Steve Brooks

Spatial coverage and temporal trends of atmospheric mercury measurements in Polar Regions

The discovery of atmospheric mercury depletion events (AMDEs) in the Canadian Arctic at Alert in 1995 initiated the intense study of atmospheric Hg processes. Mercury has unique characteristics that include long-range atmospheric transport to regions like the Arctic and the Antarctica, the transformation to more toxic methylmercury compounds and the ability of these compounds to biomagnify in the aquatic food chain. Following the discovery of AMDEs, studies have been conducted throughout Polar Regions where the same phenomenon was observed. Since then, many scientific projects have focused on studying the mechanisms related to AMDEs. Additionally, special attention is paid to the consequences of AMDEs in terms of contamination of Polar Regions because AMDEs rapidly convert atmospheric gaseous mercury into reactive and water-soluble forms that may potentially become bioavailable. Finally, the contribution of this unique reactivity occurring in polar atmospheres to the global budget of atmospheric mercury and the role played by snow and ice surfaces of these regions are important issues. This chapter presents a review of atmospheric measurements conducted both in the Arctic and the Antarctic since 1995 (continuous data). Our current understanding of AMDEs in these regions is presented.