Groundwater Circulation Research Articles

Controls on regional sulphate distribution in shallow groundwater in the western Canadian Interior Plains

Sulphate (SO4), predominantly derived from sulphur (S)-bearing glacial sediments distributed widely across the Canadian Interior Plains, contributes to high groundwater salinity and can be detrimental to riparian and dry-land ecosystems, agricultural production, and water use. While previous researchers investigated SO4 distribution and dynamics in shallow groundwater at local scales (<1500 km2), we examine SO4 occurrence in groundwater at larger scales, and to depths of ~150 m, considering variations in geology, glacial history, climate, and geochemical and hydrogeological settings in the Canadian province of Alberta. Sulphate concentrations in groundwater vary considerably, with 15 % of 139,130 samples above the 500 mg/L Canadian drinking water aesthetic objective. Analysis of δ34SSO4 and δ18OSO4 from 179 wells throughout Alberta shows SO4 is dominantly derived from oxidation of S-bearing material. At this large scale, marine shale bedrock subcrops, glacial ice flow directions, and climate control SO4 distribution. Groundwater contains less SO4 (<200 mg/L) in western Alberta compared to the east due to a lack of S-bearing bedrock, higher groundwater recharge rates, thinner glacial sediments, and increased groundwater circulation. Focusing on a region in south-central Alberta (Red Deer area), hydrogeological characteristics relating to SO4 formation, recharge, permeability, hydraulic gradient, and travel time are included in a principal component analysis to identify six groundwater groups at varying stages of evolution and SO4 concentrations depending on their hydrogeological setting. Low SO4 concentrations are associated with areas of high recharge, where SO4 has been leached from the sediments, or with more evolved bedrock groundwater where SO4 has been reduced or was recharged in pre-glacial times. High SO4 concentrations are found in areas of lower recharge and permeability, where flushing occurs more slowly. Combining the Red Deer area and province-wide analyses, we identify seven regions across Alberta with characteristic distribution and controls on SO4 occurrence in shallow groundwater.

Isotopic study for evaluating complex groundwater circulation patterns, hydrogeological zoning, and water-rock interaction in a Mediterranean coastal karst environment

In this study groundwater provenance, circulation, and rock interaction processes have been assessed by cross processing the spatial distribution of chemical and isotopic signatures in freshwater with the hydrogeological features of the coastal karst carbonate aquifer of Murgia, located in the southeastern end of Italy, along the Adriatic Sea. Thanks to widespread groundwater quality monitoring (major, minor, and trace-element analyses) and multi-isotopic measures of O, H, Sr, and B, some assumptions about complex groundwater circulation patterns, hydrogeological zoning, and water-rock interaction have been drawn. Three sectors have been distinguished into the Adriatic side of the Murgia aquifer all fed by two main recharge areas located on the most elevated, inner side of the aquifer. Each sector is characterized by different groundwater circulation patterns, residence time, and hydrogeochemical features. The water samples collected into the western sector evidence a certain degree of water-rock interaction, which allows us to assume long groundwater flow paths and residence time. On the contrary, the eastern sector of Murgia has been proven to be characterized by short residence times and a possible direct freshwater contribution even in the downstream course due to the massive presence of karst forms. Herein, the isotopic analysis of the water samples does not provide evidence of water-rock interaction. Finally, in the third, central sector, water infiltrated at different locations mixes flowing through relatively long paths even though not sufficient to allow groundwater to gain the rock's isotopic signature.

