Major Ions In Groundwater Research Articles

Ion sources and seasonal recharge characteristics of groundwater around Dali Lake in semi-arid region of Inner Mongolia Plateau, China

The interaction between groundwater and surface water around an inland lake in semi-arid regions creates a unique ecological pattern and is a key link in the regional ecohydrological cycle. In this paper, the major ions and hydrogen and oxygen isotope characteristics of groundwater, lake water, river water, and rain water were analyzed, which were sampled in Dali Lake and its surrounding areas in the dry and wet seasons. The ion ratio method and the end-member mixing analysis (EMMA) based on principal component analysis (PCA) were applied. The causes of the major ions in groundwater during the dry and wet seasons were analyzed. The temporal and spatial recharge sources and characteristics of groundwater were identified and quantified. The hydraulic relation between groundwater and surface water was clarified. The main hydrochemical type of groundwater was Ca-HCO3 with changed to Ca-Mg-Cl type in some areas in the wet seasons. Rock weathering was the main genetic mechanism of groundwater hydrochemistry which mainly from the dissolution of silicate. River water and precipitation were the main sources of groundwater recharge. However, there was a large difference in spatio-temporal distribution and recharge contribution. Gongar River water and precipitation were the main recharge sources of groundwater during the dry season with a contribution rate of 49 % and 48 % respectively. Haolai River water and Liangzi River water together became the main recharge sources of groundwater during the wet season with a contribution rate of between 83 % and 92 %. Rain water covered from 7 % to 13 % of groundwater recharge during the wet season. Overall, compared with river water and precipitation, the contribution of lake water to groundwater recharge was almost negligible, ranging from 0 % to 6 %.

The Effects of Toluene Mineralization under Denitrification Conditions on Carbonate Dissolution and Precipitation in Water: Mechanism and Model

The mineralization of benzene, toluene, ethylbenzene, and xylene (BTEX) into inorganic substances by microorganisms may affect the water–rock interaction. However, few studies have quantitatively analyzed the processes. To quantitatively reveal this mechanism, in this study, nitrate and toluene were taken as the typical electron acceptor and BTEX, respectively. Based on hydro-geochemical theory, the mechanism and mathematical model were established. In addition, the model was verified with a toluene mineralization experiment. The mechanism model demonstrated that H+ was the main factor in the dissolution or precipitation of CaCO3. The mathematical model derived the equations quantitatively between the amount of toluene mineralization, CaCO3, and some biogeochemical indicators, including temperature, microbial consumption, and other major ions in groundwater. According to the model, the amount of dissolved CaCO3 increased with the increasing proportion of completely reduced nitrate. For a complete reaction, the greater the microorganisms’ consumption of toluene was, the smaller the precipitation of CaCO3. CaCO3 dissolution was a nonmonotonic function that varied with temperature and the milligram equivalent of other ions. Furthermore, the validation experiments agreed well with the mathematical model, indicating its practicality. The established model provides a tool for assessing the biodegradation of toluene by monitoring the concentration of groundwater ions.

Assessing groundwater quality: a case study in Ghana Talensi district

Abstract Because most life processes are directly or indirectly related to water, people are investigating on the various sources of drinking water supply. Surface water and groundwater are the most common sources of water for domestic and other uses. The availability of safe and sufficient drinking water in developing countries’ rural and many urban areas is critical. Groundwater has become the primary source of drinking water supply in northern Ghana, particularly in rural areas. Tongo, in northern Ghana, is entirely dependent on groundwater for its drinking water supply. The quality of groundwater from 15 boreholes and open well samples was assessed in this study. The primary goals of the research are to assess the quality of groundwater for drinking and to determine the distribution of major ions in groundwater and the factors that control them. Groundwater physicochemical parameters were within the WHO guidelines limit. However, coliform bacteria were found in some groundwater sources. Anthropogenic, natural, and ion exchange processes were also identified as controlling groundwater major ion distribution. Insanitary conditions were identified as potential sources of contamination during field observations. As a result, the regular monitoring of groundwater resources could reveal more about the area's groundwater quality status.

