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Titel |
Are biogenic emissions a significant source of summertime atmospheric toluene in the rural Northeastern United States? |
VerfasserIn |
M. L. White, R. S. Russo, Y. Zhou, J. L. Ambrose, K. Haase, E. K. Frinak, R. K. Varner, O. W. Wingenter, H. Mao, R. Talbot, B. C. Sive |
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 ; 9, no. 1 ; Nr. 9, no. 1 (2009-01-08), S.81-92 |
Datensatznummer |
250006631
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Publikation (Nr.) |
copernicus.org/acp-9-81-2009.pdf |
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Zusammenfassung |
Summertime atmospheric toluene enhancements at Thompson Farm in the rural
northeastern United States were unexpected and resulted in a toluene/benzene
seasonal pattern that was distinctly different from that of other
anthropogenic volatile organic compounds. Consequently, three hydrocarbon
sources were investigated for potential contributions to the enhancements
during 2004–2006. These included: (1) increased warm season fuel
evaporation coupled with changes in reformulated gasoline (RFG) content to
meet US EPA summertime volatility standards, (2) local industrial emissions
and (3) local vegetative emissions. The contribution of fuel evaporation
emission to summer toluene mixing ratios was estimated to range from 16 to
30 pptv d−1, and did not fully account for the observed enhancements
(20–50 pptv) in 2004–2006. Static chamber measurements of alfalfa, a crop
at Thompson Farm, and dynamic branch enclosure measurements of loblolly pine
trees in North Carolina suggested vegetative emissions of 5 and 12 pptv d−1 for crops and coniferous trees, respectively. Toluene emission
rates from alfalfa are potentially much larger as these plants were only
sampled at the end of the growing season. Measured biogenic fluxes were on
the same order of magnitude as the influence from gasoline evaporation and
industrial sources (regional industrial emissions estimated at 7 pptv d−1 and indicated that local vegetative emissions make a significant
contribution to summertime toluene enhancements. Additional studies are
needed to characterize the variability and factors controlling toluene
emissions from alfalfa and other vegetation types throughout the growing
season. |
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