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首页> 外文期刊>Environmental Science & Technology >Thermodynamic Modeling of the Solubility and Chemical Speciation of Mercury and Methylmercury Driven by Organic Thiols and Micromolar Sulfide Concentrations in Boreal Wetland Soils
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Thermodynamic Modeling of the Solubility and Chemical Speciation of Mercury and Methylmercury Driven by Organic Thiols and Micromolar Sulfide Concentrations in Boreal Wetland Soils

机译：北方湿地土壤中有机硫醇和微摩尔硫化物浓度驱动的汞和甲基汞溶解度和化学形态的热力学模型

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摘要

Boreal wetlands have been identified as environments in which inorganic divalent mercury (Hg~(II)) is transformed to methylmercury (MeHg) by anaerobic microbes. In order to understand this transformation and the mobility and transport of Hg~(II) and MeHg, factors and conditions in control of the solubility and chemical speciation of Hg~(II) and MeHg need to be clarified. Here we explore the ability of thermodynamic models to simulate measured solubility of Hg~(II) and MeHg in different types of boreal wetland soils. With the input of measured concentrations of MeHg, sulfide, eight low molecular mass thiols and thiol groups associated with natural organic matter (NOM), as determined by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and Hg L_(III)-edge extended X-ray absorption fine structure spectroscopy (EXAFS), the model could accurately predict porewater concentrations of MeHg in the wetlands. A similar model for Hg~(II) successfully predicted the average level of its concentration in the porewaters, but the variability among samples, driven mainly by the concentration of aqueous inorganic sulfide, was predicted to be larger than measurements. The smaller than predicted variability in Hg~(II) solubility is discussed in light of possible formation of colloidal HgS(s) passing the 0.22 μm filters used to define the aqueous phase. The chemical speciation of the solid/adsorbed and aqueous phases were dominated by NOM associated thiol complexes for MeHg and by an equal contribution from NOM associated thiols and HgS(s) for Hg~υ.
机译：北方湿地已被确定为其中厌氧微生物将无机二价汞（Hg〜（II））转化为甲基汞（MeHg）的环境。为了理解这种转变以及Hg〜（II）和MeHg的迁移和迁移，需要弄清楚控制Hg〜（II）和MeHg的溶解度和化学形态的因素和条件。在这里，我们探索了热力学模型模拟Hg〜（II）和MeHg在不同类型的北方湿地土壤中的溶解度的能力。输入测得的MeHg，硫化物，八个低分子量硫醇和与天然有机物（NOM）相关的硫醇基团的浓度，通过硫K边缘X射线吸收近边缘结构（XANES）光谱法和Hg L_确定（III）边缘扩展X射线吸收精细结构光谱（EXAFS），该模型可以准确预测湿地中MeHg的孔隙水浓度。类似的Hg〜（II）模型可以成功预测孔隙水中Hg〜（II）的平均浓度，但是样品之间的变异性主要受无机硫化物水溶液浓度的驱动，预计会大于测量值。根据可能形成的胶体HgS通过用于定义水相的0.22μm过滤器，讨论了Hg-（II）溶解度小于预期的变异性。固相/吸附相和水相的化学形态以MeHg的NOM关联的硫醇配合物和Hg〜υ的NOM关联的硫醇和HgS的相等贡献为主。

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  • 来源
    《Environmental Science & Technology》 |2017年第7期|3678-3686|共9页
  • 作者

    Van Liem-Nguyen; Ulf Skyllberg; Erik Björn;

  • 作者单位

    Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden;

    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden;

    Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden;

  • 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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