The 14CO2 bomb pulse in firn air at Aurora Basin, East Antarctica

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Australian Partnerships in Ice Core Sciences (APICS) Workshop
The 14C isotope of CO2 produced in the atmosphere by nuclear weapons testing in the 1960’s is incorporated in air in open pores of firn before close-off in bubbles in Antarctic ice. The rapid growth and subsequent decline provides a unique test for the smoothing of atmospheric CO2 signals due to firn diffusion and bubble close off, and the level of smoothing quantifies the time resolution with which trace gas histories can be reconstructed from ice cores. The presence of a ‘bomb pulse’ in the record also permits accurate dating of CO2 and other gases in air. Aurora Basin North (ABN) will contribute new and valuable 2000-year atmospheric records from this data sparse region of inland East Antarctica. ABN has an annual snow accumulation up to 150 kgm-2 year-1, a low mean annual temperature and high elevation. Firn air samples were collected from ABN during December 2013 in stainless-steel canisters and cylinders and 0.5L glass flasks, from varying depths covering the whole firn column at the ABN site. Extraction of CO2 from ABN samples has been performed at the CSIRO ICELAB and transferred to ANSTO to derive the 14C activity of CO2 in ABN firn air. As expected, results suggest the age spread at ABN is wider than sites with higher accumulation, such as Law Dome. Firn modelling is also planned and the 14C results will be used as inputs for the modelling to help determine (with other gas measurements) the age and age spread of air in firn and ice at ABN.
Bombs, Pulses, Antarctica, Carbon 14, Air, Drill cores, Ice
Thornton, D. P., Etheridge, D. M, Trudinger, C. M., Rubino, M, Smith, A. M., Curran, M. A. J, Vance, & T. R., Chappellaz, J. (2016). The 14CO2 bomb pulse in firn air at Aurora Basin, East Antarctica. Paper presented at the International Partnerships in Ice Core Sciences (IPICS) Second Open Science Conference held in Hobart, Australia from 7-11 March 2016.