HR: 09:29h
AN: A11C-06    [Abstracts]
TI: Halomethane Fluxes in the Northern Alaskan Coastal Tundra
AU: * Rhew, R C
EM: rrhew@berkeley.edu
AF: University of California, Berkeley, Department of Geography 507 McCone Hall #4740, Berkeley, CA 94720-4740 United States
AU: Teh, Y
EM: yit@nature.berkeley.edu
AF: University of California, Berkeley, Department of Geography 507 McCone Hall #4740, Berkeley, CA 94720-4740 United States
AU: Abel, T
EM: triffid@berkeley.edu
AF: University of California, Berkeley, Department of Geography 507 McCone Hall #4740, Berkeley, CA 94720-4740 United States
AB: Fluxes of methyl halides (CH₃Br, CH₃Cl, and CH₃I) and chloroform (CHCl₃) were measured in a northern Alaskan tundra ecosystem (71° N, 157° W) during the 2005 growing season. These compounds are important carriers of halogens in the atmosphere, contributing most of the natural chlorine and bromine to the stratosphere. However, our understanding of the tropospheric budgets of these compounds remains out of balance, with large uncertainties about the magnitude of biosphere-atmosphere fluxes. Temperate and tropical coastal ecosystems are believed to be major sources of methyl halides to the atmosphere, but flux measurements from the Arctic coastal system have not yet been reported. Tundra fluxes of chloroform (CHCl₃) are also poorly known, although at least half of the global CHCl₃ source apparently emanates from the extratropical Northern Hemisphere. In this study, twenty flux chamber sites within the Barrow Environmental Observatory were chosen to cover the range of microtopographic features that characterize the wet-moist coastal sedge tundra. Flux measurements were conducted in June and August during the beginning and middle of the growing season, respectively. Although production of methyl halides was observed at some sites, the majority of sites consumed CH₃ Br and CH₃Cl, with much higher uptake rates at the drier sites. All sites emitted CHCl₃, suggesting that the tundra may be an important source of this compound to the atmosphere. Tundra-atmosphere gas exchange of these compounds may influence the seasonality of their background concentrations at high latitudes of the Northern Hemisphere.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0322 Constituent sources and sinks
DE: 0490 Trace gases
DE: 0718 Tundra (9315)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005