Collaborative Research: Unraveling the Dynamics of Microbial Mercury Methylation in Two Meromictic Lakes in Central New York, USA

汞是一种广泛存在的污染物，其对人类和生态系统健康的影响促使制定了旨在限制其排放和运输的国内和国际政策和法规。人为汞污染是由于汞向大气排放以及向土地和水的释放造成的。水生生态系统是大气和陆地汞的最终接收者。它们在汞转化为最具生物累积性的形式甲基汞的过程中发挥着核心作用，甲基汞是一种已知的影响人类和野生动物大脑发育、生殖、免疫和心血管系统的神经毒素。因此，迫切需要进一步了解影响甲基汞就地生产的因素。该项目将改进对湖泊和其他内陆系统中甲基汞浓度的预测。它将区分化学相互作用的影响和微生物转化在控制甲基汞生产和积累方面的作用。这项研究将在纽约中部进行，在附近两个具有不同垂直化学和生物结构的湖泊：冰川湖和费耶特维尔绿色湖。拟议的工作将为来自不同和非传统背景的本科生和研究生提供培训机会。科学实践探索将吸引来自不同年龄组，文化，民族和种族认同的K-12学生。这项研究的结果将通过会议和科学出版物传播。主要研究人员将通过在缔约方大会会议、专家工作组会议以及《汞问题水俣公约》闭会期间磋商会议上的政策简报和简短演讲，向更广泛的科学和政策界传授科学发现。汞的甲基化是连接大气汞排放、景观沉积和水生生态系统中汞生物利用度的关键过程。甲基汞对人类和野生动物健康构成风险，可能需要管理干预。该项目将调查两个邻近的部分分解湖泊的水柱中汞的动态，这些湖泊具有明确的氧化还原剖面和超过一米的过渡化学跃层。明确的自然地球化学梯度与离散薄层采样相结合，将能够区分湖泊中汞甲基化的地球化学和生物调节剂。该团队将对溶解的有机物化合物进行荧光和分子表征，这些化合物可以螯合汞。主要元素（S、C、N）的深度分布、汞的形态、溶解有机物质及其与汞的络合作用的测定以及溶解低分子量酸和醇将被综合起来，以评估推动现场汞供应和甲基汞生产的因素。此外，还将利用分子分析来确定能够使汞甲基化的有机体的性质、分类特性和空间位置。以基因组为中心的宏基因组学将使汞甲基化与其他代谢特征联系起来，并为元转录组学提供一个支架，这将揭示微生物在没有底物限制的情况下使汞甲基化的生理条件。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Mercury is a widespread pollutant and its impacts on human and ecosystem health have spurred domestic and international policies and regulations that aim to limit its release and transport. Anthropogenic mercury contamination results from emissions to the atmosphere and releases to land and water. Aquatic ecosystems are the ultimate recipients of atmospheric and terrestrial mercury. They play a central role in the transformation of mercury to its most biologically accumulative form, methyl mercury—a known neurotoxin affecting brain development and reproductive, immune, and cardiovascular systems in humans and wildlife. Therefore, a critical need is to advance the understanding of factors influencing in-situ production of methylmercury. This project will improve the prediction of methylmercury concentrations in lakes and other inland systems. It will distinguish the effects of chemical interactions from the roles of microbial transformations in controlling methylmercury production and accumulation. The study will be conducted in Central New York, at two nearby lakes with distinct vertical chemical and biological structure: Glacier Lake and Fayetteville Green Lake. The proposed work will provide training opportunities for undergraduate and graduate students from diverse and non-traditional backgrounds. Scientific hand-on exploration will engage K-12 students from different age groups, culture, ethnical and racial identity. The results of this study will be disseminated through conferences and scientific publications. The principal investigators will impart the scientific findings to the broader scientific and policy community through policy briefs and short presentations at the meetings of the Conference of the Parties, expert working groups, and the intersessional consultations of the Minamata Convention on Mercury.Methylation of mercury is the critical process linking the atmospheric mercury emissions, deposition to the landscape, and mercury bioavailability in aquatic ecosystems. Methylmercury poses a risk to human and wildlife health and may require management interventions. This project will investigate the dynamics of mercury in the water column of two proximal meromictic lakes with well-defined redox profiles and a transitional chemocline of over a meter. The clear natural geochemical gradient combined with discrete thin-layer sampling will enable the distinction between geochemical and biological regulators of mercury methylation in the lakes. The team will perform fluorescence and molecular characterization of dissolved organic matter compounds that sequester mercury. Depth profiles of major elements (S, C, N), speciation of mercury, determination of dissolved organic material and its complexation with mercury, and dissolved low-molecular weight acids and alcohols will be integrated to evaluate factors driving in-situ mercury availability and methylmercury production. In addition, molecular analysis will be used to determine the nature, taxonomic identity, and spatial position of organisms capable of methylating mercury. Genome-centric metagenomics will enable the linkage of mercury methylation to other metabolic traits and provide a scaffold for metatranscriptomics, which will reveal the physiological conditions under which microorganisms methylate mercury absent substrate limitation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.