Hydrogeochemical Data Research Articles

Interpretation of hydrogeochemical data using Hierarchical Cluster Analysis: A case study at Wadi El-Natrun, Egypt

Multivariate Statistical techniques have been widely applied in hydrogeology, geochemistry, and hydrology to identify commonalities or differences between large data sets. In this article, Hierarchical Cluster Analysis was performed on recent hydrogeochemical data (27 wells and 8 inland lakes) obtained at Wadi El-Natrun in April 2013 and April 2015. The purpose of this exercise was to understand the variability and similarities between ground and surface water quality in a less complex way. As well, to identify key variables in these environmental settings that could help to monitor the water quality of these resources. An additional purpose has been to shed some light, from a chemistry point of view, on the witnessed ‘salinization’ of these resources within this area. Overall, HCA provided an indication that both resources received had a potential water recharge during 2015 relative to 2013 that was supported by other regional reporting. Rearrangement of some surface water variables within clusters relative to groundwater was indicative of topsoil mineralization as well as the change in water levels due to recharge and/or evaporation.

The use of very low-frequency electromagnetic survey in the mapping of groundwater condition in oporoza-gbamaratu area of the Niger Delta

The use of VLF-EM in sedimentary basins has not been fully understood and has not attracted substantial usage in groundwater exploration, specifically in coastal Niger Delta. In the present study, VLF and 2D electrical resistivity imaging (ERI) surveys were combined with hydrogeochemical data to examine groundwater quality. Both interpretations of VLF and 2D ERI uncovered subsurface conductive geologic materials. Eight groundwater and one river water samples as well as static water level were analyzed to complement geophysical data (VLF-EM and ERI). The results suggested that conductive materials detected in the subsurface are unconnected with intrusion of sea water but depicted clay material typical of tidal flat deposits. Furthermore, hydraulic heads estimated from water level and land elevation measurements did suggest that groundwater flows into the Escravos River. Also, the stage of the Escravos River is above water levels in boreholes and hand-dug wells, which is not an indicative of the incursion of salt water into aquifer from the river. The slight level of nitrate loading in groundwater probably suggests contamination emanating from anthropogenic sources such as septic tanks and leachates from diffuse refuse dumps. The study has validated the effectiveness of VLF technique usage in sedimentary basins for the delineation of groundwater quality, but not without important hydrogeochemical data.

The application of selected hydrochemical indicators in the interpretation of hydrogeochemical data – A case study from Busko-Zdrój and Solec-Zdrój (Poland)

Abstract The processes affecting the formation of the chemical composition of the waters take place in specific hydrochemical zones. The knowledge of such phenomena allows to draw conclusions regarding the origin and conditions prevailing in the regions of their occurrence, e.g. indicate a zone of active water exchange, i.e. an inflow of infiltration waters, or a zone of isolated geological structures, where diagenesis processes take place. The aim of the study was to assess the hydrochemical conditions which affect the formation of chemical composition and genesis of origin of sulfide waters from the Busko-Zdroj and Solec-Zdroj region (Poland) using selected hydrochemical indices (rNa+/rCl−, rNa+/rK+, rNa+/(rNa++rCl−), rSO42− × 100/rCl−, rCl−/rBr−, rHCO3−/rCl− and the weight index: Cl−/Br−). A detailed analysis was carried out for sulfide waters from fifteen intakes and five springs. Several aquifer systems are found in the study area. Investigated intakes and springs differ in terms of stratigraphy and lithology. The analysis of changes in the values of selected hydrochemical indices confirms that waters of the Busko-Zdroj and Solec-Zdroj region belong to two systems of circulation — “shallow” and “deep”. The formation of the chemical composition of analysed waters occurs mainly in the aquifer. The values of rNa+/rCl−, rCl−/rBr−, rNa+/(rNa++rCl−), and Cl−/Br− indices suggest that the salinity of sulfide waters may result from leaching of salt interburdens and inclusions. In the area of occurrence of sulfide springs, tectonic cracking zones enable the inflow of highly mineralized waters and thus contribute to the mixing of waters of different aquifers. High content of Cl− and Na+ ions as well as mineralization higher than in sea waters indicate the formation of waters from the upper Cretaceous level together with deposits in a sedimentary basin.

