Submarine groundwater discharge (SGD), including both land-based fresh groundwater that enters the ocean from coastal aquifers as well as recirculated seawater that is continuously recharged and discharged on the seabed, has been considered as an important component of the global water and biogenic element (e.g., nitrogen, phosphorus, silicon and carbon) sources and a significant pathway for material exchange at the land-sea interface of coastal ecosystems. Some researchers reported that SGD associated nutrient additions to coastal waters have caused unwanted ecological issues, including red tides, coastal acidification and hypoxia. Natural radon isotope (²²²Rn, t_1/2 = 3.8 _d) is an excellent tracer for studying SGD and other oceanographic processes including air-sea gas exchange, sediment-water diffusion, and earthquake prediction. However, the conventional radon measurement methods suffer many technical disadvantages. We consequently developed a convenient submersible radon determination approach (“OUC-Rn”) using a commercial pulsed ionization chamber (PIC) radon sensor and gas extraction membrane module to produce high precision and high resolution observations. We demonstrate the radon degassing efficiency of the membrane contactor is comparable to the shower-head type air-water exchanger but is independent of operating position. The radon measurement efficiency of the PIC is 2-fold higher than the RAD7 detector and is far less influenced by moisture. We successfully deployed the system in 2.5 meters water depth over a 100 hours period in an anthropogenic influenced bay. Based on our high temporal resolution observations, the SGD flux was estimated to be 0-43.0 cm/d (mean: 25.4 ± 14.5 cm/d). The SGD fluxes pattern plotted together with the tidal variations revealed that tidal pumping may be the main force driving seawater recirculation into aquifers and thus affecting nutrient, carbon and other dissolved matters dynamics in coastal regions.

海底地下水排放（SGD），包括从沿海含水层进入海洋的陆基淡水地下水以及在海床上不断补给和排放的再循环海水，被认为是全球水和生物成因的重要组成部分（例如，氮、磷、硅和碳）来源和沿海生态系统陆海界面物质交换的重要途径。一些研究人员报告说，向沿海水域添加与 SGD 相关的营养物质已导致不必要的生态问题，包括赤潮、沿海酸化和缺氧。天然氡同位素 ( ²²² Rn, t _1/2 = 3.8 _d) 是研究 SGD 和其他海洋学过程（包括海气交换、沉积物-水扩散和地震预测）的出色示踪剂。然而，传统的氡测量方法存在许多技术缺陷。因此，我们使用商用脉冲电离室 (PIC) 氡传感器和气体提取膜模块开发了一种方便的潜水式氡测定方法 (“OUC-Rn”)，以产生高精度和高分辨率的观测结果。我们证明了膜接触器的氡气脱气效率与喷头式空气-水交换器相当，但与操作位置无关。PIC 的氡气测量效率是 RAD7 探测器的 2 倍，并且受水分的影响要小得多。我们在 2 中成功部署了系统。在人为影响的海湾中，100 小时内水深 5 米。根据我们的高时间分辨率观察，SGD 通量估计为 0-43.0 cm/d（平均值：25.4 ± 14.5 cm/d）。与潮汐变化一起绘制的 SGD 通量模式表明，潮汐抽吸可能是推动海水再循环进入含水层的主要动力，从而影响沿海地区的养分、碳和其他溶解物质的动态。