Chinese Journal of Polar Research

Chinese Journal of Polar Research ›› 2024, Vol. 36 ›› Issue (4): 555-568.DOI: 10.13679/j.jdyj.20230062

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Distributions, fluxes and influencing factors of dissolved CH4 in the Kongsfjorden and the Bayelva river in Spitsbergen, Arctic#br#

ZHANG Ziqiang1, 2, DU Guanxiang1, 2, YIN Hang1, ZHU Zhuoyi3, ZHANG Ruifeng3, JIN Jie4, ZHANG Guosen4, ZHANG Guiling1, 2   

  1. 1 Center for Frontier Science of Deep Oceanosphere and Earth System and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China;
    2 Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao 266237, China;
    3 School of Oceanology, Shanghai Jiao Tong University, Shanghai 200030, China;
    4 State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
  • Received:2023-10-09 Revised:2024-01-30 Online:2024-12-31 Published:2025-01-15

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Abstract: Methane (CH4) is an important greenhouse gas in the atmosphere, and the melting of permafrost caused by rapid warming in the Arctic has become a global hotspot for CH4 emissions. The distributions and fluxes of CH4 were investigated in the Kongsfjorden and the Bayelva River of the Ny-Ålesund of the Spitsbergen, during the Arctic Yellow River Station expeditions in August 2013 and August 2015. Dissolved CH4 concentrations in the surface water of the Bayelva River were 3.9~21.5 nmol·L–1 (average (12.6±6.4) nmol·L–1) and 3.9~21.1 nmol·L–1 (average 7.0±6.9 nmol·L–1) in August 2013 and August 2015, respectively, showing a general trend of increase downward. Dissolved CH4 concentrations in the Qingchuan and Bayelva River varied greatly in time and space, and were mainly influenced by basin area and the interaction of glacial meltwater input with sediment and atmosphere. Dissolved CH4 in the surface water of the Kongsfjorden was 6.3~37.3 nmol·L–1(average (13.1±8.2) nmol·L–1) and 4.3~22.2 nmol·L–1 (average (12.0±5.4) nmol·L–1) in August 2013 and August 2015, respectively, with higher values in the head and the mouth of the fjord and lower values in the middle of the fjord. Dissolved CH4 in the water column of Kongsfjorden was 5.7~37.3 nmol·L–1 (average (15.1±8.5) nmol·L–1) in August 2013. High CH4 concentrations were observed at the water depths of 100~250 m, mainly influenced by the release from the sediments and the transport of methane from the shelf water into the fjord. The distributions of methane in the fjord of the Spitsbergen were influenced by glacial meltwater inputs, mixing of water masses and seafloor sediments. Because of the oversaturation of dissolved CH4, Kongsfjorden and the Bayelva River were sources of atmospheric CH4. The air-sea CH4 fluxes of the surface waters of the Kongsfjorden were 0.4~12.4 nmol·L–1 (average (3.5±3.4) µmol·(m2·d)–1) and 2.0~4.6 µmol·(m2·d)–1 (average (3.2±0.9) µmol·(m2·d)–1) in August 2013 and August 2015, respectively.

Key words: Arctic, fjord, methane, glacier meltwater, river