Dynamics of 137Cs bioavailability in a soil-plant system in areas of the Chernobyl Nuclear Power Plant accident zone with a different physico-chemical composition of radioactive fallout

A quantitative analysis of the dynamics of 137Cs bioavailability in soils contaminated following the Chernobyl NPP accident, based on a 6-year (1987–1992) observation period, and a dynamic model describing the behaviour of radiocaesium in meadow ecosystems are presented. It has been shown that the type of deposition and soil characteristics are main factors that significantly affect (up to five times) the changes in bioavailability of this radionuclide in the soil-plant system. The presence of particles, distinguished by their resistance in the environment, can result in an irregular decrease of 137Cs uptake by plants. During the first period after fallout, 137Cs uptake by plants is considerably (up to eight times) influenced by radionuclide distribution between the soil and the mat. The rates of decrease of 137Cs uptake by plants can differ by factor of 3–5, being dependent on soil properties. The effect of these factors depends on the time lapsed after the deposition.