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Nitrous oxide (N₂O) is the third most important greenhouse gas in the atmosphere, and the ocean is an important source of N₂O. As the Arctic Ocean is strongly affected by global warming, rapid ice melting can have a significant impact on the N₂O pattern in the Arctic environment. To better understand this impact, N₂O concentration in ice core and underlying seawater (USW) was measured during the seventh Chinese National Arctic Research Expedition (CHINARE2016). The results showed that the average N₂O concentration in first-year ice (FYI) was 4.5 ± 1.0 nmol kg⁻¹, and that in multi-year ice (MYI) was 4.8 ± 1.9 nmol kg⁻¹. Under the influence of exchange among atmosphere-sea ice-seawater systems, brine dynamics and possible N₂O generation processes at the bottom of sea ice, the FYI showed higher N₂O concentrations at the bottom and surface, while lower N₂O concentrations were seen inside sea ice. Due to the melting of sea ice and biogeochemical processes, USW presented as the sink of N₂O, and the saturation varied from 47.2% to 102.2%. However, the observed N₂O concentrations in USW were higher than that of T-N₂O_USW due to the sea–air exchange, diffusion process, possible N₂O generation mechanism, and the influence of precipitation, and a more detailed mechanism is needed to understand this process in the Arctic Ocean.