American Association for Aerosol Research - Abstract Submission

AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA

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Plant Stress in a Changing Environment and its Impacts on Future Climate: The Effects of Simulated Herbivory on Biogenic Secondary Organic Aerosol

CELIA FAIOLA, Graham VanderSchelden, Miao Wen, B. Thomas Jobson, Timothy M. VanReken, Washington State University

     Abstract Number: 434
     Working Group: Carbonaceous Aerosols in the Atmosphere

The largest global source of volatile organic compounds (VOCs) in the atmosphere is from biogenic emissions. These VOCs are one of the principal factors influencing the oxidative capacity of the atmosphere in forested regions, and impact both ozone concentration and secondary organic aerosol (SOA) formation. Emission rates of biogenic VOCs are predominantly controlled by temperature. However, plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. Alterations to the biogenic VOC profile could impact the characteristics of the SOA formed from those emissions. This study investigated the effects of one global change stressor, increased herbivory, on the characteristics of SOA derived from real plant emissions. Plants were housed in the laboratory within a 0.3 cubic meter biogenic chamber. Herbivory was simulated via exogenous application of methyl jasmonate, an herbivory proxy. Plant emissions were transported from the biogenic chamber to a 7 cubic meter FEP Teflon aerosol growth chamber, where they were oxidized with ozone in the absence of light. The evolution of gas-phase species and particle characteristics were monitored over the following eight hours. Experiments were repeated under baseline and stressed conditions for a variety of species including, but not limited to, ponderosa pine, Douglas-fir, blue spruce, and bur oak. Gas-phase species were measured with a gas chromatograph coupled to a mass spectrometer and flame ionization detector (GC-MS-FID). Particle size distribution, chemical composition, and hygroscopic properties were measured with a scanning mobility particle sizer (SMPS), high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), and cloud condensation nuclei counter (CCNc) respectively. A comparison of the BVOC emissions and resultant SOA characteristics under baseline and stressed conditions will be presented.