es9b06433_si_001.pdf (1.62 MB)
Investigation of East Asian Emissions of CFC-11 Using Atmospheric Observations in Taiwan
journal contribution
posted on 2020-03-12, 13:08 authored by Karina E. Adcock, Matthew J. Ashfold, Charles C.-K. Chou, Lauren J. Gooch, Norfazrin Mohd Hanif, Johannes C. Laube, David E. Oram, Chang-Feng Ou-Yang, Marios Panagi, William T. Sturges, Claire E. ReevesRecent 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.