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| Titel |
Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley |
| VerfasserIn |
D. R. Gentner, T. B. Ford, A. Guha, K. Boulanger, J. Brioude, W. M. Angevine, J. A. de Gouw, C. Warneke, J. B. Gilman, T. B. Ryerson, J. Peischl, S. Meinardi, D. R. Blake, E. Atlas, W. A. Lonneman, T. E. Kleindienst, M. R. Beaver, J. M. St. Clair, P. O. Wennberg, T. C. VandenBoer, M. Z. Markovic, J. G. Murphy, R. A. Harley, A. H. Goldstein |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 10 ; Nr. 14, no. 10 (2014-05-21), S.4955-4978 |
| Datensatznummer |
250118726
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| Publikation (Nr.) |
 copernicus.org/acp-14-4955-2014.pdf |
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| Zusammenfassung |
| 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. |
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