Henneberry Yumiko, Kraus Tamara E C, Krabbenhoft David P, Horwath William R
Department of Land Air and Water Resources, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA.
Delta Stewardship Council, Science Program, 980 9th street, Suite 1500, Sacramento, CA, 95814, USA.
Environ Manage. 2016 Jan;57(1):220-8. doi: 10.1007/s00267-015-0601-2. Epub 2015 Sep 2.
The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69-79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81-95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.
汞（Hg）尤其是甲基汞（MeHg）的存在，对人类健康和生态健康都构成了威胁，因为甲基汞是一种神经毒素，会在营养级较高的生物体内生物累积至致死水平。最近的研究表明，与金属盐进行混凝能够通过与溶解有机物（DOM）结合并随后絮凝和沉淀，有效地从溶液中去除无机汞（IHg）和甲基汞。在本研究中，我们试图进一步研究汞与溶解有机物之间的相互作用以及由此产生的有机金属沉淀物（絮凝物），以评估：（1）新添加的无机汞能否与环境中的无机汞以相同程度被去除，或者无机汞与溶解有机物之间的结合是否需要时间；（2）一旦形成，絮凝物是否有能力从溶液中去除更多的汞。含有环境浓度的溶解有机物和无机汞的农业排水水样，添加了可追踪量的同位素富集无机汞，并在0、1、5和30天后加入硫酸铁。环境中的和新添加的无机汞在数小时内都被去除了，去除率为69% - 79%。对于另一组样品，在絮凝物形成后向溶液中添加同位素富集无机汞。在这些条件下，即使汞浓度比环境水平高1000倍，新添加汞的81% - 95%也能被去除。本研究结果表明，用硫酸铁进行混凝能有效去除进入系统的环境中的和新添加的无机汞，并表明无机汞与溶解有机物之间能快速结合。这项工作还提供了关于絮凝物即使在形成后仍有能力从溶液中去除更多汞的新信息。