Towards sustainable development goals: Leveraging multi-data remote sensing fusion for monitoring groundwater-induced bedrock subsidence dynamics in Egypt's Nile Valley

Egypt's Golden Triangle megaproject within Egypt's vision 2030, involving land reclamation in Qena Bend's densely populated governorate, develops sustainable land management strategies. Advanced technologies and low-cost remote sensing multi-data fusion are utilized to understand subsidence dynamics influenced by geologic structure, groundwater, climate change, and human activities in Egypt's Nile Valley. This approach identifies environmental hazards and provides a detailed explanation for groundwater-induced bedrock subsidence, aiding in informed decision-making and risk avoidance. Landsat images reveal 13% increased cultivation, 28.28% urban-growth, and decreased water by 8.46%, impacting groundwater resources and controlling the situation. The Gravity Recovery and Climate Experiment(GRACE) and Global Land Data Assimilation System (GLDAS) satellite observations reveal changes in water storage, impacting climate change, groundwater storage dynamics, and aquifer behavior. Historical data indicates a significant southwest-northeast gradient in precipitation from 5 to 60 mm. GLDAS shows soil moisture decline from 0.25 to 0.23 mm. GRACE (total water storage) depleting, then slightly increasing from 2020 to 2023 with an average value (−5 cm/yr). Groundwater storage increases in wet seasons, in 2015 showing (+3–4 mm), less than (+1 mm) in (2018), and (+6–8 mm) in (2020–2023). The NE-SW and NW-SE faults increase hydraulic connection and recharge from aquifers, causing groundwater circulation and karstification in Eocene limestone aquifers, posing risks to urban development and human safety. The InSAR (Synthetic Aperture Radar) measures ground subsidence over time, revealing a range of (−0.04 to −0.07m) in the northwest to (+0.03m) in the southeast, with average subsidence (-4 cm), primarily associated with increased groundwater storage motivate the interaction between the carbonate and groundwater. The ArcGIS overlay model divides the region into three zones: northern, middle, and southern, each with varying degrees of displacement and groundwater storage. The findings emphasize the significance of remote sensing in hazard evaluation for development planning due to its cost-effectiveness and accuracy, applicable globally in hydrogeologically similar areas.

Identification of shallow groundwater recharge and circulation in an intensive agricultural area of the Sanjiang Plain, China, based on hydrochemistry, isotopes and hydrogeological conditions

Identification of shallow groundwater recharge and circulation in an intensive agricultural area of the Sanjiang Plain, China, based on hydrochemistry, isotopes and hydrogeological conditions

Using hydrochemistry and stable isotopes to character the karst water environment in a cave site, South China

For cave sites located within the seasonal fluctuation zone of groundwater, obtaining a comprehensive understanding of the hydrogeological conditions and hydrochemical environment is of utmost importance in assessing the preservation of cultural deposits. However, due to the heterogeneity of karst development, the hydrochemical environment of the overburden karst water-bearing unit may exhibit complex variations. In this study, the characteristics of the water environment in a foot cave system and its surrounding aquifer were investigated at the Zengpiyan site, employing hydrochemistry, hydrogen and oxygen isotope analysis, as well as sulfate isotope analysis, in conjunction with the hydrogeological background. Based on the exposure of the karst cave and the groundwater flow conditions, the water-bearing medium was categorized into five types. The aquifer exhibited either an oxidation or reduction condition, with a distinct "dissolved oxygen hole" observed in the saturated zone of the cave site. Ion concentration analysis revealed that the groundwater was influenced by the prior accumulation of cinders in the upstream region, leading to sulfate contamination within the foot cave system. However, during the groundwater movement from upstream to downstream, the attenuation rate of pollutants displayed significant variations. Notably, the sulfate content was unusually low within the site cave. Hydrogen and oxygen isotopes provided insights into the differing circulation and movement velocities of groundwater within the local environment. Additionally, sulfate isotopes confirmed the sources of sulfate and the occurrence of bacterial sulfate reduction within the site cave. Consequently, an environmental zoning classification was established based on these analyses. Although the concentration of dissolved ions appears low in the anoxic area, it does not imply a diminished environmental risk. Under reducing conditions, these pollutants can be converted into more aggressive gases, posing a substantial threat to the preservation environment of cave sites. Therefore, sufficient attention should be given to this aspect in order to ensure adequate protection.

