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| Titel |
Wintertime particulate pollution episodes in an urban valley of the Western US: a case study |
| VerfasserIn |
L.-W. A. Chen, J. G. Watson, J. C. Chow, M. C. Green, D. Inouye, K. Dick |
| 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 (2012-11-02), S.10051-10064 |
| Datensatznummer |
250011551
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| Publikation (Nr.) |
 copernicus.org/acp-12-10051-2012.pdf |
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| Zusammenfassung |
| This study investigates the causes of elevated PM2.5 episodes and
potential exceedences of the US National Ambient Air Quality Standards
(NAAQS) in Truckee Meadows, Nevada, an urban valley of the Western US,
during winter 2009/2010, an unusually cold and snowy winter. Continuous PM2.5 mass and time-integrated chemical speciation data were acquired from a central valley monitoring site, along with meteorological measurements from nearby sites. All nine days with PM2.5 > 35 μg m−3 showed 24-h average
temperature inversion of 1.5–4.5 °C and snow cover of 8–18 cm. Stagnant atmospheric conditions limited wind ventilation while highly
reflective snow cover reduced daytime surface heating creating persistent
inversion. Elevated ammonium nitrate (NH4NO3) and water
associated with it are found to be main reasons for the PM2.5 exceedances. An effective-variance chemical mass balance (EV-CMB) receptor model using locally-derived geological profiles and inorganic/organic markers confirmed secondary NH4NO3 (27–37%), residential wood combustion (RWC; 11–51%), and diesel engine exhaust (7–22%) as the dominant
PM2.5 contributors. Paved road dust and de-icing materials were minor, but
detectable contributors. RWC is a more important source than diesel for
organic carbon (OC), but vice versa for elemental carbon (EC). A majority of
secondary NH4NO3 is also attributed to RWC and diesel engines (including snow removal equipment) through oxides of nitrogen (NOx) emissions from these sources. Findings from this study may apply to similar situations experienced by other urban valleys. |
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