Accelerating growth of HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) in the atmosphere

Abstract

We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in air samples originating from remote regions of the atmosphere and present evidence for its accelerating growth. Observed mixing ratios ranged from below 0.01 ppt in deep firn air to 0.59 ppt in the current northern mid-latitudinal upper troposphere. Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.029 ppt per year in 2000 to 0.056 ppt per year in 2007. Upper tropospheric air samples provide evidence for a continuing growth until late 2009. Furthermore we calculated a stratospheric lifetime of 370 years from measurements of air samples collected on board high altitude aircraft and balloons. Emission estimates were determined from the reconstructed atmospheric trend and suggest that current "bottom-up" estimates of global emissions for 2005 are too high by a factor of three

Evaluation of stratospheric age-of-air from CF<sub>4</sub>, C<sub>2</sub>F<sub>6</sub>, C<sub>3</sub>F<sub>8</sub>, CHF<sub>3</sub>, HFC-125, HFC-227ea and SF<sub>6</sub>; implications for the calculations of halocarbon lifetimes, fractional release factors and ozone depletion potentials

“…These measurements have been published either as time series or as comparisons to other long-term data sets for SF6 , C2F6 (Trudinger et al, 2016), C3F8 (Trudinger et al, 2016;Ray et al, 2017), CHF3 (Oram et al, 1998), and HFC-227ea (Laube et al 2010a;Ray et al, 2017). UEA HFC-125 has not been published previously, but the UEA data agrees very well with Advanced Global Atmospheric Gases Experiment (AGAGE) CG observations 100 (data not shown).…”

“…Briefly, analysis is performed using an in-house built manual cryogenic extraction and pre-85 concentration system connected to an Agilent 6890 gas chromatograph and a high-sensitivity tri-sector mass spectrometer. Full details of the analytical system can be found in Laube et al (2010aLaube et al ( , 2016. Of note is the instrument change detailed in Laube et al (2016) whereby C2F6 precision is improved by analysing samples on a KCl-passivated Al-PLOT column, alongside measurements of SF6, C3F8, CHF3, HFC-125, and HFC-227ea with an Agilent GS GasPro column.…”

“…B34 SF6 data were provided by the Goethe University Frankfurt. Sample collection and campaign details for OB09, K2010 and K2011 are discussed in and OB09 and B44 are discussed in Laube et al (2010a). The B34 campaign used the same equipment outlined in B44.…”

Stable carbon isotope fractionation in the UV photolysis of CFC-11 and CFC-12

“…The gas mixture used in the experiments was prepared using a custom dilution system with sample loops of 2.5 and 0.1 mL (Laube et al, 2010b). This system is built into a HP5890 GC oven and is maintained at 353 K to ensure that compounds are in the gas phase when they are diluted.…”

Rainwater trifluoroacetic acid (TFA) in Guangzhou, South China: Levels, wet deposition fluxes and source implication

“…But halothane and isoflurane anesthetics formed TFA mainly through metabolism other than oxidative degradation in the atmosphere. Mixing ratios of HFC-227ea reported in the northern mid-latitudinal upper troposphere were lower than 1.0 pptv (Laube et al, 2010;Vollmer et al, 2011). Besides, HFC-227ea has a lifetime of 34 years (http://www.…”