FLUXES OF MERCURY TO LAKE-SEDIMENTS IN CENTRAL AND NORTHERN CANADA INFERRED FROM DATED SEDIMENT CORES

Sediment cores were collected from lakes in central and northern Canad a and from Hudson Bay to compare current and historic net depositions of mercury. Cores from most locations were enriched in mercury in the upper layers deposited recently relative to deeper, historic layers. T he lakes with the greatest enrichments in mercury were located in cent ral/southern Canada. This enrichment was interpreted as being of anthr opogenic origin. Mercury inputs at the Experimental Lakes Area (ELA) i n northwestern Ontario inferred from a core profile agreed well with i nputs calculated independently from precipitation and runoff data. Ant hropogenic inputs of mercury to northwestern Ontario were calculated t o be about 9 mu g m(-2) y(-1). Considering all the locations over the geographic range, the core profiles infer that fluxes of mercury have increased on average by about 2 fold over the past half century. This is consistent with results from other sites in North America and Europ e.