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| Titel |
Emissions of terpenoids, benzenoids, and other biogenic gas-phase organic compounds from agricultural crops and their potential implications for air quality |
| VerfasserIn |
D. R. Gentner, E. Ormeño, S. Fares, T. B. Ford, R. Weber, J.-H. Park, J. Brioude, W. M. Angevine, J. F. Karlik, 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. 11 ; Nr. 14, no. 11 (2014-06-03), S.5393-5413 |
| Datensatznummer |
250118765
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| Publikation (Nr.) |
 copernicus.org/acp-14-5393-2014.pdf |
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| Zusammenfassung |
| Agriculture comprises a substantial, and increasing, fraction of land use in
many regions of the world. Emissions from agricultural vegetation and other
biogenic and anthropogenic sources react in the atmosphere to produce ozone
and secondary organic aerosol, which comprises a substantial fraction of
particulate matter (PM2.5). Using data from three measurement
campaigns, we examine the magnitude and composition of reactive gas-phase
organic carbon emissions from agricultural crops and their potential to
impact regional air quality relative to anthropogenic emissions from motor
vehicles in California's San Joaquin Valley, which is out of compliance with
state and federal standards for tropospheric ozone PM2.5. Emission
rates for a suite of terpenoid compounds were measured in a greenhouse for
25 representative crops from California in 2008. Ambient measurements of
terpenoids and other biogenic compounds in the volatile and
intermediate-volatility organic compound ranges were made in the urban area
of Bakersfield and over an orange orchard in a rural area of the San Joaquin
Valley during two 2010 seasons: summer and spring flowering. We combined
measurements from the orchard site with ozone modeling methods to assess the
net effect of the orange trees on regional ozone. When accounting for both
emissions of reactive precursors and the deposition of ozone to the orchard,
the orange trees are a net source of ozone in the springtime during
flowering, and relatively neutral for most of the summer until the fall, when
it becomes a sink. Flowering was a major emission event and caused a large
increase in emissions including a suite of compounds that had not been
measured in the atmosphere before. Such biogenic emission events need to be
better parameterized in models as they have significant potential to impact
regional air quality since emissions increase by several factors to over an
order of magnitude. In regions like the San Joaquin Valley, the mass of
biogenic emissions from agricultural crops during the summer (without
flowering) and the potential ozone and secondary organic aerosol formation
from these emissions are on the same order as anthropogenic emissions from
motor vehicles and must be considered in air quality models and secondary
pollution control strategies. |
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