Specific-activity and concentration model applied to cesium movement in an oligotrophic lake

A linear systems-analysis model was derived to simulate the time-dependent dynamics of specific activity and concentration of radionuclides in aquatic systems. Transfer coefficients were determined for movement of 137Cs in the components of an oligotrophic lake. These coefficients were defined in terms of basic environmental and ecological data so that the model can be applied to a wide variety of sites. Simulations with a model that ignored sediment--water interactions predicted much higher 137Cs specific activities in the lake water and biota than did those with the complete model. Comparing 137Cs concentrations predicted by the model with concentrations reported for the biota of an experimentally contaminated oligotrophic lake indicated that the transfer coefficients derived for the biota are adequate