Antimonite Binding to Natural Organic Matter: Spectroscopic Evidence from a Mine Water Impacted Peatland.
Antimonite Binding to Natural Organic Matter: Spectroscopic Evidence from a Mine Water Impacted Peatland.
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DOI：
10.1021/acs.est.9b03924
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发表时间：
2019-08
影响因子：
11.4
通讯作者：
J. Besold;A. Eberle;V. Noël;K. Kujala;Naresh Kumar;Andreas C Scheinost;J. Lezama-Pacheco;S. Fendorf
中科院分区：
文献类型：
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作者：
J. Besold;A. Eberle;V. Noël;K. Kujala;Naresh Kumar;Andreas C Scheinost;J. Lezama-Pacheco;S. Fendorf
泥炭地和其他湿地是锑（Sb）的汇，固体天然有机质（NOM）可能在控制锑的结合中起重要作用。然而，缺乏天然泥炭样品中Sb固存的直接证据。在这里，我们分析了芬兰北部一个矿井水影响泥炭地的三个剖面的固相Sb、铁（Fe）和硫(S)以及水态Sb形态，深度达80厘米。扩展x射线吸收精细结构谱的线性组合拟合表明，Sb与Fe相结合的重要性较小，仅在泥炭地的最上层观察到。相反，主要的（几乎是唯一的）隔离机制是Sb（III）与含氧官能团的结合，并且在更深的深度，越来越多的Sb（III）与NOM的硫基结合。水中Sb的形态主要是锑酸盐，而锑酸盐浓度很低，进一步支持了我们的发现Sb（III）比Sb(V)对泥炭表面的反应性要高得多。由于停留时间不足，锑酸盐无法有效地还原为锑矿，这阻碍了泥炭地对锑的高效去除。综上所述，我们的研究结果表明，在泥炭地和其他高有机质环境中，Sb（III）与固体NOM的结合是还原条件下的重要固存机制。
Peatlands and other wetlands are sinks for antimony (Sb), and solid natural organic matter (NOM) may play an important role in controlling Sb binding. However, direct evidence of Sb sequestration in natural peat samples is lacking. Here, we analyzed solid phase Sb, iron (Fe), and sulfur (S) as well as aqueous Sb speciation in three profiles up to a depth of 80 cm in a mine water impacted peatland in northern Finland. Linear combination fittings of extended X-ray absorption fine structure spectra showed that Sb binding to Fe phases was of minor importance and observed only in the uppermost layers of the peatland. Instead, the dominant (to almost exclusive) sequestration mechanism was Sb(III) binding to oxygen-containing functional groups, and at greater depths, increasingly Sb(III) binding to thiol groups of NOM. Aqueous Sb speciation was dominated by antimonate, while antimonite concentrations were low, further supporting our findings of much higher reactivity of Sb(III) than Sb(V) towards peat surfaces. Insufficient residence time for efficient reduction of antimonate to antimonite currently hinders higher Sb removal in the studied peatland. Overall, our findings imply that Sb(III) binding to solid NOM acts as an important sequestration mechanism under reducing conditions in peatlands and other high-organic matter environments.