Microbially Catalyzed Nitrate-Dependent Oxidation of Biogenic Solid-Phase Fe(II) Compounds

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• 作者：Karrie A. Weber ; Flynn W. Picardal ; and Eric E. Roden
• 刊名：Environmental Science & Technology
• 出版年：2001
• 出版时间：April 15, 2001
• 年：2001
• 卷：35
• 期：8
• 页码：1644 - 1650
• 全文大小：92K
• 年卷期：v.35,no.8(April 15, 2001)
• ISSN：1520-5851

文摘

The potential for microbially catalyzed NO₃^--dependentoxidation of solid-phase Fe(II) compounds was examinedusing a previously described autotrophic, denitrifying, Fe(II)-oxidizing enrichment culture. The following solid-phase Fe(II)-bearing minerals were considered: microbiallyreduced synthetic goethite, two different end productsof microbially hydrous ferric oxide (HFO) reduction (biogenicFe₃O₄ and biogenic FeCO₃), chemically precipitatedFeCO₃, and two microbially reduced iron(III) oxide-richsubsoils. The microbially reduced goethite, subsoils, andchemically precipitated FeCO₃ were subject to rapid NO₃^--dependent Fe(II) oxidation. Significant oxidation ofbiogenic Fe₃O₄ was observed. Very little biogenic FeCO₃was oxidized. No reduction of NO₃^- or oxidation of Fe(II)occurred in pasteurized cultures. The molar ratio of NO₃^-reduced to Fe(II) oxidized in cultures containing chemicallyprecipitated FeCO₃, and one of the microbially reducedsubsoils approximated the theoretical stoichiometry of 0.2:1. However, molar ratios obtained for oxidation ofmicrobially reduced goethite, the other subsoil, and theHFO reduction end products did not agree with this theoreticalvalue. These discrepancies may be related to heterotrophicNO₃^- reduction coupled to oxidation of dead Fe(III)-reducing bacterial biomass. Our findings demonstrate thatmicrobally catalyzed NO₃^--dependent Fe(II) oxidationhas the potential to significantly accelerate the oxidationof solid-phase Fe(II) compounds by oxidized N species. Thisprocess could have an important influence on themigration of contaminant metals and radionuclides insubsurface environments.