Mercury and selenium in livers of waterfowl harvested in Northern Canada

Total mercury and selenium were measured in livers of green-winged teal, northern pintails, buffleheads, king eiders, Barrow's and common goldeneyes, surf and white-winged scoters collected from 12 sites across northern Canada between 1988 and 1994. Hepatic mercury concentrations were <1.0 mg x kg(-1) ww in 80% of the birds analyzed. Mercury levels did not vary much among species, with green-winged teal, northern pintails, and white-winged scoters, in particular, generally having quite low levels (<0.5 mg x kg(-1) ww). Northern pintails had the lowest Se concentrations (<2.5 mg x kg(-1) ww) overall whereas the higher Se concentrations (10-20 mg x kg(-1) ww) were found in the king eiders and scoters. Selenium showed a much greater variation in concentrations, particularly in the king eiders and scoters. Hepatic mercury concentrations found in the waterfowl analyzed in this study were an order of magnitude lower than toxicological threshold levels found in the literature. However, hepatic selenium concentrations in 33% of the females exceeded 3.0 mg x kg(-1) ww and some king eiders as well as some surf and white-winged scoters contained hepatic selenium concentrations >10 mg x kg(-1) ww suggesting levels of potential concern.