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| Titel |
Air quality and atmospheric deposition in the eastern US: 20 years of change |
| VerfasserIn |
J. E. Sickles II, D. S. Shadwick |
| 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 ; 15, no. 1 ; Nr. 15, no. 1 (2015-01-09), S.173-197 |
| Datensatznummer |
250119292
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| Publikation (Nr.) |
 copernicus.org/acp-15-173-2015.pdf |
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| Zusammenfassung |
Data collected in the eastern US between 1990 and 2009 at 34
paired dry and wet monitoring sites are examined. A goal is to evaluate the
air quality impacts occurring between 1990 and 2009 that are associated with
concurrent legislatively mandated changes in emissions. Four 5-year periods,
1990–1994 (P1), 1995–1999 (P2), 2000–2004 (P3), and 2005–2009 (P4) are
considered, with a primary focus on P1-to-P4 changes. Results suggest that
legislatively mandated air pollution mitigation strategies have been
successful in improving air quality and reducing atmospheric deposition in
the eastern US.
Respective P1-to-P4 reductions of estimated sulfur dioxide (SO2) and
nitrogen oxides (NOx) emissions in the eastern US are 50 and 42%.
Corresponding behavior of the following metrics associated with these
emissions reductions is examined: monitored atmospheric concentrations of
SO2, aerosol sulfate (SO4), and oxidized sulfur (S); dry, wet, and
total deposition of S; monitored atmospheric concentrations of nitric acid
(HNO3), aerosol nitrate (NO3), and their sum, oxidized nitrogen
(OxN); dry, wet, and total deposition of OxN; monitored atmospheric
concentration of aerosol ammonium (NH4); dry, wet, and total deposition
of NH4; summed monitored atmospheric concentration of oxidized and
reduced nitrogen (N); dry, wet, and total deposition of N; wet deposition of
hydrogen ion (H+); monitored atmospheric concentration of ozone
(O3); dry deposition of O3; and the summed monitored atmospheric
concentration of aerosol NO3, SO4, and NH4 (Clean Air
Status and Trends Network particulate matter – CASTNET PM).
Other metrics (e.g., ratios of dry to total deposition) are also considered.
Selected period-to-period changes of air quality and deposition metrics at
site, regional, and seasonal scales are discussed. As an example, despite
P1-to-P3 reductions in estimated emissions of both SO2 and NOx, aerosol
NO3 concentration increased in the east, with widespread wintertime
numerical increases in both aerosol NO3 concentration and CASTNET PM.
However, a reversal of this behavior is associated with continuing P3-to-P4
reductions of SO2 and NOx emissions. Thus, additional P3-to-P4
reductions of these emissions, especially NOx, appear to have made progress
in altering the chemical regime of the wintertime eastern US atmosphere so
that future emissions reductions and their resulting reductions in aerosol
concentrations may no longer be accompanied by sub-linear changes (or actual
increases) in CASTNET PM. |
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