Migration of heavy elements in granitic waters: nature of inorganic particles

Safety assessment of radioactive waste disposals requires to understand and to predict the behaviour of radiotoxic elements which could be released into the host geological environment, and transported by continental waters towards the biosphere. Thus, the topic of our studies is the knowledge of continental waters in which such elements are naturally present. Previous studies devoted to the geochemistry of granitic waters (1) showed that numerous elements (alkalis, earth-alkalis, transition metals...) are controlled by thermodynamic equilibria, except for heavy elements (tri and tetravalents, Th, REE, Zr, Hf, Sc...) which are associated to suspended matter. Thus, our study will be focused on the behaviour of heavy elements, natural analogues of radiotoxic ones, and more accurately on their scavenging by suspended matter. (authors). 5 figs., 18 refs