Plume mapping and isotopic characterisation of anthropogenic methane sources
Plume mapping and isotopic characterisation of anthropogenic methane sources
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DOI：
10.1016/j.atmosenv.2015.03.029
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发表时间：
2015-06-01
影响因子：
5
通讯作者：
Nisbet, E. G.
中科院分区：
文献类型：
--
作者：
Zazzeri, G.;Lowry, D.;Nisbet, E. G.
甲烷稳定同位素分析结合摩尔分数测量，已被用于将同位素特征与英国垃圾填埋场、煤矿和气体泄漏的甲烷排放联系起来。在一辆汽车上安装了一台移动Picarro G2301 CRDS(腔振铃光谱)分析仪，以及一个风速计和GPS接收器，以测量大气中甲烷的摩尔分数及其相对位置，同时以每小时80公里的速度行驶。在目标区域，当甲烷羽流被截获时，空气样本被收集在特德拉袋中，用于使用连续流动气相色谱-同位素比质谱仪(CF-GC-IRMS)进行Delta C-13-CH4同位素分析。这种方法提供了高精度的同位素值，测定了每密尔的增量C-13-CH4到+/-0.05。通过基林图分析获得了甲烷羽流从整个源区进入大气的总体特征，并对每个甲烷源分配了具有相对不确定性的增量C-13-CH4特征。英格兰东南部的垃圾填埋场和天然气排放都严格限制了同位素特征。垃圾填埋场的平均C-13-CH4增量为-58+/-3‰。气体泄漏的增量C-13-CH4特征也相当恒定，约为-36+/-2ppm，这是北海均质供应的一个数值特征。相比之下，英格兰北部和威尔士煤矿的签名范围在-51.2+/-0.3ppm到30.9+/-1.4ppm之间，但可以受到地区的严格限制。研究表明，基于CRDS的移动式甲烷测量与羽流样品的离线高精度同位素分析相结合是表征甲烷来源的一种有效方法。它表明，现场测量可以识别类型，并可能定位以前未知的甲烷来源。在模拟研究中，这一测量为确定不同来源对区域甲烷预算的贡献和核实库存来源分布提供了一个独立的约束。(C)2015爱思唯尔有限公司。保留所有权利。
Methane stable isotope analysis, coupled with mole fraction measurement, has been used to link isotopic signature to methane emissions from landfill sites, coal mines and gas leaks in the United Kingdom. A mobile Picarro G2301 CRDS (Cavity Ring-Down Spectroscopy) analyser was installed on a vehicle, together with an anemometer and GPS receiver, to measure atmospheric methane mole fractions and their relative location while driving at speeds up to 80 kph. In targeted areas, when the methane plume was intercepted, air samples were collected in Tedlar bags, for delta C-13-CH4 isotopic analysis by CF-GC-IRMS (Continuous Flow Gas Chromatography-Isotope Ratio Mass Spectrometry). This method provides high precision isotopic values, determining delta C-13-CH4 to +/- 0.05 per mil. The bulk signature of the methane plume into the atmosphere from the whole source area was obtained by Keeling plot analysis, and a delta C-13 -CH4 signature, with the relative uncertainty, allocated to each methane source investigated. Both landfill and natural gas emissions in SE England have tightly constrained isotopic signatures. The averaged delta C-13-CH4 for landfill sites is -58 +/- 3%o. The delta C-13-CH4 signature for gas leaks is also fairly constant around -36 +/- 2 parts per thousand, a value characteristic of homogenised North Sea supply. In contrast, signatures for coal mines in N. England and Wales fall in a range of -51.2 +/- 0.3 parts per thousand to 30.9 +/- 1.4 parts per thousand, but can be tightly constrained by region. The study demonstrates that CRDS-based mobile methane measurement coupled with off-line high precision isotopic analysis of plume samples is an efficient way of characterising methane sources. It shows that iiotopic measurements allow type identification, and possible location of previously unknown methane sources. In modelling studies this measurement provides an independent constraint to determine the contributions of different sources to the regional methane budget and in the verification of inventory source distribution. (C) 2015 Elsevier Ltd. All rights reserved.