Acetic-soluble phases containing heavy metals in soils, as assessed from dynamic extractograms

Abstract

We used sequential static chemical extraction methods for studying soil pollution with heavy metals. This allowed determining the amount of metals extracted with this reagent. The new equipment for dynamic extraction of HM and obtaining extractograms, opens up additional possibilities: to determine the number of particles’ groups that differ in resistance to this reagent and to determine the statistical indicators of each group of particles. The technique for decrypting extractograms is based on their deconvolution into a series of asymmetric Gaussians corresponding to a separate group of particles – carriers of HM. The statistical indicators of Gaussians include the relative stability of each group of particles to this reagent, their dispersion D, asymmetry As, and excess Ex. Statistical indicators of Ca-Mg particles of HM carriers in urban soils show a high heterogeneity in the resistance of particles to acetic acid compared to particles in non-urban soils. The probable reason for the difference between urban and non-urban soils is a different composition of Ca-Mg minerals: , most Ca-Mg minerals in non-urban soils are carbonates. Urban, initially carbon-free soils are contaminated with Ca-Mg-containing construction waste: cement, lime and asbestos, and also contain secondary carbonates formed from Ca-Mg-waste. Urban acetic soluble pollutants belong to the following groups of minerals: technogenic hydroxides, silicates and aluminates of calcium and magnesium, which greatly distinguishes their chemical properties from the properties of carbonates. The abundance of pollutant forms as carriers of HM determines the diversity and heterogeneity of groups of particles soluble by acetic acid in urban soils.