Submarine groundwater discharge and chemical behavior of tracers in Laizhou Bay, China

Publication date: September 2018
Source:Journal of Environmental Radioactivity, Volume 189
Author(s): Yan Zhang, Hailong Li, Xuejing Wang, Chaoyue Wang, Kai Xiao, Wenjing Qu
Naturally occurring radon (²²²Rn) and radium isotopes are widely used to trace water mixing and submarine groundwater discharge (SGD) in the coastal zones. However, their activities in groundwater are variable both spatially and temporally. Here, time series sampling of ²²²Rn and radium was conducted to investigate their behavior in intertidal groundwater of Laizhou Bay, China. The result shows that groundwater redox conditions have an important impact on the behavior of tracers. The activities of tracers will decrease under oxidizing conditions and increase under reducing conditions. Radon and radium mass balance models were used to evaluate the flushing time and SGD based on spatial surveys in Laizhou Bay. The flushing time is estimated to be 32.9–55.3 d with coupled models, which agrees well with the result of tidal prism model. The trace-derived SGD in the whole bay ranges from 6.1 × 10⁸ to 9.0 × 10⁸ m³/d and the re-circulated seawater (RSGD) ranges from 5.5 × 10⁸ to 8.5 × 10⁸ m³/d. The average SGD and RSGD fluxes are 22.8 and 21.1 times greater than the Yellow River discharge in April 2014, respectively. The study provides a better understanding of the dynamics of coastal groundwater and behavior of tracers in a well-studied bay system.



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