Simultaneous stable isotope analysis of methane and nitrous oxide on ice core samples

van der Veen, C.; Sapart, C. J.; Vigano, I.; Brass, M.; van de Wal, R. S. W.; Bock, Michael; Fischer, Hubertus; Sowers, T.; Buizert, C.; Sperlich, P.; Blunier, Thomas; Behrens, M.; Schmitt, Jochen; Seth, Barbara; Röckmann, T. (2011). Simultaneous stable isotope analysis of methane and nitrous oxide on ice core samples. Atmospheric Measurement Techniques (AMT), 4(12), 2607 -2618. Göttingen: Copernicus Publications 10.5194/amt-4-2607-2011

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Methane and nitrous oxide are important greenhouse gases which show a strong increase in atmospheric mixing ratios since pre-industrial time as well as large variations during past climate changes. The understanding of their biogeochemical cycles can be improved using stable isotope analysis. However, high-precision isotope measurements on air trapped in ice cores are challenging because of the high susceptibility to contamination and fractionation. Here, we present a dry extraction system for combined CH4 and N2O stable isotope analysis from ice core air, using an ice grating device. The system allows simultaneous analysis of δD(CH4) or δ13C(CH4), together with δ15N(N2O), δ18O(N2O) and δ15N(NO+ fragment) on a single ice core sample, using two isotope mass spectrometry systems. The optimum quantity of ice for analysis is about 600 g with typical "Holocene" mixing ratios for CH4 and N2O. In this case, the reproducibility (1σ ) is 2.1‰ for δD(CH4), 0.18‰ for δ13C(CH4), 0.51‰ for δ15N(N2O), 0.69‰ for δ18O(N2O) and 1.12‰ for δ15N(NO+ fragment). For smaller amounts of ice the standard deviation increases, particularly for N2O isotopologues. For both gases, small-scale intercalibrations using air and/or ice samples have been carried out in collaboration with other institutes that are currently involved in isotope measurements of ice core air. Significant differences are shown between the calibration scales, but those offsets are consistent and can therefore be corrected for.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics

UniBE Contributor:

Bock, Michael; Fischer, Hubertus; Blunier, Thomas; Schmitt, Jochen and Seth, Barbara

Subjects:

500 Science > 530 Physics

ISSN:

1867-1381

Publisher:

Copernicus Publications

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:27

Last Modified:

07 Dec 2014 10:09

Publisher DOI:

10.5194/amt-4-2607-2011

Web of Science ID:

000298492400002

BORIS DOI:

10.7892/boris.10129

URI:

https://boris.unibe.ch/id/eprint/10129 (FactScience: 215971)

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