The Use of Environmental Isotopes in Hydrogeology

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrogeology".

Deadline for manuscript submissions: closed (1 August 2023) | Viewed by 10811

Special Issue Editors

Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, University of Lisbon, 2695-066 Bobadela, Portugal
Interests: isotope hydrology; groundwater dating; geochemistry; water–rock interaction; hydrogeology; palaeoclimatology; environmental earth sciences; water management and protection
1. Department of Civil Engineering, Architecture and Georesources, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
2. CERENA (Centro de Recursos Naturais e Ambiente), 1041-001 Lisbon, Portugal
Interests: hydrogeology; water-rock interaction; thermal and mineral waters; groundwater pollution and protection; geothermal resources
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Special Issue Information

Dear Colleagues,

In many parts of the world, water resources are at risk, due to climate change, population growth, overexploitation, agricultural practices, and anthropogenic pollution, among others. Access to freshwater, in quantity and in quality, is one of the United Nations Sustainable Development Goals. In this context, environmental isotopes are crucial tools that provide vital information in hydrogeological studies, in order to understand aquifers dynamics, water resources assessment, vulnerability, and management issues. The use of environmental isotopes as natural tracers in hydrogeology is increasing with the progress of laboratory equipment and analytical methods. These environmental isotopic approaches play a vital role in the identification of potential pollution sources on current and past flow conditions that are independent of what can be determined by traditional hydrogeological studies and hydrogeochemical signatures.

In this Special Issue dedicated to “Environmental Isotopes in Hydrogeology”, we welcome original papers dealing with:

i) spatial isotope patterns to understand hydrological processes;
ii) isotopes in precipitation modeling and climate changes;
iii) environmental/climate change and impact on water resources;
iv) synthesis of isotope data to identify emerging water quality/quantity issues;
v) groundwater dating and palaeohydrology;
vi) water resources assessment and management;
vii) new trends and challenges in isotope hydrology.

The objective of this Special Issue is to enhance the potential contribution of environmental isotope tracers, to increase knowledge on water resources in a changing environment.

Dr. Paula M. Carreira
Prof. Dr. José Manuel Marques
Guest Editors

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Keywords

  • Environmental isotopes
  • Groundwater dating
  • Isotopes and hydrogeochemistry
  • Water–rock interaction
  • Water resources assessment and protection
  • Water resources management

Published Papers (8 papers)

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Editorial

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6 pages, 207 KiB  
Editorial
The Use of Environmental Isotopes in Hydrogeology
by Paula M. Carreira and José M. Marques
Water 2024, 16(7), 914; https://doi.org/10.3390/w16070914 - 22 Mar 2024
Viewed by 419
Abstract
As a consequence of the population increase, there is a growing need for groundwater use worldwide, leading to the intensification of agricultural practices alongside the growth of industrial development [...] Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)

