AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Comparison of Aerosol Chemical Characterization Techniques Utilizing a PTR-ToF-MS: A Study on Biogenic SOA Formation and Gas-To-Particle Partitioning
GEORGIOS GKATZELIS, Philipp Eichler, Iulia Gensch, Thorsten Hohaus, Markus Mueller, Patrick Schlag, Sebastian Schmitt, Ralf Tillmann, Kang-Ming Xu, Zhujun Yu, Rupert Holzinger, Armin Wisthaler, Astrid Kiendler-Scharr, Forschungszentrum Jülich
Abstract Number: 709 Working Group: Instrumentation and Methods
Abstract Atmospheric organic aerosol (OA) play a key role in climate change and air quality. OA are either directly emitted through e.g. combustion processes or formed as secondary OA (SOA) through the oxidation of volatile organic compounds. SOA constitute a major fraction of OA with biogenic VOC oxidation products strongly affecting their global contribution. A detailed understanding of biogenic SOA (BSOA) formation and aging still remains a challenge. In order to better quantify and chemically characterize BSOA, new online and semi online measurement techniques have been developed.
In this framework, a comparison of three different aerosol chemical characterization techniques has been performed. The aerosol collection module (ACM, Hohaus et al. 2010), the chemical analysis of aerosol online (CHARON, Eichler et al. 2015) and the collection thermal desorption unit (TD, Holzinger et al. 2010) are different inlets utilizing a PTR-ToF-MS. These techniques were deployed in a set of chamber experiments at the atmosphere simulation chamber SAPHIR to investigate the composition of fresh and aged BSOA from the ozonolysis and photooxidation of β-pinene, limonene and real plant emissions.
Comparison of the measured mass concentration of the individual instruments to an SMPS showed recovery rates between 20 and 80 %, independent of the identity of the monoterpene oxidized. Further classification of the SOA composition showed that the conditions in the reaction ionization chambers of the PTR-ToF-MS (E/N) played a key role in the fragmentation patterns. Increasing recovery rates of organic mass were observed for reduced E/N conditions thus reduced fragmentation. A detailed analysis of the gas-to-particle partitioning of major BVOC oxidation products was performed. The observed saturation concentrations were compared with values predicted from the molecular structure of the individual compounds. Good agreement within the range of uncertainty was found for most of the compounds studied.