ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-5-39-2005 Oxygenated compounds in aged biomass burning plumes over the Eastern Mediterranean: evidence for strong secondary production of methanol and acetone Holzinger R. 1 2 Williams J. 1 Salisbury G. 1 Klüpfel T. 1 de Reus M. 1 Traub M. 1 Crutzen P. J. 1 Lelieveld J. 1 Max-Planck-Institut für Chemie, Postfach 3060, 55020 Mainz, Germany now at: University of California at Berkeley, Dept. Environm. Sci. Policy & Management, Berkeley, CA 94720 USA 17 01 2005 5 1 39 46 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/5/39/2005/acp-5-39-2005.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/39/2005/acp-5-39-2005.pdf

Airborne measurements of acetone, methanol, PAN, acetonitrile (by Proton Transfer Reaction Mass Spectrometry), and CO (by Tunable Diode Laser Absorption Spectroscopy) have been performed during the Mediterranean Intensive Oxidants Study (MINOS August 2001). We have identified ten biomass burning plumes from strongly elevated acetonitrile mixing ratios. The characteristic biomass burning signatures obtained from these plumes reveal secondary production of acetone and methanol, while CO photochemically declines in the plumes. Mean excess mixing ratios - normalized to CO - of 1.8%, 0.20%, 3.8%, and 0.65% for acetone, acetonitrile, methanol, and PAN, respectively, were found. By scaling to an assumed global annual source of 663-807Tg CO, biomass burning emissions of 25-31 and 29-35 Tg/yr for acetone and methanol are estimated, respectively. Our measurements suggest that the present biomass burning contributions of acetone and methanol are significantly underestimated due to the neglect of secondary formation within the plume. Median acetonitrile mixing ratios throughout the troposphere were around 150pmol/mol, in accord with current biomass burning inventories and an atmospheric lifetime of ~6 months.