Cl SO4 Research Articles

Hydrogeochemistry of the groundwater system of the transboundary basement and volcanic aquifers of the Bulal catchment, Southern Ethiopia

The evaluation of groundwater geochemistry of transboundary aquifers has an important role in the management and sustainable use of groundwater resources in arid and semi-arid regions. This study presents the results of an integrated hydrogeochemical study of the Bulal transboundary aquifers located in the Borena zone, along the Ethiopia-Kenya border. The main aquifers are basic volcanic rocks, subordinate felsic pyroclastic deposits, and metamorphic basement rocks. These aquifers are overlain by alluvio-lacustrine sediments, eluvial soil and regolith. The groundwaters are dominated by Na+ and HCO3− and mixed water types. Silicate weathering and evaporation are the dominant hydrogeochemical processes controlling the chemistry of the groundwaters in most parts of the catchment. However, dissolution of evaporitic minerals might have also played a significant role in adding major ions into the groundwater system. Groundwater in the volcanic aquifers are Na–HCO3, Ca–Mg–HCO3, Na–Ca–HCO3 and Na–Cl–SO4 water types while Ca–Mg–HCO3, Na–Ca–Cl–SO4 and Ca–Mg–SO4 water types are dominant in the metamorphic basement aquifers. The groundwater in the catchment mainly evolved from Na–HCO3 in the west, Ca–Mg–HCO3 in the north, and Na–Ca–Cl–SO4 in the central east and southeast to Na–Ca–HCO3 type in the southern low-lying areas along the groundwater flow direction. The study has significant implications for the management of groundwater quality in the region.

Predicting and analysing the quality of water resources for industrial purposes using integrated data-intelligent algorithms

The continuous increase in the rate of industrialization in developing countries, in recent times, calls for continuous industrial water quality assessment and prediction. This is to create more awareness and ensure cleaner and sustainable industrial production. Water quality for industrial uses is often described in terms of corrosion and scaling potentials (CSPs). In this paper, optimized artificial intelligence models (e.g. multiple regressions (MR), hierarchical clusters (HCs), and artificial neural networks (ANNs)) for assessing and predicting the CSPs of water resources were developed, for Ojoto suburb (SE Nigeria). Indices used in evaluating the CSPs are chloride–sulphate mass ratio (CSMR), Larson-Skold index (LSI), Langelier index (LI), aggressive index (AI), Ryznar stability index (RSI), Puckorius scaling index (PSI), and Revelle index (RI). This work is the first of its kind to utilize predictive models in simultaneously predicting the industrial water quality indices. Prior to the predictive modeling, R-mode HCs, correlation, principal component, and factor analyses were used to analyze the relationships between the physicochemical variables (pH–T–EC–TDS–TH–Ca–HCO3–Cl–SO4–Fe–Zn–Pb) and the CSP indices. Q-mode HCs effectively identified the spatiotemporal water corrosion/scaling risk classification and distribution in the area. Both MR and ANN models suitably predicted the CSP indices. However, both models better predicted AI, LI, RSI and PSI than LSI, RI and CSMR. The MR models’ performances were analyzed using R, R2, adjusted R2 and F-ratio values whereas the ANN models were verified using parity plots, R2, RMSE, and residual error plots. For the ANN modeling, scaled-conjugate-gradient optimizer outperformed gradient-descent optimizer. Also, ANN models outperformed the MR models. The practical implications of the present research findings were also discussed.

Water quality indices and multivariate statistical analysis of urban groundwater in semi-arid Sokoto Basin, Northwestern Nigeria

