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

ABSTRACT 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 137Cs and 241Am were determined using a Canberra GX-2020 solid-state gamma-spectrometer system. Activity concentrations of 90Sr and 239+240Pu 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 241Am (up to 64 Bq/kg) and 239+240Pu (up to 75 Bq/kg) transuranium radionuclides. Maximum concentrations of 241Am, 137Cs and 239+240Pu were registered in the top 5-cm layer, while 90Sr 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: 90Sr > 239+240Pu > 241Am > 137Cs. Conclusion: 137Cs 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 241Am, 239+240Pu and 90Sr in brown soils at the researched territory is higher than at conditionally «background» territories of the STS.