The Atlantic Ocean surface microlayer from 50°N to 50°S is ubiquitously enriched in surfactants at wind speeds up to 13 m s⁻¹

We report the first measurements of surfactant activity (SA) in the sea surface microlayer (SML) and in subsurface waters (SSW) at the ocean basin scale, for two Atlantic Meridional Transect from cruises 50°N to 50°S during 2014 and 2015. Northern Hemisphere (NH) SA was significantly higher than Southern Hemisphere (SH) SA in the SML and in the SSW. SA enrichment factors (EF = SA_SML/SA_SSW) were also higher in the NH, for wind speeds up to ~13 m s⁻¹, questioning a prior assertion that Atlantic Ocean wind speeds >12 m s⁻¹ poleward of 30°N and 30°S would preclude high EFs and showing the SML to be self-sustaining with respect to SA. Our results imply that surfactants exert a control on air-sea CO₂ exchange across the whole North Atlantic CO₂ sink region and that the contribution made by high wind, high latitude oceans to air-sea gas exchange globally should be reexamined.