HR: 0800h
AN: A51C-0594    [Abstracts]
TI: Tallgrass Prairie as a Source and Sink of Methyl Halides
AU: * Abel, T
EM: triffid@berkeley.edu
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AU: Rhew, R C
EM: rrhew@atmos.berkeley.edu
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AU: Mazeas, O
EM: omazeas@berkeley.edu
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AU: Atwood, A
EM: aatwood@u.washington.edu
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AU: Atwood, A
EM: aatwood@u.washington.edu
AF: School of Oceanography, University of Washington, Box 357940, University of Washington, Seattle, WA 98195,
AU: King, A J
EM: ajking@berkeley.edu
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AU: Ma, L
EM: lan@berkeley.edu
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AU: Whelan, M
EM: mary.whelan@gmail.com
AF: Department of Geography, University of California, Berkeley, 507 McCone Hall #4740, Berkeley, CA 94720,
AB: Temperate grasslands are believed to be a globally significant sink for methyl bromide (CH₃Br) and perhaps methyl chloride (CH₃Cl), compounds which lead to stratospheric ozone destruction. Fluxes of these compounds were measured at Konza Prairie, a tallgrass prairie in the Flint Hills of Kansas, during June 2006 and August 2007. A stable isotope tracer technique was used to distinguish between simultaneous production and oxidation processes, allowing the first gross flux measurements of CH₃Cl and CH₃Br from a tallgrass prairie. Observed gross uptake rates of CH₃Cl and CH₃Br were similar to what we previously observed from the shortgrass steppe in Colorado and annual grasslands in California, but much lower than reported fluxes from a grassland in northeastern North America. A water manipulation experiment was performed both under controlled laboratory conditions, as well as in the field, demonstrating that uptake rates of both CH₃Cl and CH₃Br were strongly affected by soil moisture. On the production side, new sources of methyl halides were identified in association with certain plant species. Fluxes of these halogenated trace gases were compared to environmental variables, such as air temperature and volumetric water content. Net fluxes of methyl iodide (CH₃I), carbon tetrachloride (CCl₄), and other halogenated volatile organic compounds (HVOCs), were also measured.
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
DE: 0489 Trace element cycling (4875)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting