Journal of Marine Sciences ›› 2023, Vol. 41 ›› Issue (4): 1-11.DOI: 10.3969/j.issn.1001-909X.2023.04.001

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The seasonal blooming characteristics of phytoplankton and POC export flux in the waters around South Georgia Island: Based on BGC-Argo and satellite remote sensing observations

ZHAO Yueran1(), FAN Gaojing2, WU Jiaqi1,3, SUN Weiping1, PAN Jianming1, HAN Zhengbing1,*()   

  1. 1. Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, MNR, Hangzhou 310012, China
    2. Polar Research Institute of China, Shanghai 201209, China
    3. Ocean College, Zhejiang University, Zhoushan 316000, China
  • Received:2023-03-01 Revised:2023-05-05 Online:2023-12-15 Published:2024-01-30


The waters surrounding South Georgia Island are one of the highest primary productivity regions in the Southern Ocean with enormous carbon sequestration potential. However, the strength of the biological pump efficiency in this area is still uncertain due to the lack of continuous upper ocean observation data.In this study, the hydrological and biogeochemical parameters obtained from the Biogeochemical Argo (BGC-Argo) floats deployed in the South Georgia Island vicinity during the period of 2017-2020 were utilized to investigate the impacts of physical processes on biogeochemical processes and to estimate the carbon export flux in the Antarctic summer. Results indicated that both upstream (northeast of the Antarctic Peninsula) and downstream (Georgia Basin) regions of South Georgia Island exhibited strong seasonal characteristics in Chl-a, with the latter area having a 4-month sustained period of phytoplankton bloom, suggesting a stable and continuous supply of iron. Using the temporal variability of the seasonal particulate organic carbon (POC) export, the summer POC export fluxes of the upstream and downstream regions were estimated to be 7.12±3.90 mmol·m-2·d-1 and 45.29±5.40 mmol·m-2·d-1, respectively, indicating that the difference might be due to enhanced downward export of organic carbon after the deepening of the mixed layer. The study found that the region maintained a high biological pump efficiency, contrary to the previous conclusion that the Georgia Basin had “high productivity low export efficiency”, which might have been caused by the limited “real-time” representation of the entire seasonal characteristics during ship-based surveys. BGC-Argo provides high spatiotemporal resolution of multi-parameter observation data, and this study demonstrates that it can more accurately quantify and evaluate marine biogeochemical processes and carbon sequestration potential.

Key words: Southern Ocean, South Georgia Island, BGC-Argo, POC export production, Chl-a

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