Investigation into factors controlling groundwater evolution in mining areas with an integrated approach

The study of groundwater evolution is of great significance for water resource protection and management, groundwater pollution control, and ecological environment protection. Experts and scholars have found that the hydrochemical processes and evolutionary patterns of groundwater are determined by both natural processes and human activities. However, there is relatively little research on the evolution of groundwater in mining areas where human activities have a significant impact. Therefore, to study the main controlling factors affecting the hydrogeochemical evolution of groundwater in mining areas, this paper proposes a method combining mixed ratio calculation and multivariate statistical analysis. Firstly, a total of 40 groundwater samples are classified into six clusters via hierarchical cluster analysis. By comprehensively analyzing the spatial location of the samples, it was found that there was no obvious distribution pattern of groundwater in space. Furthermore, the rationality of the cluster analysis is evaluated via principal component analysis. Next, hydrochemical and isotopic analyses were conducted to determine the source of groundwater in the mining area, and a three terminal element mixing model was established to identify the source of pollutants and calculate the terminal element mixing ratio. The research results indicate that groundwater in mining areas is formed by a mixture of shallow bedrock fissure water, deep bedrock fissure water, and rainwater, and the mixing effect is the main factor affecting the evolution of groundwater in mining areas, with a more significant impact than the depth of groundwater circulation. In addition, different types and degrees of water–rock interaction in different regions have altered the hydrochemical characteristics of groundwater in mining areas, such as the dissolution of multiple minerals, cation exchange, and common ion effects. Based on the above analysis results, a water circulation model for the mining area has been established. The findings of this study not only contribute to the protection of shallow fissure groundwater in the study area, but also provide a basis for investigating the groundwater evolution patterns in other metal mines.

The paleo-oceanic environment and organic matter enrichment mechanism of the early Cambrian in the southern Lower Yangtze Platform, China

This study focuses on the Lower Yangtze Platform located in southern Anhui Province, focusing on the black shale of the early Cambrian Hetang Formation as the primary research subject. Three field sections representing distinct sedimentary structural units were selected for investigation. Analytical methodologies encompassing organic geochemistry, elemental geochemistry, and scanning electron microscopy were employed to reconstruct paleo-oceanic environmental conditions. These analyses aimed to elucidate the characteristics of marine surface productivity and identify the factors controlling organic matter formation, thereby establishing a model for organic matter accumulation processes. These findings suggest that the Jiangnan paleo-uplift exerted differentiated control over organic matter formation and accumulation. Specifically, the barrier function of the paleo-uplift fostered a relatively enclosed and restricted water environment in certain regions, which proved conducive to the formation, accumulation, and preservation of organic matter. Furthermore, the paleo-upwelling system and hydrothermal groundwater circulation triggered by the activation of the Jiangnan deep fault played crucial roles in controlling the formation and accumulation of organic matter in the early Cambrian. Notably, the research also revealed that intermittent hydrothermal activity had a dual impact on organic matter accumulation within various paleo-oceanic settings. This process potentially facilitated organic matter enrichment and led to the dilution of organic matter concentrations.

Enrichment mechanism of groundwater fluoride and its hydrogeological indications in the Badain Jaran Desert, northwest China

