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首页> 外文期刊>Environmental Science & Technology >Oxidation of Organosulfur-Coordinated Arsenic and Realgar in Peat: Implications for the Fate of Arsenic
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Oxidation of Organosulfur-Coordinated Arsenic and Realgar in Peat: Implications for the Fate of Arsenic

机译：泥炭中有机硫配位的砷和雄黄的氧化作用：对砷命运的影响

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摘要

Organosulfur-coordinated As(Ⅲ) and realgar (α-As_4S_4) have been identified as the dominant As species in the naturally As-enriched minerotrophic peatland Gola di Lago, Switzerland. In this study, we explored their oxidation kinetics in peat exposed to atmospheric O_2 for up to 180 days under sterile and nonsterile conditions (25 ℃, ～100% relative humidity). Anoxic peat samples were collected from a near-surface (0-38 cm) and a deep peat layer (200-250 cm) and studied by bulk As, Fe, and S K-edge X-ray absorption spectroscopy as well as selective extractions as a function of time. Over 180 days, only up to 33% of organosulfur-coordinated As(Ⅲ) and 44% of realgar were oxidized, corresponding to half-life times, t_(1/2), of 312 and 215 days, respectively. The oxidation of both As species was mainly controlled by abiotic processes. Realgar was oxidized orders of magnitude slower than predicted from published mixed-flow reactor experiments, indicating that mass-transfer processes were rate-limiting. Most of the As released (＞97%) was sequestered by Fe(Ⅲ)-(hydr)oxides. However, water-extractable As reached concentrations of 0.7-19 μmol As L~(-1), exceeding the WHO drinking water limit by up to 145 times. Only a fraction (20-36%) of reduced S(-Ⅱ to Ⅰ) was sensitive to oxidation and was oxidized faster (t_(1/2) = 50-173 days) than organosulfur-coordinated As(Ⅲ) and realgar, suggesting a rapid loss of reactive As-sequestering S species following a drop in the water table. Our results imply that wetlands like Gola di Lago can serve as long-term sources for As under prolonged oxidizing conditions. The maintenance of reducing conditions is thus regarded as the primary strategy in the management of this and other As-rich peatlands.
机译：在瑞士富天然富营养化的泥炭地泥炭地Gola di Lago中，有机硫配位的As（Ⅲ）和雄黄（α-As_4S_4）被确定为主要的As物种。在这项研究中，我们探索了在无菌和非无菌条件下（25℃，相对湿度〜100％）暴露于大气O_2长达180天的泥炭中它们的氧化动力学。从近地表泥炭（0-38 cm）和深层泥炭层（200-250 cm）收集缺氧泥炭样品，并通过大量As，Fe和S K边缘X射线吸收光谱法以及选择性提取进行研究作为时间的函数。在180天的时间内，只有多达33％的有机硫配位的As（Ⅲ）和44％的雄黄被氧化，相应的半衰期t_（1/2）分别为312天和215天。两种砷的氧化主要受非生物过程控制。雄黄的氧化速度比已发表的混合流反应器实验预测的慢了几个数量级，表明传质过程是限速的。 Fe（Ⅲ）-（氢）氧化物螯合了大部分的As（＞ 97％）。然而，水可萃取砷的浓度达到L-19（-1）的0.7-19μmol，超过了WHO的饮用水极限达145倍。与有机硫配位的As（Ⅲ）和雄黄相比，还原的S（-Ⅱ至Ⅰ）中只有一小部分（20-36％）对氧化敏感，并且被氧化的速度更快（t_（1/2）= 50-173天），这表明，地下水位下降后，反应性As螯合S物种迅速丧失。我们的结果表明，在长期的氧化条件下，像戈拉迪拉戈这样的湿地可以长期作为砷的来源。因此，维持还原条件被视为管理该和其他富砷泥炭地的主要策略。

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  • 来源
    《Environmental Science & Technology》 |2014年第4期|2281-2289|共9页
  • 作者

    Peggy Langner; Christian Mikutta; Ruben Kretzschmar;

  • 作者单位

    Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich, CH-8092 Zurich, Switzerland;

    Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich, CH-8092 Zurich, Switzerland;

    Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich, CH-8092 Zurich, Switzerland;

  • 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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  • 正文语种 eng
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