AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Efficient Organic Aerosol Formation from Isoprene Photooxidation in Pristine Conditions
JIUMENG LIU, Ben H. Lee, Emma D'Ambro, Felipe Lopez-Hilfiker, Becky Alexander, Rahul Zaveri, Jean C. Rivera-Rios, Frank Keutsch, Siddharth Iyer, Theo Kurten, Ying-Hsuan Lin, Jason Surratt, Pattanun Achakulwisut, Loretta Mickley, Joel A. Thornton, John Shilling, Pacific Northwest National Laboratory
Abstract Number: 179 Working Group: Aerosol Chemistry
Abstract With a global flux of ~500 Tg/year, emission of isoprene by vegetation is the largest source of non-methane hydrocarbons to the atmosphere, where its photochemical oxidation is a potentially substantial source of secondary organic aerosol (SOA) mass. The pathways by which isoprene converts to SOA, and how anthropogenic pollutants such as nitrogen oxides and sulfur affect this process, are a subject of intense research, in part because atmospheric particles profoundly affect Earth’s climate and regional air quality. In the absence of nitrogen oxides and acidic seed particles, we measure SOA mass yields from isoprene photochemical oxidation of up to 15%, which are factors of 2, or more, higher than previously reported. Direct online measurements of aerosol molecular composition and the controlled addition of nitrogen oxides show that di-hydroxy di-hydroperoxides are major contributors to such efficient SOA formation. These insights allow for improved quantitative estimates of SOA formation in the pre-industrial atmosphere and in biogenic-rich regions with limited anthropogenic impacts with consequences for calculating a robust estimate of an anthropogenic forcing of aerosol-climate effects.