| Summary: | Uranium is a radioactive contaminant of concern for the aquatic environment, with potentially deleterious releases to freshwaters due to mining, processing and waste disposal. As a metallic element forming cations in aqueous solution, with a chemotoxic mode of action, uranyl is in principle suitable for the development of Biotic Ligand Models to describe the influence of chemistry on its toxicity. Although past research has demonstrated relationships between uranyl (U(VI)) toxicity and key freshwater quality parameters such as dissolved organic carbon concentration, no biotic ligand model has so far been developed for this metal. Ongoing research within the EU Network of Excellence STAR (STrategy for Allied Radioecology) aims to generate uranyl toxicity data for freshwater species suitable for development of Biotic Ligand Models. The species under study are Atlantic salmon (Salmo salar), common duckweed (Lemna minor) and water flea (Daphnia magna). For each species, toxic responses across relevant ranges of water chemistry variations (e.g. pH, Na, Mg, K, Ca concentrations) have been measured. Chemical speciation in exposure waters will be computed using the WHAM7 model, following review and updating of the uranyl binding constants. We will present a selection of experimental results to show the key water quality parameters influencing uranyl toxicity to each organism, and will also show how the results will be used to develop Biotic Ligand Models for each organism to allow the effects of water chemistry on uranyl toxicity to be predicted.
|
|---|