Photosensitized Aging of Secondary Organic Aerosol by Nitrophenols

AVERY DALTON, Maggie Chou, Sergey Nizkorodov, University of California, Irvine

     Abstract Number: 60
     Working Group: Aerosol Chemistry

Abstract
Nitrophenols are a class of aromatic organic compounds that have gained much interest because of their intercontinental environmental presence. Atmospheric sources include both primary sources, such as automobile engines and biomass burning, and secondary sources, by reactions between phenols and NO2/NO3 radicals. An important piece to the evolution of nitrophenols is their presence in gaseous, aqueous, and organic particle phases, providing a wide variety of possible chemistries. This work aims to investigate the influence of nitrophenols on the photodegradation of secondary organic aerosol (SOA). Preliminary results indicate that 2-nitrophenol, which is well known to lose HONO from photolysis, is significantly more resistant to photodegredation in an organic matrix than in the aqueous phase. While the photochemical lifetimes of nitrophenols are relatively long, generally on the order of multiple days, they could also sustain indirect photochemistry by acting as photosensitizers. To test this hypothesis photochemistry experiments are conducted with a quartz-crystal microbalance (QCM) to monitor SOA mass loss rates and the results will be compared to SOA samples without nitrophenols present. We anticipate that the presence of these nitrophenols will accelerate the photodegradation of SOA, particularly in SOA which does not nominally absorb at tropospherically relevant wavelengths.