Distribution and Driving Mechanism of N 2 O in Sea Ice and Its Underlying Seawater during Arctic Melt Season

• Published in: Water
• Main Authors: Jian Liu, Liyang Zhan, Qingkai Wang, Man Wu, Wangwang Ye, Jiexia Zhang, Yuhong Li, Jianwen Wen, Liqi Chen
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2022
• Subjects: nitrous oxide; Arctic Ocean; sea ice; underlying seawater; ice melting; Hydraulic engineering; TC1-978; Water supply for domestic and industrial purposes; TD201-500; Arctic; Global warming; ice core; Sea ice
• Online Access: https://doi.org/10.3390/w14020145; https://doaj.org/article/429b1a36a3dc4c6aa4d98d0585d78b90

Nitrous oxide (N 2 O) is the third most important greenhouse gas in the atmosphere, and the ocean is an important source of N 2 O. As the Arctic Ocean is strongly affected by global warming, rapid ice melting can have a significant impact on the N 2 O pattern in the Arctic environment. To better understand this impact, N 2 O 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 N 2 O 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 N 2 O generation processes at the bottom of sea ice, the FYI showed higher N 2 O concentrations at the bottom and surface, while lower N 2 O concentrations were seen inside sea ice. Due to the melting of sea ice and biogeochemical processes, USW presented as the sink of N 2 O, and the saturation varied from 47.2% to 102.2%. However, the observed N 2 O concentrations in USW were higher than that of T-N 2 O USW due to the sea–air exchange, diffusion process, possible N 2 O generation mechanism, and the influence of precipitation, and a more detailed mechanism is needed to understand this process in the Arctic Ocean.