HR: 0800h
AN: A21C-0875    [Abstracts]
TI: Uptake of SO₂ on HOBr-Ice Surfaces
AU: * Chu, L
EM: lchu@albany.edu
AF: Wadsworth Center, NYS Health Dept and Dept of Environmental Health Sciences, SUNY-Albany, Empire State Plaza, P. O. Box 509, Albany, NY 12201-0509 United States
AU: Jin, R
EM: rjin@wadsworth.org
AF: Wadsworth Center, NYS Health Dept and Dept of Environmental Health Sciences, SUNY-Albany, Empire State Plaza, P. O. Box 509, Albany, NY 12201-0509 United States
AB: Uptake of SO₂ on HOBr-treated ice surfaces has been studied using a flow reactor coupled with a differentially pumped quadrupole mass spectrometer at 190-240 K. The initial uptake coefficient was determined as a function of HOBr surface coverage, θ_HOBr, on the ice. The uptake coefficients increase as the HOBr coverage increases. The uptake coefficient can be expressed as γ_t=k_h θ_HOBr, where k_h=5.7×10^-20 molecules^-1cm^-2 at 191 K, and k_h=5.5×10^-21 molecules^-1cm^-2 at 210 K, θ _HOBr is in the range of 8×10¹³-1.2×10¹⁵ molecules.cm^-2. The effect of temperature on the uptake coefficients of SO₂ by the HOBr-treated ice films was also studied. The activation energy E_a of SO₂ on HOBr-ice surfaces is approximately -76±11 kJ/mol in the 190-215 K range. Other effects on the uptake coefficient of SO₂ for the HOBr-treated ice surfaces were also investigated, and kinetic results were interpreted in terms of the Eley-Rideal mechanism. In addition, SO₂ uptake coefficient on HOCl-ice surfaces was investigated. This study suggests that the uptake of SO₂ on ice/snow surfaces is enhanced by the presence of HOBr or HOCl near the ice surface. The implication for atmospheric chemistry is that HOBr-ice surfaces may provide an efficient pathway for oxidation of S(IV) in the boundary layer, similar to S(IV) oxidation by HOBr in the aqueous phase.
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: Fall Meeting 2005