AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
On the Link Between Hygroscopicity, Volatility, and Oxidation State of Ambient and Water-soluble Aerosol in the Southeastern United States
KATE CERULLY, Aikaterini Bougiatioti, Lu Xu, Hongyu Guo, James Hite, Nga Lee Ng, Rodney Weber, Athanasios Nenes, TSI, Inc.
Abstract Number: 471 Working Group: Air Quality and Climate in the Southeast US: Insights from Recent Measurement Campaigns
Abstract The formation of secondary organic aerosol combined with the partitioning of semi-volatile organic components can impact numerous aerosol properties including cloud condensation nuclei (CCN) activity, hygroscopicity, and volatility. During the summer 2013 Southern Oxidant and Aerosol Study (SOAS) field campaign in rural Alabama, a suite of instruments including a CCN counter, thermodenuder (TD), and high resolution time-of-flight aerosol mass spectrometer (AMS) were used to measure CCN activity as well as aerosol volatility, hygroscopicity, composition, and oxidation state. Particles were either sampled directly from ambient or through a Particle-Into-Liquid-Sampler (PILS), allowing for the investigation of water-soluble aerosol components. Ambient aerosol exhibited size-dependent composition with larger particles being more hygroscopic. The hygroscopicity of thermally-denuded aerosol was similar between ambient and PILS-generated aerosol and showed limited dependence on volatilization at TD temperatures up to 100°C. The organic hygroscopicity appeared to decrease with increased heating, opposing the conventional view of the most volatile compounds being the least hygroscopic. No clear relationship was found between organic hygroscopicity and oyxgen to carbon ratio, while average carbon oxidation state increased with increased volatilization.