The 14C “bomb spike” determines the age spread and age of CO2 in Law Dome firn and ice
- 15 November 1996
- journal article
- Published by American Geophysical Union (AGU) in Geophysical Research Letters
- Vol. 23 (23) , 3345-3348
- https://doi.org/10.1029/96gl03156
Abstract
We report a precise, model‐independent determination of the age and age spread of CO2 in air trapped in ice. A large pulse of atmospheric radiocarbon, generated in the atmosphere by nuclear tests, peaked in the early‐to‐mid 1960's. We measure the profile of the radiocarbon “bomb spike” in firn air and ice bubbles from high snow‐accumulation sites drilled in 1987 and 1993 on Law Dome, East Antarctica, by employing high precision AMS (Accelerator Mass Spectrometry). Large 14C atmospheric growth rates and a high signal‐to‐noise ratio lead to a direct and precise determination of the CO2 age and age‐spread in the ice. A least‐squares comparison with the atmospheric history gives a mean CO2 age of 8.9±0.5 years at the bottom of the firn (where vertical gas diffusion ceases) with an age spread in the ice (full width of a moving average smoothing window) of 12.5±1.5 years. These results confirm the possibility of examining decadal trace gas variations prior to direct instrumental measurements.This publication has 20 references indexed in Scilit:
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