J Air Waste Manag Assoc. 2014 Jan;64(1):61-72. doi: 10.1080/10962247.2013.832713.
Information regarding air emissions from shale gas extraction and production is critically important given production is occurring in highly urbanized areas across the United States. Objectives of this exploratory study were to collect ambient air samples in residential areas within 61 m (200 feet) of shale gas extraction/production and determine whether a "fingerprint" of chemicals can be associated with shale gas activity. Statistical analyses correlating fingerprint chemicals with methane, equipment, and processes of extraction/production were performed. Ambient air sampling in residential areas of shale gas extraction and production was conducted at six counties in the Dallas/Fort Worth (DFW) Metroplex from 2008 to 2010. The 39 locations tested were identified by clients that requested monitoring. Seven sites were sampled on 2 days (typically months later in another season), and two sites were sampled on 3 days, resulting in 50 sets of monitoring data. Twenty-four-hour passive samples were collected using summa canisters. Gas chromatography/mass spectrometer analysis was used to identify organic compounds present. Methane was present in concentrations above laboratory detection limits in 49 out of 50 sampling data sets. Most of the areas investigated had atmospheric methane concentrations considerably higher than reported urban background concentrations (1.8-2.0 ppm(v)). Other chemical constituents were found to be correlated with presence of methane. A principal components analysis (PCA) identified multivariate patterns of concentrations that potentially constitute signatures of emissions from different phases of operation at natural gas sites. The first factor identified through the PCA proved most informative. Extreme negative values were strongly and statistically associated with the presence of compressors at sample sites. The seven chemicals strongly associated with this factor (o-xylene, ethylbenzene, 1,2,4-trimethylbenzene, m- and p-xylene, 1,3,5-trimethylbenzene, toluene, and benzene) thus constitute a potential fingerprint of emissions associated with compression.
Information regarding air emissions from shale gas development and production is critically important given production is now occurring in highly urbanized areas across the United States. Methane, the primary shale gas constituent, contributes substantially to climate change; other natural gas constituents are known to have adverse health effects. This study goes beyond previous Barnett Shale field studies by encompassing a wider variety of production equipment (wells, tanks, compressors, and separators) and a wider geographical region. The principal components analysis, unique to this study, provides valuable information regarding the ability to anticipate associated shale gas chemical constituents.
鉴于页岩气开采和生产正在美国人口高度密集的地区进行，因此获取有关其空气排放的信息至关重要。本探索性研究的目的是采集距离页岩气开采/生产场地 61 米（200 英尺）以内的居民区的环境空气样本，并确定是否可以识别出与页岩气活动相关的“特征指纹”。对与甲烷、设备和开采/生产过程相关的特征指纹化学物质进行了统计分析。2008 年至 2010 年，在达拉斯/沃斯堡（DFW）都会区的六个县的页岩气开采和生产居民区进行了环境空气采样。这些测试地点是由要求进行监测的客户确定的。其中 7 个地点在两天（通常是在另一个季节的几个月后）进行了采样，另外 2 个地点进行了 3 天的采样，共获得了 50 组监测数据。使用苏玛罐采集了 24 小时的被动式样品。采用气相色谱/质谱联用仪分析来鉴定存在的有机化合物。在 50 个采样数据集中，有 49 个的甲烷浓度高于实验室检测限。在所调查的大部分地区，大气中的甲烷浓度远高于报告的城市背景浓度（1.8-2.0ppm（v））。还发现其他化学成分与甲烷的存在有关。主成分分析（PCA）确定了浓度的多变量模式，这些模式可能构成了来自天然气站点不同操作阶段排放的特征。通过 PCA 确定的第一个因素被证明是最有信息的。极端负值与采样点处压缩机的存在具有很强的统计学关联。与该因子强烈相关的七种化学物质（间二甲苯、乙苯、1,2,4-三甲苯、间/对二甲苯、1,3,5-三甲苯、甲苯和苯）由此构成了与压缩相关的排放的潜在特征指纹。
鉴于页岩气开发和生产目前正在美国人口高度密集的地区进行，因此获取有关其空气排放的信息至关重要。甲烷是页岩气的主要成分，它对气候变化有很大的影响；天然气的其他成分已知对健康有不良影响。本研究通过涵盖更广泛的生产设备（井、罐、压缩机和分离器）和更广泛的地理区域，超越了之前的 Barnett Shale 实地研究。本研究中使用的主成分分析提供了有关预测相关页岩气化学成分的能力的有价值的信息。