Drinking water is limited in quantity and quality in fast-growing cities in developing countries. Water quality has been impacted by competing demands by industry, municipal supplies, and agriculture. This study investigates groundwater quality in three urban centres in the semiarid Sokoto Basin, North-Western Nigeria. The study employed in situ and laboratory analyses and 30 water samples were analysed. Physical parameters (pH, Temp., EC, and TDS) were analysed using hand-held metres during sampling. Separate water samples were collected to determine chemical parameters (Ca2+, Cu2+, Fe3+, K+, Mg2+, Na+, Zn2+, Cl−, CO32−, HC03-, NO3−, PO43− and SO42−). Results indicate that most sampling locations in the study area have good quality water; 10% of sampling locations fell in the poor water class based on the Water Quality Index (WQI). Iron (Fe3+) and NO3− were the major pollutants and occurred at concentrations above (WHO, 2011) and (NSDWQ, 2007) reference guidelines. Hydrogeochemical facies revealed Ca–Mg–SO4–Cl and Ca–Cl water types. There is no dominant water type in the cation triangle, though the Cl-water type is formed in an anion triangle. Rock weathering controls groundwater quality primarily, as revealed by multivariate statistical analysis and the Gibbs model. The HCA results showed that, though clusters 1 and 2 can be classified as NO3− polluted boreholes, the boreholes ARG7 and ARG10 revealed relatively different groundwater compositions. The study, therefore, concludes that despite the increased urbanisation in the semiarid Sokoto basin, there is little evidence of groundwater quality deterioration. The WQI and multivariate statistics provide a framework for researchers who may require more accurate results while considering multiple groundwater quality parameters. This approach can be applied in other urban centres, mainly in arid and semiarid environments.

New hydrogeochemical insights on a West Texas desert spring cluster: Trans-Pecos Balmorhea-Area Springs

Perennial Balmorhea-area springs (including San Solomon spring), located at the southern boundary of the tectonic Delaware Basin, have been investigated for decades. Distantly-sourced brackish (∼2200 mg/L) baseflow and local low-TDS Ca–HCO3 stormflow (<500 mg/L) components mix in various proportions. Competing hypotheses have been offered to explain the slow spring flowrate decline (currently ∼20-30 cfs, 0.55–0.85 m3/s) during the past century. Despite many studies, aspects of spring behavior remain poorly defined, mostly due to geological, structural, and hydrogeological complexity of the capture area, including the ultimate source and multiple flow paths to the springs. Using a total of 84 samples (springs and neighboring wells), we clarified the spatial extent of the characteristic spring hydrofacies. We analyzed samples for major and trace elements, stable water isotopes, sulfur and oxygen isotopes of sulfate, and strontium isotope ratio. The geochemical data set was complemented by historical data (∼2250 samples) from the larger region and 134 ∼weekly measurements at San Solomon spring in Balmorhea State Park. In addition to refining earlier findings, we determined the combined evaporitic Guadalupian platform units and Castile Formation are the likely source of the mixed Na–Ca cation and mixed Cl–SO4 anion spring water type, and that brines from underlying formations do not contribute significantly, if any, to spring flow. The spring evaporitic Cl/Br signature is not compatible with the low value of the ratio in the brines. We also clarified the non-artesian nature of some of the Balmorhea-area springs. Located downslope and downgradient of the main springs, these gravity springs exhibit a higher TDS than the artesian springs but also lack an evaporative signal, which combined with higher nitrate (>3 mg/L N–NO3), and lower DIC 13C isotope, is consistent with irrigation return flow.

Hydrogeochemical characteristics and sources of mirabilite in the high saline system of Sabkha Oum El Khialate, Southern Tunisia

Using hydrogeochemical approaches and geochemical modeling, integrated with data from 83 samples, including brines and fresh water, the main factors controlling the evolution of brine in the Sabkha Oum El Khialate catchment area in southeastern Tunisia are determined. Samples with high total dissolved solids (TDS), in the continental saline depression, are consistently dominated by Na–SO4 and Na–SO4–Cl water types while Ca–SO4–HCO3 and Ca–HCO3–SO4–Cl are the dominated facies in the catchment area of the sabkha. The PHREEQC geochemical modeling using PITZER database shows that most samples of the saline depression are oversaturated with respect to (sulfate minerals) thenardite, bloedite, glauberite, gypsum, and mirabilite and undersaturated with respect to calcite, halite, and dolomite. The most important hydrogeochemical processes that affect brine evolution in the Sabkha along the flow path are evaporation, gypsum dissolution, and the cationic exchange on clay minerals.

