Mercury (Hg) concentrations normalized to their dominant hosts have been widely used to identify geological events such as massive volcanic eruptions. However, the modern Hg cycle has significantly changed, and the implications of host-normalized Hg concentrations for the Hg dynamics in contemporary coastal environments (e.g., sources, delivery mechanisms, and Hg fluxes) remain poorly understood. In this study, 66 surface sediment samples from the continental shelf of the East China Sea (ECS) were analyzed, and the total organic carbon (TOC), aluminum (Al), total sulfur (TS), and Hg concentrations were determined. Our results support that organic matter predominantly hosts Hg in these sediments. Factors such as the Hg source and abundances of organic fractions influence Hg distributions, with notable enrichment in the Changjiang River estuary and the inner shelf of the ECS, especially near the mud depocenter located off the Oujiang River estuary. The oxic to suboxic redox state and the lack of significant sulfide accumulation in surface sediments suggest that sulfides are not the primary Hg hosts. The Hg/TOC ratios, ranging from 3.0 to 169.6 (ppb/%), are particularly high in the Changjiang River estuary and exhibit an exponential correlation with the Hg accumulation rates (Hg-AR). These findings suggest that the host-normalized Hg concentration could serve as a valuable tool for assessing Hg dynamics where the accumulation rates are uncertain.

中文翻译：

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东海内陆架沉积物中汞的主要宿主相：对汞输入的影响


根据其主要宿主归一化的汞 (Hg) 浓度已被广泛用于识别大规模火山喷发等地质事件。然而，现代汞循环已经发生了显着变化，并且宿主标准化汞浓度对当代沿海环境中汞动态的影响（例如来源、传递机制和汞通量）仍然知之甚少。本研究对东海大陆架 (ECS) 的 66 个表层沉积物样品进行了分析，测定了总有机碳 (TOC)、铝 (Al)、总硫 (TS) 和汞 (Hg) 浓度。我们的结果支持这些沉积物中有机质主要含有汞。汞来源和有机组分丰度等因素影响汞分布，长江口和东海内陆架汞富集显着，尤其是瓯江口外泥沉积中心附近。从有氧到低氧的氧化还原状态以及表面沉积物中没有显着的硫化物积累表明硫化物不是主要的汞宿主。 Hg/TOC 比率范围为 3.0 至 169.6 (ppb/%)，在长江口特别高，并且与 Hg 累积率 (Hg-AR) 呈指数相关。这些发现表明，宿主归一化的汞浓度可以作为评估累积率不确定的汞动态的有价值的工具。