High atmosphere-ocean exchange of organic carbon in the NE subtropical Atlantic -: art. no. L21807

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 (FDDOC, - 0.98 mmol C m(-2) d(-1)) and net CO2 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.