Research

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26 pages, 4011 KiB  
Article
Stable Isotopes and Water Level Monitoring Integrated to Characterize Groundwater Recharge in the Pra Basin, Ghana
by Evans Manu, Marco De Lucia, Thomas Tetteh Akiti and Michael Kühn
Water 2023, 15(21), 3760; https://doi.org/10.3390/w15213760 - 27 Oct 2023
Viewed by 1217
Abstract
In the Pra Basin of Ghana, groundwater is increasingly becoming the alternative water supply due to the continual pollution of surface water resources through illegal mining and indiscriminate waste discharges into rivers. However, our understanding of hydrogeology and the dynamics of groundwater quality [...] Read more.
In the Pra Basin of Ghana, groundwater is increasingly becoming the alternative water supply due to the continual pollution of surface water resources through illegal mining and indiscriminate waste discharges into rivers. However, our understanding of hydrogeology and the dynamics of groundwater quality remains inadequate, posing challenges for sustainable water resource management. This study aims to characterize groundwater recharge by determining its origin and mechanism of recharge prior to entering the saturated zone and to provide spatial estimates of groundwater recharge using stable isotopes and water level measurements relevant to groundwater management in the basin. Ninety (90) water samples (surface water and groundwater) were collected to determine stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) and chloride concentration. In addition, ten boreholes were installed with automatic divers to collect time series data on groundwater levels for the 2022 water year. The Chloride Mass Balance (CMB) and the Water Table Fluctuation (WTF) methods were employed to estimate the total amount and spatial distribution of groundwater recharge for the basin. Analysis of the stable isotope data shows that the surface water samples in the Pra Basin have oxygen (δ18O) and hydrogen (δ2H) isotope ratios ranging from −2.8 to 2.2‰ vrs V-SMOW for δ18O and from −9.4 to 12.8‰ vrs V-SMOW for δ2H, with a mean of −0.9‰ vrs V-SMOW and 0.5‰ vrs V-SMOW, respectively. Measures in groundwater ranges from −3.0 to −1.5‰ vrs V-SMOW for δ18O and from −10.4 to −2.4‰ vrs V-SMOW for δ2H, with a mean of −2.3 and −7.0‰ vrs V-SMOW, respectively. The water in the Pra Basin originates from meteoric source. Groundwater has a relatively depleted isotopic signature compared to surface water due to the short residence time of infiltration within the extinction depth of evaporation in the vadose zone. Estimated evaporative losses in the catchment range from 51 to 77%, with a mean of 62% for surface water and from 55 to 61% with a mean of 57% for groundwater, respectively. Analysis of the stable isotope data and water level measurements suggests a potential hydraulic connection between surface water and groundwater. This hypothesis is supported by the fact that the isotopes of groundwater have comparatively lower values than surface water. Furthermore, the observation that the groundwater level remains constant in months with lower rainfall further supports this conclusion. The estimated annual groundwater recharge in the catchment ranges from 9 to 667 mm (average 165 mm) and accounts for 0.6% to 33.5% (average 10.7%) of mean annual precipitation. The total estimated mean recharge for the study catchment is 228 M m3, higher than the estimated total surface water use for the entire Pra Basin of 144 M m3 for 2010, indicating vast groundwater potential. Overall, our study provides a novel insight into the recharge mechanism and spatial quantification of groundwater recharge, which can be used to constrain groundwater flow and hydrogeochemical evolution models, which are crucial for effective groundwater management within the framework of the Pra Basin’s Integrated Water Resources Management Plan. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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19 pages, 30442 KiB  
Article
Analysis of the Recharge Area of the Perrot Spring (Aosta Valley) Using a Hydrochemical and Isotopic Approach
by Luis Miguel Santillán-Quiroga, Daniele Cocca, Manuela Lasagna, Chiara Marchina, Enrico Destefanis, Maria Gabriella Forno, Marco Gattiglio, Giacomo Vescovo and Domenico Antonio De Luca
Water 2023, 15(21), 3756; https://doi.org/10.3390/w15213756 - 27 Oct 2023
Viewed by 877
Abstract
The Perrot Spring (1300 m a.s.l.), located to the right of the Chalamy valley in the Monte Avic Natural Park (Valle d’Aosta, Italy), is an important source of drinking water for the municipality of Champdepraz. This spring is located on a large slope [...] Read more.
The Perrot Spring (1300 m a.s.l.), located to the right of the Chalamy valley in the Monte Avic Natural Park (Valle d’Aosta, Italy), is an important source of drinking water for the municipality of Champdepraz. This spring is located on a large slope characterised by the presence of a Quaternary cover of various origins (glacial, glaciolacustrine, and landslide) above the bedrock (essentially serpentinite referred to the Zermatt–Saas Zone, Penninic Domain). Water emerges at the contact between the landslide bodies and impermeable or semi-permeable glaciolacustrine deposits. The aim of this study is to define the processes and recharge zones of this spring. The analysis of the data revealed the presence of two contributions to the Perrot Spring input: a spring thaw contribution defined by a small increase in flow and an autumn contribution from rainwater infiltration. The low average temperature and low variation of the annual temperature (4.8–6.5 °C) suggest a sufficiently deep flow circuit. Chemical analyses showed a groundwater chemistry consistent with the regional geology: the hydrochemical facies is calcium–magnesium bicarbonate and isotopic analyses (δ2H and δ18O) of rainfall and spring water suggested a recharge altitude of about 2100 m a.s.l. In conclusion, this study makes it possible to recognize the water inputs to the spring discharge and to delineate its recharge area, which can be proposed to implement strategies to protect the resource. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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24 pages, 12061 KiB  
