DOES ACID-RAIN INCREASE HUMAN EXPOSURE TO MERCURY - A REVIEW AND ANALYSIS OF RECENT LITERATURE

The literature suggests that acid deposition may lead to increased mer cury (Hg) contamination of fish. Employing published empirical relatio nships, we have estimated the change in associated Hg contamination wi th an increase in sulphate deposition from 0.25 to 1.25 g sulfur/m(2)/ year. In seepage lakes, one can predict that Hp in walleye from these lakes, and subsequent human exposure due to consumption of these fish, would be elevated at the higher rate of sulphate deposition. However, for drainage lakes, increasing acidic deposition was predicted to red uce Hg accumulation in lake trout and northern pike. Subsequent human exposure to Hg due to consumption of these species from drainage lakes was therefore also predicted to be lower at the higher rate of acidic deposition. We concluded that the hypothesis that acidic deposition i ncreases mercury (Hg) contamination in fish, and thereby mercury expos ure in humans via fish consumption, is only true for acidic deposition onto seepage lakes.