The fate of methylmercury in the Arctic Ocean and its interplay with methane – from microscale processes to the Pan-Arctic biogeochemical cycling

Mercury (Hg) is a global pollutant and its organic form, methylmercury (MeHg) is a neurotoxin that bioaccumulates in organisms and biomagnifies in marine food webs to concentrations of concern for humans and wildlife health in the Arctic Ocean.

While the microbial transformation of MeHg is related to methane (CH4), the interplay between Hg and CH4 cycling is still unknown in Arctic sediment, despite massive releases of CH4 over extensive Arctic scales.

This proposal aims to address this uncertainty by linking large-scale biogeochemical cycling of Hg to microscales processes, especially in Arctic CH4-rich sediment by addressing key research questions:1- How is the distribution of MeHg in Arctic sediments related to the distribution of organic carbon and CH4?2- What are the biogeochemical processes involved in MeHg transformation?3- What are the drivers for microbial CH4 degradation in MeHg demethylation?Research question 1 will be addressed by constructing the first pan-Arctic MeHg database to elucidate large-sale trends in MeHg distribution (12 months at Stockholm University, SU).

Research questions 2 and 3 will be addressed using microbial consortia isolated from CH4-rich sediment collected in the Arctic Ocean (24 months at the University of Ottawa).

The product of this research will greatly advance our understanding of Hg cycling in the Arctic Ocean and ultimately help us to better predict and manage future risks of Hg pollution under a changing climate.