Article
Isotope Discrimination of Source Waters, Flowpaths, and Travel Times at an Acid-Generating, Lead–Zinc–Silver Mine, Silver Valley, Idaho, USA
by Jeff B. Langman, Ethan Gaddy, Timothy E. Link, Jan Boll, Bradley Barnett and Morgan Hill
Water 2023, 15(19), 3362; https://doi.org/10.3390/w15193362 - 25 Sep 2023
Viewed by 1299
Abstract
Precipitation infiltrates into the lead–zinc–silver Bunker Hill Mine, oxidizes pyrite, and produces acidic waters that discharge from the mine portal. The metasedimentary geology and alteration from 100+ yr of mining provide a heterogeneous environment for source water infiltration and flow within the mine. [...] Read more.
Precipitation infiltrates into the lead–zinc–silver Bunker Hill Mine, oxidizes pyrite, and produces acidic waters that discharge from the mine portal. The metasedimentary geology and alteration from 100+ yr of mining provide a heterogeneous environment for source water infiltration and flow within the mine. A university–industry partnership was developed to trace the mine water sources, flowpaths, and travel times to identify potential areas for infiltration reduction. Snowpack, creek, and mine water samples were collected over a 1-year period for the analysis of δ2H, δ18O, and 3H, along with the in situ measurement of temperature, specific conductance, pH, dissolved oxygen, and flow. The isotope tracers were used to identify the source waters, unmix mine water as it moved deeper in the mine, and examine flowpaths in and near the acid-generating pyritic zone. The results indicate creek water infiltrating relatively quickly through the anthropogenically-modified pathways and causing the largest amount of acidic water in the upper levels of the mine. Slower, natural pathways associated with faults, fractures, and bedding planes produce mostly neutral waters with the source waters typically originating at higher elevations. Travel times ranged from <1 to 22 years with shorter pathways to the upper levels of the mine and increasing contributions deeper in the mine from pathways containing older, higher-elevation snowmelt. These slower and older inflows were identified by depleted δ18O values, smaller 3H concentrations, the dampening of the variability of the isotope signals, and pH increases. Reduction of infiltration zones near the upper workings of the mine likely will decrease the acidic waters in the upper levels of the mine, but the higher elevation infiltration zones will continue to contribute snowmelt-derived waters at all mine levels. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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23 pages, 9229 KiB  
Article
Stable Isotope Signatures in Tehran’s Precipitation: Insights from Artificial Neural Networks, Stepwise Regression, Wavelet Coherence, and Ensemble Machine Learning Approaches
by Mojtaba Heydarizad, Luis Gimeno, Masoud Minaei and Marjan Shahsavan Gharehghouni
Water 2023, 15(13), 2357; https://doi.org/10.3390/w15132357 - 26 Jun 2023
Cited by 1 | Viewed by 1117
Abstract
This study investigates the impact of precipitation on Middle Eastern countries like Iran using precise methods such as stable isotope techniques. Stable isotope data for precipitation in Tehran were obtained from the Global Network of Isotopes in Precipitation (GNIP) station and sampled for [...] Read more.
This study investigates the impact of precipitation on Middle Eastern countries like Iran using precise methods such as stable isotope techniques. Stable isotope data for precipitation in Tehran were obtained from the Global Network of Isotopes in Precipitation (GNIP) station and sampled for two periods: 1961–1987 and 2000–2004. Precipitation samples were collected, stored, and shipped to a laboratory for stable isotope analyses using the GNIP procedure. Several models, including artificial neural networks (ANNs), stepwise regression, and ensemble machine learning approaches, were applied to simulate stable isotope signatures in precipitation. Among the studied machine learning models, XGboost showed the most accurate simulation with higher R2 (0.84 and 0.86) and lower RMSE (1.97 and 12.54), NSE (0.83 and 0.85), AIC (517.44 and 965.57), and BIC values (531.42 and 979.55) for 18O and 2H compared to other models, respectively. The uncertainty in the simulations of the XGboost model was assessed using the bootstrap technique, indicating that this model accurately predicted stable isotope values. Various wavelet coherence analyses were applied to study the associations between stable isotope signatures and their controlling parameters. The BWC analysis results show coherence relationships, mainly ranging from 16 to 32 months for both δ18O–temperature and δ2H–temperature pairs with the highest average wavelet coherence (AWC). Temperature is the dominant predictor influencing stable isotope signatures of precipitation, while precipitation has lower impacts. This study provides valuable insights into the relationship between stable isotopes and climatological parameters of precipitation in Tehran. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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25 pages, 5547 KiB  
