Nature of radioactive contamination in soils of the pine forest in the territory adjacent to Semipalatinsk test site

Background: This work investigated radioactive contamination in soils of the pine forest in the territory adjacent to Semipalatinsk test site. Materials and Methods: Thirty samples from the soil were collected from six different a soil profile was laid out (research areas). Activity concentrations of Cs and Am were determined using a Canberra GX-2020 solid-state gammaspectrometer system. Activity concentrations of Sr and Pu were determined after application of radiochemical analysis. In addition, the soil physicochemical characteristics such as pH value, the amount of organic content and texture of soil were investigated by pH meter, the Tiurin’s techniques, modified by Nikitin, and particle size distribution (Pipette) methods, respectively. Results: The highest specific activity values were registered for Am (up to 64 Bq/kg) and Pu (up to 75 Bq/kg) transuranium radionuclides. Maximum concentrations of Am, Cs and Pu were registered in the top 5-cm layer, while Sr is uniformly distributed up to the depth of 20 cm. In general, researched artificial radionuclides by their level of mobility in vertical soil profile can be arranged in sequence as follows: Sr > Pu > Am > Cs. Conclusion: Cs by the character of its distribution in vertical soil profile is similar to its vertical distribution in brown soils at conditionally «background» STS territories. Mobility of Am, Pu and Sr in brown soils at the researched territory is higher than at conditionally «background» territories of the STS.