Mercury, DDT and PCB in the Atlantic Walrus (<i>Odobenus rosmarus rosmarus</i>) from the Thule District, North Greenland

Abstract

Tissue samples of 69 Atlantic walruses (Odobenus rosmarus rosmarus) were collected in the Thule district, North Greenland, in May-July 1975 and 1977. The mean concentration of total mercury in liver was 1.78 mg/kg (SD=1.54; N=46), wet weight basis, with the mean percentage of methyl mercury being 5.5%. The mean concentration in muscle was 0.08 mg/kg (SD=0.05; N=58; mean age = 10.9 years; range: 1-26 years; neonates excluded). In neonates (N=9) the mean concentration of total mercury was 0.31 mg/kg (SD=0.45) in liver (19.9% methyl mercury) and 0.06 mg/kg (SD=0.03) in muscle. Mean Sigma DDT and PCB concentrations in blubber of 28 walruses (mean age = 7.4 years; range: 0-19 years) were 0.063 mg/kg (SD=0.080) and 0.221 mg/kg (SD=0.207), respectively. In males the concentration of Sigma DDT and PCB increased with age. In females there was no correlation between the concentration of Sigma DDT and age, while there was a negative correlation between the concentration of PCB and age. The values of mercury concentrations are low compared with values for seals in Greenland and the eastern Canadian Arctic, and the values of organochlorine concentrations are the lowest reported for pinnipeds.

Key words: Mercury, DDT, PCB, Atlantic walrus, Odobenus rosmarus rosmarus, North Greenland