Method for calculation the selectivity of reagents extracting heavy metals mobile compounds from soil

摘要

A method for computing the selectivity (S) of reagents designed for dissolving the mobile heavy metal (HM) compounds in soils is proposed. Phytoavailability of HM is higher than the selectivity of reagents with respect to their mobile compounds, since plants absorb the metals from compounds with different stability. The object of study was Haplic Chernozem and Calcic Kastanozems artificially contaminated with the Pb, Cu and Zn acetate in a 2-year-long model experiment. Selectivity of reagents depends strongly upon the compositional alterations of HM compounds during the interaction of metal-pollutants with the contaminated soil. The acetate-ammonia buffer (AAB) demonstrates the highest selectivity with respect to the mobile Pb, Cu and Zn compounds in the studied soils. Temporal intensification of the crystallisation of the introduced metal-pollutant salts influences differently on their dissolution by the reagents. Reinforcement of the newly formed metal compounds hampers their dissolution in the AAB, resulting in enhancement of the selectivity of reagent. Selectivity of the EDTA + AAB reagent with respect to these metals was lower and decreased in the course of their interaction with soils.