Biotransformation of Ni-Substituted Hydrous Ferric Oxide by an Fe(III)-Reducing Bacterium

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• 作者：James K. Fredrickson ; John M. Zachara ; Ravi K. Kukkadapu ; Yuri A. Gorby ; Steven C. Smith ; and Christopher F. Brown
• 刊名：Environmental Science & Technology
• 出版年：2001
• 出版时间：February 15, 2001
• 年：2001
• 卷：35
• 期：4
• 页码：703 - 712
• 全文大小：360K
• 年卷期：v.35,no.4(February 15, 2001)
• ISSN：1520-5851

文摘

The reductive biotransformation of a Ni²⁺-substituted (5mol %) hydrous ferric oxide (NiHFO) by Shewanellaputrefaciens, strain CN32, was investigated under anoxicconditions at circumneutral pH. Our objectives were to definethe influence of Ni²⁺ substitution on the bioreducibilityof the HFO and the biomineralization products formed andto identify biogeochemical factors controlling the phasedistribution of Ni²⁺ during bioreduction. Incubations withCN32 and NiHFO were sampled after 14 and 32 d, and bothaqueous chemistry and solid phases were characterized.By comparison of these results with a previous study(Fredrickson, J. K.; Zachara, J. M.; Kennedy, D. W.; Dong,H.; Onstott, T. C.; Hinman, N. W.; Li, S. W. Geochim.Cosmochim. Acta 1998, 62, 3239-3257), it was concludedthat coprecipitated/sorbed Ni²⁺ inhibited the bioreductionof HFO through an undefined chemical mechanism. Mössbauerspectroscopy allowed analysis of the residual HFOphase and the identity and approximate mass percent ofbiogenic mineral phases. The presence of AQDS, a solubleelectron shuttle that obviates need for cell-oxide contact,was found to counteract the inhibiting effect of Ni²⁺.Nickel was generally mobilized during bioreduction in atrend that correlated with final pH, except in cases wherePO₄^3- was present and vivianite precipitation occurred.CN32 promoted the formation of Ni²⁺-substituted magnetite(O₄) in media with AQDS but withoutPO₄^3-. The formation of this biogenic coprecipitate, however,had little discernible impact on final aqueous Ni²⁺concentrations. These results demonstrate that coprecipitatedNi can inhibit dissimilatory microbial reduction ofamorphous iron oxide, but the presence of humic acidsmay facilitate the immobilization of Ni within the crystalstructure of biogenic magnetite.