LAUSR

This paper describes the quantification of extracellular carbonic anhydrase (eCA) concentrations in the sea surface microlayer (SML), the boundary layer between the ocean and the atmosphere of the Indo-West Pacific. We demonstrated that the SML is enriched with eCA by 1.5 ± 0.7 compared to the mixed underlying water. Enrichment remains up to a wind speed of 7 m s 1 (i.e., under typical oceanic conditions). As eCA catalyzes the interconversion of HCO3 and CO2, it has been hypothesized that its enrichment in the SML enhances the air-sea CO2 exchange. We detected concentrations in the range of 0.12 to 0.76 nM, which can enhance the exchange by up to 15% based on the model approach described in the literature.