Barbara J. Finlayson-Pitts
Department of Chemistry
University of California, Irvine
Irvine, CA 92697-2025
949-824-7670
fax 949-824-3168
bjfinlay@uci.edu

Despite the central importance of tropospheric ozone in determining the radiation balance, oxidative properties and health impacts of the lower atmosphere, there remain key gaps in understanding the processes leading to its formation and loss. One of these gaps is the role of highly reactive halogen atoms in determining ozone levels in the troposphere. Sources of tropospheric halogens include sea salt, particles from alkaline dry salt lakes, and industrial emissions.

A variety of laboratory studies are being carried out to determine the kinetics and mechanisms of the reactions of sea salt and its components with O₃, OH and bromine nitrate over a range of tropospheric temperatures typical of mid-latitudes to the polar regions. An aerosol chamber with long path Fourier transform infrared and differential optical absorption spectroscopies, as well as atmospheric pressure ionization mass spectrometry (API-MS), is being used to follow O₃ and the gaseous products of its reaction with sea salt particles and its components. Diffuse reflectance Fourier transform infrared spectrometry is being used to probe for the production of hydroxide ions in the salts during the reactions with O₃ and OH. The reactions of O₃ and OH with the same solutions, but frozen into ice as is found in the polar regions, are being studied using a flow cell with API-MS and long path FTIR detection systems, as well as a Knudsen cell interfaced to an EI-MS. Similar studies of the reaction of BrONO₂ with synthetic sea salt at room temperature and frozen seawater will be performed to assess its role in the bromine cycles in the marine boundary layer. Finally, the kinetics and mechanisms of bromine atom reactions with some unsaturated biogenic hydrocarbons, potential reactants with bromine in coastal regions, are being probed using relative rate and long path Fourier transform infrared studies.

Some further information can be found in the viewgraphs from a presentation at the Atmospheric Sciences Program Annual Meeting held in February 2001. Additional information can be found in the viewgraphs from a presentation at the Atmospheric Sciences Program Annual Meeting held in March 2002.