MODELING THE MOBILITY OF RADIUM-226 BASED ON THE DATA OF ITS PROFILE DISTRIBUTION IN CONTAMINATED PODZOLIC SOIL
For modeling of behavior of pollutants in taiga ecosystems, long-term distribution and transformation of radium-226 speciation in upper 50-centimeter layer of typical podzolic soil were studied, the statistical relationships between parameters of these processes and soil physicochemical characteristics were investigated. It was revealed that upon long-term contact, watersoluble compounds of radionuclide are transformed and firmly bound in soil absorbing complex. At same time, main stock of mobile radium is deposited in soil layer (0-20) cm in composition of potentially mobile compounds, which are extracted with 1 mol /dm3 of hydrochloric acid, which is important for selection of methods for decontamination of soils that are similar in physical and chemical composition and soil formation type. In soil layer deeper than 20 cm, no more than 11,2 % of radium amount in thickness (0-50) cm migrates. In total, about 95 % of radium stock is concentrated in acid-soluble and fixed fractions, readily mobile watersoluble and exchangeable radionuclide forms provide 1 and 4 % of radium amount in soil layer (0-50) cm. The results of linear regression and correlation analyzes indicate, that under radioactive contamination, radium differentiation in profile of podzolic soils is controlled by distribution of calcium compounds. To approximate indicators of radium migration, mathematical models are proposed, the quality of which is estimated by determination coefficients 0,467-0,997. The results of modeling have shown that interaction of iron and calcium compounds determines radionuclide mobility in contaminated soil. The data obtained can be used to predict the distribution and localization of radium in ecosystems.