Accumulation of 137Cs and 90Sr by lettuce culture (Lactuca sativa L.) from radioactively contaminated soils of the former Semipalatinsk test site

The paper presents the study of 137Cs and 90Sr transfer from soils of the former technical sites of the Semipalatinsk test site to the salad culture ( Lactuca sativa L. ) as an example of the leaf vegetable. The factors affecting the transfer of the radionuclides from soils with a different character of radioactive contamination to the salad culture were identified under the model vegetation experiment conditions. The variation ranges of 137Cs and 90Sr transfer factors values were 2 and 1 orders of magnitude respectively. With the use of the private correlation method, it was found that the content of biologically available forms of 137Cs and 90Sr in the soils of the former Semipalatinsk test site, and, consequently, accumulation of these radionuclides by the salad, depended on their non-isotopic analogs K and Ca concentration in the soil, respectively (rxy-z=-0.81; n=4, p137Cs and gross K; rxy-z=-0.64; n=4, p90Sr). There was a moderate positive relationship between the value of 137Cs transfer factor and physical clay content (fraction >0.01%) in the soil (ρ=0.47; n=12, p90Sr transfer factor and the physical clay content was weak negative (ρ=-0.3; n=11, p137Cs and 90Sr to the salad culture from the radioactively contaminated soils of the Semipalatinsk test site mainly depended on biologically available forms content of radionuclides and their non-isotopic analogs K and Ca speciation, respectively. The impact of physical clay on the accumulation of 137Cs and 90Sr by the salad culture was less pronounced, it could be due to the specific conditions for radioactive contamination of the soil surface in the territory of the former technical sites of the Semipalatinsk test site.