Groundwater-Based Drinking Water Supply in Sri Lanka: Status and Perspectives

Drinking water is largely from groundwater in Sri Lanka, so quality management is of great concern. In order to achieve the 6th goal of United Nations (UN) Sustainable Development Goals (SDG), more efforts are being undertaken to secure drinking water quality. In this paper, the current status, challenges and opportunities of groundwater quality management and improvement in Sri Lanka were reviewed and discussed, based on previous studies. There are Ca-HCO3 type, Ca–Mg-HCO3 type and Na–SO4–Cl type groundwater dominated in the wet zone, intermediate and the dry zone, respectively. Elevated levels of hardness, fluoride, DOC, and alkalinity, and salinity are reported in the groundwater in the dry zone controlled by geology and arid climate. Although groundwater in some regions contain significant levels of nitrates, arsenic, cadmium and lead, the majority remain at acceptable levels for drinking purposes. As for treatment technologies, existing membrane-based drinking water treatment technologies such as RO (Reverse Osmosis) stations can produce safe and clean drinking water to the community, but this has still a limited coverage. To achieve a safe drinking water supply for all, especially in rural communities of Sri Lanka under the 6th goal of the UN SDG, more efforts in building up the infrastructure and man power are needed to monitor and assess groundwater quality regularly so as to develop management strategies. Research and development can be directed towards more cost-effective water treatment technologies. Protection of groundwater from being polluted, and educational and awareness programs for the stakeholders are also essential tasks in the future.

Silica geothermometry and multi indices approach to characterize groundwater from Midyan region in Northwestern Saudi Arabia

This research was performed in the northwestern part of Saudi Arabia, where physico-chemical parameters obtained from 81 groundwater samples were interpreted. High heat flow granites underlie the study area, and their weathering and erosion cause the accumulation of radioactive elements in sediments surrounding these granites, resulting in a high temperature of the circulating water. The chalcedony (no steam loss) temperature of the circulating groundwater was determined using the dissolved silica values in the samples. Based on the obtained chalcedony temperature, the samples were categorized into two groups. The first group contained 63 samples with chalcedony temperatures less than 50 °C, and the second group contained 18 samples with temperatures above 50 °C. The Cl–SO4–HCO3 ternary diagram showed that the samples with higher temperatures were chloride type and plotted close to the mature water. The silica concentration showed a strong correlation with chloride, indicating that Cl was mostly obtained from mineral dissolution, although the wide variation in Cl and TDS for a narrow range of silica values indicated groundwater mixing or anthropogenic influence. According to the Piper plot, the (Ca + Mg)-(SO4+Cl), (Ca + Mg)-(HCO3+CO3), and (Na + K)–(SO4–Cl) types are the three key groundwater facies in the area. The TDS levels in water with chalcedony temperatures above 50 °C were high (over 5000 mg/L), with chloride dominating the composition. Pollution indices of the samples in terms of heavy metals and major ions were also calculated to determine the suitability of the groundwater for human consumption. The heavy metal pollution index, heavy metal evaluation index, and heavy metal contamination index indicated no HM pollution. However, the water quality index, which uses major ions to determine drinking water quality, showed that approximately 50% of the examined samples were unfit for consumption without any primary treatment.

Application of Correlation and Regression Models in Predicting the Physico-chemical Quality of Groundwater from Insitu Measured Parameters

Groundwater is the major source of municipal and private potable water supply for meeting the drinking, domestic, agricultural and industrial requirements on man around the world. The cost of analyzing water quality in the laboratory to ascertain its potability is usually high and sometimes not available. Groundwater samples were collected from fifty (50) spatially referenced bore well locations in Warri and its environs in the dry and wet seasons (November 2019 to January 2020) in the study area. The water samples were analyzed for twenty-six (26) physical, chemical and bacteriological parameters both in the field and laboratory in line with APHA standard procedures for testing water and waste water inorder to evaluate the status of potability of groundwater across Warri, Delta State Nigeria. The data analysis tool in Microsoft Excel was used to explore and study the interrelationship between some conservative parameters measured in the field (pH, EC, TDS, and DO) as independent variables and some cations, anions and heavy metals (Na, Mg, Ca, HCO3, SO4 Cl, Fe, Cd, Cr, Cu and Pb) analysed in the laboratory as dependent variables. The results obtained from the parameters analysed insitu in the field which are cheap to perform and easily affordable were used to check and evaluate and the inter-relationships with some cations, anions and heavy metals. Highly correlated water quality parameters were determined by correlation coefficient (R) values obtained from correlation matrix and related by Regression equations (models). The regression models can be adopted to predict the concentration of these cations, anions and heavy metals before the rigorous laboratory analysis, to serve as a quick check for concentration of most disease-causing pollutants and to save time, money and resources, especially the near absence of AAS for analysing heavy metals in a good number of laboratories. The regression models developed in the study can be used for monitoring the water quality parameters by knowing the concentration of independent parameters obtained in the field alone. There is a relationship between variables which show that one variable actually causes changes in another variable. It was observed that multiple regression models can predict most parameters at 5% level of significance. Significantly positive correlation at 1 and 5% was found between many parameters. This technique studied and calculated the correlation coefficients between various physico-chemical parameters of drinking water and provided an excellent device for the calculation of parameter values within realistic degree of accuracy. The results proved to be easiest, useful, and rapid means for monitoring of water quality with the help of systematic calculations of correlation coefficient. It is recommended to treat groundwater prior to domestic use.

Application of Correlation and Regression Models in Predicting the Physico-chemical Quality of Groundwater from Insitu Measured Parameters

Groundwater is the major source of municipal and private potable water supply for meeting the drinking, domestic, agricultural and industrial requirements on man around the world. The cost of analyzing water quality in the laboratory to ascertain its potability is usually high and sometimes not available. Groundwater samples were collected from fifty (50) spatially referenced bore well locations in Warri and its environs in the dry and wet seasons (November 2019 to January 2020) in the study area. The water samples were analyzed for twenty-six (26) physical, chemical and bacteriological parameters both in the field and laboratory in line with APHA standard procedures for testing water and waste water inorder to evaluate the status of potability of groundwater across Warri, Delta State Nigeria. The data analysis tool in Microsoft Excel was used to explore and study the interrelationship between some conservative parameters measured in the field (pH, EC, TDS, and DO) as independent variables and some cations, anions and heavy metals (Na, Mg, Ca, HCO3, SO4 Cl, Fe, Cd, Cr, Cu and Pb) analysed in the laboratory as dependent variables. The results obtained from the parameters analysed insitu in the field which are cheap to perform and easily affordable were used to check and evaluate and the inter-relationships with some cations, anions and heavy metals. Highly correlated water quality parameters were determined by correlation coefficient (R) values obtained from correlation matrix and related by Regression equations (models). The regression models can be adopted to predict the concentration of these cations, anions and heavy metals before the rigorous laboratory analysis, to serve as a quick check for concentration of most disease-causing pollutants and to save time, money and resources, especially the near absence of AAS for analysing heavy metals in a good number of laboratories. The regression models developed in the study can be used for monitoring the water quality parameters by knowing the concentration of independent parameters obtained in the field alone. There is a relationship between variables which show that one variable actually causes changes in another variable. It was observed that multiple regression models can predict most parameters at 5% level of significance. Significantly positive correlation at 1 and 5% was found between many parameters. This technique studied and calculated the correlation coefficients between various physico-chemical parameters of drinking water and provided an excellent device for the calculation of parameter values within realistic degree of accuracy. The results proved to be easiest, useful, and rapid means for monitoring of water quality with the help of systematic calculations of correlation coefficient. It is recommended to treat groundwater prior to domestic use.

