HR: 11:50h
AN: A41G-06    [PDF]
TI: Dissolution and Speciation of Oxygenated Organic Compounds in Sulfate Particles: Acetaldehyde
AU: * Michelsen, R R
EM: rmichelsen@mail.arc.nasa.gov
AF: Earth Science Division NASA Ames Research Center, MS 245-5, Moffett Field, CA 94035-1000 United States
AU: Ashbourn, S F
AF: Earth Science Division NASA Ames Research Center, MS 245-5, Moffett Field, CA 94035-1000 United States
AU: Iraci, L T
AF: Earth Science Division NASA Ames Research Center, MS 245-5, Moffett Field, CA 94035-1000 United States
AB: The uptake of small organic compounds by sulfate particles is enhanced by the speciation of the compounds in acidic aqueous solution. Acetaldehyde [CH$_{3}$CHO] exists in such solutions in several forms: molecular, hydrated, enolized, and protonated acetaldehyde. The contribution of these various dissolution pathways to the heterogeneous interactions of acetaldehyde with upper tropospheric sulfate solutions will be evaluated. The uptake of acetaldehyde by aqueous sulfuric acid has been studied via Knudsen cell experiments over ranges of temperature (210-250 K) and acid composition (40-80 wt. %) representative of the upper troposphere. The Henry's law solubility coefficients for acetaldehyde calculated from these data range from 10$^{2}$ to 10$^{5}$ M atm$^{-1}$. Results from the interaction of acetaldehyde with solutions of formaldehyde in sulfuric acid will be presented as well. The physical and chemical processes that affect organic uptake by aqueous aerosols will be explored, with the aim of evaluating organic species not yet studied in low temperature aqueous sulfuric acid.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting