Extraction of Dissolved Organic Carbon from Glacier Ice for Radiocarbon Analysis

• Published in: Radiocarbon
• Main Authors: Fang, L, Schindler, J, Jenk, T M, Uglietti, C, Szidat, S, Schwikowski, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2019
• Subjects: ice core
• Online Access: http://dx.doi.org/10.1017/rdc.2019.36; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822219000365

ABSTRACT Alpine glaciers are valuable archives for the reconstruction of human impact on the environment. Besides dating purposes, measurement of radiocarbon ( 14 C) content provides a powerful tool for long-term source apportionment studies on the carbonaceous aerosols incorporated in ice cores. In this work, we present an extraction system for 14 C analyses of dissolved organic carbon (DOC) in ice cores. The setup can process ice samples of up to 350 g mass and offers ultra-clean working conditions for all extraction steps. A photo-oxidation method is applied by means of external UV irradiation of the sample. For an irradiation time of 30 min with catalyzation by addition of Fe 2+ and H 2 O 2 , we achieve an efficiency of 96 ± 6% on average. Inert gas working conditions and stringent decontamination procedures enable a low overall blank of 1.9 ± 1.6 μg C with a F 14 C value of 0.68 ± 0.13. This makes it possible to analyze the DOC in ice samples with a carbon content of as low as 25 μg C kg −1 ice. For a first validation, the new method was applied to ice core samples from the Swiss Alps. The average DOC concentration and F 14 C values for the Fiescherhorn ice core samples show good agreement with previously reported data for the investigated period of 1925–1936 AD.