Nitrous oxide fluxes in Caribbean and tropical Atlantic waters: evidence for near surface production

Nitrous oxide is recognized as a potent greenhouse gas and an intermediate in the destruction of stratospheric ozone, as well as a source of tropospheric ozone. We present data on the vertical and latitudinal distribution of nitrous oxide and estimation of fluxes across the sea–air and thermocline interfaces in tropical ocean waters north and south of Puerto Rico. Air–sea nitrous oxide fluxes computed from data collected during April 1995 and June 1996 are comparable to rates reported for marginal seas. However, close to 70% of the sea–air flux is not accounted for by cross-thermocline flux. Although the effect of physical processes cannot be ruled out as a factor in this differential at all locations, our observations provide evidence for active nitrous oxide production in near-surface tropical waters.