Groundwater‐controlled phosphorus release and transport from sandy aquifer into lake

AbstractAwareness of groundwater‐borne dissolved inorganic phosphorus (DIP) loadings into lakes and its role in lake eutrophication is increasing, albeit DIP of natural origin is often ignored. Release of geogenic DIP from an adjacent aquifer and its transport with groundwater into a eutrophic lake is described by combining hydrogeochemical data collected in this study (sampling of piezometers, hydrogeochemical profiles, and seepage meters) with groundwater flow and discharge rates from earlier studies. The major part of the DIP that entered the lake with discharging groundwater was mobilized from iron hydroxides reduced by organic matter buried in the sediments of the old lake bottom. This is indicated by the correlation between DIP and ferrous iron (Fe2+) concentrations, with a DIP/Fe2+ molar ratio of 0.06, and an increase in pH. One‐dimensional reactive transport modeling indicated that high discharge rates (> 0.1 m d−1) of anoxic groundwater upwelling in areas adjacent to the lakeshore prevent downward diffusion of oxygen into the aquifer and do not leave enough time for DIP to become rebounding to the mineral phases at the sediment‐water interface. The groundwater‐controlled DIP input into the lake calculated along a two‐dimensional cross‐section averaged 0.01 mol DIP m−2 yr−1. A 2 m wide offshore high discharge zone delivered approximately 13% of the DIP into the lake. The continuous, external loading of geogenic DIP sustains lake eutrophication and explains the failure of two previous lake restoration attempts.

Hydrogeochemistry characteristic contrasts between low- and high-antimony in shallow drinkable groundwater at the largest antimony mine in hunan province, China

The antimony (Sb) content of shallow drinkable groundwater at Xikuangshang mine area (in Hunan province, China) has exceeded China's national drinking water quality guidelines, posing a serious threat to the health of residents in the mine area. The difference in hydrogeochemistry characteristics and water-rock interactions between low Sb groundwater (<0.015 mg/L) and high Sb groundwater (>0.015 mg/L), however, remains unclear. In this study, 24 samples were collected from shallow drinkable groundwater at the mine area. The hydrogeochemistry data and water-rock interactions were analyzed to reveal the condition leading to the formation of high Sb groundwater. Compared with low Sb groundwater, high Sb groundwater has a higher level of Na+, TDS, and SO42-, which increase by 6.38, 1.84, and 4.04 times, respectively. The low Sb groundwater is mainly controlled by Ca–HCO3–SO4 type, whereas the high Sb groundwater is controlled by Ca–HCO3–SO4 type as the main facies, and Ca–Na–SO4 type and Ca–SO4–HCO3 type as the secondary facies. The chemical composition of low Sb groundwater is mainly influenced by the dissolution of carbonate minerals and the chemical composition of high Sb groundwater is controlled by ion-exchange interaction and dissolution of carbonate minerals and silicate minerals, among which ion-exchange interaction is the most important factor. The outcomes of this research provide a better understanding of the mechanisms of Sb pollution in groundwater and it will help in securing safe drinking water sources for local communities.