Hydrogeochemistry and surface water quality assessment of IB valley coalfield area, India

Coal mining and ancillary activities have the potential to cause water pollution characterized by acid mine drainage, acid mine leachates, extreme pH conditions and heavy metal contaminations. In the present work, 33 water samples in premonsoon and 34 water samples in monsoon were collected from the surface water bodies of Ib Valley coalfield, India for hydrogeochemical analysis. In premonsoon, pH, TSS, Turbidity, DO, BOD, COD, Magnesium, Cadmium, Selenium, Nickel, Aluminum and in monsoon, pH, TSS, Turbidity, DO, BOD, COD, Iron, Cadmium, Selenium, Nickel and Aluminum were nonconforming to the permissible limit set by the Bureau of Indian Standards, World Health Organisation and Ministry of Environment, Forest and Climate Change, Government of India. The average BOD/COD ratio of less than 0.6 in both seasons indicated Ib valley coalfield water was not fairly biodegradable. The analysis of variance (ANOVA) revealed that significant seasonal variation (p < 0.05) was observed in the hydro-chemical parameters viz. TSS, turbidity, redox potential, acidity, total hardness, bicarbonate alkalinity, chloride, sulfate, nitrate, sodium, calcium, magnesium, iron, cadmium, chromium and magnesium during the entire sampling period. Whereas, no significant seasonal variation (p > 0.05) was observed in pH, EC, TDS, DO, BOD, residual chlorine, COD, oil and grease, fluoride, potassium, zinc, copper, selenium, nickel, aluminum, boron, silica, temperature, salinity, cyanide and phenol. Water Quality Index revealed that 39.39% and 35.29% samples belong to poor water quality category in premonsoon and monsoon, respectively. As per Heavy Metal Pollution Index, Degree of Contamination (Cd) and Heavy metal evaluation index, medium degree of pollution were exhibited by 51.52%, 30.30% and 45.45% samples in premonsoon and 20.59%, 35.29% and 26.47% samples in monsoon. Whereas, 5.88%, 2.94% and 5.88% samples were having high degree of pollution in monsoon and 15.15% samples caused high degree of pollution with respect to Cd in premonsoon. However, EC, Na%, PI, SAR and RSC values suggested that the water can be used for irrigation. Water type of the region had been found to be Ca–Mg–Cl–SO4 by Piper diagram.

Integrated statistical and hydro-geochemical approach to identify the origin and process of saline contamination of Remila plain groundwater (Khenchela, Algeria)

ABSTRACTGroundwater is widely used in the semi-arid region of Remila plain (Khenchela, Algeria) for urban and agricultural supplies. An integrated statistical and hydro-geochemical approach was performed with 70 water samples in order to identify the main processes and the origin of water salinisation. The results have suggested the dominance of three chemical facies: Sulphato cloruro calcic (SO4–Cl–Ca) in the northeastern part, Sulphato cloruro calci magnisian (SO–4Cl–Ca–Mg) in most of the waters andalkali-earth bicarbonate (HCO3–Ca–Mg) in the southeastern part. Although based on principal component analysis and hierarchical clustering analysis, the statistical approach identified three water groups: (1) saline water (17 %; total dissolved solids &gt;1000 mg l−1 with the dominance of Sulphate (SO42−)); (2) moderately saline water (17 %) with a dominance of bicarbonate (HCO3−); and (3) moderately saline water (66 %) with mixed facies. The binary diagrams confirmed the predominance of three processes: evaporite dissolution and/or precipitation, combined by ionic exchange. In the northeastern part of the area, however, another process was detected – the saline intrusion of Sabkha water, favoured by extensive groundwater use.

Evaluation of groundwater quality in central Saudi Arabia using hydrogeochemical characteristics and pollution indices.

The groundwater quality and heavy metal (HM) contamination were evaluated in palm farms, central Saudi Arabia, using pollution indices, irrigation quality parameters, and multivariate statistical analyses. Thirty groundwater samples were collected in October 2020 for major anions, cations, and HMs analyses and interpretation. The results showed that the average concentrations of total dissolved solids (TDS), Ca+, Na+, K+, Cl-, SO42-, and F- were greater than the permissible limits of the WHO standards for drinking water. The groundwater facies types were Ca-Na-SO4-Cl (23 samples), Ca-Cl-SO4, (4 samples), and Ca-SO4-Cl type (3 samples). The groundwater quality index indicated that 15 groundwater samples were of good quality and 15 were of poor quality, whereas the metal index and heavy metal pollution index indicated that all samples were categorized as slightly affected and with low pollution, respectively. The variation is attributed to the increasing average concentrations of some ions and decreasing HMs. The dissolution/precipitation of silicates, gypsum, and carbonates and soil leaching were the natural factors affecting groundwater chemistry, whereas higher PO43-, NO3-, F-, Pb, and Zn values in some samples may be attributed to human activities from the extensive use of fertilizers and pesticides on the investigated farms.

