Analysis of heavy metals phases-carriers in soils

Abstract

A method of extractograms analysis reflecting the dissolution of heavy metals (HM) in soils by dynamic sequential extraction has been developed. The technique is based on the deconvolution of complex extractograms on a series of symmetrical or asymmetrical Gaussians, corresponding to a separate HM phases-carriers. It is possible to determine after deconvolution the number of HM phases- carriers dissolved by the reagent (n), the share of HM in each phase-carrier (S) as a percentage dissolution of the HM by this reagent to the total HM-content, relative degree of each HM phase-carrier stable to the reagent (хmax), domination of fast- or slow-soluble particles in this asymmetrical phase by its asymmetry (As), dispersion of the HM phase-carrier by its dispersion (D). It was studied the action of three reagents: acetic acid, hydroxylamine and ammonium oxalate on Cu, Pb and Zn in contaminated soils. Soils contain two groups of HM carriers-carbonates with different acetic acid solubility. Soils and sediments contain three HM phases-carriers with different rates of dissolution by hydroxylamine. The number of HM-phases dissolved by ammonium oxalate depends on metal: it ranges from two for Zn to three for Cu. In total, contaminated soils contain 7-8 HM-phases, consistently soluble by three reagents. The abundance of the phases suggests that it is desirable to perform smaller fractionation of HM, taking into account the type of pollutants.