EGU21-4601, updated on 23 Sep 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Suppression of air-sea CO2 transfer by surfactants – direct evidence from the Southern Ocean

Mingxi Yang1, Timothy Smyth1, Vassilis Kitidis1, Ian Brown1, Charel Wohl1, Margaret Yelland2, and Thomas Bell1
Mingxi Yang et al.
  • 1Plymouth Marine Laboratory, Plymouth, United Kingdom of Great Britain – England, Scotland, Wales (
  • 2National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom

Uncertainty in the CO2 gas transfer velocity (K660) severely limits the accuracy of air-sea CO2 flux calculations and hence hinders our ability to produce realistic climate projections.  Recent field observations have suggested substantial variability in K660, especially at low and high wind speeds.  Laboratory experiments have shown that naturally occurring surface active organic materials, or surfactants, can suppress gas transfer.  Here we provide direct open ocean evidence of gas transfer suppression due to surfactants from a ~11,000 km long research expedition by making measurements of the gas transfer efficiency (GTE) along with direct observation of K660.  GTE varied by 20% during the Southern Ocean transect and was distinct in different watermasses.  Furthermore GTE correlated with and can explain about 9% of the scatter in K660, suggesting that surfactants exert a measurable influence on air-sea CO2 flux.  Relative gas transfer suppression due to surfactants was ~30% at a global mean wind speed of 7 m s-1 and was more important at lower wind speeds.  Neglecting surfactant suppression may result in substantial spatial and temporal biases in the computed air-sea CO2 fluxes.

How to cite: Yang, M., Smyth, T., Kitidis, V., Brown, I., Wohl, C., Yelland, M., and Bell, T.: Suppression of air-sea CO2 transfer by surfactants – direct evidence from the Southern Ocean, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4601,, 2021.


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