PH12 Analytical Environmental Chemistry of POPs
Exhibit Hall
8:00 AM - Thursday, 13 November 2003
(PH134) Sulfonation Reaction of Biogenic Hydrocarbons.
Liljestrand, H1, 1 University of Texas at Austin, Austin, Texas
ABSTRACT- Isoprene and monoterpenes such as pinene and limonene are known to be significant contributors to secondary organic aerosol formation, although the majority of the products are unknown. Terpenoid emissions do not depend strongly on light intensity and thus continue through the night, but do depend on temperature. The double bonds in these biogenic hydrocarbons makes estimated tropospheric lifetimes to be on the order of hours as a result of daytime reactions with hydroxyl radicals and ozone and nighttime reactions with nitrate radicals. In this study, another mechanism for the fate of biogenic hydrocarbons is investigated, reactions with sulfuric acid to form sulfonated hydrocarbons. The rates of reactions where characterized as a function of pH, sulfate activity, and temperature. Sulfonated products were identified by HPLC-MS. The UV-visible spectrum of the sulfonated hydrocarbon products was characterized and was found to strongly absorb. These results have implications on aerosol acidity through changes in sulfuric acid concentration and shifts in the pKa's of the sulfonated products as well as visibility through changes in aerosol absorption. These sulfonation reactions provide another sink for biogenic hydrocarbon emissions in areas of high sulfuric acid aerosol formation.
Key words: pinene, limonene, sulfonation, aerosol