High atmosphere‐ocean exchange of organic carbon in the NE subtropical Atlantic

The air‐sea exchange of organic carbon (OC) remains largely unexplored, except for few organic compounds comprising a small fraction of the total aerosol and gaseous OC in the atmosphere. Observations of high atmospheric concentrations and diffusive air‐sea exchanges for such individual organic compounds, suggest that air‐sea exchange of total OC may contribute significantly to the oceanic carbon budget. Here we quantify the atmosphere‐ocean exchanges of total OC in the NE Subtropical Atlantic. Average net gaseous diffusive air‐water fluxes averaged –31 and –25 mmol C m −2 d −1 for the spring and fall, respectively, exceeding measured OC inputs by dry aerosol deposition (FDD OC , −0.98 mmol C m −2 d −1 ) and net CO 2 exchange (F CO2 , −6.3 mmol C m −2 d −1 ). These fluxes are important to understand the regional carbon budget of the NE Subtropical Atlantic, and depict the atmosphere as a major dynamic vector for OC exchange with the ocean.