AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Comparison of Laboratory Generated Secondary Organic Aerosol from Oxidation of Biogenic Volatile Organic Compound Mixtures and Remote Ambient Samples Using High Resolution Mass Spectrometry
IVAN KOURTCHEV, Stephen Fuller, Juho Aalto, Robert Healy, Taina Ruuskanen, Willy Maenhaut, John Wenger, Markku Kulmala, Markus Kalberer, University of Cambridge
Abstract Number: 166 Working Group: Aerosol Chemistry
Abstract Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and give rise to secondary organic aerosols (SOA), which have effects on climate and human health. Laboratory chamber experiments have been performed during several decades in an attempt to mimic atmospheric SOA formation. However, it is still unclear how close the aerosol particles generated in laboratory experiments resemble atmospheric SOA with respect to their detailed chemical composition. To date, most laboratory experiments have been performed using a single organic precursor (e.g., alpha- or beta-pinene, isoprene) while in the atmosphere a wide range of precursors contribute to SOA, which results most likely in a more complex SOA composition compared to the one-precursor laboratory systems. The objective of this work is to compare laboratory generated SOA from oxidation of BVOC mixtures and remote ambient samples using ultrahigh-resolution mass spectrometry (UHR-MS) that allows detection of thousands of individual SOA constituents. We examined aerosol samples from a boreal forest site, Hyytiälä, Finland and determined that a dominant fraction of the detected compounds are reaction products of a multi-component mixture of BVOCs. In the subsequent smog chamber experiments, SOA was generated from the ozonolysis and OH initiated reactions with BVOC mixtures containing species (alpha- and beta-pinene, delta-3-carene, and isoprene) that are most abundant in Hyytiälä’s environment. The laboratory experiments were performed at conditions (e.g., RH, aerosol seed, and VOC ratios) that would resemble those at the boreal sampling site during the summer period. The elemental composition of the complex mixtures from laboratory generated SOA samples were compared with field samples using statistical data analysis methods. The possible reaction mechanisms of the most abundant compounds identified in both type of samples are discussed.