U(VI) sequestration in hydroxyapatite produced by microbial glycerol 3-phosphate metabolism.
Previous studies have demonstrated the potential for removal of U(VI) from solution via precipitation of U(VI)-bearing calcium-phosphate (Ca-P) minerals coupled to microbial hydrolysis of glycerol phosphate compounds. We evaluated this process in circumneutral-pH groundwater from Area 2 of the U.S. Department of Energy Field Research Center at Oak Ridge National Laboratory. Area 2 groundwater contains high concentrations of dissolved calcium (ca. 4 mM), and thus, release of phosphate during glycerol phosphate metabolism has the potential to create conditions favorable for U(VI) sequestration in Ca-P minerals. Microbial enumeration and isolation studies verified the presence of aerobic and nitrate-reducing glycerol 3-phosphate (G3P)-metabolizing microorganisms in Area 2 sediments. Coprecipitation of U(VI) with Ca-P minerals coupled to microbial G3P hydrolysis was demonstrated in artificial groundwater under aerobic and nitrate-reducing conditions. Transmission electron microscopy analysis and mineral-washing experiments demonstrated that U(VI) was incorporated into the structure of the insoluble Ca-P mineral hydroxyapatite [Ca5(PO4)3OH]. Our results support the idea that U(VI) can be effectively removed from solution in contaminated aquifers through stimulation of microbial organophosphate metabolism.
Shelobolina
Evgenya S
ES
Department of Geology and Geophysics, 1215 W. Dayton St., University of Wisconsin, Madison, WI 53706, USA.
Konishi
Hiromi
H
Xu
Huifang
H
Roden
Eric E
EE
D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D017886:Durapatite / Q000378:metabolism*; D020563:Gammaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005994:Glycerophosphates / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014501:Uranium / Q000378:metabolism*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D014875:Water Pollutants, Radioactive / Q000378:metabolism*
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005994:Glycerophosphates; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D014875:Water Pollutants, Radioactive; D014501:Uranium; D017886:Durapatite; C029620:alpha-glycerophosphoric acid