Laboratory and Field Measurements of Methanol Fluxes

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Volatile organic compounds (VOCs) play an active role in tropospheric chemistry, however our knowledge concerning their distribution of sources and sinks and the environmental factors driving them is often sparse. Methanol is an important oxygenated VOC found ubiquitously in the troposphere, serving as a source of global odd hydrogen (HOx=OH+HO2). It is thought to be emitted to the atmosphere mainly as a by-product of pectin demethylation during plant growth and removed from the atmosphere primarily through reaction with the hydroxyl radical. Relative contributions from these and other sources and sinks remain uncertain and will require extensive laboratory and field measurements to improve our understanding. We propose to contribute to these endeavors first by performing an in-depth laboratory study of soil exchanges of methanol, a potentially important but seldom studied player in the methanol budget, using a dynamic flux chamber monitored using an extremely sensitive methanol measurement technique developed and tested by our laboratory at the University of Bremen. We also propose to observe methanol both above, within, and below the canopy of a northern European forest ecosystem at the Kannenbruch field site operated by Dr. W. Kutsch from the MPI for Biogeochemistry in Jena, using a relaxed eddy accumulation (REA) method, an in-canopy gradient, and dynamic chambers. This combination of measurements is a positive step towards further elucidation of the methanol budget already begun in our laboratory at the University of Bremen and will strengthen the ties of our laboratory to the flux measurement community.