POLYCHLORINATED-BIPHENYLS IN ARCTIC AIR .1. TEMPORAL AND SPATIAL TRENDS - 1992-1994

In 1992, a long term program was established to measure the airborne c oncentrations of persistent organic pollutants (POPs) in the Arctic. T o maximize spatial variation over a wide geographical area, three Arct ic locations were selected; two sites in Canada, Alert on Ellesmere Is land and Tagish in the western Yukon, and one in Russia at Dunai Islan d in eastern Siberia. PCB data is presented here for the years 1992-19 94. Mean Sigma PCB concentrations for 1993, the year when all three si tes were running simultaneously, were 27.4, 17.0, and 34.0 pg/m(3) at the Alert, Tagish, and Dunai sites, respectively. With the exception o f the Tagish site in 1993, where Sigma PCB concentrations were found t o be weakly correlated with mean monthly temperatures, no correlation with temperature was observed. However, changes in the homolog group p rofile with temperature were apparent. On an annual basis, the trichlo rinated congeners made the largest single contribution to the atmosphe ric concentrations of Sigma PCB, however, this contribution declined w ith the onset of warmer months. This temperature-dependent homolog pat tern was most clearly evident at Dunai, where the contribution of the pentachlorinated congeners matched or exceeded that of the trichlorina ted congeners during May, June, and July of 1993. It was also evident at Alert and Tagish, but not to the same degree. Spatial and year-to-y ear differences at these Arctic sites were attributed to both the site 's proximity to source areas (where different PCB mixtures and quantit ies have been used) and to the influence of air mass movement from the se source regions.