Secondary Aerosol Formation from Gas and Particle Phase Reactions of Aromatic HydrocarbonsEPA Grant Number: R831084
Title: Secondary Aerosol Formation from Gas and Particle Phase Reactions of Aromatic Hydrocarbons
Investigators: Kamens, Richard M. , Jang, Myoseon
Current Investigators: Kamens, Richard M.
Institution: University of North Carolina at Chapel Hill
EPA Project Officer: Chung, Serena
Project Period: July 28, 2003 through July 27, 2006 (Extended to July 27, 2008)
Project Amount: $400,000
RFA: Measurement, Modeling, and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5) (2003) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics , Particulate Matter
The overall goal is integrate newly discovered heterogeneous processes with gas phase chemistry, as a unified, multi-phase, chemical reaction mechanism. This process will ultimately permit the prediction of the amounts of secondary organic aerosol that result from aromatics reacting in the atmosphere.
We are proposing a modular development and integration of gas and particle phase chemistry to ultimately predict secondary aerosol formation from aromatic compounds such as, toluene, xylenes and tri-methyl-benzenes. This approach requires mechanism development, outdoor smog chamber experiments with aromatic products aromatics and, and photolytic and particle phase rate constant determinations of aromatic products. To develop and test chemical mechanisms that describe SOA formation from aromatics, it is first necessary to include in mechanisms the gas phase reactions that generate semi-volatile oxygenated products, which partition between the gas and particle phases and then further react in the particle phase. These products are also very reactive and produce yet another generation of oxygenated products. Gas phase absorption spectra cross sections and quantum yields are not available for almost all of these product compounds and will be determined. Heterogeneous reactions rates of particle associated carbonyls leading to SOA will be determined in flow reactor experiments.
It is very probable that aromatics are the most important secondary organic aerosol source in the urban atmosphere. Our resulting chemical mechanisms will be responsive to the different kinds of primary aerosols that are already present in the atmosphere, as well as being able to respond to changes in temperature, and other atmospheric physical variables that influence the formation of secondary organic aerosols from aromatics.