AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Characterization of Winter Organic Aerosol in Zurich Using Extractive Electrospray Ionization Time-Of-Flight Mass Spectrometry (Eesi-Tof)
LU QI, Giulia Stefenelli, Veronika Pospisilova, Tianning Zhao, Samuel Brown, Yandong Tong, Christoph Hueglin, Martin Rigler, Mindong Chen, Xinlei Ge, Urs Baltensperger, Andre S.H. Prévôt, Jay G. Slowik, Paul Scherrer Institute
Abstract Number: 263 Working Group: Aerosol Chemistry
Abstract Organic aerosol (OA) has significant but highly uncertain effects on climate and human health. Online aerosol mass spectrometry (AMS), combined with statistical methods such as positive matrix factorization (PMF), has greatly advanced the quantification of primary organic aerosol (POA) sources and total secondary organic aerosol (SOA) mass. However, thermal vaporization and electron ionization yields extensive thermal decomposition and ionization-induced fragmentation, destroying chemical information important for SOA source apportionment and mechanistic studies. The new extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF), which provides online organic aerosol mass spectra with a linear response to mass but without fragmentation or thermal decomposition, is a promising tool for SOA characterization and source apportionment. EESI-TOF and AMS instruments were deployed for four weeks during winter 2017 at an urban site in Zurich, Switzerland. The deployment of AMS provided complementary information on major OA sources while constraining the total OA mass and atomic ratios. PMF analysis of EESI-TOF data resolved both primary OA sources such as traffic, cooking, and biomass burning, as well as SOA factors distinguished by organic nitrate content and atomic H:C ratio. The retrieved factor mass spectra are compared to spectra generated from smog chamber aging of emissions from real-world sources, and contextualized by comparison to source apportionment results from a full year of filter samples analyzed offline by EESI-TOF and AMS.