Prediction of geothermal originated boron contamination by deep learning approach: at Western Anatolia Geothermal Systems in Turkey

Geothermal fluids consist of hot water, steam and gases in water-dominated reservoirs. They contain various dissolved major elements such as sodium, potassium, calcium, silica, bicarbonate, carbonate, chlorine, sulphate and minor elements such as boron, fluorine, lithium, iron, arsenic, mercury and bromine at different concentrations in the liquid phase. The concentration of dissolved solids depends on the temperature, gas content, reservoir geology, permeability, water mixing and fluid source of a geothermal system. Some of these species exhibit a toxic effect at high concentrations and require precaution after the discharging of geothermal water. Boron is one of the important constituents and can be observed as boric acid (H₃BO₃) or HBO₂ in the water phase. The concentration of B changes between 10 and 50 ppm in chloride-type fluids and can occur in greater quantities than these values in organic-rich sedimentary rocks in geothermal fluids. Although boron is considered toxic, it is also one of the crude minerals and can be used in different industries, such as oil and gas chemistry, vehicle technologies, agriculture, ceramics, and adhesive and coating, among others. Machine learning is a method of data analytics for identifying patterns in data and using them to automatically make predictions about new data points. Deep learning is a machine learning subset that uses artificial neural networks with multiple layers. Deep learning can automatically learn representations from data without hand-coded rules or domain knowledge; this is the primary difference between deep learning and traditional machine learning techniques. In this study, a deep neural network model has been developed to predict boron concentrations based on hydrogeochemistry data for different geothermal systems. To compare the prediction performance of our proposed deep neural network model, two well-known regression approaches, linear regression and linear support vector machine (SVM), were performed, and the results have been presented. The performance comparison revealed that our deep neural network (DNN) model achieved better prediction performance than traditional machine learning techniques—linear regression and linear SVM.

Compositions and mobility of major, δD, δ18O, trace, and REEs patterns in water sources at Benue River Basin-Cameroon: implications for recharge mechanisms, geo-environmental controls, and public health.

Hydro-geochemical data are required for understanding of water quality, provenance, and chemical composition for the 2,117,700km2 Niger River Basin. This study presents hydro-geochemical analysis of the Benue River Basin, a major tributary of the Niger River. The distribution of major ions, Si, δD, and δ18O, trace and rare-earth elements (TE and REEs, respectively) composition in 86 random water samples, revealed mixing of groundwater with surface water to recharge shallow aquifers by July and September rains. Equilibration of groundwater with kaolinite and montmorillonites, by incongruent dissolution, imprints hydro-chemical signatures that vary from Ca + Mg - NO3 in shallow wells to Na + K - HCO3 in boreholes and surface waters, with undesirable concentrations of fluoride identified as major source of fluorosis in the local population. Our results further indicate non-isochemical dissolution of local rocks by water, with springs, wells and borehole waters exhibiting surface water-gaining, weakest water-rock interaction, and strongest water-rock interaction processes, respectively. Poorly mobile elements (Al, Th and Fe) are preferentially retained in the solid residue of incongruent dissolution, while alkalis, alkaline earth and oxo-anion-forming elements (U, Mo, Na, K, Rb, Ca, Li, Sr, Ba, Zn, Pb) are more mobile and enriched in the aqueous phase, whereas transition metals display an intermediate behavior. Trace elements vary in the order of Ba > Sr > Zn > Li > V > Cu > Ni > Co > As > Cr > Sc > Ti > Be > Pb > Cd, with potentially harmful elements such as Cd, As, and Pb mobilized in acidic media attaining near-undesirable levels in populated localities. With the exception of Y, REEs distribution in groundwater in the order of Eu > Sm > Ce > Nd > La > Gd > Pr > Dy > Er > Yb > Ho > Tb > Tm differs slightly with surface water composition. Post-Archean Average Australian Shale-normalized REEs patterns ranging from 1.08 to 199 point to the dissolution of silicates as key sources of trace elements to groundwater, coupled to deposition by eolian dust.

