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Environ Sci Technol. 2015 Jul 7;49(13):8158-66. doi: 10.1021/acs.est.5b00219.

Airborne Ethane Observations in the Barnett Shale: Quantification of Ethane Flux and Attribution of Methane Emissions.

Author information

1
†Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States.
2
‡CIRES, University of Colorado, Boulder, Colorado 80309, United States.
3
§NOAA Earth System Research Laboratory, Boulder, Colorado 80305, United States.
4
∥Aerodyne Research, Inc., Billerica, Massachusetts 01821, United States.

Abstract

We present high time resolution airborne ethane (C2H6) and methane (CH4) measurements made in March and October 2013 as part of the Barnett Coordinated Campaign over the Barnett Shale formation in Texas. Ethane fluxes are quantified using a downwind flight strategy, a first demonstration of this approach for C2H6. Additionally, ethane-to-methane emissions ratios (C2H6:CH4) of point sources were observationally determined from simultaneous airborne C2H6 and CH4 measurements during a survey flight over the source region. Distinct C2H6:CH4 × 100% molar ratios of 0.0%, 1.8%, and 9.6%, indicative of microbial, low-C2H6 fossil, and high-C2H6 fossil sources, respectively, emerged in observations over the emissions source region of the Barnett Shale. Ethane-to-methane correlations were used in conjunction with C2H6 and CH4 fluxes to quantify the fraction of CH4 emissions derived from fossil and microbial sources. On the basis of two analyses, we find 71-85% of the observed methane emissions quantified in the Barnett Shale are derived from fossil sources. The average ethane flux observed from the studied region of the Barnett Shale was 6.6 ± 0.2 × 10(3) kg hr(-1) and consistent across six days in spring and fall of 2013.

PMID:
26148554
DOI:
10.1021/acs.est.5b00219
[Indexed for MEDLINE]

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