scholarly journals Improved Approach for the Investigation of Submarine Groundwater Discharge by Means of Radon Mapping and Radon Mass Balancing

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 749 ◽  
Author(s):  
Schubert ◽  
Petermann ◽  
Stollberg ◽  
Gebel ◽  
Scholten ◽  
...  
Keyword(s):  
Mass Balance ◽  
Submarine Groundwater Discharge ◽  
Large Scale ◽  
Groundwater Discharge ◽  
Distribution Patterns ◽  
Hydrogeological Model ◽  
Fresh Groundwater ◽  
Area Of Interest ◽  
Submarine Groundwater ◽  
Mass Balancing

The paper presents an improved approach for investigating submarine groundwater discharge (SGD) based on radon mapping and radon mass balancing in the coastal sea. While the use of radon as an environmental tracer in SGD studies is well-established, we identified based on our longstanding experience six methodical shortcomings of the conventional approach and suggest corresponding developments. The shortcomings include: (1 and 2) inadequate consideration of both detection equipment response delay and influence of tidal stage; (3 and 4) incorrect quantification of radon losses, due to offshore mixing and degassing resulting in a potentially incorrect radon mass balance; (5) inaccurate determination of the terrestrial groundwater endmember, due to inhomogeneous radon distribution in the coastal aquifer; and (6) difficulties in distinguishing between discharged fresh groundwater and recirculated seawater. The improved approach is practically demonstrated in a step by step manner in a large-scale field study, which was carried out in False Bay (South Africa) and which consisted of two parts, namely (i) qualitative SGD localization along the entire False Bay coastline based on coastal radon distribution patterns and (ii) quantitative SGD investigation within a defined coastal area of interest (AOI) based on a radon mass balance (RMB). The plausibility of the AOI related results was evaluated by a hydrogeological model, used for qualitative SGD localization, and a hydrological model, applied for estimating groundwater recharge within the AOI catchment.

Submarine groundwater discharge (SGD) in the springs of Sahlenburg tidal flat, Germany: a geochemical approach. 

2021 ◽  
Author(s):  
Roger Carvalho da Silva ◽  
Hannelore Waska ◽  
Kai Schwalfenberg ◽  
Thorsten Dittmar
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Tidal Flat ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Fresh Groundwater ◽  
Large Reservoir ◽  
Flat Area ◽  
Submarine Groundwater ◽  
Groundwater Springs

<p>Submarine groundwater discharge (SGD) is an important connection between fresh groundwater and the marine ecosystem. The scientific interest in SGD has grown considerably during the last decades due to the recognition of SGD in coastal environments as a significant source of nutrients and pollutants.  The Sahlenburg area (Northern Germany) is known by its highly permeable sediments and high rainfall precipitation that produces a large reservoir of groundwater.  Such characteristics are essential for industry, agriculture and drinking water supply with a large regional importance. In addition, this groundwater discharges in the form of highly productive springs directly into the adjacent tidal flats, with so far unknown effects on the local biogeochemistry.  The aim of this study was to characterize the spatial distribution of salinity, fluorescence dissolved organic matter (FDOM), dissolved organic matter (DOC) and total dissolved nitrogen (TDN) of the springs of Sahlenburg tidal flat area in Cuxhaven, Germany. We hypothesize that the SGD composition is changing on its way through the tidal flat due to biogeochemical factors. This may affect the composition of the water in the final part of the pathway with more influence of seawater. Porewater springs were sampled in February 2019 during low tide in three different types of locations in the tidal flat area: nearshore where the springs are located close to the vegetated shoreline (salt marsh), offshore approximately 70 meters from the vegetation and in the middle from both locations. In addition, porewater from a nearby sandy beach (around 500 meters away from the area of spring sampling), and surface samples from a nearby lake and seawater, were obtained. Salinity and FDOM were measured in situ, and DOC and TDN in the laboratory.  The preliminary data showed low average values for salinity in all springs (0.2-1.4), as well as in beach porewater, indicating strong influence of fresh groundwater in the whole area. When comparing the three spring location types, the lowest salinities were found offshore, and the highest nearshore. This difference could be due to the size of the springs, since nearshore springs usually were smaller when compared to offshore springs. Furthermore, depressions in the tidal flat relief close to nearshore springs favored seawater retention in pools during low tide. Additionally, we found higher average values for DOC and FDOM in the nearshore when compared with the other spring areas, but lower compared to the lake, beach porewater and seawater. The average values for TDN (272-452 µmol L<sup>-1</sup>) in the groundwater springs were higher when compared to all other sample types (beach porewater, seawater, and lake water) in this study. These values suggest an anthropogenic input (e.g., agriculture influence) in the surrounding watershed and might stimulate primary productivity in the tidal flat. We conclude that groundwater springs in Sahlenburg tidal flat differ locally in their biogeochemistry due to different residence times, heterogeneity of sediment layers, and size of the springs.</p><p> </p>

scholarly journals Studies on Groundwater Problems in an Area Subjected to Sea Water Ingression and Seepage Into Groundwater in Karaikal District Using GIS

2018 ◽  
Vol 7 (3.10) ◽  
pp. 150
Author(s):  
T Subramani ◽  
P Krishnan
Keyword(s):  
Water Quality ◽  
Coastal Waters ◽  
Submarine Groundwater Discharge ◽  
Sea Water ◽  
Groundwater Discharge ◽  
Treated Wastewater ◽  
Coastal Zones ◽  
Fresh Groundwater ◽  
Submarine Groundwater ◽  
Pumping Rates

Fresh groundwater quality and accessibility in coastal zones is influenced via seawater interruption into coastal aquifers, and coastal water quality and biological community status might be altogether influenced by groundwater pollutants that are transported into coastal waters by submarine groundwater discharge (SGD). SGD and its pertinent evaluation as one associating part  among the different principle local pathways of freshwater and tracer/poison contributions from land to sea and the coordinated framework working of both and as primary segments of the same coastal groundwater framework. An elective technique might be to control seawater interruption through fake groundwater revive, for example by adequately treated wastewater, which may impressively decrease long haul patterns of saltiness increment in pumped groundwater, notwithstanding for little simulated energize rates contrasted with pumping rates. Both the outside sources and the interior wellsprings of water seepage might be distinguished via doing infrared thermo-realistic assessments subsequent to directing water snugness tests, flooding tests or pressure driven tests as suitable. A contextual investigation was led to discover the examinations on groundwater issues in a region subjected to sea water ingression and seepage into groundwater in Karaikal   

scholarly journals Estimation of submarine groundwater discharge in the Il-Gwang watershed using water budget analysis and222Rn mass balance

2013 ◽  
Vol 28 (11) ◽  
pp. 3761-3775 ◽  
Author(s):  
Yong-Seok Gwak ◽  
Sang-Hyun Kim ◽  
Yong-Woo Lee ◽  
Boo-Keun Khim ◽  
Se-Yeong Hamm ◽  
...  
Keyword(s):  
Mass Balance ◽  
Water Budget ◽  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Budget Analysis ◽  
Submarine Groundwater

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.

scholarly journals Submarine groundwater discharge to a small estuary estimated from radon and salinity measurements and a box model

2005 ◽  
Vol 2 (2) ◽  
pp. 141-157 ◽  
Author(s):  
J. Crusius ◽  
D. Koopmans ◽  
J. F. Bratton ◽  
M. A. Charette ◽  
K. Kroeger ◽  
...  
Keyword(s):  
Submarine Groundwater Discharge ◽  
Groundwater Discharge ◽  
Narrow Channel ◽  
Hydrologic Model ◽  
Early Summer ◽  
Box Model ◽  
Fresh Groundwater ◽  
Salt Pond ◽  
Groundwater Flux ◽  
Submarine Groundwater

Abstract. Submarine groundwater discharge was quantified by a variety of methods for a 4-day period during the early summer of 2004, in Salt Pond, adjacent to Nauset Marsh, on Cape Cod, USA. Discharge estimates based on radon and salinity took advantage of the presence of the narrow channel connecting Salt Pond to Nauset Marsh, which allowed constructing whole-pond mass balances as water flowed in and out due to tidal fluctuations. The data suggest that less than one quarter of the discharge in the vicinity of Salt Pond happened within the pond itself, while three quarters or more of the discharge occurred immediately seaward of the pond, either in the channel or in adjacent regions of Nauset Marsh. Much of this discharge, which maintains high radon activities and low salinity, is carried into the pond during each incoming tide. A box model was used as an aid to understand both the rates and the locations of discharge in the vicinity of Salt Pond. The model achieves a reasonable fit to both the salinity and radon data assuming submarine groundwater discharge is fresh and that most of it occurs either in the channel or in adjacent regions of Nauset Marsh. Salinity and radon data, together with seepage meter results, do not rule out discharge of saline groundwater, but suggest either that the saline discharge is at most comparable in volume to the fresh discharge or that it is depleted in radon. The estimated rate of fresh groundwater discharge in the vicinity of Salt Pond is 3000-7000 m3 d-1. This groundwater flux estimated from the radon and salinity data is comparable to a value of 3200-4500 m3 d-1 predicted by a recent hydrologic model (Masterson, 2004; Colman and Masterson, 2004), although the model predicts this rate of discharge to the pond whereas our data suggest most of the groundwater bypasses the pond prior to discharge. Additional work is needed to determine if the measured rate of discharge is representative of the long-term average, and to better constrain the rate of groundwater discharge seaward of Salt Pond.

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