HR: 0830h
AN: A11F-0056    [PDF]
TI: Methyl bromide in pre-industrial air: measurements from an Antarctic ice core
AU: * Saltzman, E S
EM: esaltzma@uci.edu
AF: University of California, Irvine, Earth System Science, Irvine, CA 92697-3100 United States
AU: Aydin, M
EM: maydin@uci.edu
AF: University of California, Irvine, Earth System Science, Irvine, CA 92697-3100 United States
AU: De Bruyn, W
EM: debruyn@chapman.edu
AF: Chapman University, Dept. of Physical Sciences, Orange, CA 92866 United States
AU: King, D B
EM: daniel.king@drexel.edu
AF: Drexel University, Chemistry Dept., Philadelphia, PA 19104 United States
AU: Yvon-Lewis, S A
EM: Shari.Yvon-Lewis@noaa.gov
AF: NOAA, AOML, Miami, FL 33149 United States
AB: This paper presents the first ice core measurements of methyl bromide (CH3Br). Samples from a shallow Antarctic ice core (Siple Dome, West Antarctica), with estimated gas dates ranging from 1671 to 1942, were analyzed using GC/MS. The ice core samples gave a mean CH3Br mixing ratio of 5.8 ppt, considerably lower than the modern southern hemispheric mean CH3Br level of 7.9 ppt. These results extend the existing historical record derived from air and Antarctic firn air to about 350 years. Model simulations illustrate that the ice core results are consistent with current estimates of the impact of anthropogenic activity (fumigation, combustion, and biomass burning) on the atmospheric CH3Br burden. A preindustrial scenario assuming no fumigation, no combustion, and a 75 per cent reduction in biomass burning sources, yields agreement with the ice core results. However, there is a significant imbalance between the known CH3Br sources and sinks in the modern atmospheric CH3Br budget, and the ice core data do not resolve the question of whether this imbalance is due to anthropogenic or natural sources.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting