AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Formation of Low-Volatility Organics in Organic Acid/Inorganic Salt Mixtures
SILJA HÄKKINEN, Ilona Riipinen, V. Faye McNeill, University of Helsinki, Columbia University
Abstract Number: 125 Working Group: Aerosol Chemistry
Abstract Previous studies have shown that particulate-phase processing within organic acid/inorganic salt aerosol mixtures can lead to enhanced partitioning of the organic acid e.g. via organic salt formation. Formation of low-volatility organics will affect the chemical and physical properties of the aerosol and may further alter its ability to act as a cloud condensation nuclei. In this study we investigate the formation of low-volatility organics within mixtures of organic acid with sodium chloride and ammonium sulfate. The main focus is on dicarboxylic acids succinic acid and oxalic acid which are among the most abundant organic acids in the atmospheric aerosol. Quantitative information on the magnitude of low-volatility organic material formation was obtained by combining experimental data with a kinetic model describing aerosol evaporation inside a flow tube. The experiments were performed with a TPD Aerosol-CIMS (Temperature Programmed Desorption Aerosol Chemical Ionization Mass Spectrometer). The aerosol was produced by atomizing a solution and dried prior to entering a vaporization flow tube. The volatilized organic compounds were ionized chemically and detected using a quadrupole mass spectrometer. The obtained results from the model-measurement analysis show that the formation of low-volatility organic material in the studied mixtures depends on the vapor pressure of the organic acid and the acidity of the aerosol mixture. The results can help explaining observed anthropogenic enhancement in the formation of secondary organic aerosol from biogenic origin.