Oceanic N₂O is a major source of atmospheric N₂O and is involved in global warming and ozone depletion. It is thought to be mainly produced by nitrification, denitrification and nitrifier denitrification processes executed by ammonia-oxidizing bacteria (AOB) and archaea (AOA) and denitrifying bacteria. The Bering Sea, especially its continental shelf area, is considered a typical source of atmospheric N₂O. During the 7th Chinese National Arctic Research Expedition (CHINARE), the distributions of N₂O and ammonia-oxidizing microorganisms in the Bering Sea continental shelf and abyssal basin water were investigated. The results show that the distribution of N₂O in the surface water of the abyssal basin is mainly affected by temperature. At a depth of 50–900 m, N₂O production is mainly dominated by ammonia oxidation, and the ammonia oxidation substrates and products are rarely found below 1000 m, where supersaturated N₂O is likely generated as a result of ocean circulation. In addition, the surface layer of the Bering Sea shelf is a weak source of N₂O, and N₂O produced by ammonia oxidation and nitrifier denitrification executed by AOB is mainly a metabolic process below the thermocline. This work confirms that ammonia oxidation and nitrifier denitrification in the water column play a leading role in N₂O production in the Bering Sea.

N2O,Bering Sea,Ammonia oxidation process,Ammonia oxidizing bacteria (AOB),Ammonia-oxidizing archaea (AOA)