Journal article
Distinct dual-isotopic signatures of major methane sources in South Asia
Atmospheric chemistry and physics, v 26(11), pp 7765-7787
02 Jun 2026
Abstract
Methane is a powerful greenhouse gas contributing significantly to global warming. South Asia is a major methane emission region, yet source-diagnostic isotopic signatures remain poorly constrained, limiting top-down source attribution. To address this gap, we conducted extensive sampling and isotopic analyses of major methane sources in South Asia. Our results reveal substantial deviations of South Asian methane source fingerprints from global means. Methane from C3 biomass burning is more depleted in delta 13C (-30.9 +/- 2.2 parts per thousand) but more enriched in delta 2H (-201 +/- 18 parts per thousand) relative to global means, while ruminant methane (C3) is strongly depleted in both delta 13C (-68.7 +/- 0.5 parts per thousand) and delta 2H (-343 +/- 6 parts per thousand). In contrast, rice paddy methane is more enriched in delta 13C (-53.8 +/- 0.8 parts per thousand) and delta 2H (-311 +/- 6 parts per thousand) than global means, with their ratios signaling pre-emission oxidation. Wastewater methane shows enriched delta 13C (-45.0 +/- 2.4 parts per thousand) and depleted delta 2H (-350 +/- 10 parts per thousand) relative to global means, with minimal oxidation or spatial variation. These pronounced regional differences highlight the importance of using regionally constrained source fingerprints in isotope-based source apportionment. A global synthesis further shows that delta 13C signatures of biomass burning and ruminant methane are primarily controlled by C3 / C4 feedstocks, whereas delta 2H is relatively insensitive to substrate type. Methane from rice paddies and wetlands exhibits strong latitudinal gradients worldwide. Combining emission inventories with source-specific isotope fingerprints reveals a mismatch with atmospheric methane in South Asia, suggesting an overestimation of rice paddy emissions and/or an underestimation of other microbial sources. These findings demonstrate the utility of top-down dual-isotope constraints to refine regional methane budgets and mitigation strategies.
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Details
- Title
- Distinct dual-isotopic signatures of major methane sources in South Asia
- Creators
- Peng Yao - Bolin Centre for Climate ResearchKatja Belec - Bolin Centre for Climate ResearchHenry Holmstrand - Bolin Centre for Climate ResearchJosh Balacky - Bolin Centre for Climate ResearchAbdus Salam - University of DhakaKrishnakant Budhavant - Maldives National UniversityMohanan Remani Manoj - Bolin Centre for Climate ResearchKhaled Shaifullah Joy - Drexel University, ChemistryMd. Alamin Hossain - University of DhakaAtinderpal Singh - University of DelhiAnil Patel - Gujarat UniversityNeeraj Rastogi - Physical Research LaboratoryChinmay Mallik - Central University of RajasthanKirpa Ram - Banaras Hindu UniversityGyanesh Kumar Singh - National Physical LaboratoryOrjan Gustafsson - Bolin Centre for Climate Research
- Publication Details
- Atmospheric chemistry and physics, v 26(11), pp 7765-7787
- Publisher
- Copernicus Gesellschaft Mbh
- Number of pages
- 23
- Grant note
- 2017-01601 / Vetenskapsrdet; Swedish Research Council 2023-01234 / Svenska Forskningsrdet Formas; Swedish Research Council Formas
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:001781139800001
- Scopus ID
- 2-s2.0-105040806749
- Other Identifier
- 991022193193004721