基于大气δ13C-CH4和C2H6现场观测识别东亚CH4排放源,Science of the Total Environment

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基于大气δ13C-CH4和C2H6现场观测识别东亚CH4排放源
Science of the Total Environment ( IF 8.2 ) Pub Date : 2023-11-08 , DOI: 10.1016/j.scitotenv.2023.168433
Sohyeon Geum ₁ , Hyeri Park ₂ , Haklim Choi ₃ , Yeaseul Kim ₃ , Haeyoung Lee ₄ , Sangwon Joo ₅ , Young-Suk Oh ₅ , Sylvia Englund Michel ₆ , Sunyoung Park ₇

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甲烷 (CH) 是受人类活动影响的第二大温室气体。大气 CH 浓度的增加对人为辐射强迫贡献了约 23%（Saunois 等人，2020）。当前的人为CH排放轨迹意味着需要大幅减排才能实现《巴黎协定》的目标（Nisbet等人，2019）。为了有效监管甲烷，重要的是确定时空排放源，特别是来自东亚（最大的甲烷排放国之一）的排放源。在这项研究中，我们对 2017 年至 2020 年高山站（GSN，33.3°N）大气中 CH 浓度（即十亿分之一 (ppb) 的干燥空气摩尔分数）和 CH 碳同位素组成进行了现场观测, 126.2°E, 72 m asl) 代表东亚区域背景条件。观察到的 CH 基线浓度的年增长率为 11 ± 1 ppb 年。CH 污染浓度的增加与相应的 δ13C-CH 表现出季节性明显的相关性。基于 Keeling 和 Miller-Tans 方法得出的冬季 CH 源同位素特征为 -40.7 ± 3.4 ‰，表明主要生热源（例如煤炭和/或天然气燃烧），而夏季的源特征估计为 - 54.1 ± 1.2 ‰，这似乎代表了 CH 排放的微生物来源（例如稻田）和化石燃料来源。根据 δ13C-CH 源特征，我们能够推断出微生物源对 CH 夏季排放的比例贡献范围为 45% 至 79%。研究结果表明，微生物来源占夏季 CH 排放量的很大一部分，与根据观察到的 CH 和 CH 之间的相关性得出的 74-80% 的估计一致，CH 是化石燃料来源的补充示踪剂。

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Identifying emission sources of CH4 in East Asia based on in-situ observations of atmospheric δ13C-CH4 and C2H6

Methane (CH) is the second most important greenhouse gas influenced by human activity. The increase in atmospheric CH concentrations contributed ~23 % to the anthropogenic radiative forcing (Saunois et al., 2020). The current anthropogenic CH emissions trajectory implies that large emissions reductions are needed to meet the target of the Paris Agreement (Nisbet et al., 2019). For effective regulation of CH, it is important to identify spatiotemporal emission sources, in particular those from East Asia – one of the largest CH emitters. In this study, we present in-situ observations of atmospheric CH concentrations (i.e., dry air mole fractions in part per billion (ppb)) and carbon isotopic compositions of CH made during 2017–2020 at the Gosan station (GSN, 33.3°N, 126.2°E, 72 m a.s.l) which is representative of regional background conditions in East Asia. The annual growth rate of the observed CH baseline concentrations was 11 ± 1 ppb yr. The enhanced pollution concentrations of CH showed seasonally distinctive correlations with the corresponding δC-CH. The CH source isotopic signature for winter derived based on both the Keeling and Miller-Tans approaches was −40.7 ± 3.4 ‰, suggesting dominant thermogenic sources (e.g., coal and/or gas combustion), whereas the source signature for summer was estimated as −54.1 ± 1.2 ‰, which seemed to represent both microbial sources (e.g., rice paddies) and fossil fuel sources of CH emissions. Based on the δC-CH source signatures, we were able to infer that the proportional contribution of microbial sources to CH summer emissions was ranges from 45 to 79 %. The finding indicates that microbial sources account for a substantial portion of CH summer emissions, consistent with estimates of 74–80 % derived from the observed correlation between CH and CH, which serves as a complementary tracer for fossil fuel sources.

更新日期：2023-11-08

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