Gas phase water-soluble organic matter (WSOMg) is ubiquitous in the troposphere.  Photochemical model simulations suggest the potential for these gases to partition to particle phase liquid water where they can form secondary organic aerosol (SOAAQ) is high during the summer in the humid Southeast U.S., where the aerosol is predicted to be hygroscopic. Recent measurements during the Southern Oxidant and Aerosol Study (SOAS) from June 1 � July 15, 2013 confirm that liquid water is a dominant component of aerosol mass in Alabama. Measured particle phase liquid water mass concentrations during SOAS are influenced by diurnal patterns in particle hygroscopicity that correlates with mass concentrations of nitrate and sulfate.  Particle phase liquid water mass concentrations during SOAS are not maxima when relative humidity (RH) is highest. During SOAS we observe that more than 90% of the organic aerosol mass is water soluble and that aerosol mass spectrometry (AMS) measured IEPOX correlates with particle phase liquid water, consistent with recent laboratory experiments by Nguyen et al., 2013. Oxalate is not observed in particle phase WSOC samples collected during SOAS, but does form during photooxidation experiments.

Atmosphere-biosphere interactions during SOAS through multiphase chemistry

248th National Meeting (2014)

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