| Abstract
| - We analyzed >400 particulate samples collected fromthroughout the Chesapeake Bay region between 1991 and1998 for polycyclic aromatic hydrocarbons (PAHs).Isomer ratios of PAHs associated with aerosol and surfacewater particles demonstrate that motor vehicles are amajor source of carcinogenic combustion-derived PAHsto Chesapeake Bay. Most of the benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene and their isomers in air,rain, and surface waters of Chesapeake Bay appear to bederived from automotive sources. Lesser, but stillsignificant amounts (53(±5)%) of these PAHs in the seasurface microlayer near urban areas are motor vehicle-derived, with 47(±5)% being coal-derived. In contrast, PAHsin surface sediments of Chesapeake Bay are predominantlycoal-derived (86(±8)%) and at most 14(±8)% motor vehicle-derived. Thus, carcinogenic PAHs input to the bay frommotor vehicles are either degraded prior to depositionto the sediments or are diluted by previously deposited coal-derived PAHs in the seabed. Like anthropogenic nitrogen(NOx), which leads to coastal eutrophication, managing theimpact of carcinogenic PAHs on coastal regions willneed to focus on motor vehicle use, which continues tooutpace population growth in areas such as ChesapeakeBay.
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