The Distribution Of N₂O In Surface Seawater And Lower Atmosphere And Their Air-Sea Flux In The Southern Ocean

Triplicate air samples were taken during the 21st and 22nd Chinese Antarctic Expedition, and water samples were taken during the 22nd Chinese Antarctic Expedition. The samples were analyzed in lab. Result shows that:â‘´nitrous oxide was relative uniformly distributed in the atmosphere with in the range of about 310³20ppb, while it also fluctuated to some extent, which might caused by several factors. It was suggested that these fluctuation might due to land emission input, retreat of sea ice and the enhancement of productivity after melting of sea ice, also the hydrographic properties of the investigated sea area.⑵the distribution of nitrous oxide in sea water was unevenly along the cruise. The concentration of nitrous oxide was high at high latitude and low in tropical area. The highest concentration of nitrous oxide in the seawater was found at 62.62°S with concentration as high as 17.54±0.27nM, while the lowest concentration of 5.67±0.17nM was found at 16.72°N. The distribution of nitrous oxide was fluctuated between 30°S～30°N, which might be result of influencing of high nitrous oxide concentration coastal waters between these latitudes, while in the southern ocean, the concentration of nitrous oxide in surface water increase along the cruise with increasing of latitude, while it was also somewhat fluctuated. The correlation between concentration and SST and other factors in this area shows that the concentration of nitrous oxide in the surface seawater was significant controlled by the SST, while the correspondence between nitrous oxide concentration abnormity of surface seawater and oceanic frontal structure suggest that the concentration of dissolved nitrous oxide is also influenced by hydrographic properties. And the correspondence of N₂O partial pressure between the surface seawater and atmosphere also shows that the atmospheric nitrous oxide concentration might be influenced by ocean and land.⑶The average air-sea flux of nitrous oxide of the whole cruise during 22nd Expedition was 2.12±1.14μmol m-2d-1. as a whole, Southern ocean was source of atmospheric nitrous oxide during the expedition, with average value of 1.70±0.95μmol m-2d-1, while the area north of 48⁵5°S act as a source and south of 48⁵5°S turn into a sink. On the other hand, the latitudes between 30°S³0°N act as a source of nitrous oxide with air sea flux of 3.62±1.03μmol m-2d-1.â‘·the air-sea flux of Pryze bay was about -1.70±0.95μmol m-2d-1 during cruise. The formation of weak sink might due to the diluted of surface waters and strong stratification during the summer time, which hamper the...