Effect of Water on the Photochemistry of Pyruvic Acid

Allison E. Reed Harris (1,2), Barbara Ervens (2,3), Richard K. Shoemaker (1), Jay A. Kroll (1,2), Rebecca J. Rapf (1,2), Elizabeth C. Griffith (1,2), Anne Monod (2,4), and Veronica Vaida (1,2)

Abstract
Pyruvic acid, an alpha-keto acid that results from the oxidation of isoprene, is photoactive in both the gas and aqueous phases in the atmosphere. Its photochemistry, however, is complex and highly variable depending on environmental conditions. This poster will describe the differences between light initiated chemistry of pyruvic acid in the aqueous phase and that in the gas phase. The divergence, rooted in the photophysics of the initial excitation of pyruvic acid, allows for an increase in the complexity of the organic products formed in the aqueous phase photochemistry, as compared with the gas phase reaction. The oligomers formed in aqueous solution are surface active and have a low vapor pressure, and thus may contribute to SOA loading under certain conditions. Further, this chemistry is not only dependent on phase, but also on the initial concentrations of pyruvic acid and oxygen and/or on the total pressure of the system. The reaction mechanism and observed kinetics of pyruvic acid as a function of its environment and concentration will be presented, along with results from an atmospheric model used to evaluate the atmospheric consequences of solvation of pyruvic acid on its atmospheric reactivity and its role as a global sink.