Mercury and Selenium in Ringed and Bearded Seal Tissues From Arctic Canada

Abstract

Analyses for total mercury, methyl Schreber mercury and selenium, with age determinations for 390 ringed seals (Phoca hispida Shreber) and 64 bearded seals [Erignathus barbatus (Erxleben)] from 7 localities across the Canadian Arctic confirm (with up to 420 ppm) earlier reports of very high values for total mercury in liver. Concentrations in muscle were higher than 0.5 ppm in mature animals. There were not significant differences between localities. Mercury and age show a strong positive correlation, and so do selenium and age; the concomitant correlation between mercury and selenium is striking, the elements occurring together in a ratio by atoms of close to 1:1. Rates of accumulation appear to be somewhat higher in bearded seals. Methyl mercury in liver amounts to less than 5 percent of the total in ringed seals and to less than 1 percent in bearded seals. There appears to be a small increase with age of the fraction present as methyl mercury. This low proportion of methyl mercury in liver, together with some 75% in muscle is in contrast to reports of 89% methyl mercury in the blood of Inuit in Arctic Bay and remains to be explained.