†U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, California 95620, United States.
‡U.S. Geological Survey, California Water Science Center, 6000 J Street, Placer Hall, Sacramento, California 95819, United States.
Environ Sci Technol. 2015 May 19;49(10):6304-11. doi: 10.1021/acs.est.5b00655. Epub 2015 May 4.
Mercury pollution is widespread globally, and strategies for managing mercury contamination in aquatic environments are necessary. We tested whether coagulation with metal-based salts could remove mercury from wetland surface waters and decrease mercury bioaccumulation in fish. In a complete randomized block design, we constructed nine experimental wetlands in California's Sacramento-San Joaquin Delta, stocked them with mosquitofish (Gambusia affinis), and then continuously applied agricultural drainage water that was either untreated (control), or treated with polyaluminum chloride or ferric sulfate coagulants. Total mercury and methylmercury concentrations in surface waters were decreased by 62% and 63% in polyaluminum chloride treated wetlands and 50% and 76% in ferric sulfate treated wetlands compared to control wetlands. Specifically, following coagulation, mercury was transferred from the filtered fraction of water into the particulate fraction of water which then settled within the wetland. Mosquitofish mercury concentrations were decreased by 35% in ferric sulfate treated wetlands compared to control wetlands. There was no reduction in mosquitofish mercury concentrations within the polyaluminum chloride treated wetlands, which may have been caused by production of bioavailable methylmercury within those wetlands. Coagulation may be an effective management strategy for reducing mercury contamination within wetlands, but further studies should explore potential effects on wetland ecosystems.
汞污染在全球范围内广泛存在，因此需要采取策略来管理水环境污染中的汞污染。我们测试了金属盐类的混凝作用是否可以去除湿地地表水中的汞并减少鱼类体内的汞生物累积。在加利福尼亚州萨克拉门托-圣华金三角洲，我们采用完全随机区组设计，建造了 9 个实验性湿地，在这些湿地中放养了食蚊鱼（Gambusia affinis），然后连续施加未经处理（对照）、或用聚合氯化铝或硫酸铁混凝剂处理过的农业排水。与对照湿地相比，聚合氯化铝处理湿地中地表水中的总汞和甲基汞浓度分别降低了 62%和 63%，硫酸铁处理湿地中分别降低了 50%和 76%。具体而言，混凝作用后，汞从水的过滤部分转移到水的颗粒部分，然后在湿地中沉降。与对照湿地相比，硫酸铁处理湿地中食蚊鱼体内的汞浓度降低了 35%。而在聚合氯化铝处理湿地中，食蚊鱼体内的汞浓度没有降低，这可能是由于这些湿地中产生了具有生物利用度的甲基汞。混凝作用可能是一种有效的管理策略，可以减少湿地中的汞污染，但还需要进一步研究其对湿地生态系统的潜在影响。
