AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Volatility of Source Apportioned Wintertime Organic Aerosol in the City of Athens
Evangelos Louvaris, Kalliopi Florou, ELENI KARNEZI, Spyros Pandis, University of Patras, Patra, Greece
Abstract Number: 156 Working Group: Aerosol Physics
Abstract This work focuses on measuring the volatility distribution of ambient organic aerosols (OA). A thermodenuder (TD) with temperature ranging from 25-400 $^(o)C and 15.8 s center-line residence time coupled to a High Resolution Time-of-Flight Aerosol Mass Spectrometer (AMS) and a Scanning Mobility Particle Sizer (SMPS) was used to measure the volatility of OA during a winter campaign carried out from 10 of January 2013 until 10 of February 2013 in an urban background site in the center of Athens. Positive Matrix Factorization (PMF) analysis of both the ambient and thermodenuder AMS spectra resulted in a four factor solution for the OA: hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking OA (COA), and oxygenated OA (OOA). The thermograms of the four factors were fitted using the approach of Karnezi et al. (2014) and the corresponding volatility distributions were estimated. The volatility basis set of Donahue et al. (2006) using logarithmically spaced volatility bins was used for the fitting. The analysis suggested that all factors included compounds with a wide range of volatilities, from 10 to less than 10$^-4 micro-g m$^-3. Approximately 40% of the OOA, 25% of the HOA and 10% or less of the COA and BBOA was extremely low volatile organic material (ELVOCs). At the same time around 35% of the BBOA, 30% of the HOA, 20% of the OOA had effective saturation concentration of 10 micro-g m$^-3.
By incorporating our results in the 2-D-VBS analysis framework of Donahue et al. (2012) we concluded that HOA and BBOA were in the expected region but also include an ELVOC component. COA is in the same range as HOA but it is slightly more oxidized and less volatile. The OOA in these wintertime conditions had a moderate O:C and included both semi-volatile and extremely low volatility components.