HR: 1340h
AN: A43A-0883    [Abstracts]
TI: Laboratory Studies of Heterogeneous Reactions of HO₂ Radical with Inorganic Aerosol Particles under the Ambient Conditions
AU: * Taketani, F
EM: taketani@jamstec.go.jp
AF: Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AU: Kanaya, Y
EM: yugo@jamstec.go.jp
AF: Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AU: Akimoto, H
EM: akimoto@jamstec.go.jp
AF: Frontier Research Center for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AB: The HO₂ uptake coefficient for aerosol particles ((NH₄)₂SO₄ and NaCl) under ambient conditions (760Torr and 296K) was measured using an aerosol flow tube(AFT) coupled with a chemical conversion/laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO₂ radical concentration as that in the atmosphere(~10⁸ molecules cm^-3). HO₂ radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at various relative humilities(RH). The uptake coefficients of dry aerosol (NaCl and (NH₄)₂SO₄) particles were < 0.05, while the uptake coefficients of wet particles of NaCl and (NH₄)₂SO₄ were estimated to be 0.10 and 0.15, respectively, which suggested that heterogeneous loss was enhanced by the particle containing water. To estimate the contribution of heterogeneous loss of HO₂ by aerosol, the diurnal variation of HO₂ using a box-model calculation was demonstrated. As a result, the daytime maximum concentrations of HO₂ were changed to 95 and 70 %, relative to an absence of heterogeneous loss for marine and urban areas, respectively.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting