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| Titel |
Particulate sulfate ion concentration and SO2 emission trends in the United States from the early 1990s through 2010 |
| VerfasserIn |
J. L. Hand, B. A. Schichtel, W. C. Malm, M. L. Pitchford |
| 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 ; 12, no. 21 ; Nr. 12, no. 21 (2012-11-07), S.10353-10365 |
| Datensatznummer |
250011570
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| Publikation (Nr.) |
 copernicus.org/acp-12-10353-2012.pdf |
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| Zusammenfassung |
| We examined particulate sulfate ion concentrations across the United States
from the early 1990s through 2010 using remote/rural data from the
Interagency Monitoring of Protected Visual Environments (IMPROVE) network
and from early 2000 through 2010 using data from the Environmental
Protection Agency's (EPA) urban Chemical Speciation Network (CSN). We also
examined measured sulfur dioxide (SO2) emissions from power plants from
1995 through 2010 from the EPA's Acid Rain Program. The 1992–2010 annual
mean sulfate concentrations at long-term rural sites in the United States
have decreased significantly and fairly consistently across the United
States at a rate of −2.7% yr−1 (p < 0.01). The short-term
(2001–2010) annual mean trend at rural sites was −4.6% yr−1 (p < 0.01) and at urban sites (2002–2010) was −6.2% yr−1 (p < 0.01). Annual total SO2 emissions from power plants across
the United States have decreased at a similar rate as sulfate concentrations
from 2001 to 2010 (−6.2% yr−1, p < 0.01), suggesting a
linear relationship between SO2 emissions and average sulfate
concentrations. This linearity was strongest in the eastern United States
and weakest in the West where power plant SO2 emissions were lowest and
sulfate concentrations were more influenced by non-power-plant and perhaps
international SO2 emissions. In addition, annual mean, short-term
sulfate concentrations decreased more rapidly in the East relative to the
West due to differences in seasonal trends at certain regions in the West.
Specifically, increased wintertime concentrations in the central and
northern Great Plains and increased springtime concentrations in the western
United States were observed. These seasonal and regional positive trends
could not be explained by changes in known local and regional
SO2 emissions, suggesting other contributing influences. This work
implies that on an annual mean basis across the United States, air quality
mitigation strategies have been successful in reducing the particulate
loading of sulfate in the atmosphere; however, for certain seasons and
regions, especially in the West, current mitigation strategies appear
insufficient. |
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