The atmospheric levels of 12 chlorinated polycyclic aromatic hydrocarbons (ClPAHs) associated with particulates at an urban site in Japan were investigated. Only 7 of the 12 species studied were detected in air samples collected monthly during 2002. 1-Chloropyrene (1-ClPy) was detected at the highest concentration (7.5 pg m -3 (annual mean)), followed by 6-chlorobenzo[a]pyrene (6-ClBaP; 5.6 pg m -3 ) and 9,10-dichlorophenanthrene (5.1 pg m -3 ). The concentrations of the ClPAHs tended to be higher in winter than in summer, with the exception of the 6-ClBaP concentration, which was high in both summer and winter. Correlation analysis also indicated that the behavior of 6-ClBaP differed significantly from that of the other ClPAHs. Comparison of the atmospheric ClPAH concentration profile normalized to 1-ClPy concentration with that for a traffic air sample revealed significant differences between the profiles. The behavior of the atmospheric ClPAHs was also influenced by the origin of the associated particulates, which varied according to season. The positions of chlorination in the detected ClPAHs were consistent with those where the frontier electron density was high. This means that the atmospheric ClPAHs were formed by secondary reactions with chlorine atoms. The photostabilities of the ClPAHs were also investigated in laboratory experiments using a chemical model system. The ClPAHs decayed according to first-order reaction rate kinetics, with photostabilities increasing in the order 6-ClBaP < 1-ClPy < 7-ClBaA < ClPhe < ClFluor, consistent with the trend for the parent PAHs. The photolyses of chlorophenanthrenes and 7-chlorobenz[a]anthracene were confirmed to proceed by initial abstraction of chlorine, followed by oxidative degradation. ES040433SFIGURE 4. Chemical structures of the ClPhe derivatives and 7-ClBaA used in the irradiation experiments.

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.

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