Usage of X-ray absorption spectroscopy and extractive fractionation in studies of the Cu (II) and Zn (II) ions in soils

摘要

XANE S spectroscopy is an effective method for the study of bonds between metals and soil components. The study of structural organization in different soil samples and soil phases saturated with Cu 2+ and Zn 2+ ions by using XANES allowed determining the mechani sm of their interaction with soil phases and all the chemical bindings taken place in the course of this process. Changes in the structure of the metal ion, in particular breakdown of the symmetry of electron orbits of atoms, take place due to interaction with soil components. Application of this method demonstrated that the state of copper and zinc introduced in chernozem as oxides did not change after one year of incubation. Copper is absorbed after being introduced as soluble salts, and copper ions are i ncorporated in the octahedral and tetrahedral sites of minerals and bonded with humic materials at the expense of covalent bond and the formation of coordination humate copper complexes. Zinc included into octahedric structures of layered min erals and hydr o(oxides) can be inner - and outer - sphere adsorbed. It is shown that the action of the metal bound to soil components becomes weakened in case of increasing the Cu and Zn load (from 2000 to 10000 mg/kg) especially applied in the form of soluble salts. Extrac tive fractionation of metal compounds in chernozem samples, artificially contaminated with copper and zinc salts serves as evidence of absorbing the applied Cu 2+ ions by the soil organic matter and Zn 2+ ions ¨C by silicates, carbonates, and Fe - Mn oxides.