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 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.