Abstract: The first observations of the feedstocks, CFC-216ba (1,2-dichlorohexafluoropropane) and CFC-216ca (1,3-dichlorohexafluoropropane), as well as the CFC substitute HCFC-225ca (3,3-dichloro-1,1,1,2,2-pentafluoropropane), are reported in air samples collected between 1978 and 2012 at Cape Grim, Tasmania. Present day (2012) mixing ratios are 37.8 ± 0.08 ppq (parts per quadrillion; 1015) and 20.2 ± 0.3 ppq for CFC-216ba and CFC-216ca, respectively. The abundance of CFC-216ba has been approximately constant for the past 20 years, whilst that of CFC-216ca is increasing, at a current rate of 0.2 ppq/year. Upper tropospheric air samples collected in 2013 suggest a further continuation of this trend. Inferred annual emissions peaked 421 at 0.18 Gg/year (CFC-216ba) and 0.05 Gg/year (CFC-216ca) in the mid-1980s and then decreased sharply as expected from the Montreal Protocol phase-out schedule for CFCs. The atmospheric trend of CFC-216ca and CFC-216ba translates into continuing emissions of around 0.01 Gg/year in 2011, indicating that significant banks still exist or that they are still being used. HCFC-225ca was not detected in air samples collected before 1992. The highest mixing ratio of 52 ± 1 ppq was observed in 2001. Increasing annual emissions were found in the 1990s (i.e., when HCFC-225ca was being introduced as a replacement for CFCs). Emissions peaked around 1999 at about 1.51 Gg/year. In accordance with the Montreal Protocol, restrictions on HCFC consumption and the short lifetime of HCFC-225ca, mixing ratios declined after 2001 to 23.3 ± 0.7 ppq by 2012.
This is an open access article distributed under the
Creative Commons Attribution License which permits unrestricted use, distribution,
and reproduction in any medium, provided the original work is properly cited.
Export to BibTeX
MDPI and ACS Style
Kloss, C.; Newland, M.J.; Oram, D.E.; Fraser, P.J.; Brenninkmeijer, C.A.M.; Röckmann, T.; Laube, J.C. Atmospheric Abundances, Trends and Emissions of CFC-216ba, CFC-216ca and HCFC-225ca. Atmosphere 2014, 5, 420-434.
Kloss C, Newland MJ, Oram DE, Fraser PJ, Brenninkmeijer CAM, Röckmann T, Laube JC. Atmospheric Abundances, Trends and Emissions of CFC-216ba, CFC-216ca and HCFC-225ca. Atmosphere. 2014; 5(2):420-434.
Kloss, Corinna; Newland, Mike J.; Oram, David E.; Fraser, Paul J.; Brenninkmeijer, Carl A.M.; Röckmann, Thomas; Laube, Johannes C. 2014. "Atmospheric Abundances, Trends and Emissions of CFC-216ba, CFC-216ca and HCFC-225ca." Atmosphere 5, no. 2: 420-434.