Fluoride (F−) enrichment in groundwater poses significant risks to drinking water safety; however, reports of high F− concentrations in groundwater in a vast desert and its hydrogeological indications are limited. In this study, we collected 275 groundwater samples from various depths in the Badain Jaran Desert (BJD) to investigate the distribution characteristics and enrichment mechanisms of F− in desert groundwater, utilizing hydrochemistry, environmental isotopes, and statistical methods. The results indicate that (1) the groundwater F− concentrations in the mountainous areas, desert areas, and downstream wetland areas are 0.10–9.45 mg/L (average of 3.05), 0.19–58.00 mg/L (average of 4.32), and 0.62–9.91 mg/L (average of 1.99), respectively, with corresponding exceedance rates (>1 mg/L) of 83%, 71%, and 80%. (2) In mountainous areas, F− enrichment mechanisms are attributed to ion exchange, evaporative concentration, and the dissolution of fluoride minerals. In desert areas, F− enrichment mechanisms involves multiple hydrogeochemical processes, with the dissolution of fluoride minerals being the most significant, followed by evaporative concentration and desorption. And evaporative concentration is particularly pronounced in shallow groundwater (depth <4 m). In wetland areas, F− enrichment mechanisms are mainly ion exchange and desorption. (3) The F− concentration characteristics (<2 mg/L) and the significant correlation between F− and HCO3− (R = 0.55, P < 0.01) in the deep groundwater of the desert suggest that groundwater does not originate from deep geothermal sources. (4) Based on the significant differences in groundwater F− concentrations, there is a weak hydrodynamic connection between the groundwater in the Quaternary aquifer and that in the underlying Cretaceous bedrock in desert areas. These findings not only facilitate the safe use of groundwater in desert environments but also provide new insights into the formation, circulation, and evolution of desert groundwater.

Permafrost Hydrogeology of Taylor Valley, Antarctica: Insights From Deep Electrical Resistivity Tomography

AbstractGlobal warming has prompted globally widespread permafrost thawing, resulting in enhanced greenhouse gas release into the atmosphere. Studies conducted in the Northern Hemisphere reveal an alarming increase in permafrost thawing. However, similar data from Antarctica are scarce. We conducted a 2‐D Deep Electrical Resistivity Tomography (DERT) survey in Taylor Valley, Antarctica, to image the distribution of permafrost, its thicknesses, lower boundaries, and hydrogeology. Results show resistive, discontinuous domains that we suggest represent permafrost units. We also find highly conductive layers (5–10 Ω·m), between 300–350 m and 600–650 m below ground level and a shallower (∼50–100 m depth) conductive layer. The combined data set reveals a broad brine system in Taylor Valley, implying multi‐tiered groundwater circulation: a shallow, localized system linked with surface water bodies and a separate deeper, regional circulation system. The arrangement of these brines across different levels, coupled with the uneven permafrost distribution, underscores potential interplay between the two systems.

Regional characteristics of groundwater sulfate source and evolution in the multi-layer aquifer system of the northern Shaanxi coal mine base, northwestern China: Evidence from geochemical and isotopic fingerprints

Groundwater sulfate contamination in mining areas has attracted widespread attention. However, deciphering the source and evolution of sulfate in large-scale mining areas remains a challenge due to intense anthropogenic influences and complex hydrogeological conditions. In this study, 94 groundwater samples were analyzed by a combination of self-organizing maps, MixSiar model, multi-isotope analyses (δ34S, δ18OSO4, δD and δ18Owater) and hydrogeochemical methods to investigate the regional characteristics of groundwater sulfate source and evolution in China's largest coalfield (the Shenfuyu Coalfield). The results showed that the source and evolution of groundwater sulfate were controlled by human activities (mining and agricultural activities) and hydrogeological conditions. The groundwater sulfate primarily originated from pyrite oxidation, gypsum dissolution and human inputs. For the mining districts with shallow mining depths, pyrite oxidation and fertilizer contributed to groundwater sulfate. In addition, the ground cracks and abandoned mines controlled the BSR and pyrite oxidation processes. In contrast, the gypsum dissolution and cation exchange dominated the sulfate evolution in the mining districts with deep mining depths due to slow groundwater circulation. This study provided new insights into the source and evolution of groundwater sulfate in large coalfields, as well as references for regional water resource utilization and protection.

Hydrochemical Characteristics, Controlling Factors and Groundwater Sources of Zaozigou Gold Mine

The Zaozigou gold deposit is recognized as one of the largest and most significant independent gold deposits in northwest China, representing a colossal orogenic gold-antimony deposit. It is imperative to delve into the hydrochemical characteristics and controlling factors within the mining area to unveil the groundwater circulation evolution process and enhance water resource management. In 2018, a comprehensive collection of 50 groups of groundwater samples was conducted, alongside 17 groups of surface water and underground mine water samples in 2023. Compositional descriptive analysis, correlation analysis, Piper three-plot, Gibbs map, ion ratio method, hydrogeochemical simulation and PCA methods were employed to reveal the chemical characteristics and evolution process of groundwater in the Zaozigou gold mine. Furthermore, employing water isotopes theory allowed for the identification of recharge sources and circulation conditions within the Zaozigou Gold Mine. The findings indicated a transition from HCO3-Na·Ca type polluted water in 2018 to primarily the SO4-Ca·Mg type and HCO3·SO4-Na·Ca·Mg type groundwater hydrochemistry types by 2023. The hydrochemical characteristics of the study area are closely related to the mining depth and time. The chemical characteristics are influenced by various factors such as rock weathering, mineral dissolution, cation exchange processes, atmospheric precipitation as well as human activities related to pollution from industrial mining activities.

Synergistic approach of GCW-ISTR for enhanced remediation of semi-volatile organic contaminants in groundwater: Modeling and experimental validation

The poor remediation performance of groundwater circulation well (GCW) on semi-volatile organic contaminants (such as aniline) has severely limited its practical application. To address the challenges posed by the low volatility and solubility of these contaminants, an innovative integration of GCW with in-situ thermal remediation (ISTR) was proposed to create a thermal enhanced circulation well (GCW-ISTR) in this study. Laboratory experiments and model simulations were performed to evaluate the heat transfer and enhanced remediation effect by GCW-ISTR. Results demonstrate that the heat transfer process is controlled by the water circulation around GCW-ISTR and is influenced by factors such as aeration flow rate, groundwater velocity and aquifer permeability. Heating area is directly proportional to the seepage velocity of groundwater which can be analyzed by multiplying the water head difference between the upper and lower screens with the aquifer permeability. Therefore, the heat transfer model, based on Darcy's seepage theory and the energy conservation equation, effectively simulates the heat transfer with an error margin of less than 10%. Compared to individual GCW, GCW-ISTR exhibits a 25.8% improvement in aniline remediation efficiency, resulting in a decrease in the average concentration from 97.95 mg/L to 0.168 mg/L within 48 h, effectively mitigating the occurrence of tailing phenomena. This study provides a feasible method of enhancing the remediation of GCW on semi-volatile contaminants and is anticipated to broaden the applicability of GCW in site application.

Nanotechnology advancements in groundwater remediation: A comprehensive analysis of current research and future prospects

Groundwater contamination is a critical environmental issue with vital health implications. This review evaluates the advancements in nanotechnology for groundwater remediation, highlighting major findings and their relevance to Sustainable Development Goals (SDGs). Key findings include the superior adsorption capabilities of multi-walled carbon nanotubes functionalized with various groups for removing heavy metals and aromatic pollutants, outperforming traditional sorbents. The review also discusses the potential of nanomaterials like zero-valent iron nanoparticles for effective contaminant degradation. Despite promising results in the studies, challenges such as the movement and dispersion of engineered nanomaterials in porous media and the need for innovative delivery methods are identified. Furthermore, this review explores the environmental and health risks associated with the use of nanomaterials, emphasizing the need for risk assessments to ensure safe application. The novel delivery methods assessed, such as the use of groundwater circulation wells and the combination of nanoremediation with other techniques like bioremediation, demonstrate potential to enhance remediation efficiency. The integration of nanotechnology in groundwater remediation directly contributes to Clean Water and Sanitation by providing innovative solutions for the purification of water resources. Advanced nanomaterials not only improve contaminant removal efficiency but also promote sustainable water management practices. Additionally, the environmental benefits align with Life on Land, as the reduction of hazardous substances in groundwater protects terrestrial ecosystems and promotes biodiversity conservation. This review study aims to enhance understanding and identify future opportunities for nanotechnology in groundwater remediation. By addressing current challenges and proposing innovative solutions, this review underscores the importance of interdisciplinary research and collaboration in advancing sustainable development.