Assessment of major ions in groundwater supplied to Monterrey metropolitan area, Mexico: quality assurance, technical analysis, and addenda

Assessment of major ions in groundwater supplied to Monterrey metropolitan area, Mexico: quality assurance, technical analysis, and addenda

δ18O and δ2H isotopes, trace metals and major ions in groundwater around uranium and fluoride contaminated Indus valley Quaternary alluvial plain, SW Punjab, India: Implications on hydrogeochemical processes, irrigation use and source

Uranium and fluoride enrichment in groundwater along alluvial plains pose a severe threat to living beings like cancer, fluorosis and crop yield as witnessed around semi-arid southwest Punjab, India. In-situ groundwater was examined for major ions, stable isotopes and trace metals to understand the hydrogeochemical processes, contaminant origin and health risks around SW Punjab, India. Groundwater from a freshly drilled bore well is found to be hard, alkaline, and saline with total dissolved solids and salinity up to 1300 and 1500 mg L−1, respectively. Fluoride (up to 4 mg L−1) and uranium (up to 90.07 μg L−1) contents exceed permissible limits in most samples and originated from fertilizer inputs and aquifer leaching. Uranium contents decline with depth, while fluoride remains invariable. Decreased U contents are inferred to be caused by U(VI) reduction to U(IV) as evidenced by an increase in Fe2+ vs. Fe3+, S2− vs. S6+ and N3− vs. N5+ with depth. NaHCO3, NaCl + NaHCO3 and NaCl are the dominant water types for shallow (<38 m), intermediate (49–83 m) and deeper groundwater (105–128 m) with Na+ and HCO3− as the dominant cations and anions, respectively. Silicate weathering majorly controlled the groundwater geochemistry together with a partial contribution from cation exchange processes. Unsuitability for drinking and irrigation use is envisaged for all depths, while deeper groundwater is safe in regard to radiological risk. δ18O and δD variations are suggestive of evaporation dominance in shallow groundwater, while intermediate groundwater witness canal and groundwater mixing and deeper groundwater are recharged through higher altitude.

Microplastic contamination in groundwater on a volcanic Jeju Island of Korea

Microplastic (MPs) contamination in groundwater has received massive attention since plastic waste has been released directly into the environment. This study investigates MPs contamination in groundwater on the Jeju volcanic Island, Korea. To the best of our knowledge, this is the first study to identify MPs in groundwater from volcanic islands. A total of 21 sites were sampled for groundwater wells and springs in July and September (2021). Sampling was performed without cross-contamination through quality assurance and quality control. The results showed that MPs abundance ranged from 0.006 to 0.192 particles/L in groundwater samples. Additionally, MPs were detected in deep groundwater wells where the groundwater level was 143 m below ground surface. Eight MPs polymer types, including polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, polyamide, acrylonitrile butadiene styrene, and polyurethane, were detected using Micro-Fourier Transform Infrared Spectroscopy (μ-FT-IR). Most of the detected MPs size ranged from 20 to 100 μm, accounting for 95% of the total. Fragments and fiber shaped MPs were detected, with the majority of them being fragmented in groundwater samples. The concentrations of MPs and major ions in groundwater showed a positive correlation. A negative correlation was observed between MPs concentration and topographic elevation (r = −0.59, p = 0.01). The source of MPs contamination is most likely attributed to agricultural activities, such as plastic mulching and greenhouses, which account for most of the land use in the study area. In this study, MPs entered the aquifer through the soil at the surface and seeped through cracks in fractured rock on basalt with sealed groundwater wells. This study takes 500 L of samples to prevent sample bias, reveal plastic contamination in groundwater, and indicating the characteristics and sources of contaminated plastics.

Groundwater quality assessment for domestic and agricultural purposes using GIS, hydrochemical facies and water quality indices: case study of Rafsanjan plain, Kerman province, Iran

