AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Limonene Ozonolysis: SOA Formation, Nucleation Threshold and Impact of Anthropogenic VOCs
WAED AHMAD, Cecile Coeur, Arnaud Cuisset, Thomas Fagniez, Patrice Coddeville, Alexandre Tomas, SAGE-DOUAI, LPCA-ULCO, UNIV LILLE, France
Abstract Number: 346 Working Group: Aerosol Chemistry
Abstract On a global scale, emissions of biogenic volatile organic compounds (BVOCs) are higher by a factor of ten than anthropogenic VOCs. Among the BVOCs, monoterpenes (alpha-pinene, limonene ...) represent a significant part of the emissions and can generate secondary organic aerosols (SOA) through their atmospheric oxidation by OH, NO3 and O3. Measurements show that organic aerosols (OA) constitute a very important fraction of the total aerosol mass (20 to 90%) and SOA are often the main components of that mass, comprising between 63 and 95% of the total. However, atmospheric chemistry models frequently deviate from OA concentration measurements, sometimes up to a factor of 100 in specific environments. Several reasons have been invoked for this difference, in particular the influence of anthropogenic air masses on SOA formation from BVOCs.
In this communication, we will present studies performed on limonene (C10H16) ozonolysis which is known to strongly produce SOA. Experiments were carried out in two complementary setups: a laminar flow reactor and an 8 m3 atmospheric simulation chamber. Different gas and particulate phase analysis tools (GC-FID / MS, CPC, SMPS) were used.
The formation of SOA through limonene ozonolysis was studied in terms of SOA yield, mass and number distribution, nucleation threshold and identification of products under various experimental conditions. The effect of anthropogenic VOCs on this formation was investigated using different compounds such as acetone, acetic acid, methylamine, 1-butanol and toluene. The results regarding the influence of anthropogenic contaminants selected as stabilized Criegee Intermediates or OH radical scavengers will be presented.