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Umezawa, T., S. J. Andrews, and T. Saito, 2020: A cryogen-free automated measurement system of stable carbon isotope ratio of atmospheric methane. J. Meteor. Soc. Japan, 98, 115-127.
https://doi.org/10.2151/jmsj.2020-007
Graphical Abstract

Plain Language Summary: Methane (CH₄) plays an important role in climate change and atmospheric chemistry. The stable carbon isotope ratio of atmospheric methane (δ¹³C-CH₄) is useful for separating contributions of different CH₄ source types. We set up a new measurement system for δ¹³C-CH₄, optimized for the automated analysis of air samples. The system is operated with no use of cryogens (e.g., liquid nitrogen) and attained reproducibility sufficient to analyze atmospheric variations (~0.1‰). Automated continuous measurements of ambient air characterized imprint of local methane sources well. Future measurement operation will provide a large number of atmospheric δ¹³C-CH₄ data.

Highlights:

• We set up a new cryogen-free measurement system for the stable carbon isotope ratio of atmospheric methane (δ¹³C-CH₄) with reproducibility of ~0.1‰.
• Automated continuous measurements of ambient air characterized atmospheric δ¹³C-CH₄ variations well.
• Future operation will provide a large number of atmospheric δ¹³C-CH₄ data.