Hydrogeological and water quality evaluation of parts of River Mamu Sub-Basin, Southeastern Nigeria

The water sources in parts of the River Mamu sub-Basin, southeastern Nigeria were evaluated for domestic and agricultural purposes using hydrogeology and water quality. Thirty water samples from both surface water and groundwater were collected and analysed for hydrochemical and biological parameters. The average depth to aquifers and their thicknesses are 109.9 and 11.8m respectively. The concentration of the major ions, TDS and EC are within the WHO permissible guidelines for drinking water. Heavy metals concentration range in mg/L for Cd2+ (0 – 0.06), Cr3+ (0 – 0.19), Hg2+ (0 -1.0), As3+ (0 – 0.14) and total Fe (0 – 2.4) which in some of the samples exceed the permissible guideline values. The fecal coliform range in 100ml/L of samples (0 – 36) exceeds the guideline values in some of the samples. The water is Ca–Mg –Cl–SO4 type with the dominant ions as Ca2+ and SO 2- for both groundwater and surface water. The dominant geochemical processes are rock-water interaction in groundwater, which is a major contributor of dissolved ions and precipitation in the surface water. The WQI (17.84- 301.99) connotes some samples are of very poor quality for domestic purposes. Irrigation indices depict most of the water as good to excellent for agriculture.

Characterization of the Groundwater within Regional Aquifers and Suitability Assessment for Various Uses and Purposes-Western Iraq

Groundwater quality investigation has been carried out in the western part of Iraq (west longitude '40°40). The physicochemical analyses of 64 groundwater samples collected from seven aquifers were used in the determination of groundwater characterization and assessment. The concept of spatial hydrochemical bi-model was prepared for quantitative and qualitative interpretation. Hydrogeochemical data referred that the groundwater is of meteoric origin and has processes responsible for observed brackishness. The geochemical facies of the groundwater reveal that none of the anions and cations pairs exceed 50% and there are practically mixtures of multi-water types (such as Ca–Mg–Cl–HCO3 and Na+K–SO4–Cl water type) as dominant types. The hydrogeochemical evolution indicates that the groundwater is mainly controlled by the leaching and dissolution process of carbonate minerals. Increasing salt content is observed at different static water levels (groundwater flow) confirming mixing cases with multi water sources. Anthropogenic activities do not have a significant alteration in the geochemical nature of groundwater in aquifer systems. Most of the groundwater is classified within the category of C3S1 and C2S1 denoting admissible to good quality of water for irrigation in 67% of the total samples. On the other hand, 33% of samples are classified as bad to very bad. The groundwater of most aquifers has precedence for irrigation, agricultural purposes, animal drinking, and good to fair class for natural preserve activities. While the groundwater of Mullusi and Jeed-Rattga aquifers are suggested for human drinking purposes. Also, the groundwater within the hydrogeologic system can be used in low-pressure boilers, mining, construction industry, and unsafe in high-pressure boilers due to the relatively high total hardness (237 to 1456 mg/l). Corrosively ratio indicates that 83 % of exploited groundwater from boreholes is safe for long transport through metallic pipelines.