Kilometer‐Scale Hydrologic Exchange Flows in a Gravel Bed River Corridor and Their Implications to Solute Migration

AbstractA well‐characterized field site along a major, gravel bed river corridor was used to investigate the dynamic pathways and impacts of subsurface hydrogeologic structure on kilometer‐scale hydrologic exchange flows between river water and groundwater. An aqueous uranium (Uaq) plume exists within a hyporheic alluvial aquifer at the site that discharges to the Columbia River. We performed temporally intensive monitoring of specific conductance (SpC) and Uaq concentrations within the plume for a 2‐year period at varying distances from the river shoreline, both within and outside a presumed subsurface pathway of lateral hydrologic exchange. SpC and Uaq were utilized as in situ tracers of hydrologic exchange and associated groundwater‐surface water mixing. Seasonal river stage variations by more than 2 m caused distinct events of river water intrusion and retreat from the nearshore, hyporheic alluvial aquifer, resulting in highly dynamic SpC and Uaq patterns in monitoring wells. Simulations of hydrologic exchange and mixing were performed with PFLOTRAN to understand the observed SpC and Uaq behaviors linked to predominant flow directions and velocities in the river corridor as influenced by river stage dynamics and variable aquitard topography. By coupling robust monitoring with numerical flow and transport modeling, we demonstrate complicated multidirectional flow behaviors at the kilometer scale that strongly influenced plume dynamics. Therefore, hyporheic aquifer must be frequently monitored under different flow conditions if water quality is of concern. The resulting hydrologic understanding enables improved interpretation of hydrogeochemical data from this site and other large gravel bed river corridors in the United States and elsewhere.

Geophysical investigation of resistivity and groundwater quality in Ogbe-Ijoh coastal area of the western Niger Delta of Nigeria

Groundwater quality assessment is essential for groundwater resource management, especially as it concerns the health of those that consume it. Consequently, we assembled resistivity and hydrogeochemical data to assess the adverse effect of anthropogenic sources on groundwater quality in Ogbe-Ijoh, a coastal area of the western Niger Delta. Geoelectrical data showed no evidence of quality degradation as reflected by high resistivity values that ranged from 29.3 to 349.9 Ωm. Aquiclude of adequate thickness capping aquifers was uncovered in most areas assessed, with the exception of areas near the bank of the river. The delineated clay sedimentary horizon probably enhanced groundwater quality sustainability by acting as a barrier to migrating contaminants, especially from leachate and septic tanks. The physical properties of groundwater sampled indicated moderate pH, TDS and EC magnitudes, with a majority having magnitudes lesser than the requisite standards. The geochemistry of groundwater revealed cations and anions with magnitudes that are distinctively lesser than the desired ranges. Piper plot revealed two different water types: NaCl− and Ca2+ + Mg2+ + Cl− + SO4, which implied that cation exchange has a weighty effect on quality of groundwater. Overall, the hydrogeochemical results are consistent with resistivity data and revealed the efficacy of the pairs in groundwater quality assessment in the absence of lithologic information. The groundwater condition is relatively safe for consumption; nevertheless, due to health implications we recommend that pH should be increased to the required standard before drinking.

Groundwater Quality Assessment of Nanjangud Industrial Hub using Statistical Tool

Hydrogeochemical data pertaining to thirty five groundwater samples in Nanjangud Industrial area were considered in this research work. The water quality parameters were analyzed for physico-chemical characteristics and correlation analysis was used as a statistical tool. Analysis of groundwater revealed that the parameters like EC, TDS, hardness and chlorides in many sampling points exceeded the limits of BIS Standards. EC varied from 0.4 – 12.7mmho/cm and hardness varied from 112 to 2545 mg/L as CaCO3. The correlation matrix clearly indicated that EC was mainly controlled by, TDS, Chlorides and Hardness in a sequence with high positive correlation(&gt; 0.7). Acidity and Sulphates of the ground water samples indicated negative values of Kurtosis (flat peak). The skewness values for the parameters of concern were positive, indicating that data were distributed in the right direction of the tail. It can be concluded that the results of physico-chemical and statistical analysis depicted the deterioration of groundwater in the Nanjangud Industrial area.

