Influence of Chemical Amelioration of Solonetzic Soils on the Presence of Heavy Metals and Radionuclides in Soil Profile

The article considers the results pertaining to the influence of solonetzic soils chemical amelioration on the presence and redistribution of heavy metals and radionuclides in meter profile of soils. Meliorative procedures were carried out 45 years ago. Phosphogypsum has been used as chemical ameliorant up to 90-s on the solonetzic soils of Tyumen region. It is a by-product of phosphates production. The objective aimed at revealing possible negative consequences connected with the introduction of the chemical elements associated with phosphogypsum. The studies showed that phosphogypsum introduction contributes to some increase in the content of active forms of heavy metals (zinc Zn, copper Cu, cadmium Cd and lead Pb) in soil. However, critical values are achieved only by active lead Pb. The evaluation of radioactive state of meadow crusted solonetzic soils after carrying out of meliorative procedures (for the same period) on the content of isotopes of thorium-232 (Th-232), calium-40 (K-40), radium-226 (Ra-226), caesium-137 (Cs-137) and strontium-90 (Sr-90) indicated that redistribution of radionuclides after chemical melioration does not cause a negative change of radiation background. Vibrations in the soil profile are connected with various initial concentration in rock formations or weathering detritus. Specific effective activity (А_eff ≤ 370 Bq/kg) testifies to the soils being studied and absence of their additional introduction with introduced doses of phosphogypsum.