by the interaction of the products of the dissolution with the soil. The transformation of the technogenictechnogenic zinc and lead oxides in the soils is more complete than that of copper and nickel oxides. This leads to a strong increase in the portion of the residual fraction of these elements under fractionating. The 1 N nitric acid almost does not extract copper and nickel oxides from the soil. This can be a reason for the erroneous estimation of the extent of soil pollution.