Hydrochemistry of tropical springs using multivariate statistical analysis in Ithikkara and Kallada river basins, Kerala, India

Spring waters are the most important natural resource used for drinking by many people around the world, especially in arid and semi-arid areas. This resource cannot be optimally used and sustained, unless the quality of groundwater is assessed. The main objective of this study is to understand the quality and hydrochemistry of spring water sources of two important river basins of Southern Western Ghats—the Ithikkara and the Kallada river basins draining Kollam district of Southern Kerala as an example. Water Quality Index (WQI) values are used to assess the drinking suitability of spring water samples. Multivariate statistical approach (factor analysis and principal component analysis) allow driving hidden information from the data set about their possible influences of the environment on water quality. Multivariate analysis was performed on matrix of hydro-geochemical data. To study the influences of the environment on water quality, multivariate statistical approach is applied. A total of 57 samples were collected and analyzed for major cations and anions for pre-monsoon, monsoon and post-monsoon seasons of 2011–2012 periods from lowland and highland regions of the study area. The results of the WQI values show that majority of the samples fall in Excellent to Good category rendering these water samples suitable for drinking purposes. From the statistical analysis, it is inferred that in catchments rich with pyrite in rocks and clays, drainage of sulphuric acid may significantly contribute to acidity. The negative loading in pH and DO is due to anaerobic conditions in the spring source from the loading of high-dissolved organic matter, which results in the formation of ammonia and organic acids leading to a decrease in pH. The positive loading of SiO2 reflects the dissolution of silica minerals and high temperature. The evaluation of the saturation index of the water samples in highland regions indicted that water was oversaturated with respect to iron minerals and undersaturated with fluorite minerals. The chemistry of the spring waters favors kaolinization and subsequent leaching of mobile elements like alkali and alkaline earth elements. The study is helpful in understanding the relationship between individual ions and for the classification of groundwater types.

Linking microbial community composition to hydrogeochemistry in the western Hetao Basin: Potential importance of ammonium as an electron donor during arsenic mobilization

Various functional groups of microorganisms and related biogeochemical processes are likely to control arsenic (As) mobilization in groundwater systems. However, spatially-dependent correlations between microbial community composition and geochemical zonation along groundwater flow paths are not fully understood, especially with respect to arsenic mobility. The western Hetao Basin was selected as the study area to address this limitation, where groundwater flows from a proximal fan (geochemical-group I: low As, oxidizing), through a transition area (geochemical-group II: moderate As, moderately-reducing) and then to a flat plain (geochemical-group III: high As, reducing). High-throughput Illumina 16S rRNA gene sequencing showed that the microbial community structure in the proximal fan included bacteria affiliated with organic carbon degradation and nitrate-reduction or even nitrate-dependant Fe(II)-oxidation, mainly resulting in As immobilization. In contrast, for the flat plain, high As groundwater contained Fe(III)- and As(V)-reducing bacteria, consistent with current models on As mobilization driven via reductive dissolution of Fe(III)/As(V) mineral assemblages. However, Spearman correlations between hydrogeochemical data and microbial community compositions indicated that ammonium as a possible electron donor induced reduction of Fe oxide minerals, suggesting a wider range of metabolic pathways (including ammonium oxidation coupled with Fe(III) reduction) driving As mobilization in high As groundwater systems.

Rapid groundwater recharge dynamics determined from hydrogeochemical and isotope data in a small permafrost watershed near Umiujaq (Nunavik, Canada)

