Latitudinal fractionation of polychlorinated biphenyls in surface seawater along a 62° N-89° N transect from the southern Norwegian Sea to the North Pole area

Surface seawater concentrations of PCBs, relative congener abundance, and possible effects of cold condensation were studied along a transect from the southern Norwegian Sea to the central Arctic Ocean (620degrees N-89degrees N). Large volume samples were collected from an ice breaker using a stainless steel surface seawater intake connected online to an ultra-clean laboratory. Concentrations of all studied PCB congeners, except for trichlorinated PCB 18, decreased with latitude. For instance, PCB 52 decreased from 470 fg L-1 at 62degrees N to 110 fg L-1 at 89degreesN and PCB 180 from 110 to 12 fg L-1. Concentrations in the central Arctic Ocean were on the order of 10-100 fg L-1 for the most abundant congeners. The relative contribution of trichlorinated PCBs to the total PCB concentration increased with latitude, the tetrachlorinated contribution to the total PCBs did not show any correlation to latitude, and the relative contribution of heavier congeners decreased with latitude. This study establishes the occurrence at very low abundances of PCBs in seawater in the central Arctic Ocean and demonstrates a northward concentration decrease. The latitudinal shift in congener pattern is reflecting the relative propensity of the PCB congeners to undergo long-range transport in the Arctic and is consistent with their relative vapor pressures.