The suitability of transfer coefficients used for stochastic calculations in radioecology

In radioecology, stochastic calculations are used to an increasing extent. It is shown that transfer coefficients which are defined as concentration ratios are not suited for stochastic calculations, at least for essential elements and their antagonists. The reason is that essential elements are regulated in plants and animals whereby their concentrations vary within narrow limits, rather independent of the concentrations in the source compartment. For a more accurate description of the transfer of radionuclides, it is proposed to include the concentrations of the essential elements in the source and target compartments into the transfer equation which leads to the specific activity model. This model has already been proposed by Comar et al. in 1956. It seems to work accurately for the transfer into animals and their products as well as into plants. Examples of its applicability are presented and discussed. Furthermore stochastic calculations seem to be more reasonable with this model.