Distribution Coefficient (Kd) of Stable Cesium in Agricultural Soil in the Rabat Region, Morocco

The presence of radioactive cesium (Cs) in soil poses a significant risk to both human health and the environment. Plant uptake is an important pathway for the migration of Cs to the human food chain. Therefore, determining the concentrations of ¹³³Cs in soil solutions is crucial for monitoring and predicting the uptake of radiocesium by soils and plants. The mobility and availability of Cs in soil can be measured by using distribution coefficient (Kd) values. In this study, soil was taken from the Rabat region and characterized in terms of granulometric distribution, organic matter, carbonate content, pH, and electrical conductivity. Batch experiments were carried out for the determination of the distribution coefficient (Kd) of cesium in aqueous suspensions. Six experiments were carried out by suspending about 2.5 g of soil particles in 50 ml of 1M CaCl2 solution and spiking it with different amounts of stable Cs, from 22 to 476 µg/L. The suspensions were kept under shaking for almost five days and then centrifuged to separate the particles from the liquid. Cesium concentration was measured in the aqueous phase using ICP-MS. Distribution coefficients were determined as the ratio of the amount of Cs adsorbed on solids to that contained initially in the aqueous phase. The preliminary findings indicated that Kd values increased almost asymptotically as Cs concentration increased. This work is part of an international coordinated research project led by the International Atomic Energy Agency.