Volatile Organic Compounds and Secondary Organic Aerosol in the Atmosphere
Recent research, when considered as a whole, suggests a substantial fraction of both gas phase and aerosol atmospheric organics have not been, or have very rarely been, directly measured. Even though knowledge of these compounds is limited, they clearly influence the reactive chemistry of the atmosphere and the formation, composition, and climate impact of aerosols.
Recent work on sources and atmospheric concentrations of volatile organic compounds (VOCs) in urban air in Melbourne, rural air in south western Australia and background air at Cape Grim Tasmania will be presented. This includes studies undertaken with traditional gas chromatography techniques and also the recently developed technique of Proton Transfer Reaction - Mass Spectrometery that is having a radical influence on VOC measurement.
A review of the global budget for organic gases shows that approximately half the loss of non-methane organic carbon entering the atmosphere cannot be accounted for. This unaccounted for loss most likely occurs through formation of secondary organic aerosol, indicating an order of magnitude larger source for this aerosol than recent estimates. A major challenge in the coming decade of atmospheric chemistry research will be to elucidate the sources, structure, chemistry, and fate of these clearly ubiquitous yet poorly constrained organic atmospheric constituents.