Characterizing the Transport of Natural Uranium and its Decay Product 226Ra, Downstream from Former Mines in France

Surface waters downstream from former uranium mines have been studied in order to characterize U and 226Ra transport and to assess their bioavailability. Filtrations and ultrafiltrations (UF) have been performed (0.45 μm/0.2 μm/500 kDa/100 kDa/10 kDa) and compared to the in situ technique, diffusive gradients in thin films (DGT). One of the study sites, a stream passing through a peatbog located in the vicinity of a former U mine, shows an increase in total U and a slight increase in 226Ra concentrations. While 226Ra is completely dissolved, U is mainly present as particles and colloids, the dissolved fraction reaching only about 5-20%.