Deposition of atmospherically transported polychlorinated biphenyls in the Canadian arctic

Snow collectors were installed in 1990 at two Canadian high arctic weather stations (Mould Bay {MB} and Eureka {EU}) in an effort to estimate annual deposition of PCBs, compare these estimates to annual snowpack measurements and to investigate the timing of the deposition. The collectors operated successfully but tended to over collect when two snow fences were used. The daily flux of ΣEPCBs in the snowpack for 1990/91 generally compared well to that of the snow collector at MB. The snowpack sample at EU for the same period was considered to be unrepresentative, due to low snow accumulation on the ground and high winds, with resulting low concentrations and fluxes. The congener makeup of snowpack and snow collector samples was similar for both sites. Mean ΣEPCB fluxes for the collectors for the winter season were 2.0 and 3.8 ng• m−2• day−1 for MB and EU respectively. Due to the tendency of the collectors to overcatch, especially late in the season, the fluxes were corrected relative to the shielded Nipher Gauge used to measure snowfall at the weather stations. The corrected ΣEPCB fluxes for MB reduced the overall contribution of a high concentration event in the winter, in favour of the fall season, the time of greatest snow accumulation. Initial assessment of the collectors for measuring the timing of and composition of PCB deposition to the arctic is very encouraging. Work is continuing to improve the collectors and to provide a better estimate of deposition of organic contaminants to the arctic environment.