title: Microbial reductive transformation of phyllosilicate Fe(III) and U(VI) in fluvial subsurface sediments.
abstract: The microbial reduction of Fe(III) and U(VI) was investigated in shallow aquifer sediments collected from subsurface flood deposits near the Hanford Reach of the Columbia River in Washington State. Increases in 0.5 N HCl-extractable Fe(II) were observed in incubated sediments and (57)Fe Mössbauer spectroscopy revealed that Fe(III) associated with phyllosilicates and pyroxene was reduced to Fe(II). Aqueous uranium(VI) concentrations decreased in subsurface sediments incubated in sulfate-containing synthetic groundwater with the rate and extent being greater in sediment amended with organic carbon. X-ray absorption spectroscopy of bioreduced sediments indicated that 67-77% of the U signal was U(VI), probably as an adsorbed species associated with a new or modified reactive mineral phase. Phylotypes within the Deltaproteobacteria were more common in Hanford sediments incubated with U(VI) than without, and in U(VI)-free incubations, members of the Clostridiales were dominant with sulfate-reducing phylotypes more common in the sulfate-amended sediments. These results demonstrate the potential for anaerobic reduction of phyllosilicate Fe(III) and sulfate in Hanford unconfined aquifer sediments and biotransformations involving reduction and adsorption leading to decreased aqueous U concentrations.
authors.affiliation: Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: James K
authors.initials: JK
authors.lastname: Fredrickson
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Kukkadapu
authors.forename: Maxim I
authors.initials: MI
authors.lastname: Boyanov
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Kemner
authors.forename: Xueju
authors.initials: X
authors.lastname: Lin
authors.forename: David W
authors.initials: DW
authors.lastname: Kennedy
authors.forename: Bruce N
authors.initials: BN
authors.lastname: Bjornstad
authors.forename: Allan E
authors.initials: AE
authors.lastname: Konopka
authors.forename: Dean A
authors.initials: DA
authors.lastname: Moore
authors.forename: Charles T
authors.initials: CT
authors.lastname: Resch
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Phillips
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001711:Biotransformation; D004583:Electrons; D055868:Floods; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000378:metabolism*; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017640:Silicates / Q000378:metabolism*; D015204:Spectroscopy, Mossbauer; D013499:Surface Properties; D013696:Temperature; D014501:Uranium / Q000378:metabolism*; D014861:Washington
chemical_list: D012336:RNA, Ribosomal, 16S; D017640:Silicates; D014501:Uranium; D007501:Iron