<br>基于大气 δ13C-CH4 和 C2H6 的原位观测确定东亚 CH4 的排放源,Science of the Total Environment

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基于大气 δ13C-CH4 和 C2H6 的原位观测确定东亚 CH4 的排放源
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（CH4）是受人类活动影响的第二大温室气体。大气中 CH4 浓度的增加对人为辐射强迫的贡献为 ~23%（Saunois等人，2020 年）。目前的人为 CH4 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，2019）。为了有效监管 CH4，确定时空排放源非常重要，尤其是来自东亚的排放源——最大的 CH4 排放源之一。在这项研究中，我们介绍了 2017-2020 年期间在高山站（GSN，33.3°N，126.2°E，海拔 72 m 处）对大气 CH4 浓度（即十亿分之一的干燥空气摩尔分数（ppb））和 CH4 碳同位素组成的原位观测，这代表了东亚的区域背景条件。观察到的 CH4 基线浓度的年增长率为 11 ± 1 ppb yr-1。CH4 污染浓度的增加与相应的 δ13C-CH4 表现出季节性显著的相关性。基于 Keeling 和 Miller-Tans 方法得出的冬季 CH4 源同位素特征为 -40.7 ± 3.4 ‰，表明主要的产热源（例如，煤和/或燃气燃烧），而夏季的源特征估计为 -54.1 ± 1.2 ‰，这似乎代表了 CH4 排放的微生物源（例如稻田）和化石燃料源。根据 δ13C-CH4 来源特征，我们能够推断微生物来源对 CH4 夏季排放的比例贡献在 45% 到 79% 之间。该发现表明，微生物来源占 CH4 夏季排放量的很大一部分，这与观察到的 CH4 和 C2H6 之间相关性得出的 74-80% 的估计一致，C2H6 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 (CH4) is the second most important greenhouse gas influenced by human activity. The increase in atmospheric CH4 concentrations contributed ~23 % to the anthropogenic radiative forcing (Saunois et al., 2020). The current anthropogenic CH4 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 CH4, it is important to identify spatiotemporal emission sources, in particular those from East Asia – one of the largest CH4 emitters. In this study, we present in-situ observations of atmospheric CH4 concentrations (i.e., dry air mole fractions in part per billion (ppb)) and carbon isotopic compositions of CH4 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 CH4 baseline concentrations was 11 ± 1 ppb yr−1. The enhanced pollution concentrations of CH4 showed seasonally distinctive correlations with the corresponding δ13C-CH4. The CH4 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 CH4 emissions. Based on the δ13C-CH4 source signatures, we were able to infer that the proportional contribution of microbial sources to CH4 summer emissions was ranges from 45 to 79 %. The finding indicates that microbial sources account for a substantial portion of CH4 summer emissions, consistent with estimates of 74–80 % derived from the observed correlation between CH4 and C2H6, which serves as a complementary tracer for fossil fuel sources.

更新日期：2023-11-08

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