Journal of Marine Sciences ›› 2023, Vol. 41 ›› Issue (2): 94-103.DOI: 10.3969/j.issn.1001-909X.2023.02.008

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A preliminary investigation on the spatial and temporal distribution of submarine groundwater discharge in the northern Beibu Gulf as indicated by 222Rn activities

SI Xiangcheng1,2(), CHEN Xiao1,2, CHEN Fajin1,2, JIN Guangzhe1,2,*(), SHI Ziyang1,2, XIE Xufeng1,2, CAI Hua3   

  1. 1. Laboratory for Coastal Ocean Variation and Disaster Prediction, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
    2. Key Laboratory of Climate, Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong Province, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
    3. Liaoning Provincial Public Resources Trading Center, Shenyang 110031, China
  • Received:2022-03-30 Revised:2022-10-18 Online:2023-06-15 Published:2023-07-27


The radioactive isotope radon-222(222Rn) is an inert element derived from the decay of uranium in the earth’s strata. Due to its stability, ease of measurement and significant difference in activity between groundwater and surface water, it has been widely used as a tracer in the study of submarine groundwater discharge (SGD) in recent years. In this study, the 222Rn activity of seawater was selected as the object of study, and the spatial and temporal characteristics of 222Rn were analyzed, and the SGD flux was estimated through a 222Rn mass balance model, based on two cruises of August-September, 2021 and December, 2021-January, 2022 from the northern Beibu Gulf. The results show a spatial and temporal variation of 222Rn distribution which was significantly affected by the terrestrial SGD process. The mean 222Rn activity decreased by about 40% in winter compared with that in summer. In summer, there show high 222Rn activity in bottom water especially from the northern part of the research area with a strong SGD process, but with low 222Rn activity in winter with weak SGD process. Based on the 222Rn mass balance model, the SGD fluxes of 4.16 cm·d-1 in summer and 2.88 cm·d-1 in winter were calculated from the research area, which shows significantly high SGD flux in summer dominant with nearshore SGD and low SGD flux in winter dominant with offshore SGD. Since the research area is surrounded by land and islands, the SGD processes were likely to be an important natural pathway for the terrestrial sources transporting to the nearshore waters.

Key words: submarine groundwater discharge (SGD), radon isotope (222Rn), mass balance model

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