1. To determine the depth profiles of mercury (Hg) and lead (Pb) as well as manganese (Mn) and iron (Fe) in fifteen dated Arctic sediment cores over a three year period. Mercury is the main focus. 2. To quantify geographical trends in fluxes of the mercury and its enrichment factors in Nunavut, NWT, Nunavik, and Labrador. To link mercury findings with those of paleolimnological indicators, POPs, as well as indicators of biogeochemical processes of manganese and iron, all of which are obtained from the same cores, or cores from the same sites whenever possible. 3. To complement existing data on mercury in Arctic sediment cores with data generated over a much wider latitudinal and longitudinal range than previous work in order to provide a better understanding of Hg in Canada North. 4. Secondary to Hg, to provide loading data for Pb which may help elucidate the understanding of Hg pathways and sources.