Global reduction of in situ CO2 transfer velocity by natural surfactants in the sea-surface microlayer. (12th February 2020)

• Record Type: Journal Article
• Authors: Mustaffa, Nur Ili Hamizah; Ribas-Ribas, Mariana; Banko-Kubis, Hanne M.; Wurl, Oliver
• Is Part Of: Proceedings. Volume 476:Number 2234(2020)
• Publication Date: 2020-02-12
• Subjects: air–sea gas exchange -- surfactant -- slick -- Western Pacific -- Norwegian fjords; Physical sciences -- Periodicals; Engineering -- Periodicals; Mathematics -- Periodicals; 500
• DOI: 10.1098/rspa.2019.0763
• Languages: English
• ISSNs: 1364-5021

Abstract

Abstract : For decades, the effect of surfactants in the sea-surface microlayer (SML) on gas transfer velocity ( k ) has been recognized; however, it has not been quantified under natural conditions due to missing coherent data on in situ k of carbon dioxide (CO2 ) and characterization of the SML. Moreover, a sea-surface phenomenon of wave-dampening, known as slicks, has been observed frequently in the ocean and potentially reduces the transfer of climate-relevant gases between the ocean and atmosphere. Therefore, this study aims to quantify the effect of natural surfactant and slicks on the in situ k of CO2 . A catamaran, Sea Surface Scanner (S 3 ), was deployed to sample the SML and corresponding underlying water, and a drifting buoy with a floating chamber was deployed to measure the in situ k of CO2 . We found a significant 23% reduction of k above surfactant concentrations of 200 µg Teq l −1, which were common in the SML except for the Western Pacific. We conclude that an error of approximately 20% in CO2 fluxes for the Western Pacific is induced by applying wind-based parametrization not developed in low surfactant regimes. Furthermore, we observed an additional 62% reduction in natural slicks, reducing global CO2 fluxes by 19% considering known frequency of slick coverage. From our observation, we identified surfactant concentrations with two different end-members which lead to an error in global CO2 flux estimation if ignored.