Temporal trends and relationships of particulate chlorinated polycyclic aromatic hydrocarbons and their parent compounds in urban air.

Concentrations of 12 chlorinated polycyclic aromatic hydrocarbons (CIPAHs) and the corresponding 5 parent PAHs associated with particulates in urban air in Shizuoka, Japan, were investigated from 1992 to 2002. Among the seven target CIPAHs that were detected in the air samples, 6-chlorobenzo[a]pyrene (6-ClBaP) had the highest mean concentration (15 pg m(-3)), followed by 1-chloropyrene (5.2 pg m(-3)) and 7-chlorobenz[a]anthracene (3.1 pg m(-3)). The concentrations of all the ClPAHs and PAHs, except 6-ClBaP, were higher in winter than in summer. Over the study period, the concentrations of the CIPAHs, except 6-ClBaP, remained almost constant, whereas the parent PAH concentrations declined moderately. There was significant correlation between the concentrations of the ClPAHs (except 3,9- and 9,10-dichlorophenanthrene) and the concentrations of the corresponding parent PAHs. Compositional analysis showed that the proportions of the detected PAHs generally did not vary over the period, whereas the proportion of 6-ClBaP relative to the total ClPAH concentration decreased over time. Comparison of the concentration profile of certain ClPAHs normalized to the concentration of 3-chlorofluoranthene, which is relatively photostable, with the profile for a traffic air sample reported previously revealed that there was no similarity between the two profiles. Factor analysis indicated that the atmospheric behavior of the ClPAHs, except for 6-ClBaP, may be similar to that of the parent PAHs, and that the atmospheric behavior of 6-ClBaP may differ from that of the other ClPAHs. The factor analysis also suggested that the emission sources for the ClPAHs (except for 6-CIBaP) may be similar to the sources of the parent PAHs.