Cyclopenta pyrene reactivity

FIGURE 10.27 Spatial and temporal distributions of two reactive particle-associated PAHs, benzo[a]pyrene and cyclopenta[cd]pyrene, and the gas-phase atmospheric reaction product 3-nitrobiphenyl during transport of a heavily polluted air parcel across southern California, September 8-9, 1993 (adapted from Fraser et al., 1998). 

The rapid depletion of these reactive PAHs during transport of this polluted air parcel is dramatic. Thus, as seen in Table 10.31, their concentrations (averaged over all times) drop from 1.04 and 0.29 ng m 3 for cyclopenta[c<7]pyrene and BaP, respectively, at central Los Angeles to 0.03 ng m 3 for both PAHs at Claremont. 

The physical effect of dilution of the aerosols due to increased mixing depths during transport of the air parcel inland is factored out by taking the ratios of the concentrations at Claremont to those at central Los Angeles. As seen in Table 10.32, the ratios are 0.21 and 0.20 for the low-reactivity PAHs benzo[k](luoranthene and i nde no[ 1,2,3-cd ]pyrene (Class V, Table 10.30), reflecting dilution, whereas the ratios are 0.10 and 0.03 for reactive BaP and cyclopenta[cd ]pyrene (Class II), respectively, indicative of reactions in addition to dilution. 

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