Is the new Arctic a source of TOXic mercury? – ATOX

Mercury (Hg) is a ubiquitous toxicant harmful to human health and the environment. Consumption of Hg-contaminated fish and seafood increases the risk for cardiovascular diseases and cognitive impairments. This global contamination issue is addressed under the 2017 Minamata Convention which commits its current 148 parties to curb anthropogenic Hg emissions. One common misconception is that mitigation policies will directly translate into reduced ecosystems contamination and human exposure. However, Hg environmental levels are driven by both modern emissions and remobilised legacy Hg from past emissions. In that context, international efforts to reduce Hg levels may be dampened as remobilisation of legacy Hg reservoirs is exacerbated by climate change. Here, we postulate that the Arctic, currently warming four times faster than the rest of the planet and already undergoing rapid ecosystem change, could become a globally-significant source of legacy Hg. This project focuses on large Hg stocks in Arctic permafrost soils that will be remobilised by intensifying permafrost thaw. What is unknown is the fate of this remobilised Hg: will it remain in the Arctic Ocean with possible dramatic effects on local food webs, or will it enter the global atmosphere and possibly counterbalance anthropogenic emissions reductions under the Minamata Convention? To address this major scientific knowledge gap, we propose novel model developments. We also address science-policy interactions by quantifying potential local and global impacts in the context of the Minamata Convention. This research will improve our ability to predict the region’s Hg contribution as a source of Hg and will have large policy implications.