A new method for determining the bioavailability of radionuclides in the soil solution

A new method for determining the pool of radionuclides in the soil solution . available for root uptake, has been compared to existing methods. The new method is based on extracting the soil solution at a soil moisture below s aturation. It uses the soaking capacity of a polyacrylamide resin deposited on a cellulose acetate membrane laid on the soil surface. The new method e xhibited the best reproductibility amongst the methods tested. It allowed u s to extract Cs-134 and a similar amount of Sr-85 relative to the other met hods. The correlation between more the observed ratio of radionuclide conce ntrations in soil and plants and the radionuclide concentration of the soil solution using the new method was better than using the existing methods. Using the measurement of Cs-134 and natural potassium in the soil solution by the new method, based on a multiple regression equation involving an exp onential form, the uptake of Cs-134 by bean and wheat was predicted with a 0.9 determination coefficient. As far as the uptake of Sr-85 is considered, this method was not very successful since the equation with a linear form involved a large number of parameters. reserved.