Effect of climate warming on subsurface temperature in basins with topography-driven groundwater flow

Climate warming has caused increased air temperature as well as increased subsurface temperature. Many previous studies on subsurface warming simplified heat advection by neglecting the horizontal component of regional groundwater flow or even neglected heat advection accompanying groundwater flow. In this study, the simultaneous control of heat advection and conduction on subsurface warming is numerically investigated in a 2D hypothetical basin cross section. By calculating the increment of subsurface temperature, we find that heat advection could accelerate subsurface warming. In a given basin, subsurface warming in the recharge area with downward groundwater flow is more significant than that in the discharge area with upward groundwater flow. By using a 1D model with vertical groundwater flow only for comparison, we find that in any part of a basin, even if the horizontal flux is very small compared with the vertical flux, neglecting the horizontal flux would underestimate the propagation depth of climate warming. This implies that when the propagation depth of climate warming is a priori known variable, existing 1D models would overestimate downward groundwater flux or underestimate upward groundwater flux. Moreover, we find pumping would cause deeper propagation depths of climate warming by accelerating groundwater circulation, whereas basin-scale heterogeneity and anisotropy of hydraulic conductivity would cause shallower propagation depths of climate warming because of the relative dominance of horizontal flow. By demonstrating the importance of 2D groundwater flow on subsurface warming, the results provide new insight into understanding the regulation of temperature among the atmosphere, the hydrosphere and the lithosphere.

Assessment of Groundwater Age in the Upper Chao Phraya River Basin Using Tritium and Carbon-14 Isotope Analysis

Groundwater is a critical resource in the Upper Chao Phraya basin, providing consistent water supplies for agricultural, domestic, and industrial activities, especially during the dry season. This study utilized tritium and carbon-14 dating techniques to investigate groundwater age, analyzing 273 samples collected in 2021 from various wells and depths across the basin. Tritium and carbon-14 were measured using liquid scintillation counting (LSC). The results revealed a wide range of groundwater ages, including recently recharged water with tritium concentrations up to 2.4 TU, corresponding to groundwater ages ranging from a few months to 44.17 years BP (Before Present), with an average of 18.26 years BP. Older groundwater was identified with carbon-14 concentrations as low as 3.22 pMC, indicating ages of up to 22,899 years, with a mean age of 6687 years BP. Correlation analysis showed a positive relationship between tritium and carbon-14 concentrations (r = 0.52). Spatial distribution patterns indicated that tritium concentrations were higher in northern and mountainous areas, identifying these as critical recharge zones. In contrast, lower carbon-14 concentrations in the central and southern areas suggested the presence of older groundwater, emphasizing the need for careful management of these ancient water reserves. The spatial variation in tritium and carbon-14 concentrations highlights differences in groundwater circulation and recharge patterns, enabling the identification of key recharge zones in the northern and highland regions. This highlights the importance of conserving these areas from pollution and over-extraction. The presence of old groundwater in the central and southern areas further emphasizes the need for ongoing monitoring to sustainably manage these long-term water resources. This study enhances the understanding of groundwater dynamics in the Upper Chao Phraya basin and provides valuable insights for improving water resource management strategies.

Numerical simulation of groundwater in hyporheic zone with coupled parameter stochastic scheme

Groundwater numerical modeling is a crucial scientific tool for understanding groundwater circulation and supporting regional water resource planning and management. The effectiveness of these models depends largely on the accuracy of hydrogeological parameters within aquifers, which are often spatially heterogeneous and randomly distributed due to complex geological and tectonic factors. Traditional modeling approaches frequently overlook this randomness, compromising the precision and resolution of groundwater simulations. This study focuses on a section of the Qingshui River in the Huaihe River Basin. Using field and laboratory data, probability distribution functions for key parameters like hydraulic conductivity, specific yield, and specific storage were developed. These functions were integrated into the groundwater model to reflect the inherent stochastic nature of aquifer properties. This integration significantly enhanced model accuracy, reducing the root mean square error of simulated water levels from 0.47–1.43 m to 0.13–0.16 m and improving the Nash-Sutcliffe efficiency coefficients (NSE) from −2.96–0.73 to 0.94–0.98. Additionally, the model facilitated analysis of the interactions between river and groundwater, particularly in the hyporheic zone, under various scenarios. It identified spatial and temporal variations in groundwater recharge dynamics and delay effects at different distances from the river channel. For instance, recharge rates at 50 m and 150 m from the river were 0.295 m/day and 0.015 m/day, respectively, indicating stronger recharge closer to the river. The study also assessed the impact of varying river flows, riverbed permeability, and irrigation practices on water exchanges between the river and groundwater. These factors were found to significantly influence the intensity of water exchange, seepage, and groundwater reserves. This research provides valuable insights for managing river-groundwater interactions and analyzing the ecological environment of surrounding groundwater systems, underscoring the importance of incorporating stochastic characteristics into groundwater modeling.

Prospecting Tungsten (Scheelite) Mineralization in the Djouzami Area (Adamawa Cameroon) Using Ultra-Violet (UV) Fluorescence and Landsat-8 OLI Images

Remote sensing technology and X-rays fluorescence are largely used in the applied geology field. In this study, we combine field observations and petrography, remote sensing applications through the processing of the Landsat-8 OLI, and Ultra-violet fluorescence to map geological structures, hydrothermal alteration minerals, and characterize tungsten mineralization in the Djouzami area (Adamawa, Cameroon). Landsat-8 OLI satellite imagery, was processed to detect both hydrothermal alteration zones and regional structural lineaments associated with tungsten mineralization. Fieldworks and petrography revealed hydrothermal mineral assemblage made of muscovite, chlorite, tourmaline, hematite, calcite and sericite associated to metallic minerals including tungsten and pyrite hosted in quartz veins. This hydrothermal mineral assemblage is also identified in the gold-bearing quartz veins reported in several areas along the Lom group. Band Ratio (BR) and Principal component analysis (PCA) were implemented to extract spectral information related to alteration minerals. The Band Ratios 6/7, 4/2, and 6/5 have permits to map clay, iron oxide/hydroxides, and ferrous minerals, respectively. This study demonstrates the significant potential of fieldwork and multispectral remote sensing data processing for tungsten prospecting as a mineral exploration technique in the Djouzami region. The mapping led to the detection of 1334 lineaments which show four main directions. The ENE-WSW directions corresponds to the trending of the Sanaga shear zone; the NE-SW direction represents the trending of the Djouzami and the Bétaré-Oya shear zones or the main shear zone which underline the Lom group; the N-S and E-W directions are equivalent to the trending of the foliation in the Meiganga area. Most of the high hydrothermal zones and tungsten-bearing quartz veins are located along the NE-SW lineaments or shear zone. Gold-related NE-SW trending Djouzami shear zone is also proposed. The NE-SW structure constitute certainly pathway for mineralizing fluids and ground water circulation, and control tungsten mineralization. Results proposed in this work provide important information for research of characteristic hydrothermal minerals assemblage that accompany tungsten mineralization, and for identify structures that control this mineralization in the area.

