Publication Type:Journal Article
Source:Geophysical Research Letters, Volume 42, p.7817–7824 (2015)
Keywords:Constituent sources and sinks, Instruments and techniques, Middle atmosphere: constituent transport and chemistry, new compound, Troposphere: composition and chemistry
We report the first multiyear atmospheric record of HCFC-31 (CH2ClF), based on flask samples and in situ analyses of air from both hemispheres. Although HCFC-31 has never been produced in large amounts, observed mole fractions in the Northern Hemisphere increased from 2000 onward, reaching 170 ppq (parts per quadrillion, 10−15) in 2011–2012 before decreasing rapidly. By combining our observations with a two-dimensional atmospheric chemistry-transport model, we infer an increase in global emissions from 240 t yr−1 in 2000 to 840 t yr−1 in 2011–2012, followed by a relatively fast decline to 570 t yr−1 in 2014. Emissions of HCFC-31 originate most probably from intermediate product release during the manufacturing process of HFC-32 (CH2F2). The rapid decline in recent years could be due to changes in production methods rather than declines in diffusive sources such as landfills or HCFC-31 contaminations in merchandised HFC-32.