U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
Environ Res. 2013 Aug;125:131-49. doi: 10.1016/j.envres.2013.01.007. Epub 2013 Mar 12.
Mercury (Hg) is a naturally-occurring element that is ubiquitous in the aquatic environment. Though efforts have been made in recent years to decrease Hg emissions, historically-emitted Hg can be retained in the sediments of aquatic bodies where they may be slowly converted to methylmercury (MeHg). Consequently, Hg in historically-contaminated sediments can result in high levels of significant exposure for aquatic species, wildlife and human populations consuming fish. Even if source control of contaminated wastewater is achievable, it may take a very long time, perhaps decades, for Hg-contaminated aquatic systems to reach relatively safe Hg levels in both water and surface sediment naturally. It may take even longer if Hg is present at higher concentration levels in deep sediment. Hg contaminated sediment results from previous releases or ongoing contributions from sources that are difficult to identify. Due to human activities or physical, chemical, or biological processes (e.g. hydrodynamic flows, bioturbation, molecular diffusion, and chemical transformation), the buried Hg can be remobilized into the overlying water. Hg speciation in the water column and sediments critically affect the reactivity (i.e. conversion of inorganic Hg(II) to MeHg), transport, and its exposure to living organisms. Also, geochemical conditions affect the activity of methylating bacteria and its availability for methylation. This review paper discusses remedial considerations (e.g. key chemical factors in fate and transport of Hg, source characterization and control, environmental management procedures, remediation options, modeling tools) and includes practical case studies for cleaning up Hg-contaminated sediment sites.
汞（Hg）是一种在水环境中普遍存在的天然元素。尽管近年来已经采取了减少汞排放的措施，但历史上排放的汞仍可能保留在水体沉积物中，并逐渐转化为甲基汞（MeHg）。因此，历史上受污染沉积物中的汞可能导致水生物种、野生动物和食用鱼类的人类群体受到高水平的显著暴露。即使可以实现受污染废水的源头控制，但受污染的水生系统可能需要很长时间（也许几十年）才能自然达到水中和表层沉积物中相对安全的汞水平。如果深层沉积物中的汞浓度较高，则需要更长的时间。受污染的汞沉积物是由于先前的排放或难以识别的来源的持续贡献造成的。由于人类活动或物理、化学或生物过程（例如水动力流、生物搅动、分子扩散和化学转化），埋藏的汞可能会重新迁移到上覆水中。水柱和沉积物中的汞形态会严重影响其反应性（即无机汞(II)向 MeHg 的转化）、迁移及其对生物体的暴露。此外，地球化学条件会影响甲基化细菌的活性及其甲基化的可用性。本文综述了补救措施的考虑因素（例如汞的归宿和迁移中的关键化学因素、来源特征和控制、环境管理程序、修复选择、建模工具），并包括了受污染沉积物场地清理的实际案例研究。
