Nitrous oxide production by denitrifying microorganisms from the eastern tropical North Pacific and the Caribbean Sea

Abstract

Abstract Nitrous oxide production during denitrification was detected in near‐surface seawater samples from six stations in the eastern tropical North Pacific and the Caribbean Sea. Seawater from particulate maxima was collected, concentrated by filtration, and incubated under conditions favoring denitrification. Nitrate supplementation and acetylene blockage were used in some cases to enhance accumulation of N2O. N2O production was observed at all stations. The sampling regime indicates that particulate‐associated microorganisms were responsible for the production of N2O. In the eastern tropical North Pacific, in situ nitrate concentrations supported denitrification, but in the Caribbean Sea, nitrate supplements were required before significant denitrification occurred. N2O production was observed both with and without C2H2 blockage. These results show that denitrifying microorganisms are common in near‐surface particulate maxima and are potential sources of N2O in oceanic waters.