title: In situ speciation of uranium in treated acid mine drainage using the diffusion gradients in thin films technique (DGT).
abstract: The exchange membranes P81 and DE81 and Chelex-100 resin were used to perform in situ speciation of uranium in treated acid mine drainage at the Osamu Utsumi mining site, Poços de Caldas city, Southeast Brazil. To investigate possible chemical modifications in the samples during analysis, the three ligands were deployed in situ and in a laboratory (in lab). The results obtained in situ were also compared to a speciation performed using Visual MINTEQ software. Chelex-100 retained total labile U for a period of up to 48 h. The labile U fraction determined by Chelex 100 ranged from 107 ± 6% to 147 ± 44% in situ and from 115 ± 22% to 191 ± 5% in lab. DE81 retained anionic U species up to 8 h, with labile fractions ranging from 37 ± 2% to 76 ± 3% in situ and 34 ± 12% to 180 ± 17% in lab. P81 exhibited a lower efficiency in retaining U species, with concentrations ranging from 6± 2% to 19± 2% in situ and 3± 2% to 18± 2% in lab. The speciation obtained from MINTEQ suggests that the major U species were UO2OH+, UO2(OH)3-, UO2(OH)2(aq), Ca2UO2(CO3)3(aq), CaUO2(CO3)32-, UO2(CO3)22-, and UO2(CO3)34-. This result is in accordance with the results obtained in situ. Differences concerning speciation and the total and soluble U concentrations were observed between the deployments performed in situ and in the laboratory, indicating that U speciation must be performed in situ.
authors.affiliation: Centro de Estudos Ambientais - CEA, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil.
authors.forename: Jorge Henrique
authors.initials: JH
authors.lastname: Pedrobom
authors.affiliation: Centro de Estudos Ambientais - CEA, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil.
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Eismann
authors.affiliation: Centro de Estudos Ambientais - CEA, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil. Electronic address: amenega@rc.unesp.br.
authors.forename: Amauri A
authors.initials: AA
authors.lastname: Menegário
authors.affiliation: Centro de Estudos Ambientais - CEA, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil.
authors.forename: Juliana Aparecida
authors.initials: JA
authors.lastname: Galhardi
authors.affiliation: Centro de Estudos Ambientais - CEA, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil.
authors.forename: Karen Silva
authors.initials: KS
authors.lastname: Luko
authors.affiliation: Centro de Estudos Ambientais - CEA, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil.
authors.forename: Thiago de Araujo
authors.initials: TA
authors.lastname: Dourado
authors.affiliation: Laboratório de Estudos de Bacias - LEBAC, Instituto de Geociências e Ciências Exatas - IGCE, UNESP - Univ Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil.
authors.forename: Chang Hung
authors.initials: CH
authors.lastname: Kiang
mesh_terms: D001938:Brazil; D008906:Mining; D011834:Radiation Monitoring / Q000379:methods*; D012117:Resins, Synthetic; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014501:Uranium / Q000032:analysis*
chemical_list: D012117:Resins, Synthetic; D012990:Soil Pollutants, Radioactive; C024997:Chelex 100; D014501:Uranium
keywords: In situ; Multiple DGT devices; Speciation; Treated acid mine drainage; Uranium