scholarly journals Submarine Groundwater Discharge in a Coastal Bay: Evidence from Radon Investigations

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2552
Author(s):  
Manhua Luo ◽  
Yan Zhang ◽  
Hailong Li ◽  
Xuejing Wang ◽  
Kai Xiao
Keyword(s):  
Submarine Groundwater Discharge ◽  
Anthropogenic Activities ◽  
Jiaozhou Bay ◽  
Groundwater Discharge ◽  
Dry Season ◽  
Balance Model ◽  
Wet Season ◽  
Discharge Rates ◽  
Submarine Groundwater ◽  
Coastal Bay

Jiaozhou Bay, an urbanized coastal bay located in the southern part of Shandong Peninsula, China, has been deeply affected by anthropogenic activities. Here, the naturally occurring 222Rn isotope was used as a tracer to assess the submarine groundwater discharge (SGD) in this bay. The time series of 222Rn concentrations in nearshore seawater were monitored continuously over several tidal cycles at two fixed sites (Tuandao (TD) and Hongdao (HD)) during the dry season in spring and the wet season in autumn of 2016. 222Rn concentrations in seawater were negatively related to the water depth, indicating the influence of tidal pumping. A 222Rn mass balance model revealed that the mean SGD rates were 21.9 cm/d at TD and 17.8 cm/d at HD in the dry season, and were 19.5 cm/d at TD and 26.9 cm/d at HD in the wet season. These rates were about 8–14 times the discharge rates of the local rivers. Enhanced groundwater inputs occurred at HD in the wet season, likely due to the large tidal amplitudes and the rapid response to local precipitation. Large inputs of SGD may have important influences on nutrients levels and structure, as well as the water eutrophication occurring in coastal waters.

scholarly journals Temporal Variations of Submarine Groundwater Discharge into a Tide-Dominated Coastal Wetland (Gaomei Wetland, Western Taiwan) Indicated by Radon and Radium Isotopes

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1806 ◽  
Author(s):  
Feng-Hsin Hsu ◽  
Chih-Chieh Su ◽  
Pei-Ling Wang ◽  
In-Tian Lin
Keyword(s):  
Coastal Waters ◽  
Seasonal Changes ◽  
Submarine Groundwater Discharge ◽  
Coastal Wetland ◽  
Groundwater Discharge ◽  
High Tide ◽  
Dry Season ◽  
Wet Season ◽  
Submarine Groundwater ◽  
Δd And Δ18o

Submarine groundwater discharge (SGD) is evidenced around Taiwan, but the seasonal/temporal changes of SGD have not been fully examined. Here, we report a time-series investigation of SGD into a tide-dominated coastal wetland, the Gaomei Wetland, located to the south of the Da-Chia River’s mouth, western Taiwan, by using environmental tracers (222Rn, 224Raex, 228Ra, δD, and δ18O). Our results showed that regardless of dry and wet seasons, the 222Rn activities in coastal waters were high at low tide but low at high tide. It represents the continuous input of 222Rn-enriched groundwater. However, the 224Raex and 228Ra activities showed seasonal changes with tide conditions. In the dry season, the 224Raex and 228Ra activities in coastal waters were low at low tide but high at high tide; whereas in the wet season, an opposite relation was observed with quite high 224Raex and 228Ra activities in the low-tide waters. Coupled with the lower δD and δ18O values of coastal and pore waters in the dry season, in comparison to those in the wet season, it is suggested that these phenomena probably reflected a seasonal difference in the main SGD component with fresh SGD in the dry season, but saline ones in the wet season. Based on a 222Rn mass balance model, the estimated SGD fluxes into the Gaomei Wetland varied with tidal fluctuations and ranged from 0.2 to 25 cm d−1 and from 0.1 to 47 cm d−1 for the dry and wet seasons, respectively. A slightly high SGD flux occurring during the wet season at spring tide, implied a stronger tidal pumping coupled with a larger hydraulic gradient between land and sea. In this study, we demonstrated that the variation of SGD into the Gaomei Wetland is not only controlled by the seasonal changes of groundwater recharge, but also by the tidal pumping process.

scholarly journals Submarine Groundwater Discharge From Sediments and Sand Boils Quantified by the Mean Residence Time of a Tracer Injection

2021 ◽  
Vol 9 ◽  
Author(s):  
Michael Schlüter ◽  
Philipp Maier
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Tracer Injection ◽  
Discharge Rates ◽  
Seepage Meter ◽  
Submarine Groundwater ◽  
Sand Boils ◽  
The Mean

To quantify submarine groundwater discharge, we developed an inexpensive automated seepage meter that applies a tracer injection and the computation of the mean residence time. The SGD-MRT is designed to measure a wide range of discharge rates from about 30 to 800 cm³/min and allows minimizing backpressures caused by pipe friction or flow sensors. By modifying the inner volume of the flow-through unit, the range of measurement is adjustable to lower or higher discharge rates. For process control and data acquisition, an Arduino controller board is used. In addition, components like temperature, conductivity, and pressure sensors or pumps extend the scope of the seepage meter. During field tests in the Wadden Sea, covering tidal cycles, discharge rates of more than 700 cm³/min were released from sand boils. Based on the measured discharge rates and numerical integration of the time series data, a water volume of about 400 dm3 with a seawater content of less than 12% was released from the sand boil within 7 h.

