Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (4): 468-479.DOI: 10.13745/j.esf.sf.2022.2.71

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Submarine groundwater discharge in Longkou coastal zones under the influence of human activities

GUO Qiaona1,*(), ZHAO Yue1, ZHOU Zhifang1, LIN Jin2, DAI Yunfeng2, LI Mengjun1   

  1. 1. School of Earth Sciences and Engineering, Hohai University, Nanjing 211100, China
    2. Nanjing Hydraulic Research Institute, Nanjing 210029, China
  • Received:2021-10-21 Revised:2022-04-28 Online:2022-07-25 Published:2022-07-28
  • Contact: GUO Qiaona


The radium mass balance model based on 223Ra and 224Ra tracers has been widely used in the study of submarine groundwater discharge (SGD) in coastal zones. However, few researches are currently done to study the influence of human activities on SGD. In this paper, the water residence time, SGD flux and nutrient flux carried by SGD were compared between the Longkou coastal zones A and B, under the influence of two different human activities, namely an impervious dam in Zone A and land reclamation in Zone B. Results showed that the average water residence time in Zone A was 14.26 days and in Zone B 10.64 days. In addition, radium activities in groundwater and seawater in Zone B were generally higher than that in Zone A; whereas salinities were lower in Zone B than in Zone A. The discharge rates for SGD in Zone A ranged from 1.26 to 1.60 cm/d and in Zone B from 1.43 to 1.82 cm/d. Therefore the discharge rates for SGD in these two zones were comparable within the margin of error. However, the discharge rates for SGD were relatively low in these two zones compared to other natural coastal areas in the country. Moreover, the nitrogen and phosphorus nutrient concentrations in Zone B were generally higher than that in Zone A. The nitrogen and phosphorus nutrient fluxes carried by SGD were different in the two zones. Such unbalanced nutrient inputs from SGD could easily change the nutrient structure of the Longkou coastal zones, which has an adverse impact on the marine ecological environment, further confirming that SGD is important for coastal ecological environment and water pollution control.

Key words: submarine groundwater discharge, residence time, radium isotopes, nitrogen and phosphorus nutrients, human activities

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