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| Titel |
Short-term variation in near-highway air pollutant gradients on a winter morning |
| VerfasserIn |
J. L. Durant, C. A. Ash, E. C. Wood, S. C. Herndon, J. T. Jayne, W. B. Knighton, M. R. Canagaratna, J. B. Trull, D. Brugge, W. Zamore, C. E. Kolb |
| 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 ; 10, no. 17 ; Nr. 10, no. 17 (2010-09-06), S.8341-8352 |
| Datensatznummer |
250008753
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| Publikation (Nr.) |
 copernicus.org/acp-10-8341-2010.pdf |
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| Zusammenfassung |
| Quantification of exposure to traffic-related air pollutants near highways
is hampered by incomplete knowledge of the scales of temporal variation of
pollutant gradients. The goal of this study was to characterize short-term
temporal variation of vehicular pollutant gradients within 200–400 m of a
major highway (>150 000 vehicles/d). Monitoring was done near Interstate 93
in Somerville (Massachusetts) from 06:00 to 11:00 on 16 January 2008 using a
mobile monitoring platform equipped with instruments that measured ultrafine
and fine particles (6–1000 nm, particle number concentration (PNC));
particle-phase (>30 nm) NO3−, SO42−, and organic
compounds; volatile organic compounds (VOCs); and CO2, NO, NO2,
and O3. We observed rapid changes in pollutant gradients due to
variations in highway traffic flow rate, wind speed, and surface boundary
layer height. Before sunrise and peak traffic flow rates, downwind
concentrations of particles, CO2, NO, and NO2 were highest within
100–250 m of the highway. After sunrise pollutant levels declined sharply
(e.g., PNC and NO were more than halved) and the gradients became less
pronounced as wind speed increased and the surface boundary layer rose
allowing mixing with cleaner air aloft. The levels of aromatic VOCs and
NO3−, SO42− and organic aerosols were generally low
throughout the morning, and their spatial and temporal variations were less
pronounced compared to PNC and NO. O3 levels increased throughout the
morning due to mixing with O3-enriched air aloft and were generally
lowest near the highway reflecting reaction with NO. There was little if any
evolution in the size distribution of 6–225 nm particles with distance from
the highway. These results suggest that to improve the accuracy of exposure
estimates to near-highway pollutants, short-term (e.g., hourly) temporal
variations in pollutant gradients must be measured to reflect changes in
traffic patterns and local meteorology. |
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