Biogeochemical Modelling of Uranium Immobilization and Aquifer Remediation Strategies Near NCCP Sludge Storage Facilities

Nitrate is a substance which influences the prevailing redox conditions in groundwater, and in turn the behaviour of U. The study of groundwater in an area with low-level radioactive sludge storage facilities has shown their contamination with sulphate and nitrate anions, uranium, and some associated metals. The uranyl ion content in the most contaminated NO3–Cl–SO4–Na borehole is 2000 times higher (1.58 mg/L) than that in the background water. At the same time, assessment of the main physiological groups of microorganisms showed a maximum number of denitrifying and sulphate-reducing bacteria (e.g., Sulfurimonas) in the water from the same borehole. Biogenic factors of radionuclide immobilization on sandy rocks of upper aquifers have been experimentally investigated. Different reduction rates of NO3−, SO42−, Fe(III) and U(VI) with stimulated microbial activity were dependent on the pollution degree. Moreover, 16S rRNA gene analysis of the microbial community after whey addition revealed a significant decrease in microbial diversity and the activation of nonspecific nitrate-reducing bacteria (genera Rhodococcus and Rhodobacter). The second influential factor can be identified as the formation of microbial biofilms on the sandy loam samples, which has a positive effect on U sorption (an increase in Kd value is up to 35%). As PHREEQC physicochemical modelling numerically confirmed, the third most influential factor that drives U mobility is the biogenic-mediated formation of a sulphide redox buffer. This study brings important information, which helps to assess the long-term stability of U in the environment of radioactive sludge storage facilities.

Entropy-weighted water quality index (EWQI) modeling of groundwater quality and spatial mapping in Uppar Odai Sub-Basin, South India

Groundwater is the primary source of water supply in Uppar Odai Sub-basin in the Amaravati River basin in South India. In this crystalline aquifer system, groundwater occurs in joints fissures, fractures at shallow depth in the partially weathered rocks. An integrated approach of hydrochemical analysis of 32 samples with numerical indexing Entropy-weighted water quality index(EWQI) model was proposed for the study area. General hydrochemical data showed that the Na–Cl and Ca–Mg–Cl–SO4 types dominated, with most of the samples are alkaline nature. More than 50% of the samples exceeded the permissible limit of TDS, and a high concentration of Cl and NO3 showed the influence of anthropogenic influences, such as industrial effluents and agricultural fertilizers. Groundwater chemistry was found to be varying along the groundwater flow paths. Geogenic contaminant F¯ was exceeding the WHO permissible limit of 1.5 mg/L. Entropy-weighted Water Quality Index (EWQI) model showed that 53% of the samples were medium, and 22% were of poor quality. Na–Cl and mixed Ca–Mg–Cl types of water were reported with high EWQI values. A high correlation for EWQI with TDS, TH, Mg, Cl, SO4, and NO3 is an indication of the human activities on the groundwater quality. GIS-based spatial variation maps of water quality parameters and EWQI specify that northern, northwestern, and central regions are poor water quality. In those regions where water quality has deteriorated, proper treatment of water is suggested before consumption to avoid health risks.

Physio-chemical properties of groundwater and their environmental hazardous impact: Case study of Southwestern Saudi Arabia

Southwestern Saudi Arabia is enriched with fractured and highly-weathered igneous and metamorphic rocks that function as the limited aquifer and supply significant quantities of water for household use and agriculture in this area. Twenty-seven groundwater samples were collected from shallow-dug wells and physio-chemically examined. It is displayed that, however the average value of total dissolved solids (792.67 mg/l) is not curiously high, the ionic component moved toward anthropogenic origin of pollution. The water in the area fits SO4–Cl type facies. The aquifer fractured properties and the existence of groundwater at near-surface depths affecting the groundwater hydrochemistry for the investigated area. Decision and policymakers must consider these results to minimize the environmental impact of local pollutants in the region.

The Influence of Non-Engineered Municipal Landfills on Groundwater Chemistry and Quality in Bloemfontein, South Africa.

