Integrating Source Apportionment Tracers into a Bottom-up Inventory of Methane Emissions in the Barnett Shale Hydraulic Fracturing Region

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• 作者：Amy Townsend-Small ; Josette E. Marrero ; David R. Lyon ; Isobel J. Simpson ; Simone Meinardi ; Donald R. Blake
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：July 7, 2015
• 年：2015
• 卷：49
• 期：13
• 页码：8175-8182
• 全文大小：454K
• ISSN：1520-5851

文摘

A growing dependence on natural gas for energy may exacerbate emissions of the greenhouse gas methane (CH₄). Identifying fingerprints of these emissions is critical to our understanding of potential impacts. Here, we compare stable isotopic and alkane ratio tracers of natural gas, agricultural, and urban CH₄ sources in the Barnett Shale hydraulic fracturing region near Fort Worth, Texas. Thermogenic and biogenic sources were compositionally distinct, and emissions from oil wells were enriched in alkanes and isotopically depleted relative to natural gas wells. Emissions from natural gas production varied in 未¹³C and alkane ratio composition, with 未D-CH₄ representing the most consistent tracer of natural gas sources. We integrated our data into a bottom-up inventory of CH₄ for the region, resulting in an inventory of ethane (C₂H₆) sources for comparison to top-down estimates of CH₄ and C₂H₆ emissions. Methane emissions in the Barnett are a complex mixture of urban, agricultural, and fossil fuel sources, which makes source apportionment challenging. For example, spatial heterogeneity in gas composition and high C₂H₆/CH₄ ratios in emissions from conventional oil production add uncertainty to top-down models of source apportionment. Future top-down studies may benefit from the addition of 未D-CH₄ to distinguish thermogenic and biogenic sources.