Article
Interdisciplinary Approach and Geodynamic Implications of the Goutitir Geothermal System (Eastern Meseta, Morocco)
by El Mehdi Jeddi, Ahmed Ntarmouchant, Maria do Rosário Carvalho, Telmo M. Bento dos Santos, Eduardo Anselmo Ferreira da Silva, Mustapha Elabouyi, Youssef Driouch, Brahim Mali, Nahla Ntarmouchant, My Hachem Smaili, Beatriz Cotrim and Mohamed Dahire
Water 2023, 15(6), 1109; https://doi.org/10.3390/w15061109 - 14 Mar 2023
Viewed by 1937
Abstract
Morocco has an important geothermal potential materialized by its several thermal springs which constitute an essential surface geothermal indicator. These springs are dispersed throughout the country and present in every major structural domain. However, a significant amount is concentrated in the northern and [...] Read more.
Morocco has an important geothermal potential materialized by its several thermal springs which constitute an essential surface geothermal indicator. These springs are dispersed throughout the country and present in every major structural domain. However, a significant amount is concentrated in the northern and northeastern areas. Associated with the great hydrothermal system of eastern Morocco, the thermal spring of Goutitir emerges in the Meso-Cenozoic sedimentary formations located east of the Guercif Basin, composed of a mixture of clays, carbonates, and marls, covered in unconformity by Quaternary tabular molasses. The upflow of the thermal water is dependent of Alpine faults systems with N30 and N100 directions, which are probable reactivated Hercynian structures that facilitate its circulation to the surface. The Goutitir spring has been studied by an interdisciplinary approach to identify the origin of the thermal water, the rock–water interactions, and the reservoir temperatures, contributing to the establishment of the conceptual model of the associated hydrothermal system. This thermal water is of chloride-sodium type with a hyperthermal character (43–47 °C). The isotopic composition (δ18O = −8.7 to −8.35‰; δ2H = −58.6 to −54.3‰) indicates a meteoric origin and a recharging zone located at around 2000 m of altitude. The chemical composition allows to classify the water as chloride-sodium hydrochemical facies, stabilized at ~100 °C in crystalline basement rocks, which, according to seismic data, are located at ~3 km depth. The concentrations, patterns, and correlations of trace elements point out water–rock interaction processes between the deep water and basic magmatic rocks. The integration of the chemical and isotopic data and the surface geological context shows that the Goutitir water flows within a hydrothermal zone were basic to ultrabasic lamprophyres rich in gabbroic xenoliths outcrop, witnessing the existence, at depth, of basic plutons. Moreover, near the source, these veins are strongly altered and hydrothermalized, showing late recrystallization of centimetric-sized biotites. The chloride-sodium composition of this water may also be a testimony to the presence and reaction with the overlying Triassic saline and gypsiferous and Meso-Cenozoic mainly carbonated formations. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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25 pages, 6338 KiB  
Article
Radiocarbon Dating and Stable Isotopes Content in the Assessment of Groundwater Recharge at Santiago Island, Republic of Cape Verde
by Paula M. Carreira, António Lobo de Pina, Alberto da Mota Gomes, José M. Marques and Fernando Monteiro Santos
Water 2022, 14(15), 2339; https://doi.org/10.3390/w14152339 - 28 Jul 2022
Cited by 6 | Viewed by 1610
Abstract
The over-exploitation of coastal aquifers has led to seawater intrusion issues in many parts of the globe; this problem, which is associated with water recharge deficit and anthropogenic pollution, represents the main source of groundwater degradation in Santiago Island in the Republic of [...] Read more.
The over-exploitation of coastal aquifers has led to seawater intrusion issues in many parts of the globe; this problem, which is associated with water recharge deficit and anthropogenic pollution, represents the main source of groundwater degradation in Santiago Island in the Republic of Cape Verde’s archipelago. Brackish groundwater for agriculture and human consumption is being provided to several areas on Santiago Island as the only type of available water. Chemical and isotopic data obtained in three main groundwater systems were used in the characterization of the groundwater resources and in the identification of the main source responsible for their degradation. The obtained results indicate water–rock interaction as the major process responsible for the groundwater quality reflecting its lithological composition. Carbonatite dissolution can be partially responsible for the calcium increase along the groundwater flow path. Isotopic data (δ2H, δ18O; 3H and 14C) combined with the water chemistry provided a wide characterization of the groundwater recharge and identification of salinization processes (like seawater intrusion and marine aerosols dissolution in different sectors of the island). In the eastern part of Santiago Island, a different isotopic pattern (2H-18O) was observed in the groundwater samples, which was likely ascribed to different climate conditions. Carbon-14 determinations indicate apparent groundwater ages between 3.5 and 5.1 ka BP. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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Review

