AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Molecular Composition of Aged Secondary Organic Aerosol Generated from a Mixture of Biogenic Volatile Compounds Using Ultrahigh Resolution Mass Spectrometry
IVAN KOURTCHEV, Chiara Giorio, Brendan Mahon, Jean-François Doussin, Nicolas Maurin, Aline Gratien, Edouard Panqui, Sebastien Morales, Manuela Cirtog, Juho Aalto, Taina Ruuskanen, Markku Kulmala, Markus Kalberer, University of Cambridge
Abstract Number: 532 Working Group: Aerosol Chemistry
Abstract A considerable lack of knowledge exists concerning the chemical composition of natural aerosols. Field observations over the past decade revealed that a significant fraction of ambient remote organic aerosol (OA) is highly oxidised (Kroll et al., 2011). The oxidation reactions (ageing) leading to formation of highly oxidised OA involve heterogeneous uptake of oxidants and multigenerational oxidation of vapours by OH radicals (Henry and Donahue, 2012). The objectives of this work were (i) to examine photochemical ageing of SOA generated from a precursor mixture containing BVOCs (i.e. α and β-pinene, Δ-3-carene, and isoprene) that are most abundant at a remote boreal forest site Hyytiälä, Finland; (ii) to characterise the aged SOA using novel ultrahigh resolution mass spectrometry (UHR-MS) that allows detection of thousands of individual SOA constituents at once providing their elemental formulae from accurate mass measurements (Nizkorodov et al., 2011); and (iii) to compare elemental composition of laboratory generated SOA with that of ambient. The laboratory experiments were performed in the CESAM (French acronym for Experimental Multiphasic Atmospheric Simulation Chamber) chamber, which is specifically designed to investigate multiphase processes and simulate atmospheric aerosol ageing due to relatively low wall loses of the OA. The applied experimental conditions (e.g., RH, VOC ratios) were selected to represent those at the boreal sampling site during the summer period. The influence of the UV radiation and/or OH radicals and acidic aerosol seed on the organic aerosol composition of the SOA was investigated. Ageing effects in the chamber were observed over 3-9 hours. The elemental composition of the complex compound mixtures from SOA samples were compared with field samples using statistical data analysis methods.
Henry and Donahue, 2012 Journal of Physical Chemistry A 116, 5932-5940.
Kroll et al., 2011. Nature Chemistry 3, 133-139.
Nizkorodov et al., 2011. Physical Chemistry Chemical Physics 13(9), 3612-3629.