US Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, California.
US Geological Survey, California Water Science Center, Sacramento, California.
Environ Toxicol Chem. 2019 Oct;38(10):2178-2196. doi: 10.1002/etc.4535. Epub 2019 Aug 28.
Wetland environments provide numerous ecosystem services but also facilitate methylmercury (MeHg) production and bioaccumulation. We developed a wetland-management technique to reduce MeHg concentrations in wetland fish and water. We physically modified seasonal wetlands by constructing open- and deep-water treatment cells at the downstream end of seasonal wetlands to promote naturally occurring MeHg-removal processes. We assessed the effectiveness of reducing mercury (Hg) concentrations in surface water and western mosquitofish that were caged at specific locations within 4 control and 4 treatment wetlands. Methylmercury concentrations in wetland water were successfully decreased within treatment cells during only the third year of study; however, treatment cells were not effective for reducing total Hg concentrations. Furthermore, treatment cells were not effective for reducing total Hg concentrations in wetland fish. Mercury concentrations in fish were not correlated with total Hg concentrations in filtered, particulate, or whole water; and the slope of the correlation with water MeHg concentrations differed between months. Fish total Hg concentrations were weakly correlated with water MeHg concentrations in April when fish were introduced into cages but were not correlated in May when fish were retrieved from cages. Fish total Hg concentrations were greater in treatment wetlands than in control wetlands the year after the treatment wetlands' construction but declined by the second year. During the third year, fish total Hg concentrations increased in both control and treatment wetlands after an unexpected regional flooding event. Overall, we found limited support for the use of open- and deep-water treatment cells at the downstream end of wetlands to reduce MeHg concentrations in water but not fish. We suggest that additional evaluation over a longer period of time is necessary. Environ Toxicol Chem 2019;38:2178-2196. Published 2019 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work, and as such, is in the public domain in the United States of America..
湿地环境提供了众多生态系统服务，但也促进了甲基汞（MeHg）的产生和生物累积。我们开发了一种湿地管理技术，以降低湿地鱼类和水中的甲基汞浓度。我们通过在下游端的季节性湿地中构建开阔水域和深水处理池，来改变季节性湿地的物理特性，以促进自然发生的甲基汞去除过程。我们评估了在 4 个对照湿地和 4 个处理湿地内的特定位置用笼子养殖西部拟蚊鱼的方法，以评估降低地表水和西部拟蚊鱼中汞浓度的有效性。在研究的第三年，仅在处理池中成功降低了湿地水中的甲基汞浓度；但是，处理池对降低总汞浓度无效。此外，处理池对降低湿地鱼类中的总汞浓度也无效。鱼类中的汞浓度与过滤后、颗粒状或整个水中的总汞浓度无关；并且，与水中甲基汞浓度的相关性斜率在不同月份之间存在差异。在 4 月将鱼放入笼子时，鱼类总汞浓度与水中甲基汞浓度之间呈弱相关，但在 5 月从笼子中取出鱼时则不相关。处理湿地建造后的次年，处理湿地中的鱼类总汞浓度高于对照湿地，但第二年就下降了。在第三年，一场意外的区域性洪水事件后，在对照和处理湿地中，鱼类总汞浓度都增加了。总体而言，我们发现，在下游端的湿地中使用开阔水域和深水处理池来降低水中的甲基汞浓度，但对鱼类无效，这种方法的支持证据有限。我们建议在更长的时间内进行进一步评估。环境毒理化学 2019；38:2178-2196。2019 年 Wiley 期刊出版公司代表 SETAC 出版。本文是美国政府的工作，因此在美国属于公有领域。
