HR: 10:50h
AN: A72B-02    [Abstracts]
TI: A Novel Method for Direct In Situ Measurements of N₂O₅ Reactivity on Ambient Aerosol Particles
AU: * Thornton, J A
EM: thornton@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences 408 ATG Building, Box 351640, Seattle, WA 98195, United States
AU: Bertram, T H
EM: tbertram@atmos.washington.edu
AF: University of Washington, Department of Atmospheric Sciences 408 ATG Building, Box 351640, Seattle, WA 98195, United States
AU: Riedel, T P
EM: tpriedel@u.washington.edu
AF: University of Washington, Department of Atmospheric Sciences 408 ATG Building, Box 351640, Seattle, WA 98195, United States
AB: An experimental approach for the direct measurement of trace gas reactivity on ambient aerosol particles has been developed. The method utilizes a newly designed entrained aerosol flow reactor coupled to a custom- built chemical ionization mass spectrometer. The experimental method is described via application to the measurement of N₂O₅ reactivity, γ(N₂O₅). Laboratory calibration on well characterized aerosol particles show that measurements of γ(N₂O₅), observed with this new technique, are in agreement with previous observations even though the new method utilizes atmospherically relevant particle surface area concentrations (0-1000 μm²cm^-3) that are orders of magnitude lower than previous laboratory studies. Sources of uncertainty in the measured γ(N₂O₅) are discussed. Examples of the capabilities and utility of the retrieved data are included from both laboratory calibrations and field observations made in two locations. The field observations demonstrate that particulate organic matter and relative humidity exert strong controls on γ(N₂O₅).
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2009 Joint Assembly