Temporal and spatial trends of persistent organochlorines in Greenland walrus Odobenus rosmarus rosmarus/

Persistent organochlorines wPCBs, DDT and chlordane related compounds, dieldrin, toxaphene, hexachlorocy- clohexane HCH., chlorobenzenesx were determined in blubber of Atlantic walrus Odobenus rosmarus rosmarus. in 1978 and 1988 from the Avanersuaq Thule. region of north-west Greenland and in 1989 from Ittoqqortoormiit Scoresbysund. in east Greenland. Lowest concentrations of organochlorines OCs. were found in the samples from the Avanersuaq region while much higher levels of all compounds, except HCH isomers and monordichlorobiphen- yls CB5r8., were observed in samples all males. from Ittoqqortoormiit. Total PCBs PCB. averaged 246 ngrg wet wt.. male walrus from Avanersuaq and 2860 ngrg in samples from Ittoqqortoormiit. DDT isomers showed the greatest difference between the two locations, 50= for p, p9-DDE and 69= higher for p, p9-DDT. Ittoqqortoormiit walrus showed the pattern of OCs characteristic of seal-eating animals although the consumption of other organisms cannot be ruled out. The higher levels of OCs in east Greenland compared to north-west Greenland animals were consistent with results for polar bears, seals and gulls from the same regions. Principal components analysis showed that the pattern of OCs in Ittoqqortoormiit walrus was very similar to that in walrus from Inukjuaq in east Hudson Bay, which have previously been reported to be seal eaters, and quite distinct from the Avanersuaq walrus. No significant differences in mean concentrations of any OCs were found between male walrus from 1978 and 1988. For females, there were significantly higher levels of CB5r8, trichlorobiphenyls, dieldrin, toxaphene and aHCH as well as HCH but not for PCBs or DDT compounds. The data for Greenland walrus from the 1970s and late 1980s provide a baseline for future trend monitoring in walrus.