Recent climate change mitigation strategies rely on the reduction of methane (CH₄) emissions. Carbon and hydrogen isotope ratio (δ¹³C${}_{{\mathrm{CH}}_{\mathrm{4}}}$ and δ²H${}_{{\mathrm{CH}}_{\mathrm{4}}}$) measurements can be used to distinguish sources and thus to understand the CH₄ budget better. The CH₄ emission estimates by models are sensitive to the isotopic signatures assigned to each source category, so it is important to provide representative estimates of the different CH₄ source isotopic signatures worldwide.We present new measurements of isotope signatures of various, mainly anthropogenic, CH₄ sources in Europe, which represent a substantial contribution to the global dataset of source isotopic measurements from the literature, especially for δ²H${}_{{\mathrm{CH}}_{\mathrm{4}}}$. They improve the definition of δ¹³C${}_{{\mathrm{CH}}_{\mathrm{4}}}$ from waste sources, and demonstrate the use of δ²H${}_{{\mathrm{CH}}_{\mathrm{4}}}$ for fossil fuel source attribution.We combined our new measurements with the last published database of CH₄ isotopic signatures and with additional literature, and present a new global database. We found that microbial sources are generally well characterised. The large variability in fossil fuel isotopic compositions requires particular care in the choice of weighting criteria for the calculation of a representative global value. The global dataset could be further improved by measurements from African, South American, and Asian countries, and more measurements from pyrogenic sources.We improved the source characterisation of CH₄ emissions using stable isotopes and associated uncertainty, to be used in top-down studies. We emphasise that an appropriate use of the database requires the analysis of specific parameters in relation to source type and the region of interest.The final version of the European CH₄ isotope database coupled with a global inventory of fossil and non-fossil δ¹³C${}_{{\mathrm{CH}}_{\mathrm{4}}}$ and δ²H${}_{{\mathrm{CH}}_{\mathrm{4}}}$ source signature measurements is available at https://doi.org/10.24416/UU01-YP43IN (Menoud et al., 2022a).

中文翻译：

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欧洲测量对全球甲烷稳定同位素组成清单的新贡献

最近的气候变化减缓战略依赖于减少甲烷 (CH ₄ ) 排放。碳氢同位素比（δ ¹³ C${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$和δ ² H${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$) 测量可用于区分来源，从而更好地了解 CH ₄预算。模型的 CH ₄排放估算对分配给每个源类别的同位素特征很敏感，因此提供全球不同 CH ₄源同位素特征的代表性估算非常重要。我们提出了各种同位素特征的新测量，主要是人为的，欧洲的CH ₄源，对来自文献的源同位素测量的全球数据集做出了重大贡献，特别是对于δ ² H${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$. 它们改进了δ ¹³ C的定义${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$来自废物源，并展示δ ² H的使用${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$用于化石燃料来源归属。我们将我们的新测量结果与上次发布的 CH ₄同位素特征数据库和其他文献相结合，并提供了一个新的全球数据库。我们发现微生物来源通常被很好地表征。化石燃料同位素组成的巨大变化需要在选择加权标准以计算具有代表性的全球值时特别小心。通过对非洲、南美和亚洲国家的测量以及更多来自热源的测量，可以进一步改进全球数据集。我们改进了 CH _{4的源表征}使用稳定同位素和相关不确定性的排放，用于自上而下的研究。我们强调，数据库的适当使用需要分析与源类型和感兴趣区域相关的特定参数。欧洲 CH ₄同位素数据库的最终版本加上化石和非化石δ ¹³ C的全球清单${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$和δ ² H${}_{{\mathrm{甲烷}}_{\mathrm{4}}}$源签名测量可在 https://doi.org/10.24416/UU01-YP43IN (Menoud et al., 2022a) 获得。