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Biogenic Formation and Growth of Uraninite (UO_2)

机译：铀矿石（UO_2）的生物成因与生长

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摘要

Biogenic UO_2 (uraninite) nanocrystals may be formed as a product of a microbial reduction process in uranium-enriched environments near the Earth's surface. We investigated the size, nanometer-scale structure, and aggregation state of UO_2 formed by iron-reducing bacterium, Shewanella putrefaciens CN32, from a uranium-rich solution. Characterization of biogenic UO_2 precipitates by high-resolution transmission electron microscopy (HRTEM) revealed that the UO_2 nanopartcles formed were highly aggregated by organic polymers. Nearly all of the nanocrystals were networked in more or less 100 nm diameter spherical aggregates that displayed some concentric UO_2 accumulation with heterogeneity. Interestingly, pure UO_2 nanocrystals were piled on one another at several positions via UO_2-UO_2 interactions, which seem to be intimately related to a specific step in the process of growing large single crystals. In the process, calcium that was easily complexed with aqueous uranium(VI) appeared not to be combined with bioreduced uranium(IV), probably due to its lower binding energy. However, when phosphate was added to the system, calcium was found to be easily associated with uranium) IV), forming a new uranium phase, ningyoite. These results will extend the limited knowledge of microbial uranrferous mineralization and may provide new insights into the fate of aqueous uranium complexes.
机译：在地球表面附近的富铀环境中，微生物还原过程的产物可能会形成生物UO_2（铀红石）纳米晶体。我们研究了铁还原细菌Shewanella putrefaciens CN32从富铀溶液中形成的UO_2的大小，纳米级结构和聚集状态。通过高分辨率透射电子显微镜（HRTEM）对生物UO_2沉淀物进行表征，结果表明形成的UO_2纳米颗粒被有机聚合物高度聚集。几乎所有的纳米晶体都以直径约100 nm的球形聚集体形成网络，这些聚集体显示出一些同心的UO_2聚集，并且具有异质性。有趣的是，纯的UO_2纳米晶体通过UO_2-UO_2相互作用在多个位置相互堆叠，这似乎与生长大型单晶的特定步骤密切相关。在此过程中，容易与铀（VI）水溶液络合的钙似乎不与生物还原铀（IV）结合，这可能是由于其结合能较低。但是，当将磷酸盐添加到系统中时，发现钙很容易与铀（IV）缔合，形成新的铀相，即次黄铁矿。这些结果将扩大微生物对铀的铀矿化的认识，并可能为含水铀络合物的命运提供新的见解。

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  • 来源
    《Environmental Science & Technology》 |2010年第22期|p.8409-8414|共6页
  • 作者

    SEUNG YEOP LEE; MIN HOON BAIK; JONG WON CHOI;

  • 作者单位

    Korea Atomic Energy Research Institute, 1045 Daedeok-daero,Yuseong-gu, Daejeon, Korea;

    Korea Atomic Energy Research Institute, 1045 Daedeok-daero,Yuseong-gu, Daejeon, Korea;

    Korea Atomic Energy Research Institute, 1045 Daedeok-daero,Yuseong-gu, Daejeon, Korea;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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