ABSTRACT

Levels of total mercury in marine sediments were surveyed in Howe Sound, a fjord near Vancouver, B.C., receiving mercury-contaminated discharges from a chlor-alkali plant since 1965. Similar mercury levels were found in the marine sediments in an area of 15.5km² near the plant for the periods 1972-3 and 1976-7, despite a drastic cut in mercury input by the plant in recent years and a decrease in mercury contents of sediments adjacent to the dock of the chlor-alkali plant. Methylmercury contents were found to be less than 1 percent of the total amount of mercury in the surface marine sediment. Mechanisms of mobilization are discussed. These processes appeared to be rather slow and could not significantly alter the mercury budget in the upper Howe Sound sediment.