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Detailed Reference Information |
Saltzman, E.S., Aydin, M., De Bruyn, W.J., King, D.B. and Yvon-Lewis, S.A. (2004). Methyl bromide in preindustrial air: Measurements from an Antarctic ice core. Journal of Geophysical Research 109: doi: 10.1029/2003JD004157. issn: 0148-0227. |
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This paper presents the first ice core measurements of methyl bromide (CH3Br). Samples from a shallow Antarctic ice core (Siple Dome, West Antarctica), ranging in mean gas dates from 1671 to 1942, had a mean CH3Br mixing ratio of 5.8 ppt. These results extend the existing historical record derived from air and Antarctic firn air to about 350 years before present. Model simulations illustrate that the ice core results are consistent with estimates of the impact of anthropogenic activity (fumigation, combustion, and biomass burning) on the atmospheric CH3Br burden, given the large current uncertainties in the modern atmospheric CH3Br budget. A preindustrial scenario assuming no fumigation, no combustion, and a 75% reduction in biomass-burning sources yields a Southern Hemisphere mean mixing ratio of 5.8 ppt, in good agreement with the ice core results. There is a significant imbalance between the known CH3Br sources and sinks in the modern atmospheric CH3Br budget. The ice core data do not sufficiently constrain the model to determine how much of the unknown source was present in the preindustrial budget. The results do indicate that most of the southern hemispheric component of this unknown source is not anthropogenic. |
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Abstract |
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Keywords
Atmospheric Composition and Structure, Constituent sources and sinks, Atmospheric Composition and Structure, Troposphere—composition and chemistry, Global Change, Atmosphere (0315, 0325), Global Change, Biogeochemical processes, methyl bromide, methyl halide, halocarbons |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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