ATMOSPHERIC DEPOSITION OF PCBS TO MOSS (HYLOCOMIUM-SPLENDENS) IN NORWAY BETWEEN 1977 AND 1990

Samples of Hylocomium splendens collected in 1977, 1985, and 1990 from the same sites in remote areas of Norway have been analyzed for a ran ge of polychlorinated biphenyl (PCB) congeners. The Sigma PCB concentr ation (sum of the concentration of the 37 congeners screened) declined in all samples from all locations. It is probable that this decline r eflects the reduction in the global use and manufacture of these compo unds. Because the samples had been ii air-dried prior to storage, the possibility of contamination due to contact with laboratory air was in vestigated. It was concluded that, while some contamination may have o ccurred, it was largely by the tri- and tetrachlorinated groups. Gener al trends in the moss Sigma PCB composition are therefore believed to reflect broad ambient changes in the PCB concentration over time. Whil e Sigma PCB concentrations have declined, temporal changes in the cong ener pattern in the samples collected from the same locations were not ed. For example, in the south of Norway the relative concentrations of hexa- and heptachlorinated homologue groups decreased to a greater ex tent than they did in the north. This observation can be interpreted a s evidence for differences in congener recycling through the environme nt according to their volatility, and it is tentatively suggested that this may provide evidence in support of the global fractionation hypo thesis.