HR: 08:22h
AN: A11C-02    [Abstracts]
TI: Gaseous Bromine Production from the Heterogeneous Reaction of Hydroxyl Radicals with Aqueous Salt Solutions
AU: * Frinak, E K
EM: efrinak@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George Street, Toronto, ON M5S 3H6 Canada
AU: Abbatt, J
EM: jabbatt@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George Street, Toronto, ON M5S 3H6 Canada
AB: Photochemically active bromine is believed to play an important role in the chemistry of the troposphere. Field measurements suggest that radical bromine produced by the photolysis of Br₂ may cause depletion of surface level ozone (O₃), particularly in polar latitudes at springtime. Though field and laboratory measurements support the proposed gas phase chemistry, the sources of Br₂ to the troposphere remain unclear. Marine algae and reactions of O₃ with sea salt particles, sea ice and frost flowers have been considered as potential sources. We have used a rotating wetted-wall flow tube coupled to a chemical ionization mass spectrometer to investigate the formation of gaseous Br₂ from the heterogeneous reaction of hydroxyl radicals with aqueous salt solutions. For the first time we have observed that Br₂ is produced not only from acidic sodium bromide solutions, but also from acidic sodium chloride solutions with varying concentrations of bromide similar to those encountered in sea water. These results are consistent with previous assertions that formation of Br₂ will occur as opposed to Cl₂ when sufficient bromide levels are present. We have explored this reaction as a function of bromide concentration and pH and will discuss the atmospheric implications of these findings.
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005