Coastal sediments are an important site for transient and long-term mercury (Hg) storage, and they foster a geochemical environment optimal for Hg methylation. Therefore, efforts have been taken to constrain the role of sediments as a source of methylmercury (MeHg) to the estuarine water column. This study employed the Gust Microcosm Erosion Core system capable of quantifying particle removal from undisturbed cores under measurable shear stress conditions to assess particulate Hg and MeHg exchange between sediments and the water column. Samples were collected from organic-rich and organic-poor sediment types from the mid- and lower Delaware Bay. It was found that bulk sediment samples from organic-rich systems overpredict total Hg and MeHg release to the water column, whereas organic-poor sediments underpredict the exchange. In general, organic-rich sediments in shallow environments have the most impact on surface particle dynamics. There is little evidence to suggest that MeHg formed in the sediments is released to the water column via particulate exchange, and therefore, nonsedimentary sources likely control MeHg levels in this estuarine water column.

中文翻译：

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泥沙悬浮在河口悬浮颗粒汞动力学中的作用

沿海沉积物是瞬态和长期汞（Hg）储存的重要场所，它们为汞甲基化创造了最佳的地球化学环境。因此，已努力限制沉积物作为河口水柱中甲基汞（MeHg）的来源。这项研究采用了Gust Microcosm侵蚀岩心系统，该系统能够量化在可测量的剪切应力条件下未扰动岩心的颗粒去除量，以评估沉积物与水柱之间的Hg和MeHg颗粒交换。从特拉华湾中部和下部的富含有机物和缺乏有机物的沉积物中收集样品。结果发现，来自富含有机物的系统的大量沉积物样品会过度预测汞和甲基汞的总释放量，而缺乏有机质的沉积物则会预测交换量不足。一般来说，浅层环境中富含有机物的沉积物对表面颗粒动力学的影响最大。几乎没有证据表明沉积物中形成的MeHg通过颗粒交换释放到水柱中，因此，非沉积物来源很可能控制该河口水柱中的MeHg水平。