Silver in sediments from the St. Lawrence River and Estuary and the Saguenay Fjord

The concentration of Ag in sediment cores from the St. Lawrence River and E stuary and the Saguenay Fjord reaches Values 2-15 times higher than its cru stal abundance, indicative of widespread dispersion of anthropogenic Ag. Th e direct discharge of wastewaters is likely the most important pathway for the introduction of anthropogenic Ag into these environments, but the input from the Great Lakes can also be important as suggested by Very high Ag co ncentrations in a core collected in the river near take Ontario. The distri bution of Ag in Pb-210-dated cores reveals that the Ag contamination increa sed markedly after 1930, reached a maximum during the 1980s, and has been d iminishing since. Estimates of the total burden of anthropogenic Ag deposit ed in the sediments are on the order of 43 tons in the lower St. Lawrence E stuary, 12 tons in the St. Lawrence River, and 2.7 tons in the Saguenay Fjo rd. The average annua I deposition since 1930 is equivalent to 0.3% of the total annual anthropogenic flux of Ag into United States waters.