Chamber investigations of secondary organic aerosol formation

Citation

Cocker, David Rea (2001) Chamber investigations of secondary organic aerosol formation. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/22w2-vk68. https://resolver.caltech.edu/CaltechETD:etd-01232007-072920

Abstract

Hydrocarbons in the atmosphere undergo oxidation that can lead to the formation of semi-volatile products. These products undergo gas-to-particle conversion to form secondary organic aerosol (SOA). Reaction chambers provide a controlled environment which gas-to-particle conversion is investigated. First, an extensive investigation into the aerosol forming potential of 14 biogenic hydrocarbons is reported. Traditionally, chamber experiments have been performed at relative humidity levels such that the aerosol investigated is water-free. However, atmospheric conditions are typically such that ambient aerosol contains water. A new facility to improve measurement of SOA formation under humid conditions is described. A comprehensive study on how the presence of water affects gas-to-particle partitioning in the alpha-pinene ozonolysis and m-xylene and mesitylene photooxidation systems is reported. The diurnal trends in the hygroscopic nature of Pasadena, CA, aerosol is reported for late summer, 1999. Presented are additional investigations into the identification of products resulting from ozonolysis of alpha-pinene, beta-pinene, sabinene, Delta^3-carene, and cyclohexene. A field campaign to identify similar monoterpene oxidation products in a forest environment is presented. Finally, an estimate of the global aerosol burden from biogenic hydrocarbons is provided.

Thesis Files