HR: 0800h
AN: A21A-0836    [Abstracts]
TI: Gas-phase molecular halogen production from sea-salt particles via interface reactions
AU: * Jimenez-Aranda, A
EM: angelja@uci.edu
AF: University of California, Irvine, Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering, Irvine, CA 92697 United States
AU: Thomas, J
EM: jenniet@uci.edu
AF: University of California, Irvine, Department of Chemistry, Irvine, CA 92697 United States
AU: Finlayson-Pitts, B J
EM: bjfinlay@uci.edu
AF: University of California, Irvine, Department of Chemistry, Irvine, CA 92697 United States
AU: Dabdub, D
EM: ddabdub@uci.edu
AF: University of California, Irvine, Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering, Irvine, CA 92697 United States
AB: Interface reactions at the surface of sea-salt particles have been suggested as an important source of photolyzable gas-phase halogen species in the troposphere. Such reactions are plausible, given theoretical evidence for ions at interfaces, predicted enhancements of some gases at the air-water interface, and the results of a number of experiments in which interface reactions had to be invoked to explain the data. Because of the contributions of halogen chemistry in determining ozone and other trace species in the troposphere, elucidating the roles of interface and bulk chemistry in generating photolyzable halogen gases is important. A revised version of the model of aerosol, gas and interfacial chemistry (MAGIC 2.0) is used in this work to examine the reactions of chloride and bromide ions with OH and O₃. The goal is to understand the factors that determine the relative importance of bulk compared to interface chemistry in the most simple chloride and bromide systems represented by deliquesced aerosols of NaCl or NaBr. Results show the interface process involving Cl^- and OH_(g) is the main source of Cl_2(g). For the analogous oxidation of bromide by OH, gaseous Br₂ is formed mainly in the bulk aqueous phase and transferred across the interface. However, the reaction of Br^- with O_3(g) at the interface is the primary source of Br_2(g) under dark conditions.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 4801 Aerosols (0305, 4906)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005