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Environ Sci Technol. 2020 Mar 12. doi: 10.1021/acs.est.9b06433. [Epub ahead of print]

Investigation of East Asian Emissions of CFC-11 Using Atmospheric Observations in Taiwan.

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Centre for Oceanography and Atmospheric Science, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, U.K.
School of Environmental and Geographical Sciences, University of Nottingham Malaysia, 43500 Semenyih, Malaysia.
Research Center for Environmental Changes, Academia Sinica, Taipei 11529, Taiwan.
National Centre for Atmospheric Science, University of East Anglia, Norwich NR4 7TJ, U.K.
Department of Atmospheric Sciences, National Central University, Taoyuan 320, Taiwan.
National Centre for Atmospheric Science, Department of Chemistry, University of Leicester, Leicester LE1 7RH, U.K.


Recent findings of an unexpected slowdown in the decline of CFC-11 mixing ratios in the atmosphere have led to the conclusion that global CFC-11 emissions have increased over the past decade and have been attributed in part to eastern China. This study independently assesses these findings by evaluating enhancements of CFC-11 mixing ratios in air samples collected in Taiwan between 2014 and 2018. Using the NAME (Numerical Atmospheric Modeling Environment) particle dispersion model, we find the likely source of the enhanced CFC-11 observed in Taiwan to be East China. Other halogenated trace gases were also measured, and there were positive interspecies correlations between CFC-11 and CHCl3, CCl4, HCFC-141b, HCFC-142b, CH2Cl2, and HCFC-22, indicating co-location of the emissions of these compounds. These correlations in combination with published emission estimates of CH2Cl2 and HCFC-22 from China, and of CHCl3 and CCl4 from eastern China, are used to estimate CFC-11 emissions. Within the uncertainties, these estimates do not differ for eastern China and the whole of China, so we combine them to derive a mean estimate that we term as being from "(eastern) China". For 2014-2018, we estimate an emission of 19 ± 5 Gg year-1 (gigagrams per year) of CFC-11 from (eastern) China, approximately one-quarter of global emissions. Comparing this to previously reported CFC-11 emissions estimated for earlier years, we estimate CFC-11 emissions from (eastern) China to have increased by 7 ± 5 Gg year-1 from the 2008-2011 average to the 2014-2018 average, which is 50 ± 40% of the estimated increase in global CFC-11 emissions and is consistent with the emission increases attributed to this region in an earlier study.


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