Observing BVOC Emissions, Oxidation, Deposition, and Interactions with Anthropogenic Pollutants to Form SOA in the Southeast United States

Wednesday, 17 December 2014: 1:40 PM
Allen H Goldstein1, Gabriel A Isaacman1, Pawel K Misztal1, Lindsay Yee1, Kevin Frederick Olson1, Joshua Moss1, Nathan M Kreisberg2, Susanne V Hering2, Jeong-Hoo Park3, Lisa Kaser3, Roger Seco4, Alex B Guenther5, Luping Su6, John E Mak6, Rupert Holzinger7, Weiwei Hu8, Pedro Campuzano Jost8, Brett B Palm8, Douglas A Day9, Jose L Jimenez8, Abigail Koss8 and Joost A De Gouw10, (1)University of California Berkeley, Berkeley, CA, United States, (2)Aerosol Dynamics Inc., Berkeley, CA, United States, (3)National Center for Atmospheric Research, Boulder, CO, United States, (4)University of California Irvine, Department of Earth System Science, Irvine, CA, United States, (5)Pacific Northwest National Laboratory, Richland, WA, United States, (6)SUNY Stony Brook, School of Marine and Atmospheric Sciences, Stony Brook, NY, United States, (7)Utrecht University, Utrecht, Netherlands, (8)University of Colorado at Boulder, Boulder, CO, United States, (9)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (10)NOAA Earth System Research Lab, Boulder, CO, United States
Our overarching goals in the SOAS 2013 campaign were to 1) quantify biogenic VOC emission and VOC deposition to understand the processes controlling these bi-directional exchanges, 2) observe a broad suite of primary VOC and their oxidation products in the field and in controlled laboratory experiments, and 3) investigate their fate to understand how anthropogenic pollution alters oxidation pathways and secondary organic aerosol (SOA) formation. We pursued these goals through measurement of atmospheric organics ranging from very volatile (using in-situ GC-MS and proton transfer reaction time-of-flight MS, PTR-ToF-MS) to semi-volatile gas and particle phase compounds (using the Semi-Volatile Thermal desorption Aerosol Gas chromatograph, SV-TAG).

Measured concentrations and fluxes of VOCs at the top of the SEARCH tower were coordinated with concentration gradients and fluxes at the AABC flux tower site, and vertical profiles using the Long-EZ aircraft to provide equivalent observations across sites. These results are informed through measurements using the same instrument during the FIXIT controlled laboratory oxidation study at CalTech that investigated oxidation pathways of BVOC with varying levels of anthropogenic pollutants.

Measurements by SV-TAG of particle-phase and total gas-plus-particle-phase compounds at the SEARCH tower provide hourly quantification of semi-volatile compounds, including the oxidation products of measured VOCs. Derivatization of hydroxyl groups prior to GC analysis allows analysis of highly oxidized chemicals, including most known tracers. Methyl tetrols, an oxidation product of isoprene, had a significant day-time gas-phase component, and their abundance was strongly correlated with particle-phase sulfate, indicative of anthropogenic influence on the formation or partitioning processes. Similar observations of pinic acid (monterpene oxidation product) and many other BVOC oxidation products were made in both the gas and particle phases.

Through measurements of specific chemical tracers across a wide range of volatilities, we explore the chemical lifecycle of BVOCs to understand anthropogenic-biogenic interactions in aerosol formation.