Dynamic mercury methylation and demethylation in oligotrophic marine water

Dynamic mercury methylation and demethylation in oligotrophic marine water
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寡营养海水中的动态汞甲基化和去甲基化

DOI：
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发表时间：
2018
期刊：
Biogeosciences
影响因子：
4.9
通讯作者：
M. Saito
M. Saito
中科院分区：
地球科学2区
文献类型：
--
作者：
K. Munson;C. Lamborg;R. Boiteau;M. Saito

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抽象的。汞在开放海洋食物网中的生物累积取决于汞的净比率 水柱中的无机汞转化为单甲基汞。我们 测量了大氧梯度下显着的甲基化率 贫营养中部太平洋的利用。总体而言，甲基化 24小时潜伏期内的比率与之前的相当 尽管存在差异，但从北极和地中海水域发布 这些海洋环境之间的生产力。与之前相比 研究将汞甲基化归因于异养细菌，我们 与未过滤的水相比，测量到过滤水的甲基化率更高 水。此外，我们观察到新产生的去甲基化增强 未过滤水与过滤水的孵化中的甲基化汞 水。添加特定站的大容量过滤颗粒物， 无机汞底物的来源和其他可能有影响的因素 化合物，不会刺激持续的甲基化，尽管是短暂的 添加后8小时内甲基化增强。补充 溶解的无机钴也会产生急剧的（如果是短暂的）增加 汞甲基化。我们的结果表明非细胞的重要作用 或细胞外甲基化机制和去甲基化在确定 海洋贫营养水域中甲基化汞的浓度。甲基化 去甲基化在公海水体中动态发生，甚至在 甲基化汞积累量较低的地区。
Abstract. Mercury bioaccumulation in open-ocean food webs depends on the net rate of inorganic mercury conversion to monomethylmercury in the water column. We measured significant methylation rates across large gradients in oxygen utilization in the oligotrophic central Pacific Ocean. Overall, methylation rates over 24 h incubation periods were comparable to those previously published from Arctic and Mediterranean waters despite differences in productivity between these marine environments. In contrast to previous studies that have attributed Hg methylation to heterotrophic bacteria, we measured higher methylation rates in filtered water compared to unfiltered water. Furthermore, we observed enhanced demethylation of newly produced methylated mercury in incubations of unfiltered water relative to filtered water. The addition of station-specific bulk filtered particulate matter, a source of inorganic mercury substrate and other possibly influential compounds, did not stimulate sustained methylation, although transient enhancement of methylation occurred within 8 h of addition. The addition of dissolved inorganic cobalt also produced dramatic, if transient, increases in mercury methylation. Our results suggest important roles for noncellular or extracellular methylation mechanisms and demethylation in determining methylated mercury concentrations in marine oligotrophic waters. Methylation and demethylation occur dynamically in the open-ocean water column, even in regions with low accumulation of methylated mercury.