Air-vegetation partitioning of polychlorinated biphenyls near a point source

We investigated polychlorinated biphenyl (PCB) emissions to the environment from a waste treatment and transfer facility over the course of three years. We show that the facility, which undertakes PCB waste consolidation and maintains a low-yield incinerator for products such as light ballasts, acted as a point source for the spatial distribution of PCBs in vegetation. Concurrent air and vegetation sampling was performed to study the relationship between air-vegetation partitioning and the octanol-air partition coefficient (KOA). We show evidence of equilibrium partitioning for lower-chlorinated congeners (log KOA between 7 and 8.5), kinetically limited deposition on plants for intermediate congeners (log KOA between 8.5 and 11), and particle-bound deposition for congeners with high log KOA values (> 11), consistent with the McLachlan partitioning model. From spring to autumn, heavier congeners become much more concentrated in samples farther away from the facility, possibly because of higher temperatures, which enhance dispersal of these congeners. Multivariate principal components analysis showed that PCB composition in vegetation near the emission source most closely resembled the Aroclor mixtures processed by the treatment facility.