UC Riverside

A study of the evolution of carbonaceous aerosol in the atmosphere was conducted with special focus on primary biomass burning and secondary organic aerosol (SOA) processing. The work is broken down into two major components: the organic aerosol mass released from biomass burning and the evolution of SOA with special emphasis on formation routes. The biomass burning work explored the evolution of organic aerosol emissions as a function of modified combustion efficiency with correlations drawn between levoglucosan emissions and wood-type, combustion type (flaming, mixed, smoldering) using high resolution aerosol mass spectrometry. The SOA work includes insights into the mechanism for SOA formation from aromatics including the impacts of temperature and particle-aging. This work conclusively demonstrates that gas-particle partitioning theory combined with enthalpies of formation are insufficient to model the formation of SOA as a function of time; that the presence of secondary reactions, in both the particle and gas-phase continue to evolve the aerosol beyond that typically simulated in environmental chambers; and that current mechanisms for SOA formation from aromatics fail to explain isotopically labeled experiments while conclusively ruling out the importance of organic nitrate products.