MIGRATION OF URANIUM - INTEGRATING GEOCHEMISTRY WITH BIOMONITORING TOEVALUATE AND PREDICT ITS ENVIRONMENTAL-IMPACT

The potential ecological impact of the migration of uranium, at concen trations elevated above background, in receiving waters downstream of a uranium mine site has been investigated by integrating geochemical a nd biomonitoring techniques. This study concluded that selected behavi oural responses of a freshwater bivalve species, exposed to a variety of uranium concentrations in a synthetic river water, bath in the pres ence and absence of a model fulvic acid (FA), was closely correlated w ith the inorganic forms of uranyl present, as predicted using the geoc hemical code HARPHRQ. The addition of a defined quantity of a model FA to the synthetic water ameliorated the behavioural responses of bival ves to uranium, by complexation with the model FA. To properly model a nd evaluate the geochemical behaviour of uranium in aquatic systems re quires the inclusion of data on interactions between the uranium and h umic substances, especially FA. Geochemical modelling of the speciatio n of uranium may assist in predicting its impact on biota exposed to e levated concentrations in natural waters resulting from releases of ur anium mine effluent.