Special issue on mercury in Canada's North: summary and recommendations for future research.

Important scientific advances have been made over the last decade in identifying the environmental fate of mercury and the processes that control its cycling in the Canadian Arctic. This special issue includes a series of six detailed reviews that summarize the main findings of a scientific assessment undertaken by the Government of Canada's Northern Contaminants Program. It was the first assessment to focus exclusively on mercury pollution in the Canadian Arctic. Key findings, as detailed in the reviews, relate to sources and long-range transport of mercury to the Canadian Arctic, its cycling within marine, freshwater, and terrestrial environments, and its bioaccumulation in, and effects on, the biota that live there. While these accomplishments are significant, the complex nature of the mercury cycle continues to provide challenges in characterizing and quantifying the relationships of mercury sources and transport processes with mercury levels in biota and biological effects of mercury exposure. Of particular concern are large uncertainties in our understanding of the processes that are contributing to increasing mercury concentrations in some Arctic fish and wildlife. Specific recommendations are provided for future research and monitoring of the environmental impacts of anthropogenic mercury emissions, influences of climate change, and the effectiveness of mitigation strategies for mercury in the Canadian Arctic. Crown