Methylmercury sources in the Canadian High Arctic

Abstract

Mercury is increasing to toxic levels in Arctic biota living at the top of food webs. The rapid bioaccumulation and biomagnification of methylmercury (MeHg) in food chains, and the subsistence lifestyle of northern populations, has resulted in high levels of Hg in their blood. No prior measurements of MeHg sources to Arctic ecosystems have been made. In southern latitudes wetlands are considered important sources of MeHg with sulfate-reducing bacteria (SRB) thought to be responsible. Thus, the production of MeHg in Arctic wetlands was evaluated as well as SRB presence. Arctic wetlands were further evaluated as sources of MeHg in Arctic ecosystems, as well since snowmelt water provides 60 to 80% of water to Arctic terrestrial systems it was also evaluated as a source of MeHg. This was the first study to evaluate sources of MeHg entering Arctic ecosystems, and showed that although wetlands produced MeHg, the export to downstream lakes was dependant on site characteristics such as DOC levels, furthermore snowmelt water was the most significant source of MeHg to Arctic ecosystems measured here. (Abstract shortened by UMI.)