Predicting the transfer of 137Cs to rice plants by a dynamic compartment model with a consideration of the soil properties.

This paper describes the predictions of the transfer of 137Cs to rice plants following soil deposition during a non-growth season of rice by a dynamic compartment model considering the soil properties, and their comparison with experimental results. Major processes considered in the model were percolation, soil mixing by plowing, plant uptake, leaching to deep soil, fixation to clay mineral, and time-dependent growth of a plant. To consider the effects of the soil properties (pH, clay mineral, organic matter content, and exchangeable K) on plant uptake and the leaching rates of 137Cs in a root zone soil, the Absalom model was used for the present model. The 137Cs aggregated transfer factors (TFa, m2kg-1 dry plant) of rice plants for two consecutive cultivation years were obtained as a result of simulated 137Cs soil deposition experiments with 17 paddy soils of different properties, all of which were performed before transplanting of the rice. Observed 137Cs TFa values of the rice plants did not show an evident trend for the pH and clay content of the soil properties, while they increased with an increasing organic matter content and a decreasing exchangeable K concentration. Predicted 137Cs TFa values of the rice plants were found to be comparable with those observed.