Atmospheric transport of organochlorines to the Arctic Ocean

Chlorinated pesticide residues and PCB’s were measured in air vapour and particulate phases, snow, ice and dissolved and particulate seawater fractions collected from the Canadian Ice Island off Axel Heiberg Island (81°N) in 1986. Concentrations of the most abundant compounds (hexachlorocyclohexanes, α and β-HCH) were higher in air vapour and snow during May than in August consistent with the inferred seasonal maximum of Arctic haze. Cyclodienes (dieldrin, heptachlor epoxide, cis and trans-chlordane) and PCB’s (quantified as Aroclor 1254) associated with particles in snow and seawater were also present in highest concentrations in late spring. p,p'-DDT and o,p' and p,p-DDE were detected associated with particles in air, snow and seawater but concentrations were below levels for accurate quantification. Concentrations of dissolved HCH’s in seawater in the uniformly mixed upper 50 m (4–5 ng 1^-1) decreased by an order-of-magnitude to 280 m depth. There were no significant differences in vertical profiles for the two sampling periods. Similarities in ratios of HCH and chlordane isomers in air, snow and seawater above 100 m imply that these compounds are transferred between environmental compartments without transformations. Lower ratios below 100 m indicate a different source or selective conversion of specific isomers.