Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 14, 4955-4978, 2014
http://www.atmos-chem-phys.net/14/4955/2014/
doi:10.5194/acp-14-4955-2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
21 May 2014
Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley
D. R. Gentner1,*, T. B. Ford2, A. Guha3, K. Boulanger1,**, J. Brioude4,5, W. M. Angevine4,5, J. A. de Gouw4,5, C. Warneke4,5, J. B. Gilman4,5, T. B. Ryerson4,5, J. Peischl4,5, S. Meinardi6, D. R. Blake6, E. Atlas7, W. A. Lonneman8, T. E. Kleindienst8, M. R. Beaver9,***, J. M. St. Clair9, P. O. Wennberg9, T. C. VandenBoer10,****, M. Z. Markovic10,*****,******, J. G. Murphy10, R. A. Harley1, and A. H. Goldstein1,3 1Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA
2Department of Chemistry, University of California, Berkeley, CA, 94720, USA
3Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, 94720, USA
4Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
5Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
6Department of Chemistry, University of California, Irvine, CA, 92697, USA
7Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, 33149, USA
8National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, NC, USA
9California Institute of Technology, Pasadena, CA, USA
10Department of Chemistry, University of Toronto, Toronto, ON, CA
*now at: Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06511, USA
**now at: Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
***now at: National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, NC, USA
****now at: Department of Chemistry, Memorial University of Newfoundland, NL, CA
*****now at: Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
******now at: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
Abstract. Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. It is essential to understand the emissions and air quality impacts of these relatively understudied sources, especially for oil/gas operations in light of increasing US production. Ground site measurements in Bakersfield and regional aircraft measurements of reactive gas-phase organic compounds and methane were part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions, and provide average source profiles. To examine the spatial distribution of emissions in the San Joaquin Valley, we developed a statistical modeling method using ground-based data and the FLEXPART-WRF transport and meteorological model. We present evidence for large sources of paraffinic hydrocarbons from petroleum operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes, most of which have limited previous in situ measurements or characterization in petroleum operation emissions. Observed dairy emissions were dominated by ethanol, methanol, acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The petroleum operations source profile was developed using the composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil. The observed source profile is consistent with fugitive emissions of condensate during storage or processing of associated gas following extraction and methane separation. Aircraft observations of concentration hotspots near oil wells and dairies are consistent with the statistical source footprint determined via our FLEXPART-WRF-based modeling method and ground-based data. We quantitatively compared our observations at Bakersfield to the California Air Resources Board emission inventory and find consistency for relative emission rates of reactive organic gases between the aforementioned sources and motor vehicles in the region. We estimate that petroleum and dairy operations each comprised 22% of anthropogenic non-methane organic carbon at Bakersfield and were each responsible for 8–13% of potential precursors to ozone. Yet, their direct impacts as potential secondary organic aerosol (SOA) precursors were estimated to be minor for the source profiles observed in the San Joaquin Valley.

Citation: Gentner, D. R., Ford, T. B., Guha, A., Boulanger, K., Brioude, J., Angevine, W. M., de Gouw, J. A., Warneke, C., Gilman, J. B., Ryerson, T. B., Peischl, J., Meinardi, S., Blake, D. R., Atlas, E., Lonneman, W. A., Kleindienst, T. E., Beaver, M. R., Clair, J. M. St., Wennberg, P. O., VandenBoer, T. C., Markovic, M. Z., Murphy, J. G., Harley, R. A., and Goldstein, A. H.: Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley, Atmos. Chem. Phys., 14, 4955-4978, doi:10.5194/acp-14-4955-2014, 2014.
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