Radioisotopes of CHernobyl fallouts - radiation condition of soils and potential risks groundwater quality estimation

The results of the behavior of Cs and Sr of Chernobyl fallouts in different types of soils distributed over a wide territory in the contaminated Belarusian areas including 30 km zone around the Chernobyl are presented in the paper. The advective-dispersion equation was applied to quantify rates of vertical migration of radioisotopes through the soil profile and to predict the time of maximum (peak) activity transport of the radioisotopes in groundwater. Monitoring data of Cs and Sr-activity in groundwater and deeper aquifer horizons (Quaternary, Paleogene andUpper Cretaceous) allowed to estimate their contemporary contamination in comparisonwith drinkingwater standard in Belarus and background activity before accident. It was established that Cs and Sractivity in groundwater remains high, especially if the non-threshold hypothesis of dose-effect relationship in the context of impact of low levels radiation on the population is taken into account.