Advanced mercury isotope fractionation measurement to study the fate of mercury in the environment

汞污染在地方、区域和全球范围内对人类健康和自然生态系统构成重大威胁。自前工业化时代以来，人为汞排放不仅急剧增加，而且工业活动有时也在地方或区域范围内造成严重污染。这种元素是一种独特的污染物，因为当代人为排放只占整个环境清单的一小部分。全球循环中相当大比例的汞是自然的、地质成因的。这给负责管理环境中汞的监管机构带来了相当大的挑战，最好将天然汞源与人为汞源区分开来。因此，详细了解汞的生物地球化学循环是必要的，但并不总是充分的。稳定汞同位素比值的测量和汞同位素分馏的测定有助于从污染源向鱼类追踪汞。***本研究将开发测量甲基汞精确同位素比率的新方法，并将新技术应用于实地建立沉积物中汞与鱼类中汞的同位素关系。将特别关注追踪历史上在英国-瓦比贡河系统中排放的遗留汞。我们将建立氯碱生产源释放汞的同位素指纹图谱，并监测其在瓦比贡河水系和Grassy Narrows社区的扩散。我们将直接测定沉积物、生物群和水中甲基汞的汞指纹图谱。环境样品的测量将为当前瓦比贡-英格里河水系沉积物和鱼类中的汞同位素比值特征确定一个参考。这个当代基线将作为即将于2018/19年开始的修复活动的检查点。这项技术将作为一种监测工具，监测补救措施的效果，这些措施的目的是减轻目前鱼类体内的高汞含量。***该计划将培养至少四名研究生，他们将在提供准确、精确和因此可辩护的方法方面开辟新天地，解决科学家和监管机构目前面临的挑战，即区分环境中的地质和人为汞。在加拿大的情况下，这项工作对社区尤其重要，在这些社区，遗留的汞污染早已得到承认，但直到现在才实施认真的减排计划。这项研究将有助于制定未来在加拿大和世界受影响社区和其他脆弱生态系统中管理汞的政策。

Mercury contamination poses a significant threat for human health and natural ecosystems at local, regional and global scales. Man-made mercury emissions have not only increased dramatically since pre-industrial times, but industrial activities also occasionally resulted in dramatic pollution at the local or regional scale. This element is a unique contaminant as contemporary anthropogenic emissions only represent a fraction of the entire environmental inventory. A significant proportion of mercury in the global cycle is of natural, geogenic origin. This creates considerable challenges for regulators tasked with managing mercury in the environment, and it would be desirable to distinguish natural from anthropogenic mercury sources. Thus, a detailed understanding of the biogeochemical cycle of mercury is essential, but not always sufficient. The measurement of stable mercury isotope ratios and determination of mercury isotope fractionation can aid to trace mercury from the pollution source to fish.***The proposed research will develop new methods for measuring precise isotope ratios in methylmercury and apply the new technology in the field to establish the isotopic relationship between mercury in sediments and mercury in fish. Special focus will be on tracing legacy mercury that was historically discharged in the English-Wabigoon river system. We will establish the isotope fingerprint of mercury released from the chlor-alkali production source and monitor its spread throughout the Wabigoon River system and the community of Grassy Narrows. We will directly determine the mercury fingerprint of methylmercury in sediments, biota and water. Measurement of environmental samples will define a reference for the current mercury isotope ratio signature in sediments and fish of the Wabigoon-English River system. This contemporary baseline will serve as a check point for impending remediation activities that are due to commence in 2018/19. The technology will serve as a monitoring tool to monitor the efficacy of the remediation measures, which are planned to mitigate the currently high levels of mercury in fish.***The proposed program will train a minimum of four graduates students, who will break new ground in providing accurate and precise and therefore defensible methods addressing the current challenge for scientists and regulatory agencies, which is to distinguish between geogenic and anthropogenic mercury in the environment. In the Canadian context, this work is particularly important for communities, where legacy mercury pollution has long been recognized, but where serious abatement plans are only now put into place. This research will help shaping policies for the future management of mercury in affected communities and other vulnerable ecosystems in Canada and the world.