National Oceanic and
Atmospheric Administration
United States Department of Commerce

Atmospheric Inputs of Chlorofluorocarbons

Atmospheric Inputs of Chlorofluorocarbons

Chlorofluorocarbons (CFCs)

  • CFC-11 (F-11) - CCl3F
  • CFC-12 (F-12) - CCl2F2
  • Carbon tetrachloride -  CCl4
  • Sulfur Hexafluoride - SF6
  • Nitrous Oxide - N2O

Each of these compounds has a unique history of increase in the atmosphere:  https://www.nodc.noaa.gov/ocads/oceans/CFC_ATM_Hist2015.html  Restrictions on CFC production and release in the 1980’s slowed CFC-11 (F11) and CFC-12 (F12) growth in the atmosphere, while sulfur hexafluoride (SF6) has continued to increase rapidly. These compounds dissolve in the surface ocean and measurements of the concentrations and ratios of these compounds can be used to provide useful age and rate information for oceanic processes.

Characteristics of CFCs as Time-Dependent Tracers in the Ocean

  • Anthropogenic
  • Well characterized input history
  • Conservative in seawater
  • Extraordinarily sensitive analytical techniques available, with current detection limits: CFC-12=0.002 pmol kg-1; SF6=0.00002 pmol kg-1 (1 pmol=1 picomole=10-12 mole)
  • Provide information on rates and pathways of ocean circulation and mixing processes
  • Useful in the estimation of the uptake of anthropogenic CO2 in the ocean
Line graph of northern hemisphere atmospheric concentrations: CFCs, CCL4 and SF6.

Northern Hemisphere Atmospheric Concentrations:  CFCs, CCL4 and SF6.