Rozko A. Distribution of 137-Cs and 90-Sr in the organic-clay of soil component of Ukrainian Polissia

The thesis contains theoretical colligation of physico-chemical processes sorption going on in soils contaminated as a result of Chernobyl accident. Systematic study of the system soil - radionuclide - clay minerals - organo-clay minerals was carried out. Sorptive capacity of organomineral compounds with regard to137Cs and 90Sr has been studied. Mechanism of sorption of Cs and Sr radionuclides by these compounds was examined. Conditions of radionuclide adsorption by some clay minerals and minerals treated by organic acids were determined in the work. It was demonstrated that the mechanism of ligand exchange with formation of complex compounds is the main mechanism of sorption of natural humic acids on the clay mineral surface. In radioactive contaminated soils besides physico-chemical processes, we observed distribution of radionuclides among the soil components in accordance with fractal dimensions of the surface of particles. Perfection of humine acid molecular mass determining using a tracer has been scientifically argumented. Humine acids of sod-podzol soils were found to have lower molecular mass than those from peat swamps. Characteristics of fractal nature of clay mineral particle surface were studied to find the most promising materials for reducing penetration and increasing sorption of Cs and Sr radionuclides. On the strength of the carried out studies, we created a new complex compositional material based on clay mineral and cellulose, which can be used as a mobile geochemical barrier. Key words: soil, localization radionuclides, adsorption, radionuclides, radioactive contamination, concentration of humic and fulvic acids, fractal dimensions.