Kirill Vasilyevich Pavlov

The study of ¹³⁷Cs and K behavior in «soil-plant» system of chernozem zone in remote period after Chernobyl accident was carried out. Experimental plots in agrosystems such as wheat, soybean, buckwheat, rapeseed, sunflower, grass mixture, and natural biosystem of a dry meadow were selected in the central part of Plavsk radioactive hotspot in Tula region. The level of ¹³⁷Cs soil contamination was 171 ± 26 kBq/m² (498 ± 100 Bq/kg). Average gross K content in soils was 2,0 ± 0,1%, including exchangeable K — 235 ± 54 mg/kg and non–exchangeable K — 816 ± 116 mg/kg. Vertical distribution of ¹³⁷Cs within contaminated 30-cm soil layer of agrosystems, as well as gross K, was uniformly accumulative, while K_ex and K_non-ex distribution was regressive and accumulative. At the same time, ¹³⁷Cs microdistribution in root zone was invariant, and gradient enrichment of soil near the root surface was shown for mobile forms of potassium. Intensity of ¹³⁷Cs transfer from soils to plants for all studied crops was 1–2 orders lower than intensity of K root uptake. Element distribution between plant organs differed. ¹³⁷Cs distribution was acropetal for Cereals and basipetal for crops from other families, and K was distributed basipetally in all tested plants.