Photochemical Aging of Polycyclic Aromatic Hydrocarbons on Asian Particulate Matter

Oregon State University, Corvallis OR

Investigators

Abstract

The primary objective of the research is to understand the effect of photochemical aging on the polycyclic aromatic hydrocarbon (PAH) composition of Asian particulate matter (PM) during trans-Pacific atmospheric transport to the U.S. West Coast. The principal investigators hypothesize that nitro-PAHs (NPAHs) and oxy-PAHs (OPAHs) are formed on Asian PM during trans-Pacific atmospheric transport. The specific goal of this research is to use aerosol reactors to study the photochemical aging of size-fractionated Asian PM in the laboratory. While incomplete combustion results in the formation of unsubstituted PAHs, both nitro-PAHs and oxy-PAHs result from both direct emission during incomplete combustion and reactions of unsubstituted PAHs with photochemical reactants (ozone, hydroxyl radical and nitrogen oxides) during the daytime and reactions with nitrate radicals at night. It is likely that PAHs react with these oxidants during trans-Pacific transport to form NPAH and OPAH. Existing aerosol samples from both Asia and Oregon, containing Asian PM, will be used for the laboratory studies of PAH aging. Chemical oxidation of PAHs on aerosol samples will be carried out and subsequently analyzed in collaboration with colleagues at the University of Bordeaux. The activity includes training a graduate student and continued inclusion of a faculty member from Central Oregon Community College (COCC) and her undergraduate students in the research. COCC undergraduate students will learn to conduct statistical manipulations of a large research data set, as well as understand the process of identifying and quantifying PAHs using mass spectrometry. Finally, the results of the research could have global environmental policy implications with regard to combustion emission controls in Asia.