Dissolved organic carbon in the equatorial Atlantic Ocean

We measured the concentration of dissolved organic carbon (DOC) in the equatorial Atlantic Ocean, using a high-temperature carbon oxidation technique and platinized-quartz catalysts. Below 400 m, values are nearly homogeneous near 46 ± 7 μM C. Concentrations are higher, up to 97 μM C at the surface, outside of the equatorial upwelling during the warm season. They are somewhat lower, near 66 μM C on average, in upwelling waters during the cold season. These values are close to previously published data from the subtropical Atlantic Ocean, and to recent values for the Pacific Ocean. A box model of the equatorial upwelling suggests that only 20 ± 15% of the exported flux of total biogenic carbon is in dissolved form.