BENZ[A]ANTHRACENE PHOTODEGRADATION IN THE PRESENCE OF KNOWN ORGANIC-CONSTITUENTS OF ATMOSPHERIC AEROSOLS

Benz[a]anthracene photodegradation rates in toluene solutions containi ng co-solutes were compared using a photochemical turntable reactor. E ach cosolute investigated was found at relatively high concentrations in atmospheric particulate matter. Benz[a]anthracene photodegradation was accelerated by the presence of 9,10-anthraquinone, xanthone, 2-fur aldehyde, 2,4-dimethylbenzaldehyde, 9,10-phenanthrenequinone, 2-acetyl furan, and furfuryl alcohol. Decay was inhibited by 7-benzanthrone. Ot her compounds had little or no effect on benz[a]anthracene decay. Poss ible photochemical reaction mechanisms are discussed, and it is conclu ded that several competing mechanisms may be responsible, including el ectronic energy transfer followed by reaction from the triplet state, singlet oxygen attack, and radical chain reactions initiated by hydrog en abstraction of aerosol constituents. The results suggest that parti cle organic composition can strongly influence polycyclic aromatic hyd rocarbon photodegradation rates in atmospheric aerosols.