Hydrogeochemical data are used to better understand recharge dynamics and to support a hydrogeological conceptual model in a 2-km2 watershed in a discontinuous permafrost zone in Nunavik, Canada. The watershed contains an upper (surficial) and lower aquifer within Quaternary deposits, above and below a marine silt layer containing ice-rich permafrost mounds. The analysis is based on water samples from precipitation, groundwater monitoring wells, ground ice in permafrost mounds, thermokarst lakes and a perennial stream. Groundwater geochemistry in both aquifers reflects young, poorly evolved waters, with mainly Ca-HCO3 water types and low mineralisation ranging from 11 to 158 mg/L total dissolved solids (TDS), implying short pathways and rapid travel times of a year or less. While relatively low, TDS signatures in groundwater and surface water show increasing values downgradient. Groundwater isotope values (δ18OH2O and δ2HH2O) are often strongly influenced by snowmelt, while those of thermokarst lakes show evidence of evaporation. Recharge along the cuesta contributes to a transverse component of groundwater flow within the valley with higher TDS and δ13CDIC values influenced by open-system weathering. Even where permafrost-free, the marine silt unit has a strong confining effect and plays a more important role on recharge dynamics than the discontinuous permafrost. Nevertheless, the vulnerability of these types of hydrogeological aquifer systems is expected to increase due to rapid recharge dynamics associated with the gradual loss of the confining effect of permafrost. This hydrogeochemical data set will be useful as a baseline to document impacts of permafrost degradation on the hydrogeological system.

Origin and Evolution of the Halo-Volcanic Complex of Dallol: Proto-Volcanism in Northern Afar (Ethiopia)

Contextual early observations on volcano genesis are valuable but scarce. Resembling a shield volcano, the Dallol dome is a complex 40 m-high geological structure on the Danakil depression, a North-South-elongated salt plain lying 120 m below sea level in the North Afar (Ethiopia). Dallol has become a tourist destination famous for its colorful hydrothermal features and raised scientific interest due to its life-challenging polyextreme conditions. Although some general models for its genesis exist, little is known about the origin and temporal evolution of both, the dome and its geothermal activity resulting in hyperacidic and halite-oversaturated brines. In this study, we combine published information with data obtained from our three multidisciplinary field campaigns (January 2016, 2017, and 2019) to refine the geological mapping of the North Danakil and the Dallol dome. The analysis of stratigraphic, geomorphological, geochemical, and hydrogeochemical data as well as satellite, drone and infrared aerial images allows us to shed light in its complex temporal evolution. Our results suggest that the recorded history of the dome began when at least one deep magmatic basalt intrusion occurred later than 6000 years ago, forcing the uplifting of the lacustrine deposits of that age covering the west side of the dome. The interaction of the magma with the buried salt deposit resulted in a halo-volcanic activity with, likely, several melted-salt effusion events. Substrate accommodation after effusion led to the current collapsing crater on the dome top and the geothermal still-ongoing degassing. An important hydrothermal reactivation took place after a dyke intrusion event in October–November 2004. It triggered the appearance of new fractures on the dome top and the northward migration of the hydrothermal activity, as we inferred from the analysis of historical aerial images combined with high-definition visible and infrared images taken from a drone during our field campaigns. Based on our observations, we present an updated hydrogeothermal conceptual model linking deep magmatic activity with halokinetic processes and geothermal fluids to explain the origin and evolution of the Dallol halo-volcanic complex. These geothermal manifestations may potentially inform about rarely documented premises of a volcano’s birth

Seasonal δ13CDIC sourcing and geochemical flux in telogenetic epikarst of south‐central Kentucky

AbstractTelogenetic epikarst carbon sourcing and transport processes and their associated hydrogeochemical responses are complex and dynamic. Carbon dioxide (CO2) transport rates in the epikarst zone are often driven by hydrogeochemical responses, which influence carbonate dissolution and conduit formation. This study examines the influence of land use on carbon sourcing and carbonate dissolution kinetics through a comparative analysis of separate, but similar, epikarst systems in south‐central Kentucky. The use of high‐resolution hydrogeochemical data from multiple data loggers and isotope analysis from collected water samples reflects the processes within these epikarst aquifers, which are estimated to contribute significantly to bedrock dissolution. Results indicate that, in an agricultural setting, long‐term variability and dissolution is governed by seasonal production of CO2. In a more urbanized, shallower epikarst system, land cover may affect CO2 transport between the soil and underlying bedrock. This concentration of CO2 potentially contributes to ongoing dissolution and conduit development, irrespective of seasonality. The observed responses in telogenetic epikarst systems seem to be more similar to eogenetic settings, which is suggested to be driven by CO2 transport occurring independent of high matrix porosity. The results of this study indicate site‐specific responses with respect to both geochemical and δ13CDIC changes on a seasonal scale, despite regional geologic similarities. The results indicate that further comparative analyses between rural and urban landscapes in other karst settings is needed to delineate the impact of land use and seasonality on dissolution and carbon sourcing during karst formation processes. © 2019 John Wiley &amp; Sons, Ltd.

