Quantifying sources of methane using light alkanes in the Los Angeles basin, California

Authors

  • J. Peischl,

    Corresponding author
    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
    • Corresponding author: J. Peischl, Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, CO, USA. (jeff.peischl@noaa.gov)

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  • T. B. Ryerson,

    1. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • J. Brioude,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • K. C. Aikin,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • A. E. Andrews,

    1. Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • E. Atlas,

    1. Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
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  • D. Blake,

    1. Department of Chemistry, University of California, Irvine, California, USA
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  • B. C. Daube,

    1. School of Engineering and Applied Science and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
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  • J. A. de Gouw,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • E. Dlugokencky,

    1. Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • G. J. Frost,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • D. R. Gentner,

    1. Department of Civil and Environmental Engineering, University of California, Berkeley, California, USA
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  • J. B. Gilman,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • A. H. Goldstein,

    1. Department of Civil and Environmental Engineering, University of California, Berkeley, California, USA
    2. Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, USA
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  • R. A. Harley,

    1. Department of Civil and Environmental Engineering, University of California, Berkeley, California, USA
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  • J. S. Holloway,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • J. Kofler,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • W. C. Kuster,

    1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, USA
    2. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • P. M. Lang,

    1. Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • P. C. Novelli,

    1. Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • G. W. Santoni,

    1. School of Engineering and Applied Science and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
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  • M. Trainer,

    1. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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  • S. C. Wofsy,

    1. School of Engineering and Applied Science and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
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  • D. D. Parrish

    1. Chemical Sciences Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder, Colorado, USA
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Abstract

[1] Methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and C2–C5 alkanes were measured throughout the Los Angeles (L.A.) basin in May and June 2010. We use these data to show that the emission ratios of CH4/CO and CH4/CO2 in the L.A. basin are larger than expected from population-apportioned bottom-up state inventories, consistent with previously published work. We use experimentally determined CH4/CO and CH4/CO2 emission ratios in combination with annual State of California CO and CO2 inventories to derive a yearly emission rate of CH4 to the L.A. basin. We further use the airborne measurements to directly derive CH4 emission rates from dairy operations in Chino, and from the two largest landfills in the L.A. basin, and show these sources are accurately represented in the California Air Resources Board greenhouse gas inventory for CH4. We then use measurements of C2–C5 alkanes to quantify the relative contribution of other CH4 sources in the L.A. basin, with results differing from those of previous studies. The atmospheric data are consistent with the majority of CH4 emissions in the region coming from fugitive losses from natural gas in pipelines and urban distribution systems and/or geologic seeps, as well as landfills and dairies. The local oil and gas industry also provides a significant source of CH4 in the area. The addition of CH4 emissions from natural gas pipelines and urban distribution systems and/or geologic seeps and from the local oil and gas industry is sufficient to account for the differences between the top-down and bottom-up CH4 inventories identified in previously published work.

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