Radiocarbon analyses along the EDML ice core in Antarctica

Abstract

Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for ¹⁴CO and ¹⁴CO₂ with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced ¹⁴CO fraction show a very low concentration of in situ produced ¹⁴CO. Despite these low levels in carbon monoxide, a significant in situ production is observed in the carbon dioxide fraction. For the first time we found background values for the ice samples which are equal to line blanks. The data set is used to test a model for the production of 14C in the ice matrix, in combination with a degassing as ¹⁴CO₂ and possibly as ¹⁴CO into the air bubbles. Application of the model, for which no independent validation is yet possible, offers the opportunity to use radiocarbon analysis as dating technique for the air bubbles in the ice. Assigning an arbitrary error of 25% to the calculation of the in situ production leads to age estimates, after correction for the in situ production, which are in agreement with age estimates based on a volcanic layer match of EDML to the Dome C timescale in combination with a correction for firn diffusion.