Measurement report: Isotopic composition of CH <sub>4</sub> emitted from gas exploration sites in the Transylvanian Basin, Romania
Abstract. Isotope measurements are increasingly used to constrain the methane budget on various scales, from global to regional. The success of isotope-based source attribution depends to a large degree on the knowledge of the isotope signatures of the various source categories at the point of emission, but this information is in many cases lacking. Here we report the isotopic composition of CH4 emitted from 48 installations in the gas production region of Transylvania, Romania. The isotopic source signatures are quite homogeneous across the basin with average values of δ13C = (-65.6 ± 0.5 ‰) and δD = (-184 ± 1 ‰) confirming the biogenic origin of the Transylvanian gas, produced by hydrogenotrophic CO2 reduction. This is similar to values reported previously from natural seeps in Transylvania, to the natural gas exploited in the Dolj region in Southwestern Romania, and to the natural gas in the distribution grid in Cluj-Napoca. However, is more depleted in heavy isotopes than the oil-associated gas emitted in the Southern Romanian Plain, and gas leakages in the city of Bucharest. In addition, we present a step-by-step derivation of the underlying "Keeling plot" mass balance approach that is used to derive isotope source signatures.
Authors
- Hossein Maazallahi (ORCID: https://orcid.org/0000-0002-7400-1001)
- Alexandru Mereuță (ORCID: https://orcid.org/0000-0001-8826-7962)
- Jakub Bartyzel (ORCID: https://orcid.org/0000-0001-8163-2680)
- Călin Baciu (ORCID: https://orcid.org/0000-0002-1142-0620)
- Sorin Ghemulet
- Malika Menoud (ORCID: https://orcid.org/0000-0001-7061-2684)
- Marius Corbu (ORCID: https://orcid.org/0000-0003-4763-0918)
- Horaţiu Ștefӑnie (ORCID: https://orcid.org/0000-0002-5741-1527)
- Magdalena Ardelean (ORCID: https://orcid.org/0000-0002-5666-9593)
- Jacoline van Es
- Andreea Calcan (ORCID: https://orcid.org/0000-0002-1268-7933)
- Thomas Röckmann (ORCID: https://orcid.org/0000-0002-6688-8968)
- Sebastian Iancu
- Piotr Korbeń
- Andrei Radovici (ORCID: https://orcid.org/0000-0003-1281-1129)
- Sara Defratyka (ORCID: https://orcid.org/0000-0002-9488-4518)
- Paweł Jagoda (ORCID: https://orcid.org/0000-0002-2538-6355)
- Jarosław Nęcki (ORCID: https://orcid.org/0000-0002-0225-2581)
- V. Pop (ORCID: https://orcid.org/0000-0001-5125-4412)
- Carina van der Veen (ORCID: https://orcid.org/0000-0001-6827-9616)
- Martina Schmidt (ORCID: https://orcid.org/0000-0002-4648-769X)
Institutions
- National Physical Laboratory (GB)
- University of Bucharest (RO)
- Utrecht University (NL)
- Heidelberg University (DE)
- Babeș-Bolyai University (RO)
- Centre d'études et de recherches internationales de Sciences Po (FR)
- National Institute for Aerospace Research Elie Carafoli (RO)
- Renewable Energy and Energy Efficiency Organization (IR)
- AGH University of Krakow (PL)
Publication Details
- Published
- 2025-10-09
- DOI
- https://doi.org/10.5194/egusphere-2025-4461
- Primary Topic
- Atmospheric and Environmental Gas Dynamics
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- European Commission