Influence of Physicochemical Factors on Radionuclide Leaching from Soil

Abstract

The degree of radionuclide leaching from soil in the region of the Atomic Lake (Kazakhstan) was determined. The ³H and ⁹⁰Sr concentrations in aqueous extracts increase with increasing time of interaction of the soil with the leaching solution. A decrease in the ^239+240Pu transfer into the solution with time may be due to the formation of colloids in the course of leaching, followed by their deposition or sorption onto soil components. Despite relatively high initial content of γ-emitting radionuclides (¹³⁷Cs, ²⁴¹Am, ^152,154Eu, ⁶⁰Co) on the level from n × 10² to n × 10⁴ Bq kg⁻¹ in the soil, in leaching experiments the content of these radionuclides in aqueous extracts was below the detection limit of the procedure used (<1 Bq L⁻¹). The influence exerted on the leaching by the grain-size distribution of soil, pH of the medium, degree of mineralization, and chemical composition of water was determined. The tests performed suggest that the transfer of artificial radionuclides from the soil into water by leaching is one of the main mechanisms of radioactive contamination of the Atomic Lake water.