Anchor QEA, LLC, 720 Olive Way #1900, Seattle, WA 98101, USA.
University of Western Ontario, Department of Biology and Centre for Environment and Sustainability, London, ON, Canada.
Sci Total Environ. 2015 Aug 15;524-525:260-8. doi: 10.1016/j.scitotenv.2015.04.015. Epub 2015 Apr 20.
Mercury pollution has not been well documented in the inland lakes or fishes of Mexico, despite the importance of freshwater fish as a source of protein in local diets. Total mercury and methylmercury in waters, sediments, and the commercial fish catch were investigated in Lake Zapotlán, Mexico. Concentrations of total and methylmercury were very high in runoff and wastewater inputs, but very low in sediments and surface waters of the open water area of the lake. Concentrations of total mercury in tilapia and carp were very low, consistent with the low concentrations in lake water and sediments. Particle settling, sorption, the biogeochemical environment, and/or bloom dilution are all plausible explanations for the significant reductions in both total mercury and methylmercury. Despite very high loading of mercury, this shallow tropical lake was not a mercury-impaired ecosystem, and these findings may translate across other shallow, alkaline tropical lakes. Importantly, the ecosystem services that seemed to be provided by peripheral wetlands in reducing mercury inputs highlight the potential for wetland conservation or restoration in Mexico.
墨西哥内陆湖泊或鱼类的汞污染问题尚未得到充分记录，尽管淡水鱼类作为当地饮食中蛋白质的来源非常重要。本研究调查了墨西哥萨波特兰湖的水体、沉积物和商业鱼类捕捞物中的总汞和甲基汞。在径流水和废水输入中，总汞和甲基汞的浓度非常高，但在湖泊开阔水域的沉积物和地表水的浓度非常低。罗非鱼和鲤鱼体内的总汞浓度非常低，与湖水和沉积物中的低浓度一致。颗粒沉降、吸附、生物地球化学环境和/或浮游生物大量繁殖的稀释作用都是总汞和甲基汞显著减少的合理解释。尽管汞的负荷很高，但这个浅热带湖泊并不是一个受汞影响的生态系统，这些发现可能适用于其他浅碱性热带湖泊。重要的是，周边湿地在减少汞输入方面提供的生态系统服务突显了墨西哥保护或恢复湿地的潜力。
