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| Titel |
Characteristics of PM2.5 speciation in representative megacities and across China |
| VerfasserIn |
F. Yang, J. Tan, Q. Zhao, Z. Du, K. He, Y. Ma, F. Duan, G. Chen, Q. Zhao |
| 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 ; 11, no. 11 ; Nr. 11, no. 11 (2011-06-01), S.5207-5219 |
| Datensatznummer |
250009798
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| Publikation (Nr.) |
 copernicus.org/acp-11-5207-2011.pdf |
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| Zusammenfassung |
| Based on PM2.5 chemical data sets from literature and from our surface
observations, chemical species and reconstructed speciation of PM2.5 in
representative Chinese megacities and across China were compared to draw
insights into the characteristics of PM2.5 speciation. PM2.5 mass
concentrations and speciation compositions varied substantially over
geographical regions in China. Near six-fold variations in average
PM2.5 concentrations (34.0–193.4 μg m−3) across China were
found with high PM2.5 levels (>100 μg m−3) appearing in the
cities in the northern and western regions and low levels
(<40 μg m−3) in the remote forest area (Changbai Mountain) and in Hong Kong.
The percentages of the sum of sulfate, nitrate and ammonium, organic matter,
crustal material, and elemental carbon in PM2.5 mass ranged 7.1–57 %,
17.7–53 %, 7.1–43 %, and 1.3–12.8 %, respectively. At both urban and
rural sites in the eastern region, the sum of sulfate, nitrate and ammonia
typically constituted much higher fractions (40–57 %) of PM2.5 mass,
indicative of more local formation/production and regional transport of the
secondary aerosols, thus more intensive characteristic of "complex
atmospheric pollution" compared to the western region. Organic matter had
significant contribution to PM2.5 over all the sites. Organic matter
plus sulfate, nitrate, and ammonia accounted for 53–90 % of PM2.5
mass across China. PM2.5 speciation across China was also characterized
by high content of crustal material, which was usually at more than
~10 μg m−3 level or shared ~10 % of PM2.5 mass in
urban areas, due to transported desert dust and locally induced dust. In
four representative megacities (i.e. Beijing, Chongqing, Shanghai, and
Guangzhou), PM2.5 mass and major components (except sulfate) were at
higher levels than those in US continental east by one order of magnitude.
Distinct differences in nitrate and sulfate levels and their mass ratio
[NO3−]/[SO42−] imply that mobile sources are likely more
important in Guangzhou, whereas in Chongqing it is stationary (coal
combustion) sources. The observed intra-city variations in PM2.5 mass
and speciation indicate that both local emissions and regional
transportation contributed significantly to high fine particle loadings in
Beijing, while local contribution likely played a predominant role in
Chongqing. During the ten-year period from 1999 through 2008 in urban
Beijing, both the sum of sulfate, nitrate, and ammonia and
[NO3−]/[SO42−] ratio exhibited steadily increasing
trends, implying that the characteristic of "complex atmospheric pollution"
and the contribution from mobile sources were being enhanced. |
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