title: Uranium aqueous speciation in the vicinity of the former uranium mining sites using the diffusive gradients in thin films and ultrafiltration techniques.
abstract: The performance of the Diffusive Gradients in Thin films (DGT) technique with Chelex(®)-100, Metsorb™ and Diphonix(®) as binding phases was evaluated in the vicinity of the former uranium mining sites of Chardon and L'Ecarpière (Loire-Atlantique department in western France). This is the first time that the DGT technique with three different binding agents was employed for the aqueous U determination in the context of uranium mining environments. The fractionation and speciation of uranium were investigated using a multi-methodological approach using filtration (0.45 μm, 0.2 μm), ultrafiltration (500 kDa, 100 kDa and 10 kDa) coupled to geochemical speciation modelling (PhreeQC) and the DGT technique. The ultrafiltration data showed that at each sampling point uranium was present mostly in the 10 kDa truly dissolved fraction and the geochemical modelling speciation calculations indicated that U speciation was markedly predominated by CaUO2(CO3)3(2-). In natural waters, no significant difference was observed in terms of U uptake between Chelex(®)-100 and Metsorb™, while similar or inferior U uptake was observed on Diphonix(®) resin. In turn, at mining influenced sampling spots, the U accumulation on DGT-Diphonix(®) was higher than on DGT-Chelex(®)-100 and DGT-Metsorb™, probably because their performance was disturbed by the extreme composition of the mining waters. The use of Diphonix(®) resin leads to a significant advance in the application and development of the DGT technique for determination of U in mining influenced environments. This investigation demonstrated that such multi-technique approach provides a better picture of U speciation and enables to assess more accurately the potentially bioavailable U pool.
authors.affiliation: Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium. Electronic address: jdrozdza@vub.ac.be.
authors.forename: Jagoda
authors.initials: J
authors.lastname: Drozdzak
authors.affiliation: Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Martine
authors.initials: M
authors.lastname: Leermakers
authors.affiliation: Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Yue
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Analytical, Environmental and Geochemistry (AMGC), Vrije Universiteit Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Elskens
authors.affiliation: AREVA Mines - R&D Dpt., Tour AREVA, 1 Place Jean Millier, 92084 Paris La Défense, France.
authors.forename: Vannapha
authors.initials: V
authors.lastname: Phrommavanh
authors.affiliation: AREVA Mines - R&D Dpt., Tour AREVA, 1 Place Jean Millier, 92084 Paris La Défense, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Descostes
mesh_terms: D004058:Diffusion; D008906:Mining; D008962:Models, Theoretical; D014462:Ultrafiltration / Q000379:methods*; D014501:Uranium / Q000145:classification*; D014867:Water
chemical_list: D014867:Water; D014501:Uranium
keywords: Bioavailable fraction; Diffusive gradients in thin films; Diphonix(®); Former mining sites; Ultrafiltration; Uranium