EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Isotopic characterization of methane: insights from clumped isotope (13CDH3 and CD2H2) measurements

Malavika Sivan1, Thomas Röckmann1, Caroline P. Slomp2, Carina van der Veen1, and Maria Elena Popa1
Malavika Sivan et al.
  • 1Institute of Marine and Atmospheric Research Utrecht, Utrecht University, Netherlands
  • 2Department of Earth Sciences-Geochemistry, Faculty of Geosciences, Utrecht University, Netherlands

Atmospheric methane is an important greenhouse gas, and various methods are used to identify and quantify its sources. The measurement of bulk isotopic composition (δ13C and δD) is a widely used characterization technique, but due to the overlap of source signatures, it is often difficult to distinguish between thermogenic, microbial, and other sources. With the advancement of high-resolution mass spectrometry, it is now possible to measure the rare clumped isotopologues of methane 13CDH3 and CD2H2.

This novel method can give additional information to help constrain methane sources and processes. The clumping anomaly is temperature-dependent and can thus be used to calculate the formation or equilibration temperature when methane is in thermodynamic equilibrium. In case of thermodynamic disequilibrium, the clumped signatures can be exploited to identify various kinetic gas formation and fractionation (mixing, diffusion, etc.) processes. 

We have developed a technique to extract pure methane from air and water samples and to measure the clumped isotope signatures (Δ13CDH3 and ΔCD2H2) with high precision and reproducibility, using the Thermo Ultra mass spectrometer. We will present the current capabilities of this setup, and the results of the first sets of samples measured from different natural environments.

How to cite: Sivan, M., Röckmann, T., Slomp, C. P., van der Veen, C., and Popa, M. E.: Isotopic characterization of methane: insights from clumped isotope (13CDH3 and CD2H2) measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4029,, 2022.

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