Journal of East China Normal University(Natural Science) ›› 2023, Vol. 2023 ›› Issue (3): 93-107.doi: 10.3969/j.issn.1000-5641.2023.03.010

• Estuary and Coastal Research • Previous Articles     Next Articles

Fluxes and influencing factors of dissolved CH4 in coastal wetlands

Ying ZHANG1, Xiaohui ZHANG1, Tingting LIU1, Zhixuan YANG1, Jianwu TANG1,2,3,*()   

  1. 1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
    2. Institute of Eco-Chongming, Shanghai 202162, China
    3. Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai Science and Technology Committee, Shanghai 200241, China
  • Received:2022-01-29 Accepted:2022-05-23 Online:2023-05-25 Published:2023-05-25
  • Contact: Jianwu TANG


The process of change and factors influencing dissolved CH4 concentration and flux in the coastal wetlands of Jiuduansha (JDS) and Xisha (XS) in the Yangtze Estuary were explored. The concentration of dissolved CH4 varied significantly during the sampling period, with the highest in JDS wetland being (0.30±0.19) μmol·L–1 during autumn, while that in XS wetland being (1.16±1.52) μmol·L–1 during summer. The average dissolved CH4 concentration in XS wetland ((0.56±0.91) μmol·L–1) was slightly higher than that in JDS wetland ((0.18±0.17) μmol·L–1). Principal component analysis revealed that the temporal and spatial variations in CH4 were mainly related to seasonal variation and tidal cycling in coastal wetlands. The CH4 emission under low-temperature, high-salinity, and oxygen-rich water environments was limited. The fluxes of dissolved CH4 also showed seasonal and regional variations. The water-to-air diffusion of CH4 was the largest in autumn in JDS wetlands ((0.45±0.43) nmol·m–2·s–1) and in summer in XS wetlands ((3.34±5.21) nmol·m–2·s–1). The lateral fluxes of dissolved CH4 were maximum in autumn in JDS wetlands ((2.32±9.32) nmol·m–2·s–1) and in summer in XS wetlands ((1.66±5.06) nmol·m–2·s–1). Use of water quality parameters and dissolved CH4 concentration to fit a multiple regression equation produced a high-frequency and continuous CH4 concentration. The annual average lateral transport flux (JDS wetland: 1.46 mg·m–2·d–1; XS wetland: 0.34 mg·m–2·d–1) and annual average vertical diffusion flux (JDS wetland: 1.85 mg·m–2·d–1; XS wetland: 2.90 mg·m–2·d–1) of dissolved CH4 was calculated. The results show that dissolved CH4 in coastal wetlands is an important sources of CH4 in the atmosphere and coastal waters.

Key words: coastal wetland, dissolved CH4, in-situ continuous observation method, CH4 flux

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