HR: 08:23h
AN: A41B-02 INVITED     [PDF]
TI: Reactive Heterogeneous Chemistry on Organic Aerosols: Two Case Studies
AU: * Abbatt, J
EM: jabbatt@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George St., Toronto, ON M5S 3H6 Canada
AU: Braban, C
EM: cbraban@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George St., Toronto, ON M5S 3H6 Canada
AU: Broekhuizen, K
EM: kbroekhu@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George St., Toronto, ON M5S 3H6 Canada
AU: Thornberry, T
EM: tthornbe@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George St., Toronto, ON M5S 3H6 Canada
AU: Thornton, J
EM: jthornto@chem.utoronto.ca
AF: University of Toronto, Department of Chemistry 80 St. George St., Toronto, ON M5S 3H6 Canada
AB: Two sets of laboratory studies will be discussed to illustrate the impact that heterogeneous chemistry involving tropospheric organic aerosols may have on both the gas-phase composition of the atmosphere and the chemical nature of the particles themselves. In the first case, the reactive uptake coefficient for the hydrolysis of dinitrogen pentoxide (N2O5) on organic aerosols has been measured in an entrained aerosol flow tube coupled to a Chemical-Ionization Mass Spectrometer (CIMS). The general observation is that the reaction on aqueous malonic acid aerosols behaves in an analogous manner to that on aqueous inorganic salts, i.e. the uptake coefficient shows a linear dependence on the particle water content up to 50% relative humidity (RH), at which point the effect saturates. In addition, there is evidence for the kinetics being dependent on both the size of the particles and the levels of dissolved nitrate. By contrast, the N2O5 hydrolysis kinetics on solid azelaic acid particles are too slow to be atmospherically significant, even at 85% RH. In the second case, the kinetics and product yields from the oxidation of liquid oleic acid by ozone have been studied in considerable detail, with emphasis on the quantification of gas-phase products (nonanal) by CIMS and water-soluble species by HPLC/Electrospray-Ionization Mass Spectrometry (azelaic acid, nonanoic acid). The atmospheric importance of these results will be discussed, in particular with respect to the role of organic aerosol oxidation as a source of cloud condensation nuclei.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting