MERCURY IN THE CANADIAN ENVIRONMENT - CURRENT RESEARCH CHALLENGES

Elevated methylmercury concentrations are common in fish and other wil dlife in ecosystems remote from any industrial point sources. Concern about chronic exposure to methylmercury for people who depend on fish as a dietary staple has focused attention on mercury sources and cycli ng processes in rural and remote areas, and on the potential for airbo rne mercury to travel hundreds to thousands of kilometres. A number of other studies have demonstrated that elevated concentrations Of mercu ry in fish may be attributable to local geological sources. Compared t o the large body of literature that is emerging on anthropogenic sourc es, however, there is a relative lack of research aimed at quantifying the contribution of mercury from natural sources. This has resulted i n a debate over the relative significance of anthropogenic and natural mercury inputs to rural and remote lakes. Geoscience research is need ed to improve our understanding of the biogeochemical cycling of mercu ry species released from common sulphide minerals and other crustal so urces into soil, sediments, air, water, vegetation and ultimately into the human food chain.