Mercury methylation linked to nitrification in the tropical North Atlantic Ocean
Mercury methylation linked to nitrification in the tropical North Atlantic Ocean
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DOI：
10.1016/j.marchem.2022.104174
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发表时间：
2022-12
期刊：
影响因子：
3
通讯作者：
L. Starr;M. J. McCarthy;C. R. Hammerschmidt;A. Subramaniam;Marissa C. Despins;J. Montoya;Silvia E. Newell
中科院分区：
文献类型：
--
作者：
L. Starr;M. J. McCarthy;C. R. Hammerschmidt;A. Subramaniam;Marissa C. Despins;J. Montoya;Silvia E. Newell
甲基汞是一种毒素，主要通过食用海产品对人类和野生动物造成健康风险（桑德兰和Mason，2007年）。海洋鱼类对甲基汞的生物积累可能大多发生在海洋上部200米处，那里大多是含氧的（Mason等人，2012年）。然而，汞在含氧海水中的甲基化机制仍然未知，因为编码甲基汞生产蛋白质的hgcAB基因簇仅在厌氧微生物中发现（Gilmour等人，2013; Parks等人，2013年）。然而，最近的研究表明，gc基因广泛存在于好氧海水中，包括微需氧硝化菌Nitrospina（Tada等人，2020; Tada等人，2021年; Gionfriddo等人，2016; Bowman等人，2020年）。在这里，我们表明，潜在的甲基汞生产率在西北热带北大西洋表面沃茨，内和附近的亚马逊河羽，正相关，强烈的硝化速率andNitrospina特定的16 S基因表达。潜在的汞甲基化和硝化率最高，在最咸，最浑浊的站，这表明沉积物颗粒和营养丰富，河流排放的主要因素，促进这两个过程。这些新的结果在好氧海水提供了进一步的证据，汞甲基化与丰富的硝化微生物，并可能有助于解释海洋甲基汞的分布。
Methylmercury (MeHg) is a toxin that poses health risks to humans and wildlife, primarily through consumption of seafood (Sunderland and Mason, 2007). Most MeHg bioaccumulation by marine fish likely occurs in the upper 200 m of the ocean, which is mostly oxygenated (Mason et al., 2012). However, mechanisms of Hg methylation in oxic seawater remain unknown, since thehgcABgene cluster, which encodes proteins for MeHg production, had been found exclusively in anaerobic microbes (Gilmour et al., 2013; Parks et al., 2013). Recent work, however, has shown thathgcgenes are widespread in oxic seawater, including in the microaerophilic nitrifier,Nitrospina(Tada et al., 2020; Tada et al., 2021; Gionfriddo et al., 2016; Bowman et al., 2020). Here, we show that potential MeHg production rates in Western Tropical North Atlantic Ocean surface waters, within and near the Amazon River plume, were correlated positively and strongly to nitrification rates andNitrospina-specific 16S gene expression. Potential Hg methylation and nitrification rates were highest at the most saline and least turbid stations, indicating that sediment particles and nutrient-rich, riverine discharges were not the primary factors promoting either process. These novel results in oxic seawater provide further evidence that Hg methylation is linked to abundant, nitrifying microbes and may help explain marine MeHg distributions.