Performances of models for predicting mercury concentrations in fresh-water fish after chronic releases into rivers

The performances of assessment models for estimating the transfer and bioaccumulation of mercury in fresh-water ecosystems were tested by being applied to a test scenario proposed in an international cooperative study BIOMOVS. Two kinds of models have been developed to estimate mercury concentrations in fish after chronic releases into rivers. One uses a bioaccumulation factor approach which is applied to ecosystems in equilibrium, whereas the other is a dynamic model which considers the change of the concentrations in water and the metabolism in fish. The success of the models tested by three different scenarios depended upon whether mercury was in equilibrium in the environment. For the scenario where mercury concentrations reached equilibrium, the first model performed satisfactorily. For the scenario where equilibrium was not attained, the first model was not adequate but the second model could predict more accurately. The limitations of applications were suggested for the two models employed here. (author)