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Speciation and bioavailability of mercury in well-mixed estuarine sediments

机译：充分混合的河口沉积物中汞的形态和生物利用度

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Despite regulations controlling anthropogenic mercury sources in North America, high levels of mercury in coastal fish and shellfish are an ongoing problem in Maritime Canada and the Northeastern United States. This study presents sediment core data from a macrotidal estuary located at the mouth of the Bay of Fundy showing stratigraphic profiles of total and methylmercury concentrations and potential methylation rates measured using stable mercury isotopes. The results show that in contrast to the expected methylmercury profile typically observed in unmixed sediments, methylmercury production occurs throughout the estimated 15-cm-thick active surface layer of these well-mixed sediments. The resulting large reservoir of methylmercury in these sediments helps to explain why mercury concentrations in organisms in this system remain high despite emissions reductions. Current management policies should take into account the expected delay in the response time of well-mixed estuarine systems to declines in mercury loading, considering the greater reservoir of historic mercury available in these sediments that can potentially be converted to methylmercury and biomagnify in coastal food chains.
机译：尽管北美有管制人为汞源的法规，但加拿大海事和美国东北部沿海鱼类和贝类中的高汞含量仍是一个持续存在的问题。这项研究提供了位于芬迪湾口大潮汐河口的沉积物核心数据，显示了总汞含量和甲基汞浓度的地层剖面以及使用稳定的汞同位素测得的潜在甲基化率。结果表明，与通常在未混合的沉积物中观察到的预期甲基汞曲线相反，甲基汞的产生发生在这些充分混合的沉积物的估计15厘米厚的活性表层中。在这些沉积物中形成的大量甲基汞储存库有助于解释为什么尽管排放量减少了，但该系统中生物体内的汞浓度仍然很高。当前的管理政策应考虑到充分混合的河口系统对汞含量下降的响应时间的预期延迟，考虑到这些沉积物中可利用的历史汞储量更大，有可能在沿海食物链中转化为甲基汞并被生物放大。 。

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