Microgram-Level Radiocarbon Determination of Carbonaceous Particles in Firn and Ice Samples: Pretreatment and Oc/Ec Separation

Cao, Fang; Zhang, Yanlin; Szidat, Sönke; Zapf, Alexander; Wacker, Lukas; Schwikowski, Margit (2013). Microgram-Level Radiocarbon Determination of Carbonaceous Particles in Firn and Ice Samples: Pretreatment and Oc/Ec Separation. Radiocarbon, 55(2-3), pp. 383-390. Arizona Board of Regents, University of Arizona 10.2458/azu_js_rc.55.16291

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Carbonaceous particles that comprise organic carbon (OC) and elemental carbon (EC) are of increasing interest in climate research because of their influence on the radiation balance of the Earth. The radiocarbon determination of particulate OC and EC extracted from ice cores provides a powerful tool to reconstruct the long-term natural and anthropogenic emissions of carbonaceous particles. However, this C-14-based source apportionment method has not been applied for the firn section, which is the uppermost part of Alpine glaciers with a typical thickness of up to 50 m. In contrast to glacier ice, firn samples are more easily contaminated through drilling and handling operations. In this study, an alternative decontamination method for firn samples consisting of chiselling off the outer parts instead of rinsing them was developed and verified. The obtained procedural blank of 2.8 +/- 0.8 mu g C for OC is a factor of 2 higher compared to the rinsing method used for ice, but still relatively low compared to the typical OC concentration in firn samples from Alpine glaciers. The EC blank of 0.3 +/- 0.1 mu g C is similar for both methods. For separation of OC and EC for subsequent C-14 analysis, a thermal-optical method instead of the purely thermal method was applied for the first time to firn and ice samples, resulting in a reduced uncertainty of both the mass and C-14 determination. OC and EC concentrations as well as their corresponding fraction of modern for firn and ice samples from Fiescherhorn and Jungfraujoch agree well with published results, validating the new method.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Zhang, Yanlin; Szidat, Sönke and Schwikowski, Margit

Subjects:

500 Science > 540 Chemistry

ISSN:

0033-8222

Publisher:

Arizona Board of Regents, University of Arizona

Language:

English

Submitter:

Brigitte Oggier

Date Deposited:

31 Mar 2014 17:49

Last Modified:

08 Jan 2016 12:01

Publisher DOI:

10.2458/azu_js_rc.55.16291

BORIS DOI:

10.7892/boris.47129

URI:

https://boris.unibe.ch/id/eprint/47129

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