Arctic marine mammals as integrators and indicators of mercury in the Arctic

Mercury concentrations were determined in liver, kidney and muscle of belugas, narwhal, white-beaked dolphins, pilot whales, ringed seals, harp seals and walrus. Tissue collections and analyses were performed largely over the past 10 years. Sampling sites ranged across the Canadian Arctic from the Mackenzie Delta and Banks Island in the west, Grise Fjord in the north, the Atlantic coast in the east and south. High Hg levels in the liver of ringed seals from the western Arctic, collected in 1987 and 1988 were similar to previously-reported values for ringed seals collected in 1973 and 1972 from the same area. Comparison among different marine mammal species showed substantial inherent differences in Hg levels among different species. White-beaked dolphins and walrus had much less Hg than pilot whales. A comparison of Hg levels in ringed seals from locations across the Arctic and Hudson Bay showed that Hg was generally higher in ringed seals from the western than the eastern Arctic, indicating a possible influence of the different geological settings in the eastern and western Arctic. The effect of age was considered in these comparisons. A similar, but less pronounced effect was noted for belugas, with some possible anthropogenic influence on animals in Hudson Bay. The spatial trend in Hg levels in animals appeared to be largely present-day background concentration reflecting geological differences between the eastern and western Arctic. Higher Hg concentration were present in surficial sediments and coastal waters in the western Arctic than the eastern Arctic in accord with the Hg trend observed in seals and belugas.