title: Isotopic investigation of the colloidal mobility of depleted uranium in a podzolic soil.
abstract: The mobility and colloidal migration of uranium were investigated in a soil where limited amounts of anthropogenic uranium (depleted in the 235U isotope) were deposited, adding to the naturally occurring uranium. The colloidal fraction was assumed to correspond to the operational fraction between 10 kDa and 1.2 μm after (ultra)filtration. Experimental leaching tests indicate that approximately 8-15% of uranium is desorbed from the soil. Significant enrichment of the leachate in the depleted uranium (DU) content indicates that uranium from recent anthropogenic DU deposit is weakly bound to soil aggregates and more mobile than geologically occurring natural uranium (NU). Moreover, 80% of uranium in leachates was located in the colloidal fractions. Nevertheless, the percentage of DU in the colloidal and dissolved fractions suggests that NU is mainly associated with the non-mobile coarser fractions of the soil. A field investigation revealed that the calculated percentages of DU in soil and groundwater samples result in the enhanced mobility of uranium downstream from the deposit area. Colloidal uranium represents between 10% and 32% of uranium in surface water and between 68% and 90% of uranium in groundwater where physicochemical parameters are similar to those of the leachates. Finally, as observed in batch leaching tests, the colloidal fractions of groundwater contain slightly less DU than the dissolved fraction, indicating that DU is primarily associated with macromolecules in dissolved fraction.
authors.affiliation: Université de Pau et des Pays de l'Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM-UMR 5254 Pau, France; CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: S
authors.initials: S
authors.lastname: Harguindeguy
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: P
authors.initials: P
authors.lastname: Crançon
authors.affiliation: CEA, DAM, DIF, F-91297 Arpajon, France.
authors.forename: F
authors.initials: F
authors.lastname: Pointurier
authors.affiliation: Université de Pau et des Pays de l'Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM-UMR 5254 Pau, France.
authors.forename: M
authors.initials: M
authors.lastname: Potin-Gautier
authors.affiliation: Université de Pau et des Pays de l'Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM-UMR 5254 Pau, France. Electronic address: gaetane.lespes@univ-pau.fr.
authors.forename: G
authors.initials: G
authors.lastname: Lespes
mesh_terms: D003102:Colloids / Q000737:chemistry*; D007554:Isotopes; D012987:Soil / Q000737:chemistry*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D003102:Colloids; D007554:Isotopes; D012987:Soil; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive; D014501:Uranium
keywords: Batch experiments; Colloids; Depleted uranium; Leaching; Mobility; Ultrafiltration