| Abstract
| - Air samples were taken concurrently for four samplingevents in the winter of 1998 at three contrasting sites: anurban center and two rural sites. The rural sites werecharacterized by the extensive usage of coal and woodfor space heating. Samples were analyzed for PCDD/Fs,PCBs, and PAHs. Recently measured octanol−air partitioncoefficients (Koa) for PCDD/Fs enabled a comparison ofthe Koa-based versus the subcooled liquid vapor pressure (pL)-based partition model for all three compound classes.Both Koa and pL were found to be excellent descriptors ofthe gas-particle partitioning of PCDD/Fs, PCBs, andPAHs. However, regressions for log Kp-log pL gave higherregression coefficients than for log Kp-log Koa. Bothmodels showed roughly similar relative states of equilibriumfor PCDD/Fs, PCBs, and PAHs. PCBs were closest toequilibrium at the urban site. It is argued that newly releasedparticles at the rural sites caused nonequilibriumpartitioning at those sites for PCBs. PAHs were releasedat all sites and were, in line with expectations, approachingequilibrium. The Koa-based and the pL-based model gavecontradictory results for PCDD/Fs: according to the pL-model,PCDD/Fs were in equilibrium for event I but not for theother events, whereas the Koa-model showed the PCDD/Fs not being in equilibrium for event I. A simple Koa-model,combining advective transport and locally released PCDD/Fs and PAHs, can explain the observed nonequilibriumpartitioning for the first sampling event.
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