Diffusional modelling of radiocaesium fixation by soils

A diffusional model of radiocaesium fixation in soils and bottom sediments was developed. According to this model fixation is a result of radiocaesium cations diffusing into the surface layer of soil or sediment particles. Good agreement between predicted and experimental time dependences of Cs-137 fixation rate in soils indicates that the proposed model seems adequately to reflect the actual mechanism of radiocaesium fixation and can be used for prediction of this radionuclide's long-term behaviour in natural soil-water systems. Its major advantage is a small number of parameters which have a clear physical meaning and can, in principle, be determined in an independent experiment or assessed theoretically.