Radioactive trace in semi natural grassland. Effect of 40K in soil and potential remediation

The uptake of radionuclides by plant roots constitutes the main pathway for the migration of radiocaesium from soil to humans, via food chain. In this study we assessed radiocaesium uptake by plant in order to piece together information on factors affecting uptake processes, particularly K supply and differential uptake among different plant species. Soil contaminated by the Chernobyl accident and forage from a semi-natural alpine grassland, situated in Tarvisio, Italy, were sampled during 1999. Under field conditions, 137 Cs uptake for Graminaceae and Taraxacum officinale seem to behave in a comparable way. Higher 40K soil activity concentration leads to a lower 137Cs plant uptake, suggesting an inhibitory pattern of potassium on radiocaesium plants uptake. For forage samples, a similar tendency was observed. We analyzed the influence of the ratio of 137Cs/ 40K in soil on 137Cs plant uptake. Under field conditions, the ratio observed varied in a range of 0.5 to 1.3. For most of the species, at higher 40K soil concentration a lower 137Cs uptake was observed, a fact that reflects the resulting effect of the complexity of factors controlling ion absorption from soil