Hydrogeochemistry of Pre-Jurassic Aquifers in West Siberia

Abstract ––For the first time in the last 35 years, hydrogeochemical data on pre-Jurassic complexes in West Siberia have been generalized. Groundwater and brines of Cl–Na and Cl–HCO3–Na type with total salinity (TDS) varying from 4 to 330 g/L are found to be widespread in the area under study, with the former type dominating. A detailed analysis of the hydrogeochemical data allowed us to assume the presence of three genetic groups of groundwater and brines in the hydrogeologic section: (1) sedimentogenic, (2) lithogenic (revived) and ancient infiltrogenic, and (3) condensatogenic. An integrated analysis of coefficients rNa/rCl, Ca/Cl, (Br/Cl)·10–3, and (Sr/Cl)·10–3 and integrated index S of brine metamorphization in the Siberian sedimentary basins has corroborated the fact that groundwater and brines in West Siberia are at the initial stage of metamorphization of their chemical composition. Groundwater and brines in the studied Siberian sedimentary basins show an increase in the degree of metamorphization (catagenetic changes) of their chemical composition in transition from the areas of igneous and metamorphic deposits at the base of the Meso–Cenozoic sedimentary cover of the young West Siberian sedimentary basin to the structures of the ancient Siberian Platform, where ultrastrong Ca–Na and Ca chloride brines are widespread.

Geochemical and statistical evaluation of spring water in Sarduiyeh Basin, SE Iran

This study investigates the natural processes that influence the chemistry of surface and spring water within the Sarduiyeh region using correlation matrix and factor analysis techniques. A total of 27 spring samples were collected during April 2011, and analyzed for their physico-chemical constituents. Hydrogeochemical data of samples suggested that the water types are: Na–Cl (40.74%), Ca–Mg–HCO3 (37.04%), Na–HCO3–Cl–Mg (14.81%) and Ca–Mg–SO4–Cl (7.41%). The order of cations and anions abundance is Na+> K+> Mg2+> Ca2+ and Cl− > SO42− > HCO3− > NO3−. The very high As concentrations are observed in three samples (numbers 24, 3 and 2) with value 25,000, 2327 and 2178 µg/L. The multivariate statistical methods indicate that hydrogeochemistry of the spring water in study area is mainly controlled by water–rock interaction, and weathering and dissolution of silicate minerals mainly extend in the area.

Possible links between groundwater geochemistry and chronic kidney disease of unknown etiology (CKDu): an investigation from the Ginnoruwa region in Sri Lanka

