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首页> 外文期刊>Environmental Science & Technology >Methylation of Mercury by Bacteria Exposed to Dissolved, Nanoparticulate, and Microparticulate Mercuric Sulfides
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Methylation of Mercury by Bacteria Exposed to Dissolved, Nanoparticulate, and Microparticulate Mercuric Sulfides

机译：细菌暴露于溶解，纳米微粒和微粒硫化汞中的汞甲基化细菌

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摘要

The production of the neurotoxic methylmer-cury in the environment is partly controlled by the bioavailability of inorganic divalent mercury (Hg(II)) to anaerobic bacteria that methylate Hg(II). In sediment porewater, Hg(II) associates with sulfides and natural organic matter to form chemical species that include organic-coated mercury sulfide nanoparticles as reaction intermediates of heterogeneous mineral precipitation. Here, we exposed two strains of sulfate-reducing bacteria to three forms of inorganic mercury: dissolved Hg and sulfide, nanoparticulate HgS, and microparticulate HgS. The bacteria cultures exposed to HgS nanoparticles methylated mercury at a rate slower than cultures exposed to dissolved forms of mercury. However, net methylmercury production in cultures exposed to nanoparticles was 6 times greater than in cultures treated with microscale particles, even when normalized to specific surface area. Furthermore, the methylation potential of HgS nanoparticles decreased with storage time of the nanoparticles in their original stock solution. In bacteria cultures amended with nano-HgS from a 16 h-old nanoparticle stock, 6-10% of total mercury was converted to methylmercury after one day. In contrast, 2-4% was methylated in cultures amended with nano-HgS that was aged for 3 days or 1 week. The methylation of mercury derived from nanoparticles (in contrast to the larger particles) would not be predicted by equilibrium speciation of mercury in the aqueous phase (<0.2 μm) and was possibly caused by the disordered structure of nanoparticles that facilitated release of chemically labile mercury species immediately adjacent to cell surfaces. Our results add new dimensions to the mechanistic understanding of mercury methylation potential by demonstrating that bioavailability is related to the geochemical intermediates of rate-limited mercury sulfide precipitation reactions. These findings could help explain observations that the "aging" of mercury in sediments reduces its methylation potential and provide a basis for assessing and remediating methylmercury hotspots in the environment.
机译：在环境中神经毒性甲基汞的生产部分受无机二价汞（Hg（II））对将Hg（II）甲基化的厌氧细菌的生物利用度控制。在沉积物孔隙水中，Hg（II）与硫化物和天然有机物缔合，形成化学物种，其中包括有机包覆的硫化汞纳米颗粒，作为非均质矿物沉淀的反应中间体。在这里，我们将两种还原硫酸盐的细菌暴露于三种形式的无机汞中：溶解的汞和硫化物，纳米颗粒的HgS和微粒的HgS。暴露于HgS纳米颗粒的甲基化汞的细菌培养物的速率比暴露于溶解形式的汞的细菌培养物的速率慢。但是，即使将其标准化为比表面积，暴露于纳米粒子的培养物中的甲基汞净产量也比用微尺度颗粒处理的培养物高6倍。此外，HgS纳米颗粒的甲基化潜力随着纳米颗粒在其原始储备溶液中的储存时间而降低。在细菌培养物中，用来自16小时的纳米颗粒储备液的纳米HgS进行了修正，一天后，总汞的6-10％被转化为甲基汞。相比之下，在老化3天或1周的纳米HgS修正的培养物中，有2-4％被甲基化。来自纳米颗粒的汞的甲基化（与较大的颗粒相反）无法通过水相中汞的平衡形态（<0.2μm）来预测，并且可能是由促进化学不稳定的汞释放的纳米颗粒的无序结构引起的物种紧邻细胞表面。我们的研究结果表明，生物利用度与限速硫化汞沉淀反应的地球化学中间体有关，从而为汞甲基化潜力的机理理解提供了新的维度。这些发现可以帮助解释这样的观察结果，即沉积物中汞的“老化”会降低其甲基化潜力，并为评估和修复环境中的甲基汞热点提供基础。

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  • 来源
    《Environmental Science & Technology》 |2012年第13期|p.6950-6958|共9页
  • 作者

    Tong Zhang; Bojeong Kim; Clement Levard; Brian C. Reinsch; Gregory V. Lowry; Marc A. Deshusses; Heileen Hsu-Kim;

  • 作者单位

    Department of Civil & Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, North Carolina 27708,United States;

    Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States;

    Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305, United States;

    Department of Civil & Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States;

    Department of Civil & Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States;

    Department of Civil & Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, North Carolina 27708,United States;

    Department of Civil & Environmental Engineering, Duke University, 121 Hudson Hall, Box 90287, Durham, North Carolina 27708,United States;

  • 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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