Geochemical tracers in submarine groundwater discharge research: practice and challenges from a view of climate changes

2020 ◽  
Author(s):  
Shan Jiang ◽  
Juan Severino Pino Ibánhez ◽  
Ying Wu ◽  
Jing Zhang
Keyword(s):  
Submarine Groundwater Discharge ◽  
Climate Changes ◽  
Groundwater Discharge ◽  
Economic Losses ◽  
Geochemical Tracers ◽  
Algae Blooms ◽  
Discharge Rates ◽  
Submarine Groundwater ◽  
Application Requirements ◽  
Temperature Water

Submarine groundwater discharge (SGD), the flux of porewater from permeable seabed or karst conduits to surface water bodies delivers a significant quantity of land-borne solutes to coastal oceans. This input of land-derived solutes is frequently linked with eutrophication, harmful algae blooms and benthic hypoxia, and hence has the potential to trigger great economic losses. Geophysical and geochemical tracers, including salinity, temperature, water stable isotopes and radioactive elements, have been widely applied in SGD studies for more than 50 years in order to, amongst others, identify water sources, estimate residence times and quantify discharge rates. Here we review advantages and shortcomings of these tracers in the study of SGD. Application requirements are outlined based on previous research and combined tracer approaches in karst environments, permeable coasts and estuaries are illustrated under the view of climate changes. Current challenges with the use of geochemical tracers in SGD studies are highlighted and opportunities to develop these tracers for improved coastal management showcased.

Evaluation of submarine groundwater discharge into the northern Bohai Bay, China using 226Ra

2015 ◽  
Vol 16 (2) ◽  
pp. 362-368 ◽  
Author(s):  
Xuejing Wang ◽  
Hailong Li ◽  
Yan Zhang ◽  
Chaoyue Wang ◽  
Wenjing Qu ◽  
...  
Keyword(s):  
Mass Balance ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Balance Model ◽  
Return Flow ◽  
Bohai Bay ◽  
Mass Balance Model ◽  
Material Transport ◽  
Radium Isotope ◽  
Submarine Groundwater

Submarine groundwater discharge (SGD) has been widely recognized as a significant source of water and dissolved material transport from land to ocean. To quantify SGD into the northern Bohai Bay, China, naturally occurring radium isotope (226Ra) was measured in water samples collected along two transects in September 2012. Based on a tidal prism model, two different flushing times of the coastal water were determined to be 9.1 d and 11.5 d with respect to the different return flow factor (b) obtained from a physical model and a mass balance model of 226Ra and salinity, respectively. Using the derived flushing time, we developed a 226Ra mass balance model to estimate the SGD into the bay, which includes mixing, sedimentary input and SGD. The 226Ra budget indicated the 226Ra input from SGD accounted for 99% of the total tracer input to the northern Bohai Bay. We arrived at an average flux from SGD of 4.83 × 107 m3/d. The large volume of SGD confirms its importance in supplying a considerable quantity of nutrients to the bay.

Estimating coastal mixing rates and submarine groundwater discharge (SGD) in Guangdong-HongKong-Macau Greater Bay Area, China using radium isotopes

2020 ◽  
Author(s):  
Xuejing Wang ◽  
Hailong Li ◽  
Chunmiao Zheng
Keyword(s):  
Diffusion Coefficient ◽  
Submarine Groundwater Discharge ◽  
Hydrological Cycle ◽  
Groundwater Discharge ◽  
Balance Model ◽  
Material Transport ◽  
Radium Isotopes ◽  
Bay Area ◽  
Submarine Groundwater ◽  
Mixing Rates

<p>As a major component of the hydrological cycle, submarine groundwater discharge (SGD) has been widely recognized as a significant source of water and an important pathway for dissolved material transport from land to ocean. Natural radium isotopes are recognized as ideal tracers for effective and efficient assessment of SGD in local scales and global scales since they are conservative chemically and widely enriched in SGD. Here we report the estimates of coastal mixing rates and SGD in Guangdong-HongKong-Macau Greater Bay Area, China using radium isotopes. The distributions of short-lived <sup>223</sup>Ra, <sup>224</sup>Ra and long-lived <sup>228</sup>Ra in seawater and coastal groundwater were investigated. Based on the horizontal distribution of short-lived Ra and a mixing model, the horizontal eddy diffusion coefficient in the region was estimated to be 230-1085 m<sup>2</sup>/s. The offshore fluxes of <sup>228</sup>Ra can be derived from their across-shelf activity gradients and the eddy horizontal diffusion coefficient. Such <sup>228</sup>Ra fluxes require a substantial volume of groundwater discharge to balance Ra removal, and thus SGD can be estimated via radium mass balance model.</p>

Improving Estimation of Submarine Groundwater Discharge Using Radium and Radon Tracers: Application in Jiaozhou Bay, China

2017 ◽  
Vol 122 (10) ◽  
pp. 8263-8277 ◽  
Author(s):  
Yan Zhang ◽  
Hailong Li ◽  
Kai Xiao ◽  
Xuejing Wang ◽  
Xiaoting Lu ◽  
...  
Keyword(s):  
Submarine Groundwater Discharge ◽  
Jiaozhou Bay ◽  
Groundwater Discharge ◽  
Submarine Groundwater
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