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

NSF Award Abstract:

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.