SOA Formation from a/b-farnesene mixture
Abstract
Chemical analysis of SOA produced from the oxidation of a/b-farnesene mixture was conducted in a 14.5 m3smog chamber. Gas phase compounds and SOA collected on denuders and glass-fiber filters respectively were solvent extracted, derivatized using BSTFA, and GC-MS analyzed. Gas-phase products were also analyzed using a combination of GC-FID and GC-MS. This analysis showed the occurrence of more than 30 SOA oxygenated species and more than 20 species in the gas phase. The major SOA components measured include conjugated a-farnesene trienols, C3-C7 linear dicarboxylic acids, carbonyl compounds, and hydroxy/carbonyl/carboxylic compounds. In the gas phase, the main species identified were formaldehyde, glyoxal, methylglyoxal, acetone, 2,3-dimethyl-oxirane, 2(3H)-furanone, 2-butenedioic acid, 4-oxopentanal, 4-methylenehex-5-enal, and 6-methylhept-5-en-2-one. Proposed reaction schemes are provided for selected compounds. H-atom abstraction and OH addition in a-farnesene oxidation seem to play an important role via the formation of unsaturated radicals containing different numbers of delocalized electrons. Allylic hydrogen abstraction and hydroperoxyalkyl radical channels might play a key role in the oxidation of a-farnesene. The contribution of farnesene SOA products to ambient PM2.5was investigated by analyzing samples collected during SOAS (Southern Oxidant Aerosol Study) 2013 field study at a site in Research Triangle Park, NC. The importance of these findings was supported by the occurrence of several organic species in both field and laboratory samples, suggesting the impact of farnesene on the ambient aerosol burden, mainly in areas where farnesene emissions are high. Although, pentanedioic acid and methylsuccinic acid appear to be candidate markers for farnesene SOA, additional chamber and mechanistic studies are required to estimate the contributions of farnesene to ambient SOA.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A33E0285J
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE