Radium isotopes as submarine groundwater discharge (SGD) tracers: Review and recommendations

García-Orellana, Jordi; Rodellas, Valentí; Tamborski, Joseph; Diego-Feliu, Marc; Beek, Pieter van; Weinstein, Yishai; Charette, Matthew A.; Alorda-Kleinglass, Aaron; Michael, H.A.; Stieglitz, Thomas; Scholten, Jan

doi:10.1016/j.earscirev.2021.103681

Cited by 79 publications

(44 citation statements)

References 259 publications

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“…Unlike single images, the multi-temporal SST series method allows several images and, thus, several points in time to be integrated, accentuating the small thermal anomalies for easy identification. An example of the usefulness of the multi-temporal SST series method is in the Serra d'Irta (eastern Iberian Peninsula; Mejías et al, 2012;Garcia-Solsona et al, 2010;Trezzi et al, 2016). At this site, Mejías et al (2012) identified four large thermal anomalies (Torre Badum, Punta del Pebret and Les Fonts springs), by using airborne thermal remote sensing, that were not identified using Landsat 7.…”

Section: Application Of the Multi-temporal Sst Series Methodsmentioning

confidence: 99%

“…1). In this study, we focus on a set of 54 springs mentioned in the scientific peer review literature published in English Bakalowicz, 2018;Fleury et al, 2007;Mejías et al, 2012;Garcia-Solsona et al, 2010) where groundwater discharge is known to occur, and where there is a description of the hydrogeological context of each spring (Supplement 1). The number of springs included in the study represents at least 88 % of the submarine karst springs described in the English peer review literature concerning the Mediterranean basin.…”

Section: Study Areamentioning

confidence: 99%

“…The discharge of fresh groundwater (pathway 1) and, to a lesser extent, density-driven seawater circulation (pathway 2) is the only mechanism that represents a net source of freshwater, usually mixed with seawater, to the coastal ocean. The SGD discharge process related to this fresher fraction of SGD occurs mainly through three different ways, namely coastal onshore springs, which discharge on the coastline via surface sinkholes (Garcia-Solsona et al, 2010;Mejías et al, 2012), submarine springs, where the discharge occurs via deep sinkholes (Bakalowicz, 2015;Fleury et al, 2007), and diffuse discharge, a type of discharge which is not concentrated and occurs throughout sediments (Rodellas et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Applicability of Landsat 8 thermal infrared sensor for identifying submarine groundwater discharge springs in the Mediterranean Sea basin

Jou-Claus

Folch

García-Orellana

2021

Hydrol. Earth Syst. Sci.

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Abstract. Submarine groundwater discharge (SGD) has received increasing attention over the past 2 decades as a source of nutrients, trace elements and ocean pollutants that may alter coastal biogeochemical cycles. Assessing SGD flows and their impact on coastal marine environments is a difficult task, since it is not easy to identify and measure these water flows discharging into the sea. The aim of this study is to demonstrate the significant usefulness of the freely available thermal infrared (TIR) imagery of the Landsat 8 thermal infrared sensor (TIRS) as an exploratory tool for identifying SGD springs worldwide, from local to regional scales, for long-term analysis. The use of satellite thermal data as a technique for identifying SGD springs in seawater is based on the identification of thermally anomalous plumes obtained from the thermal contrasts between groundwater and sea surface water. In this study, we use the TIR remote sensing (TIR-RS) imagery provided by Landsat 8 at a regional scale and discuss the principle limiting factors of using this technique in SGD studies. The study was developed in karstic coastal aquifers in the Mediterranean Sea basin during different seasons and under diverse meteorological conditions. Although this study demonstrates that freely available satellite TIR remote sensing is a useful method for identifying coastal springs in karst aquifers both locally and regionally, the limiting factors include technical limitations, geological and hydrogeological characteristics, environmental and marine conditions and coastal geomorphology.

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Section: Application Of the Multi-temporal Sst Series Methodsmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Applicability of Landsat 8 thermal infrared sensor for identifying submarine groundwater discharge springs in the Mediterranean Sea basin

Jou-Claus

Folch

García-Orellana

2021

Hydrol. Earth Syst. Sci.

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“…We suggest that this could be attributed to seawater infiltration in the Island's water-table aquifer, which entrains river-born Ra into it. During such conditions, oxygenated waters most likely result in co-precipitation of Ra onto STE sediments resulting in negative f RSGD in the mixing model (Garcia-Orellana et al, 2021). While the three-endmember mixing model is a simplification of the system, the result of negligible RSGD is plausible due to the geology of southeastern Dauphin Island, which supports the occurrence of fresh SGD instead of RSGD.…”

Section: Preferential Groundwater Pathways Of Sgdmentioning

confidence: 88%

Storm-Driven Fresh Submarine Groundwater Discharge and Nutrient Fluxes From a Barrier Island

et al. 2021

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Quantifying and characterizing groundwater flow and discharge from barrier islands to coastal waters is crucial for assessing freshwater resources and contaminant transport to the ocean. In this study, we examined the groundwater hydrological response, discharge, and associated nutrient fluxes in Dauphin Island, a barrier island located in the northeastern Gulf of Mexico. We employed radon (222Rn) and radium (Ra) isotopes as tracers to evaluate the temporal and spatial variability of fresh and recirculated submarine groundwater discharge (SGD) in the nearshore waters. The results from a 40-day continuous 222Rn time series conducted during a rainy season suggest that the coastal area surrounding Dauphin Island was river-dominated in the days after storm events. Groundwater response was detected about 1 week after the precipitation and peak river discharge. During the period when SGD was a factor in the nutrient budget of the coastal area, the total SGD rates were as high as 1.36 m day–1, or almost three times higher than detected fluxes during the river-dominated period. We found from a three-endmember Ra mixing model that most of the SGD from the barrier island was composed of fresh groundwater. SGD was driven by marine and terrestrial forces, and focused on the southeastern part of the island. We observed spatial variability of nutrients in the subterranean estuary across this part of the island. Reduced nitrogen (i.e., NH4+ and dissolved organic nitrogen) fluxes dominated the eastern shore with average rates of 4.88 and 5.20 mmol m–2 day–1, respectively. In contrast, NO3– was prevalent along the south-central shore, which has significant tourism developments. The contrasting nutrient dynamics resulted in N- and P-limited coastal water in the different parts of the island. This study emphasizes the importance of understanding groundwater flow and dynamics in barrier islands, particularly those urbanized, prone to storm events, or located near large estuaries.

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“…Samples were collected for Ra isotopes ( 223 Ra, 224 Ra, 226 Ra, and 228 Ra; 25 -120 L each sample), which are widely applied tracers of SGD (Garcia-Orellana et al, 2021) and nutrient analysis. Depth profiles of salinity and temperature were performed at each station by using a YSI 600XL probe.…”

Section: Field Methodsmentioning

confidence: 99%

Extreme precipitation events induce high fluxes of groundwater and associated nutrients to the coastal ocean

Diego-Feliu

Rodellas

Alorda-Kleinglass

et al. 2022

Preprint

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Abstract. Current Submarine Groundwater Discharge (SGD) studies are commonly conducted under aquifer baseflow conditions, neglecting the influence of episodic events that can significantly increase the supply of nutrients and water. This limits our understanding of the social, biogeochemical, and ecological impacts of SGD. In this study, we evaluated the influence of an extreme precipitation event (EPE) on the magnitude of both the terrestrial and marine components of SGD. To do so, three seawater sampling campaigns were performed at a Mediterranean ephemeral stream-dominated basin after an extreme precipitation event (~90 mm in few hours) and in baseflow conditions. Results indicate that the groundwater flows of terrestrial and marine SGD after the extreme precipitation event were 1 order of magnitude higher than those in baseflow conditions. SGD induced by extreme precipitation events, which only take place a few days per year, represented up to one third of the annual discharge of groundwater and associated nutrients at the study site. This work accentuates the need to account for episodic increases in the supply of water and nutrients when aiming at providing reliable annual SGD estimates, particularly in the current context of climate change, since the occurrence of such events is expected to increase worldwide.

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Radium isotopes as submarine groundwater discharge (SGD) tracers: Review and recommendations

Cited by 79 publications

References 259 publications

Applicability of Landsat 8 thermal infrared sensor for identifying submarine groundwater discharge springs in the Mediterranean Sea basin

Applicability of Landsat 8 thermal infrared sensor for identifying submarine groundwater discharge springs in the Mediterranean Sea basin

Storm-Driven Fresh Submarine Groundwater Discharge and Nutrient Fluxes From a Barrier Island

Extreme precipitation events induce high fluxes of groundwater and associated nutrients to the coastal ocean

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