Sources and pathways of selected organochlorine pesticides to the Arctic and the effect of pathway divergence on HCH trends in biota: a review

Historical global usage and emissions for organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDT), toxaphene and endosulfan, are presented. Relationships between the air concentrations of these OCPs and their global emissions are also discussed. Differences between the pathways of a- and h-HCH to the Arctic Ocean are described in the context of environmental concentrating and diluting processes. These concentrating and diluting processes are shown to control the temporal and spatial loading of northern oceans and that the HCH burdens in marine biota from these oceans respond accordingly. The HCHs provide an elegant example of how hemispheric-scale solvent switching processes can alter the ocean into which an HCH congener partitions, how air–water partitioning controls the pathway for HCHs entering the Arctic, and how the various pathways impact spatial and temporal trends of HCH residues in arctic animals feeding out of marine and terrestrial foodwebs.