Aerodyne Research Inc., Billerica, Massachusetts 01821, United States.
Environ Sci Technol. 2014 Jul 15;48(14):8028-34. doi: 10.1021/es501475q. Epub 2014 Jul 2.
Methane is an important greenhouse gas and tropospheric ozone precursor. Simultaneous observation of ethane with methane can help identify specific methane source types. Aerodyne Ethane-Mini spectrometers, employing recently available mid-infrared distributed feedback tunable diode lasers (DFB-TDL), provide 1 s ethane measurements with sub-ppb precision. In this work, an Ethane-Mini spectrometer has been integrated into two mobile sampling platforms, a ground vehicle and a small airplane, and used to measure ethane/methane enhancement ratios downwind of methane sources. Methane emissions with precisely known sources are shown to have ethane/methane enhancement ratios that differ greatly depending on the source type. Large differences between biogenic and thermogenic sources are observed. Variation within thermogenic sources are detected and tabulated. Methane emitters are classified by their expected ethane content. Categories include the following: biogenic (<0.2%), dry gas (1-6%), wet gas (>6%), pipeline grade natural gas (<15%), and processed natural gas liquids (>30%). Regional scale observations in the Dallas/Fort Worth area of Texas show two distinct ethane/methane enhancement ratios bridged by a transitional region. These results demonstrate the usefulness of continuous and fast ethane measurements in experimental studies of methane emissions, particularly in the oil and natural gas sector.
甲烷是一种重要的温室气体和对流层臭氧前体。同时观测乙烷和甲烷可以帮助识别特定的甲烷源类型。采用最近可用的中红外分布式反馈可调谐二极管激光器（DFB-TDL）的 Aerodyne 乙烷微型光谱仪可提供具有亚 ppb 精度的 1 秒乙烷测量值。在这项工作中，一台乙烷微型光谱仪已集成到两个移动采样平台中，即地面车辆和小型飞机，并用于测量甲烷源下风处的乙烷/甲烷增强比。具有精确已知源的甲烷排放具有很大差异的乙烷/甲烷增强比，具体取决于源类型。观察到生物成因和热成因源之间存在很大差异。检测并列出了热成因源内的变化。根据预期的乙烷含量对甲烷排放源进行分类。类别包括：生物成因（<0.2%）、干气（1-6%）、湿气（>6%）、管道级天然气（<15%）和加工天然气液体（>30%）。在德克萨斯州达拉斯/沃思堡地区的区域尺度观测显示，两个截然不同的乙烷/甲烷增强比由一个过渡区连接。这些结果表明，连续快速的乙烷测量在甲烷排放的实验研究中非常有用，特别是在石油和天然气行业。