This study assessed the groundwater quality around two municipal solid waste landfill sites, in the city of Bloemfontein, Free State Province, South Africa. The two landfill sites are located in two contrasting geological terrains, with both lacking some basic facilities found in a well-designed landfill. A total of eight groundwater samples were collected from pollution monitoring boreholes near the two landfill sites, with five samples representing the northern landfill site and three samples representing the southern landfill site. The samples were collected in the autumn and winter seasons to assess any possible seasonal variations. They were analysed for physicochemical (pH, electrical conductivity (EC), total dissolve solids (TDS), chemical oxygen demand (COD) and total organic carbon (TOC)) and microbiological parameters (Escherichia coli, total coliform). The results of the analysis showed that the waters from both landfills were generally dominated by Ca, Mg, SO4, and HCO3 ions. Some of the major anions and cations in the water samples were above the South African National Standard (SANS241:2015) and World Health Organisation (WHO) permissible limits for drinking water. Majority of the boreholes had total dissolved solids and electrical conductivity values exceeding the SANS 241:2015 and WHO permissible limits. Piper trilinear plots for the two landfill sites showed that Ca(Mg)HCO3 water type predominates, but Ca(Mg)SO4 and Ca(Mg)Cl were also found. These water types were further confirmed with expanded Durov diagrams, indicating that that the boreholes represented a water type that is seldom found which is undergoing ion exchange, typical of sulphate contamination. From the SAR diagrams, boreholes in the northern landfill site had a high salinity hazard with only one borehole in the southern landfill site having a high salinity hazard. The geology was found to play a significant role in the distribution of contaminants into the groundwater systems in the study area. The study concluded that the northern landfill site had a poorer water quality in comparison to the southern landfill site based on the analysed physicochemical parameters. However, the southern landfill site showed significant microbial contamination, due to the elevated amount of E. coli and total coliform concentrations. The high permeability of the weathered dolerites in the northern landfill site might have enabled the percolation of contaminants into the groundwater resulting in the poorer water quality.

Hydrochemical evaluation of the quaternary aquifer and its suitability for different purposes at south Al Waqf city, Qena, Upper Egypt

Groundwater is the second most important natural resource of freshwater in Egypt after the River Nile. Groundwater is the unique reliable water resource in the Egyptian Deserts, for domestic, agriculture and industrial uses. Field hydrological data and twenty groundwater samples were collected from the Quaternary aquifer boreholes to ascertain their quality for drinking and agricultural purposes in the desert area south Al Waqf, Upper Egypt. The groundwater is slightly alkaline with variable salinity; TDS varies from 455 to 4595 mg/l. The predominant ions were Na and Cl, and the predominant water type is Na–K–Cl–SO4. The water-sediment interaction considered the main controller of water chemistry. The groundwater is unsuitable for human drinking purposes, wherein the case of one suitable element, another element is not suitable especially the pollution of water with As and Pb. It was detected that studied samples were permissible (especially for sodium adsorption ratio and heavy metals) for irrigation and suitable for growing most types of crops with attention to wells of high salinity.

Origin and hydrochemical characteristics of groundwater in the Northeastern Patagonia, Argentina: the relationship with geomorphology and soils

In arid zones, geomorphology and soils play a fundamental role in groundwater surveys as they condition the recharge phenomenon and some processes that modify water chemistry. The objective of this work was to identify the groundwater provenance and the relationship between its chemistry and isotope contents with the geomorphology and soil in the northeastern Patagonia, Argentina. Over an area of 10,600 km2, groundwater levels and major ionic and stable isotopic contents were measured. The main geomorphological units were mapped using satellite images and digital elevation models. In soils, pedogenetic carbonate contents (PC) and clay accumulation index (CAI) were measured. Different hydrochemical facies were identified in relation to geomorphological units, being the Cl–SO4–Na and Cl–Na ionic types dominant in fluvial terrace plains (terrace associations, TAs). The Cl–SO4–Na types are the most saline groundwaters and are coincident with the TA where Petrocalcids are the dominant soils. With less salinity contents, Cl–SO4–Na and Cl–Na types are the groundwaters associated with TA where the dominant soils are Natrargids and Haplocalcids. The only sector with Cl–HCO3–Na is those with fresh water coincident with the Aeolian field unit, where Psamments soils develop. Likewise, groundwater is isotopically differentiated in response to the origin being mostly allocthonus in the fluvial terrace plains and from local recharge in the Aeolian fields. The fluvial terraces are gravel deposits that would favor a local recharge, but this is prevented both by pedogenic carbonate and clay contents which developed in the upper part of the deposit. In this way, the measurement of pedogenetic carbonates and clays becomes soil properties of utmost importance to be considered in groundwater prospecting in arid regions worldwide.