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| Titel |
Photochemical aging of volatile organic compounds associated with oil and natural gas extraction in the Uintah Basin, UT, during a wintertime ozone formation event |
| VerfasserIn |
A. R. Koss, J. Gouw, C. Warneke, J. B. Gilman, B. M. Lerner, M. Graus, B. Yuan, P. Edwards, S. S. Brown, R. Wild, J. M. Roberts, T. S. Bates, P. K. Quinn |
| 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 ; 15, no. 10 ; Nr. 15, no. 10 (2015-05-26), S.5727-5741 |
| Datensatznummer |
250119752
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| Publikation (Nr.) |
 copernicus.org/acp-15-5727-2015.pdf |
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| Zusammenfassung |
| High concentrations of volatile organic compounds (VOCs) associated with oil
and natural gas extraction were measured during a strong temperature
inversion in the winter of 2013 at a rural site in the Uintah Basin, Utah. During
this period, photochemistry enhanced by the stagnant meteorological
conditions and concentrated VOCs led to high ozone mixing ratios (150 ppbv).
A simple analysis of aromatic VOCs measured by proton-transfer-reaction
mass-spectrometry (PTR-MS) is used to estimate (1) VOC emission ratios (the
ratio of two VOCs at the time of emission) relative to benzene, (2) aromatic
VOC emission rates, and (3) ambient OH radical concentrations. These
quantities are determined from a best fit to VOC : benzene ratios as a
function of time. The main findings are that (1) emission ratios are
consistent with contributions from both oil and gas producing wells; (2) the
emission rate of methane (27–57 × 103 kg methane h−1),
extrapolated from the emission rate of benzene
(4.1 ± 0.4 × 105 molecules cm−3 s−1), agrees
with an independent estimate of methane emissions from aircraft measurements
in 2012; and (3) calculated daily OH concentrations are low, peaking at
1 × 106 molecules cm−3, and are consistent with Master
Chemical Mechanism (MCM) modeling. The analysis is extended to photochemical
production of oxygenated VOCs measured by PTR-MS and is able to explain
daytime variability of these species. It is not able to completely reproduce
nighttime behavior, possibly due to surface deposition. Using results from
this analysis, the carbon mass of secondary compounds expected to have formed
by the sixth day of the stagnation event was calculated, then compared to the
measured mass of primary and secondary compounds. Only 17% of the
expected secondary carbon mass is accounted for by gas phase, aerosol, and
snow organic carbon measurements. The disparity is likely due to substantial
amounts of unquantified oxygenated products. |
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