Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439-4843, USA.
Environ Sci Technol. 2010 Mar 1;44(5):1656-61. doi: 10.1021/es9027953.
Biogenic Fe(II) phases (magnetite, green rust, siderite, vivianite, etc.) provide a reservoir of reducing capacity in many subsurface environments that may contribute to the reduction of contaminants such as U(VI). We have examined the uptake and reduction of U(VI) in the presence of biogenic green rust (BioGR), magnetite (BioMAG), and siderite (BioSID) formed during the reduction of Fe(III) oxides by Shewanella putrefaciens CN32. Within 48 h, total solution-phase U(VI) concentrations decreased from 500 microM to 1.5 microM, 392 microM, and 472 microM in the U-BioGR, U-BioMAG, and U-BioSID systems, respectively. Analysis of the samples by U L(III) extended X-ray absorption fine structure spectroscopy (EXAFS) indicated that despite a stoichiometric excess of Fe(II), no more than 6% of U(VI) was reduced to U(IV) in the U-BioSID system, and no more than 22% of U(VI) was reduced in the U-BioMAG system. For comparison, in the U-BioGR system, >99% of U(VI) was reduced to U(IV). Uptake of U(VI) by BioGR and BioMAG was accompanied by formation of nanoparticulate uraninite. The U EXAFS data for the U-BioSID system were consistent with partial U(VI)/U(IV) substitution for Fe(II) in the surface layer of siderite particles and adsorption of U(IV).
生物成因的 Fe(II) 相（磁铁矿、绿锈、菱铁矿、蓝铁矿等）在许多地下环境中提供了还原能力的储库，这可能有助于还原 U(VI) 等污染物。我们研究了在 Shewanella putrefaciens CN32 还原 Fe(III)氧化物过程中形成的生物绿锈 (BioGR)、磁铁矿 (BioMAG) 和菱铁矿 (BioSID) 存在下 U(VI) 的摄取和还原。在 48 小时内，U-BioGR、U-BioMAG 和 U-BioSID 体系中溶液相 U(VI) 浓度分别从 500 μM 降低到 1.5 μM、392 μM 和 472 μM。通过 U L(III) 扩展 X 射线吸收精细结构光谱 (EXAFS) 分析样品表明，尽管存在化学计量过量的 Fe(II)，但在 U-BioSID 体系中，只有不到 6%的 U(VI)被还原为 U(IV)，在 U-BioMAG 体系中，只有不到 22%的 U(VI)被还原。相比之下，在 U-BioGR 体系中，超过 99%的 U(VI)被还原为 U(IV)。BioGR 和 BioMAG 对 U(VI)的摄取伴随着纳米颗粒状的铀矿的形成。U-BioSID 体系的 U EXAFS 数据与表面层菱铁矿颗粒中部分 U(VI)/U(IV)取代 Fe(II)和 U(IV)吸附一致。
