ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-11-5011-2011 Estimate of anthropogenic halocarbon emission based on measured ratio relative to CO in the Pearl River Delta region, China Shao M. 1 Huang D. 1 Gu D. 1 Lu S. 1 Chang C. 2 Wang J. 3 State Joint Key Laboratory of Environmental Simulation and Pollution Control, College of Environmental Science and Engineering, Peking University, Beijing 100871, China Research Center for Environmental Changes, Academia Sinica, Taipei 115,Taiwan Department of Chemistry, National Central University, Chungli 320, Taiwan 30 05 2011 11 10 5011 5025 Copyright: © 2011 M. Shao et al. 2011 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/11/5011/2011/acp-11-5011-2011.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/11/5011/2011/acp-11-5011-2011.pdf

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 = CCl<sub>2</sub> (trichloroethylene, TCE), CH<sub>2</sub>Cl<sub>2</sub> (dichloromethane, DCM), CH<sub>3</sub> Br (bromomethane), HCFC-22, CHCl<sub>3</sub> (trichloromethane), CCl<sub>4</sub> (tetrachloromethane), Cl<sub>2</sub>C = CCl<sub>2</sub> (perchloroethylene, PCE), CH<sub>3</sub>CCl<sub>3</sub> (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 CH<sub>2</sub>Cl<sub>2</sub> (7.0 Gg), CH<sub>3</sub>CCl<sub>3</sub> (6.7 Gg), and Cl<sub>2</sub>C = CCl<sub>2</sub> (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 CCl<sub>4</sub>, CHCl<sub>3</sub>, CH<sub>3</sub>Br, and CH<sub>3</sub>Cl, 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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