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We analyzed the N2O content of surface seawater sampled from Prydz Bay, Antarctica, on a cruise track between 30°S and 30°N during the twenty-second Chinese National Antarctic Research Expedition during austral summer, 2006. The surface water showed an average pN 2 O value of 311.9±7.6 nL·L -1 (14.1±0.4 nmol·L -1 ), which was slightly undersaturated. The air-sea N 2 O flux in the region was -0.3±0.8 μmol·m -2 ·d -1 ; however, N 2 O in the surface water was oversaturated in most stations along the cruise track. Saturation anomalies were greater than 10%, with a maximum of 54.7% being observed at the Equator, followed by 31% at 10°N in the Sulu Sea. The air-sea fluxes at these locations were 12.4 and 4 μmol·m -2 ·d -1 , respectively. Overall, the results indicated that surface water in Prydz Bay was near equilibrium with atmospheric N 2 O, and that ocean waters in lower latitudes acted as a N 2 O source. Physical processes such as stratification, ice-melt water dilution, and solar radiation dominate the factors leading to N 2 O saturation of surface water of Prydz Bay, while biological production and upwelling are primarily responsible for the N 2 O oversaturation of surface water observed in subtropical and tropical regions along the cruise track.
We analyzed the N2O content of surface seawater sampled from Prydz Bay, Antarctica, on a cruise track between 30 ° S and 30 ° N during the twenty-second Chinese National Antarctic Research Expedition during a summer, 2006. The surface water showed an average pN 2 O value of 311.9 ± 7.6 nL·L -1 (14.1 ± 0.4 nmol·L -1), which was slightly undersaturated. The air-sea N 2 O flux in the region was -0.3 ± 0.8 μmol · m -2 · Saturation anomalies were greater than 10%, with a maximum of 54.7% being observed at the Equator, followed by 31% at 10 ° N in the Sulu Sea. The air-sea fluxes at these locations were 12.4 and 4 μmol · m -2 · d -1, respectively. Overall, the results indicated that surface water in Prydz Bay was near equilibrium with atmospheric N 2 O, and that ocean waters in lower latitudes acted as a N 2 O source. Physical processes such as stratification, ice-melt water dilution, an d solar radiation dominate the factors leading to N 2 O saturation of surface water of Prydz Bay, while biological production and upwelling are responsible for the N 2 O oversaturation of surface water observed in subtropical and tropical regions along the cruise track.