Collaborative Research: Constraining the role of chemical transformations in the cycling of mercury at the Arctic Ocean air-sea interface

该项目将结合对海水中汞形式的研究，对北极空气和海面之间的汞交换提供新的认识。研究结果将有助于预测不断增加的冰融化和变暖的海水将如何影响极地地区的汞含量。研究人员将采用一种新的方法来比较氡（一种非活性气体）和汞（一种各种形式的活性气体）的动力学，以了解影响海水中汞含量的化学和生物反应的重要性。研究结果将对国际《水俣公约》和有关人类和野生动物体内汞生物积累的资源管理人员有用。该项目将培养一名博士后研究员，他将参与研究的各个方面，并为本科生提供研究经验。调查人员还计划为非专业人士制作外联出版物，并在他们的网站上突出他们的工作。该项目将结合船上测量和孵化实验，以提高我们对无机汞和甲基化汞在水-空气界面上的循环以及冰盖在影响这种交换方面的作用的理解。为了将气体交换与地表水中的氧化还原反应和其他转化分离，研究人员将收集样品以测定氡和镭，因为氡的混合层亏空可用作气体交换通量的独立估计。研究人员将测试以下假设：1)与其他海洋不同，北冰洋水柱汞的主要吸收源不是汞的气体逃逸；2)原位水柱降解对二甲基汞的吸收比大气损失更重要；3)北极地区相对较低的汞净产量反映了较低的紫外线水平和冰盖、生产力以及可减少的生物可利用汞。结果将有助于预测甲基汞的生物积累如何被不断变化的气候和不断变化的北极海冰制度所改变。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will provide new understanding about mercury exchange between the air and sea surface in the Arctic, in conjunction with studies of the forms of mercury in seawater. Results will help predict how increasing ice melt and warming waters will affect mercury levels in polar regions. The investigators will use a novel approach of comparing the dynamics of radon, an unreactive gas, and mercury, which is reactive in all its forms, to understand the importance of chemical and biological reactions influencing mercury levels in seawater. Results will be useful for the international Minamata Convention and resource managers concerned with mercury bioaccumulation in humans and wildlife. The project will train a post-doctoral investigator, who will be involved in all aspects of the research, as well as provide research experience for undergraduate students. The investigators also plan to create outreach publications for non-specialists and highlight the work on their websites.This project will combine shipboard measurements and incubation experiments to improve our understanding of the cycling of inorganic and methylated mercury across the water-air interface and the role of ice cover in affecting this exchange. To separate gas exchange from redox reactions and other transformations in surface waters, the investigators will collect samples for the determination of radon and radium, as the mixed layer deficit in radon can be used as an independent estimate of the gas exchange flux. The investigators will test the hypotheses that: 1) gas evasion of mercury is not the primary sink for water column mercury in the Arctic Ocean, in contrast to other oceans; 2) in situ water column degradation of dimethylmercury is a more important sink than loss to the atmosphere; and 3) the relatively low net production of mercury in the Arctic reflects lower ultraviolet light levels and ice cover, productivity, and bioavailable mercury for reduction. Results will help predict how the bioaccumulation of methylmercury may be altered by a changing climate and an evolving Arctic sea ice regime.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.