Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 5 1 2005 10.5194/acp-5-67-2005 http://www.atmos-chem-phys.net/5/67/2005/ http://www.atmos-chem-phys.net/5/67/2005/acp-5-67-2005.html http://www.atmos-chem-phys.net/5/67/2005/acp-5-67-2005.pdf 67 75 2005-01-20 Observations of oxidation products above a forest imply biogenic emissions of very reactive compounds R. Holzinger A. Lee K. T. Paw U. A. H. Goldstein Department of Environmental Science, Policy, and Management (ESPM), Division of Ecosystem Sciences, University of California, Berkeley, California, 94720-3110, USA Atmospheric Science Program, Department of Land, Air, and Water Resources, University of California, Davis, California, 95616-8717, USA Vertical gradients of mixing ratios of volatile organic compounds have been measured in a Ponderosa pine forest in Central California (38.90° N, 120.63° W, 1315m). These measurements reveal large quantities of previously unreported oxidation products of short lived biogenic precursors. The emission of biogenic precursors must be in the range of 13-66µmol m^-2h^-1 to produce the observed oxidation products. That is 6-30 times the emissions of total monoterpenes observed above the forest canopy on a molar basis. These reactive precursors constitute a large fraction of biogenic emissions at this site, and are not included in current emission inventories. When oxidized by ozone they should efficiently produce secondary aerosol and hydroxyl radicals.