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20 pages, 3981 KiB  
Review
Review of Isotope Hydrology Investigations on Aquifers of Cameroon (Central Africa): What Information for the Sustainable Management of Groundwater Resources?
by Bertil Nlend, Frederic Huneau, Suzanne Ngo Boum-Nkot, Fricelle Song, David Komba, Bernard Gwodog, Parfait Meyoupe, Boris Djieugoue and Enoh Fongoh
Water 2023, 15(23), 4056; https://doi.org/10.3390/w15234056 - 22 Nov 2023
Cited by 1 | Viewed by 1021
Abstract
In Central Africa, groundwater remains the least understood component of the water cycle. Isotopic techniques that are well known to be efficient in tracking the movement of water along its path have been applied for only three decades and can be summarized in [...] Read more.
In Central Africa, groundwater remains the least understood component of the water cycle. Isotopic techniques that are well known to be efficient in tracking the movement of water along its path have been applied for only three decades and can be summarized in a handful of case studies. This review aims to put together all the stable and radioactive isotopic data (>500 samples from rainfall, surface and groundwater) published in Cameroon to: (i) identify the drivers responsible for precipitation isotopes’ spatial variation and climatological implications, (ii) elucidate the groundwater recharge mechanisms over the countries and relationships with rivers, and (iii) highlight the existence of paleo-groundwater in the country. It is found that rainfall stable isotope variation is linked to the migration of the Intertropical Convergence Zone (ITCZ): the groundwater recharge can be diffuse and focused. This latter mechanism is mainly observed in the semi-arid region. It is in this relatively dry region that most of the paleo-groundwater resources are identified thanks to 14C dating. This information will be useful to develop water management strategies regarding all the challenges (e.g., climatic and demographic) faced by the country. Finally, this paper discusses the gaps groundwater isotope hydrology can still fill for contributing to a sustainable development of the country. Full article
(This article belongs to the Special Issue The Use of Environmental Isotopes in Hydrogeology)
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