Geochemical features of uranium and thorium distribution in groundwater of the Semipalatinsk test site

The prevalence of thorium and uranium in groundwater of different composition and mineralization in the territory of the Semipalatinsk test site (STS) was studied. The studied waters are diverse in chemical composition: 14 % of the samples had a hydrocarbonate, 69 % - sulfate and 17 % - chloride types. The dependence of the uranium increase in the water with increasing salinity for sulfate, and chloride waters and its reduction in the hydrocarbonate waters was revealed. Uranium concentration in the STS groundwater exceeds clarke values for groundwater of hypergenesis zone (HZ) and continental salinity zone (CSZ) by 15 and 5 times respectively