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Secondary Organic Aerosol Formation from the Oxidation of Camphene
QI LI, Jia Jiang, Isaac Afreh, Kelley Barsanti, David R. Cocker III, University of California, Riverside
Abstract Number: 325
Working Group: Aerosol Chemistry
Abstract
Camphene is one of the dominant monoterpenes measured from biogenic and biomass burning (BB) emissions. However, camphene has not been well-studied in smog chambers and very little is known about its potential to form secondary organic aerosol (SOA). The lack of chamber-derived SOA data for camphene may lead to significant uncertainties in predictions of SOA from monoterpenes using existing parameterizations in air quality models. In this study, a series of conventional environmental chamber experiments were performed in the UCR environmental chamber to explore camphene SOA yields and properties under atmospherically-relevant conditions. Camphene SOA yields of up to 27% were measured under no/extremely low NOx conditions. Experiments performed in the presence of NOx resulted in completely different SOA formation in terms of SOA yield and particle size distribution, possibly indicating different reaction pathways. At 300k, in the presence of 100ppb of NOx and 1 ppm of H2O2, an SOA mass yield of 70% was measured, in contrast to only 27% under low/no NOx conditions and 10%-40% of typical SOA yield of α-pinene. In addition, oxidation reactions in the presence of NOx formed much larger particles (dp>600nm) than formed without NOx (100-200nm) in the same amount of time. To further advance the understanding of camphene and improve representation in air quality models, chamber results were compared with simulations using two box models, GECKO-A and SAPRC. The chamber experimental results and box modeling simulations will be presented, along with parameterizations for use in air quality models.