3D GeoRemediation: A Digital Hydrogeophysical–Chemical Clone and Virtual Hydraulic Barrier with Groundwater Circulation Wells (GCWs) for Groundwater Remediation

Identification of contamination sources and delineation of plumes in the geological environment stand as pivotal elements in reconstructing the conceptual site model (CSM) and devising remediation strategies tailored to specific physicochemical traits. This study endeavors to showcase the capabilities of a 3D digital interface, seamlessly integrating multi-source data, to elucidate site-specific contamination dynamics and steer the implementation of remediation strategies harmoniously aligned with the ethos of remediation geology. In a site historically marred by chlorinated solvent contamination, the digitization of stratigraphic, piezometric, chemical, and membrane interface probe (MIP) data underpins geomodeling endeavors and yields a meticulously crafted, data-driven CSM. The hydrogeochemical and hydrogeophysical data were interpolated to build a volumetric, digital 3D model illustrating data-driven elements. The comprehensive 3D clone adeptly delineates secondary contamination sources and renders visible the contamination plume within a georeferenced framework, mirroring the nuanced interplay of stratigraphic nuances and groundwater path. A data-centric approach to modeling facilitates the design of the first hydraulic virtual barrier leveraging groundwater circulation well (GCW) technology, its geometry finely attuned to intercept the contamination plume originating from source dissolution and aligning with preferential groundwater flow trajectories. Conventional hydrochemical monitoring and multilevel sampling substantiate the discernible reduction in chlorinated solvent concentrations across various depths within the aquifer horizon, affirming the efficacy of GCWs in their virtual barrier configuration. The findings highlight the effectiveness and limited groundwater consumption of the virtual barrier compared to the on-site pump-and-stock system. This research underscores the potency of a multi-faceted evidence-driven puzzle in conceptualizing contamination mechanisms within the geological milieu, thereby fostering the application of cutting-edge, effective, and sustainable remediation strategies.

Quantifying Seepage‐Face Evaporation and Its Effects on Groundwater Flow and Solute Transport in Small‐Slope Tidal Flat

AbstractLarge‐scale seepage faces occur on tidal flats with gentle slope, which are widely distributed worldwide. Evaporation on these seepage faces, leading to salt retention and accumulation, may significantly impact the density‐dependent groundwater flow beneath the tidal flats. However, due to nonlinear complexities of the groundwater flow and solute transport on seepage faces, explicit boundary conditions and numerical models to quantify these processes are lacking. In this study, we present both mathematical and numerical models to quantify these processes. Compared to the results of our previous study, this paper shows that seepage‐face evaporation can (a) significantly increase the groundwater salinity in the upper intertidal zone, and form multiple groundwater circulation cells in the intertidal zone, (b) cause the disappearance of multiple seepage‐faces and reduce the spatial extent of seepage faces notably, (c) and intensify the groundwater and salt exchange as well as the seawater‐groundwater circulation through the intertidal zone.

A multi-method approach for assessing groundwater vulnerability of shallow aquifers in the Marchfeld region (Austria)

Study regionMarchfeld region (Austria) Study focusA multi-method and multi-scale assessment of the intrinsic groundwater vulnerability to generic pollutants was carried out. At the regional scale, a parametric method, to assess the intrinsic groundwater vulnerability, and a transfer function model, to assess the travel time of a generic and non-reactive pollutant through the unsaturated zone, were applied. At the site-specific scale, the travel time of the peak concentration was evaluated by using a physically-based hydrological model. The comparison of results of different approaches allowed mutual validation and advanced the knowledge about the assessment of groundwater vulnerability. New hydrogeological insights for the regionTo assess the groundwater vulnerability, a detailed hydrogeological map of the study area was reconstructed. A large variability of hydrogeological, morphological and anthropic conditions was recognized. Alluvial aquifers formed by high-permeability deposits hosting shallow groundwater circulation are characterized by the highest groundwater vulnerability. Contrarily, lower groundwater vulnerability was recognized for aquifers formed by low-permeability deposits, favoring a reduction of infiltration processes and a major attenuation of pollutants’ potential effects. The presented multi-method approach revealed how comparing the results of a DRASTIC-like method and two process-based models can deliver hints regarding their suitability, different spatial densities and quality of required inputs, and effectiveness. Finally, the potential strong impact of some agricultural practices was confirmed.