AN APPROACH TO STUDYING THE EFFECT OF ORGANIC COMPOSITION ON ATMOSPHERIC AEROSOL PHOTOCHEMISTRY

Physical and chemical characteristics of atmospheric carbonaceous aero sol particles are reviewed and their likely effects on the particulate matter as a reaction medium are discussed. An approach to studying th e effects of organic components of atmospheric particulate matter on a erosol organic photochemistry based on this discussion is described. A vailable information suggests that atmospheric aerosols from common co mbustion sources, such as wood smoke or diesel soot, are almost entire ly carbonaceous, consisting of a relatively thick, possibly liquid org anic layer coating an elemental carbon core, This implies that organic compounds are fairly mobile and consequently that overall organic com position of an atmospheric aerosol could play an important role in the photochemical behavior of associated reactive organic substances, In accordance with this a photochemical turntable reactor was used to inv estigate the effects of organic aerosol constituents dissolved in an o rganic solvent, using benz[a]anthracene as a model photochemically rea ctive compound, Preliminary results showed that 4 out of 10 major orga nic compound classes found in atmospheric aerosols include compounds w hich accelerated benz[a]anthracene photodegradation. These were methox yphenols, polycyclic aromatic ketones and quinones, substituted benzal dehydes, and substituted furans.