基于涡动及走航观测的晋东南煤矿区甲烷分布特征
Analysis of the characteristics of methane in the coal mining area of southeastern Shanxi with eddy and mobile observation
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摘要: 甲烷是仅次于二氧化碳的全球第二大温室气体,在大气中的寿命仅为 10 a 左右,但其全球 增温潜势却是CO2的几十倍。 大气中的甲烷体积分数可以更加迅速地对温室减排活动做出响应, 相较于CO2减排,控制和减少甲烷排放是短期内应对气候变化的最有效手段之一。 煤炭开采行业 是我国甲烷的最主要排放源之一。 在碳达峰和碳中和的国家战略需求下,控制和利用煤炭活动产 生的甲烷排放,必将成为“十四五”期间我国甲烷排放控制行动的重点,厘清煤矿行业的甲烷排放 特征具有重要意义。 煤炭开采活动产生的甲烷排放受到地质赋存、开采方式、利用情况等众多因素 影响,传统的“ 自下而上” 排放因子清单方法不确定性较大,基于大气甲烷体积分数观测数据的“ 自 上而下”技术正成为监测核算甲烷排放的重要方法。 2021 年秋冬季,采用“固定+走航”相结合的 观测手段,以我国典型的甲烷高排放区( 晋东南煤矿区) 为实验区域,获取一手观测数据,分析并揭 示近地面甲烷体积分数特征及其潜在的排放源信息。 结果表明:1 甲烷体积分数的时空变化性 强,煤矿区本底甲烷体积分数值是清洁本底的近 1.7 倍,极端高值可达本底值的 40 ~ 50 倍;2 甲烷 体积分数在 1 d 内的变化与煤炭生产活动密切相关,逐日变化受气象扩散条件影响较大;3 绝大 多数甲烷体积分数高值位于煤矿生产相关区域,但由于扩散作用的影响,煤炭生产对甲烷体积分数 时空分布影响存在一定的空间偏离性和时间滞后性。 地面“固定+走航观测”手段可以提供精细化 的甲烷排放特征信息,研究结论可为基于观测“自上而下” 地构建煤炭行业甲烷排放清单奠定一定 基础。Abstract: Methane is the second largest greenhouse gas in the world after carbon dioxide. Its lifetime in the atmos⁃ phere is only about 10 years,but its global warming potential is dozens of times that of CO2. The concentration of methane in the atmosphere can respond more quickly to greenhouse emission reduction activities. Compared with CO2 emission reduction,controlling and reducing methane emission is one of the most effective means to cope with cli⁃ mate change in the short term. The coal mining industry is one of the main sources of methane emissions in China. Un⁃ der the national strategic needs of carbon peaking and carbon neutrality,the control and utilization of methane emis⁃ sions from coal activities will definitely become the focus of China’ s methane emission control actions during the “14th Five⁃Year Plan” period. It is of great significance to reveal the characteristics of methane emissions in the coal mining industry. The methane emissions from coal mining activities are affected by many factors,such as geo⁃ logical occurrence,mining methods,and utilization conditions. The traditional “bottom⁃up” emission factor invento⁃ ry method has great uncertainty. The “top⁃down” technique based on the observational data of atmospheric meth⁃ ane concentration is becoming an important method for monitoring and accounting for methane emissions. In the au⁃ tumn and winter of 2021,this study has adopted the observation method of “fixed + mobile”,and obtained some first⁃hand observation data over the typical high methane emission area in China ( the coal mining area of southeastern Shanxi) so as to analyze and reveal the characteristics of near⁃surface methane concentration and its po⁃ tential emission sources. The results show that 1 The methane concentration has strong temporal and spatial variability,the background methane concentration in the coal mining area is nearly 1.7 times that of the clean back⁃ ground,and the extreme high value can reach more than 40 to 50 times the background value. 2 The changes of methane concentration within a day are closely related to coal production activity,and the day⁃to⁃day changes are greatly affected by meteorological diffusion conditions. 3 Most of the high methane concentrations are located in the areas related to coal mine production,but due to the influence of diffusion,coal production has a significant im⁃ pact on the spatiotemporal methane concentration. The distribution influence has certain spatial deviation and time lag. The ground “fixed + mobile” observation method can provide refined methane emission characteristic information. Furthermore,the research conclusions can lay a foundation for constructing a “top⁃down” methane emission inventory from the coal industry based on observations.