Polychlorinated Biphenyls in the Atmosphere of Southern Norway

Abstract

Atmospheric concentrations of seven polychlorinated biphenyl (PCB) congeners (IUPAC No. 101, 105, 118, 138/163, 153, 156, 180) were measured every week from 1992 to 1995 in Lista, a coastal station in Southern Norway. This data set of 200 samples was analyzed with respect to the influence of time, temperature, air mass origin, and wind speed on both the absolute level and the relative congeneric composition of the PCBs. The geometric mean concentration of the sum of the seven PCB congeners was 114 pg·m-3, which is in the range observed at urban locations in Europe during the early 1990s. No obvious concentration decrease could be observed during the 4 years. PCB concentrations showed a clear seasonal fluctuation with higher levels during the summer. The temperature dependence of the air concentrations of individual congeners increased with the number of chlorine atoms per molecule resulting in an increase in the relative importance of the higher chlorinated congeners during warm periods. Air arriving in Southern Norway from southwesterly directions had slightly higher concentrations than air coming from the North, whereas the relative composition of the PCB congeners was not influenced by air mass origin. At higher wind speed the concentrations of PCBs decreased. Episodes of conspicuously elevated PCB concentrations neither were associated with a particular air mass origin nor had an unusual congeneric composition. The data analysis suggests that whereas regional air transport from central Europe contributes to the occurrence of PCBs in Lista, a large fraction of the PCBs stems likely from local sources.