Isotope signatures of methane sources in Asia

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The present data set is a set of stable carbon isotope signatures of various methane sources in Asia (Japan, Thailand and Bangladesh). The stable carbon isotope signatures were estimated from a set of air samples collected in proximity to individual sources including landfills, wastewater treatment facilities, rice paddies and agricultural combustion. The data set also include ethane to methane enhancement ratios for fossil fuel and combustion sources.
For each air sample collected in a glass flask, methane and ethane concentrations were measured by a mid-infrared absorption spectrometer MIRA Pico analyzer on site. The air samples were analyzed for stable carbon isotope ratio of methane by a method described by Umezawa et al. (2020). Isotope signature and ethane to methane enhancement ratio for each source were calculated from a set of air samples under influence of a single source. The methodologies are detailed in Umezawa et al. (2026).

Description
Data Set
Contributors
Acknowledgements
Reference Information
Terms and Conditions of Use*

Description

Creator	Taku Umezawa^1^2(orcid.org/0000-0003-1217-7439), Yukio Terao^1, Tomonori Ishigaki^3, Yoshitaka Ebie^3, Satoshi Kameyama^3, Akihiko Ito^4, Sutthasil Noppharit^5, Wangyao Komsilp^6, Payomthip Panida^3, Yoochatchaval Wilasinee^7, Kawser Ahmed Md^8, Rani Seema^9, Shohei Nomura^3, Yang Zhenglun^1, Shinji Saito^10, Junya Hoshi^10 ^1 Earth System Division, National Institute for Environmental Studies (NIES) ^2 Graduate School of Science, Tohoku University ^3 National Institute for Environmental Studies (NIES) ^4 The University of Tokyo ^5 Mae Fah Luang University ^6The Joint Graduate School of Energy and Environment (JGSEE), King Mongkut’s University of Technology Thonburi ^7 Department of Environmental Engineering, Faculty of Engineering, Kasetsart University ^8 Department of Oceanography, Faculty of Earth and Environmental Sciences, University of Dhakav ^9 Bangladesh Oceanographic Research Institute (BORI) ^*10 Tokyo Metropolitan Research Institute for Environmental Protection
Release date	2026/03/17
Temporal coverage	2021 - 2025
Data provider	NIES Email: cgerdb_admin(at)nies.go.jp
DOI	10.17595/20260317.001
File format	CSV
Data volume	10.1 KB
Version	ver. 1.0 (Last updated: 2026/03/17)
Language	English

Data Set

Parameters	d13C-CH4, Country, State_region, Group_type, Group, Category, Sub_category, Longitude, Latitude, Sampling_date, Unc_d13C_CH4, C2C1_ratio, Unc_C2C1_ratio, N_AirSample, AirSample_ID, Comments
Keywords	[Free keywords] Methane, Isotope, Ethane to methane ratio
Update history	[2026/03/17] The data from 2021 to 2025 have been compiled. Ver.1.0.

Contributors

Data Manager

Taku Umezawa^*1(

orcid.org/0000-0003-1217-7439), Yukio Terao^*1
Earth System Division, National Institute for Environmental Studies (NIES)

Acknowledgements

Acknowledgements

The authors acknowledge the cooperation of the Bureau of Environment, Tokyo Metropolitan Government, for site access. We are also grateful to the relevant administrative offices for site access . We thank Youichi Noguchi for cooperation to sampling in rice paddy fields.

Reference Information

References

Umezawa. T., Andrews. S. J., Saito, T. (2020), A Cryogen-Free Automated Measurement System of Stable Carbon Isotope Ratio of Atmospheric Methane, J. Meteorol. Soc. Jpn., 98(1), 115−127, doi:10.2151/jmsj.2020-007.

Umezawa, T., Terao, T., Ishigaki, T., Ebie, Y., Kameyama, S., Ito, A., Sutthasil, N., Wangyao, K., Payomthip, P., Yoochatchaval, W., Ahmed, M. K., Rani, S., Nomura, S., Yang, Z., Saito, S., Hoshi, J. (2026), Measurements of stable carbon isotope signatures of methane sources in Asian countries, in preparation.

Terms and Conditions of Use^*

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License	CC BY 4.0 (Creative Commons Attribution 4.0 International)
Citation format	When this data set is referred to in publications, it should, as a general rule, be made in the following format. Umezawa et al. (2026), Isotope signatures of methane sources in Asia, ver.x.x ^1, NIES, DOI:10.17595/20260317.001. (Reference date^2: YYYY/MM/DD) ^1 The version number is indicated in the Description. ^2 As the reference date, please indicate the date you downloaded the files.