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| Titel |
Now you see it, now you don't: Impact of temporary closures of a coal-fired power plant on air quality in the Columbia River Gorge National Scenic Area |
| VerfasserIn |
D. A. Jaffe, D. R. Reidmiller |
| 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. 20 ; Nr. 9, no. 20 (2009-10-23), S.7997-8005 |
| Datensatznummer |
250007705
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| Publikation (Nr.) |
 copernicus.org/acp-9-7997-2009.pdf |
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| Zusammenfassung |
| The goal of this study is to identify major point sources that contribute to
elevated particulate matter in the Columbia River Gorge, USA and to
quantify their contribution. To answer this question we analyzed 14 years of
aerosol data spanning 1993–2006 from the IMPROVE site at Wishram,
Washington (45.66° N, 121.00° W; 178 m a.s.l.) in the
Columbia River Gorge (CRG) National Scenic Area of the Pacific Northwest of
the USA. Two types of analyses were conducted. First, we examined the
transport for days with the highest fine mass (PM2.5) concentrations
using HYSPLIT backtrajectories. We found that the highest PM2.5
concentrations occurred during autumn and were associated with easterly
flow, down the CRG. Such flow transports emissions from a large coal power
plant in Boardman, Oregon and a large agricultural facility into the CRG.
This transport was found on 20 out of the 50 worst PM2.5 days and
resulted in an average daily concentration of 20.1 μg/m3, compared
with an average of 18.8 μg/m3 for the 50 highest days and 5.9 μg/m3
for all days. These airmasses contain not only high PM2.5
concentrations, but also elevated levels of aerosol NO3−. In the
second analysis, we examined PM2.5 concentrations in the CRG during
periods when the Boardman power plant was shut down due to repairs and
compared these values with concentrations when the facility was operating at
near full capacity. We also examined this relationship on the days when
backtrajectories suggested the greatest influence from the power plant on
air quality in the CRG. From this analysis, we found significantly higher
PM2.5 concentrations when the power plant was operating at or near full
capacity. We use these data to calculate that the contribution to PM2.5
mass in the CRG from the Boardman power plant was 0.90 μg/m3
averaged over the entire year, 3.94 μg/m3 if only the month of
November is considered and 7.40 μg/m3 if only November days when
the airflow is "down-gorge" (from east to west). This represents 14, 46
and 56% of the PM2.5 mass in the CRG for the full year, November
only and November days with "down-gorge" transport, respectively. |
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