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| Titel |
Estimate of anthropogenic halocarbon emission based on measured ratio relative to CO in the Pearl River Delta region, China |
| VerfasserIn |
M. Shao, D. Huang, D. Gu, S. Lu, C. Chang, J. Wang |
| 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. 10 ; Nr. 11, no. 10 (2011-05-30), S.5011-5025 |
| Datensatznummer |
250009769
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| Publikation (Nr.) |
 copernicus.org/acp-11-5011-2011.pdf |
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| Zusammenfassung |
| Using a GC/FID/MS system, we analyzed the mixing ratio of 16 halocarbon
species in more than 100 air samples collected in 2004 from the Pearl River
Delta (PRD) region of southern China. The results revealed that there are
elevated mixing ratios for most of halocarbons, especially for
HClC = CCl2 (trichloroethylene, TCE), CH2Cl2 (dichloromethane,
DCM), CH3 Br (bromomethane), HCFC-22, CHCl3 (trichloromethane),
CCl4 (tetrachloromethane), Cl2C = CCl2 (perchloroethylene,
PCE), CH3CCl3 (methyl chloroform, MCF), and CFC-12. Comparisons
were done with the data from TRACE-P and ALE/GAGE/AGAGE experiments, we
found that the large variability in mixing ratios (relative standard
deviation ranged from 9.31 % to 96.55 %) of the halocarbons suggested
substantial local emissions from the PRD region in 2004. Correlations
between the mixing ratio of each species and carbon monoxide (CO) was
examined, and then the emission of each halocarbon was quantified based on
scaling the optimized CO emission inventory with the slope of the regression
line fitted to each species relative to CO. The calculated results revealed
that mass of CH2Cl2 (7.0 Gg), CH3CCl3 (6.7 Gg), and
Cl2C = CCl2 (2.3 Gg) accounted for about 62.9 % of total
halocarbon emissions, it suggested a significant contribution from solvent
use in the PRD region. Emissions of HCFC-22 (3.5 Gg), an alternative
refrigerant to chlorofluorocarbons (CFCs), were about 2.3 times greater than
those of CFC-12 (1.6 Gg). CFC-12 and HCFC-22 accounted for 21.5 % of total
emissions of halocarbons, so that the refrigerant would be the second
largest source of halocarbons. However, the ratio approach found only minor
emissions of CFCs, such as CFC-11, and the emission of CFC-114 and CFC-113
were close to zero. Emissions of other anthropogenic halocarbons, such as
CCl4, CHCl3, CH3Br, and CH3Cl, were also estimated.
Where possible, the emissions estimated from the measured ratios were
compared with results from source inventory techniques, we found that both
approaches gave emissions at similar magnitude for most of the halocarbons,
except CFC-11. The comparison suggested that the ratio method may be a
useful tool for assessing regional halocarbon emissions, and emission
uncertainty could be further reduced by incorporating both longer-term and
higher-frequency observations, as well as improving the accuracy of the CO
inventory. |
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