Changes in the forms of 137Cs and its availability for plants as dependent on properties of fallout after the Chernobyl nuclear power plant accident

Abstract The dynamics of exchangeable and acid soluble 137 Cs content in soils, as well as 137 Cs transfer factors for natural vegetation were studied for different sites within a 50-km zone around the Chernobyl nuclear power plant after the 1986 accident. Changes in 137 Cs forms in soils during the 6 years after the accidental release of radioactive substances and availability of this radionuclide to plants at that time were dependent on the character of radioactive fallout (fuel particles, aerosols of different dispersion) and soil type. Transformation of different 137 Cs species in soils with time after the accident was observed (destruction of fuel particles, ageing of 137 Cs and changes in the 137 Cs sorption strength of the soil solid phase). Behaviour of 137 Cs in the ‘near’ and ‘remote’ zones was different. The content of exchangeable 137 Cs in soils was found to have decreased after the accident. The average half-life of 137 Cs in grass stand in dry meadow in the ‘remote’ zone is 3.5 years, and in the second (slower) period after the accident, this half-life for 137 Cs will amount to about 17 years. The 137 Cs transfer factors for peaty swamped soils were 3.7–6.6 times as high as for soils of automorphous series.