Since at least two decades, Chronic Kidney Disease of Uncertain Etiology (CKDu) has become an increasingly discussed health issue in Sri Lanka and as well as in other tropical regions. Areas that are particularly affected with the disease are mostly located in the dry zone of Sri Lanka. The disease is more prominent among communities that consume groundwater as their main source of drinking water. Hydrogeochemical investigations were carried out in the Ginnoruwa area, a known hotspot of CKDu. It revealed possible links between drinking water chemistry and the spreading of the disease. This work compares hydrogeochemical data of drinking water sources of wells whose consumers are affected by CKDu and other nearby wells whose consumers were not affected by the disease. A total of 63 groundwater samples were collected from selected wells. About one-third of these samples (i.e., 19) were collected from wells used by CKDu patients. Significantly higher values of pH, total hardness, electrical conductivity, Ca2+, Mg2+, F−, Cl−, PO43−, and SO42− were found in wells that were used by CKDu patients. Mean contents of Na+, Ca2+, and Mg2+ in CKDu affected wells were 33.8 mg/L, 30.1 mg/L, and 14.9 mg/L, respectively, compared to 23.1 mg/L, 26.7 mg/L, and 9.65 mg/L in non-CKDu wells. Differences in major ion geochemistry in groundwaters are possibly governed by variable time periods of water storage in fractured hard rock aquifers in this region. Hydrogeochemical parameters were statistically compared by a Mann–Whitney U test and indicated significant differences in total dissolved solids (TDS) (p = 0.016), SO42− (p = 0.005), PO43− (p = 0.030), F− (p = 0.048), Na+ (p = 0.008), and Mg2+(p = 0.008) between non-CKDu and CKDu wells at p = 0.050 level. Other suspected solutes such as nephrotoxic trace elements including As, Cd, and Pb were similar in both types of wells. They were also lower than the accepted guideline limits of the World Health Organization (WHO). Results of this study suggest that fluoride in drinking water in combination with water hardness may be one of the responsible factors for kidney damage and progression of the disease. This may be particularly the case when elevated amounts of Mg2+ are present in hard groundwater.

Geochemical appraisal of groundwater qualities and its uses in and around Maneswar Block of Sambalpur District, Odisha, India

The present study aims to approach the analysis of groundwater samples of the western part of Odisha, i.e. Maneswar Block of Sambalpur District to assess the quality of groundwater in terms of drinking and irrigation purposes. Altogether, 34 groundwater samples were collected from the Maneswar Block during the pre-monsoon period in 2017. The collected samples were analysed for different physicochemical parameters. The result of the chemical analysis revealed that the dominant hydrochemical facies for cation is Ca2+ > Na+ > Mg2+ > K+ and the dominant hydrochemical facies for anion is HCO3− > Cl− > SO42− > CO32−. The groundwater of the area is suitable for irrigation purposes except the areas having high %Na. Similarly, the water is suitable for drinking purposes in most of the cases except few where the TDS value is high. The multivariate hydrogeochemical data were plotted in various graphs and diagrams to depict the quality of groundwater of the study area. In both Piper’s trilinear and Chadha’s diagram, the groundwater samples indicate “alkaline earths exceed alkalies”. Gibbs diagram demonstrates that most of the samples fall on the “Rock dominance” and few samples fall on “Evaporation crystallization dominance” field.

Prediction of Reservoir Temperatures Using Hydrogeochemical Data, Western Anatolia Geothermal Systems (Turkey): A Machine Learning Approach

Geothermal fluids can be used for purposes such as power production, district heating/cooling, agriculture, and industrial and thermal tourism. Although using geothermal fluids is beneficial, it requires detailed exploration studies of a region. These exploration studies mainly involve geology, geophysics and geochemistry disciplines to understand the location, dimensions, possible capacity and temperature of a reservoir before beginning drilling operations. Because of the high operational costs, the exploration phase of a geothermal project is of great importance to reduce project costs. Evaluation of existing earth sciences data, detailed geology studies, mapping and some geochemical studies, such as using geothermometers, can provide information about a potential geothermal reservoir in a geothermal field. Machine learning is a technology for data analysis which identifies patterns in data and uses them to make predictions about new data points automatically. In this study, a deep learning model is developed to predict geothermal reservoir temperatures based on selected hydrogeochemistry data from different geothermal systems. Two traditional regression approaches, linear regression and linear support vector machine, are performed to compare the prediction performance of our proposed deep learning model. The objective of the study is to obtain the algorithm having the lowest root-mean-square error and mean absolute error. The results show that the deep neural network (DNN) algorithm generated the lowest errors. The DNN model provided the most accurate values close to geothermometer calculations for reservoir temperature. The performance comparison showed that our deep learning model achieved the best prediction performance compared to traditional machine learning techniques.