Journal of Marine Sciences ›› 2024, Vol. 42 ›› Issue (4): 58-69.DOI: 10.3969/j.issn.1001-909X.2024.04.006

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Distribution, flux and influencing factors of dissolved nitrous oxide in Hangzhou Bay and its adjacent waters in spring

XING Mingyao1,2,3(), LIN Hua2,3,*(), YANG Zhi2,3, WANG Bin2,3, LI Yangjie2,3, ZHANG Qianjiang3, CHEN Qianna2,3, ZHENG Hao1, CHEN Jianfang2,3   

  1. 1. Ocean College, Zhejiang University, Zhoushan 316021, China
    2. Key Laboratory of Marine Ecosystem Dynamics, MNR, Hangzhou 310012, China
    3. Second Institute of Oceanography, MNR, Hangzhou 310012, China
  • Received:2023-12-19 Revised:2024-02-12 Online:2024-12-15 Published:2025-02-08
  • Contact: LIN Hua

Abstract:

Based on a survey in Hangzhou Bay in March 2022, the distribution and sea-air exchange flux of N2O in Hangzhou Bay and its adjacent waters in spring were investigated, and the influencing factors were analyzed. The dissolved N2O concentration and saturation of surface water were 12.5-21.3 nmol·L-1 and 115%-183%, respectively. The average N2O concentration in the upper, middle and lower waters were 17.2±2.9, 14.1±0.8 and 13.2±0.7 nmol·L-1, respectively, and the average saturation were 151%±17%, 125%±6% and 123%±6%, respectively. Dissolved N2O in all sampling sites were in a supersaturated state. The spatial distribution of N2O concentration and saturation in the surface water exhibited significant variations, with high values concentrated in the upstream area and gradually decreasing from west to east, while these showed a decreasing trend from north to south in middle and lower areas. The distribution of N2O in the Hangzhou Bay and its adjacent waters was influenced by multiple factors such as temperature, estuarine mixing, river input and in situ bioproduction. The sea-air N2O exchange flux ranged from 11.4 to 71.2 μmol·m-2·d-1, with an average of 29.5±16.0 μmol·m-2·d-1. Comparing with other domestic estuaries and bays, this is relatively high in Hangzhou Bay, indicating a significant potential for N2O release. Combining the sea-air exchange flux and sea area, this study preliminarily estimated that the N2O emission in Hangzhou Bay and its adjacent waters in spring was 3.5×105 mol·d-1, indicating its important role in atmospheric N2O emissions.

Key words: Hangzhou Bay, Qiantang River, nitrous oxide, distribution feature, nitration, denitrification, sea-air exchange flux, source and sink pattern

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