title: Uptake of SO2 on HOBr-ice surfaces.
abstract: The 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, theta(HOBr), on the ice. The uptake coefficients increase as the HOBr coverage increases. The uptake coefficient can be expressed as gamma(t) = k(h)theta(HOBr), where k(h) = 1.5 x 10(-19) molecules(-1) cm(-2) at 191 K and k(h) = 6.4 x 10(-21) molecules(-1) cm(-2) at 210 K and theta(HOBr) is in the range of 8 x 10(13) to 1.2 x 10(15) molecules cm(-2). The effects of temperature and film thickness on the uptake coefficients of SO2 by the HOBr-treated ice films were also studied. The activation energy E(a) of SO(2) on HOBr-ice surfaces is approximately -81 +/- 8 kJ/mol in the 190-215 K range. Kinetic results were interpreted in terms of the Eley-Rideal mechanism. This study suggests that the uptake of SO2 on ice/snow surfaces is enhanced by the presence of HOBr near the ice surface. The implication for atmospheric chemistry is that HOBr-ice surfaces may not provide a significant pathway to oxide S(IV) in the boundary layer due to both lower uptake coefficient and smaller HOBr surface coverage at T > 220 K.
authors.affiliation: Wadsworth Center, New York State Health Department and Department of Environmental Health Sciences, State University of New York at Albany, P.O. Box 509, Albany, New York 12201-0509, USA.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Jin
authors.forename: Liang T
authors.initials: LT
authors.lastname: Chu
mesh_terms: D001959:Bromates / Q000737:chemistry*; D007053:Ice; D007700:Kinetics; D013458:Sulfur Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D001959:Bromates; D007053:Ice; D014867:Water; D013458:Sulfur Dioxide; C027664:hypobromous acid