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| Titel |
Patterns in atmospheric carbonaceous aerosols in China: emission estimates and observed concentrations |
| VerfasserIn |
H. Cui, P. Mao, Y. Zhao, C. P. Nielsen, J. Zhang |
| 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. 15 ; Nr. 15, no. 15 (2015-08-06), S.8657-8678 |
| Datensatznummer |
250119948
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| Publikation (Nr.) |
 copernicus.org/acp-15-8657-2015.pdf |
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| Zusammenfassung |
| China is experiencing severe carbonaceous aerosol pollution driven mainly by
large emissions resulting from intensive use of solid fuels. To gain a
better understanding of the levels and trends of carbonaceous aerosol
emissions and the resulting ambient concentrations at the national scale, we
update an emission inventory of anthropogenic organic carbon (OC) and
elemental carbon (EC) and employ existing observational studies to analyze
characteristics of these aerosols including temporal, spatial, and size
distributions, and the levels and shares of secondary organic carbon (SOC)
in total OC. We further use ground observations to test the levels and
inter-annual trends of the calculated national and provincial emissions of
carbonaceous aerosols, and propose possible improvements in emission
estimation for the future. The national OC emissions are estimated to have
increased 29 % from 2000 (2127 Gg) to 2012 (2749 Gg) and EC by 37 %
(from 1356 to 1857 Gg). The residential, industrial, and transportation
sectors contributed an estimated 74–78, 17–21, and 4–6 % of the
total emissions of OC, respectively, and 49–55, 30–34, and 14–18 %
of EC. Updated emission factors (EFs) based on the most recent local field
measurements, particularly for biofuel stoves, led to considerably lower
emissions of OC compared to previous inventories. Compiling observational
data across the country, higher concentrations of OC and EC are found in
northern and inland cities, while higher OC / EC ratios are found in southern
sites, due to the joint effects of primary emissions and meteorology.
Higher OC / EC ratios are estimated at rural and remote sites compared to
urban ones, attributed to more emissions of OC from biofuel use, more
biogenic emissions of volatile organic compound (VOC) precursors to SOC,
and/or transport of aged aerosols. For most sites, higher concentrations of
OC, EC, and SOC are observed in colder seasons, while SOC / OC is reduced,
particularly at rural and remote sites, attributed partly to weaker
atmospheric oxidation and SOC formation compared to summer. Enhanced SOC
formation from oxidization and anthropogenic activities like biomass
combustion is judged to have crucial effects on severe haze events
characterized by high particle concentrations. Several observational studies
indicate an increasing trend in ambient OC / EC (but not in OC or EC
individually) from 2000 to 2010, confirming increased atmospheric oxidation
of OC across the country. Combining the results of emission estimation and
observations, the improvement over prior emission inventories is indicated
by inter-annual comparisons and correlation analysis. It is also indicated,
however, that the estimated growth in emissions might be faster than
observed growth, and that some sources with high primary OC / EC, such as burning
of biomass, are still underestimated. Further studies to determine changing
EFs over time in the residential sector and to compare to other
measurements, such as satellite observations, are thus suggested to improve
understanding of the levels and trends of primary carbonaceous aerosol
emissions in China. |
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