This paper investigates the suitability of groundwater for domestic and agricultural use in the Rafsanjan plain, southwest part of the Daranjir–Saghand basin, Iran. Fifty-five groundwater samples were collected and analyzed by six methods including the water quality index (WQI), Schoeller diagram, irrigation water quality (IWQ) parameters, Piper diagram, US salinity diagram and Wilcox diagram. The spatial distribution maps of chemical parameters and groundwater quality indices were plotted using the IDW method in GIS. The results showed a low concentration of major ions in the southeastern part and a high concentration from the central part towards northwestern part of the plain. The concentration of major ions in groundwater was strongly affected by groundwater flow, geological setting and the existence of the evaporative layers in the studied area. Moreover, results revealed that most of samples exceeded the acceptable limits recommended by the WHO and ISIRI1053 standards for domestic and agricultural purposes. In most of the wells, groundwater was classified into saline and very hard categories. The analyses based on WQI values indicated that above 87% of water samples were unsuitable for drinking purposes. IWQ parameters expressed that 85%, 67%, 32%, 51%, 43% and 50% of samples had EC > 3000, Na% > 60%, MAR > 50%, KR > 1, SAR > 9 and Cl− > 350, respectively, which were unsuitable for irrigation use. The dominant hydrochemical facies of water was Na–Cl–SO4 type, and 63% and 22.8% of samples were categorized as C4S4 and C4S3 class, with very high-salinity–high-sodium hazards and very high-salinity–high-sodium hazards, respectively. It indicated that most irrigated lands in this study area were affected by different levels of salinity and sodicity hazards that caused decreases in plant growth and crop productivity. The results can assist decision-makers and planners in prioritizing groundwater resources management in the region.

Impact of Aquifer Sediments - Minerals - Groundwater Interaction on Hydrochemistry, Aligarh District, Central Ganga Plain, India

Abstract The sedimentological/mineralogical characteristics of the aquifer material have been determined and their impact on groundwater chemistry is evaluated in the Aligarh district. It is found that 35 % of the aquifer is characterized by sand fraction containing (17-8) % of plagioclase and rock fragment (4-5%). Dominant aquifer material (silt and clay) fraction is dominated by plagioclase, K-feldspar, calcite, chlorite, kaolinite/mica, and halite. Spatial variation in relative positions and thickness of aquifer of silt, clay, and sandy layers resulting to particular hydro-chemical types. Major ions in groundwater shows a high degree of spatial variation along with multisource for the ions. Water quality index suggests that 22% of the water samples fall under the unsuitable category in the area characterized by aquifer material dominant with clay layers. Groundwater types in the area are dominated by Na+–Cl– and Ca2+ – HCO3–, Ca+2 Mg+ – HCO3– Ca+2 Mg+2 – Cl– (mixed type). Silicate weathering, Carbonates, salt dissolution, and base ion exchange are the major mechanisms that control the major ionic composition of the groundwater. It is saturated with calcite, dolomite, chalcedony, and Mg-silicate (Sepiolite). The unstable Speiolite under climate conditions prevails in the region rapidly change to smectite clay, which constitutes a major clay mineral of Indo-Gangetic alluvium. ANN (Artificial Neural Networking) analysis indicated that irrigation quality parameters Permeability Index (PI) and Na% are showing strong relation with selected parameters EC, and Na+ concentration. SAR values mostly depend on Na+, Mg+2 conc. and EC, while residual sodium carbonate (RSC) of groundwater can be predicted using Mg2+, HCO3–, and Ca2+ concentration in groundwater.

Hydrochemical characterization, mechanism of mobilization, and natural background level evaluation of arsenic in the aquifers of upper Gangetic plain, India

Although arsenic (As) contamination has been extensively investigated in the aquifers of the lower and middle Gangetic plains, less attention has been given to the distribution and fate of As in the groundwater of the upper Gangetic plain, India. In the current study, groundwater samples (n = 40) were collected from Moradabad district in the upper Gangetic plain and analyzed for several physicochemical parameters to characterize the groundwater chemistry and evaluate various geogenic and anthropogenic factors controlling the occurrence, mobilization, and fate of As in the plain. Arsenic concentrations in groundwater ranged from 0.17 μg/L to 139 μg/L, with the majority of high-As groundwater associated with high Fe, Mn, and HCO3− and low NO3−, SO42−, and negative Eh values, implying that As was released via reductive dissolution of Fe and Mn oxyhydroxides in reducing conditions under the influence of organic matter degradation. Interrelationships between various geochemical variables and the natural background level (NBL) quantification of As suggested the influence of anthropogenic processes on the mobility of As in groundwater. Piper and Gibbs diagrams and various bivariate plots revealed that the majority of groundwater was of the Ca2+ − Mg2+ − HCO3− type and that the major ions in groundwater were derived from carbonate and silicate weathering, cation exchange and reverse ion exchange processes, and anthropogenic activities. Moreover, the results of principal component analysis (PCA), and hierarchical cluster analysis (HCA) also suggested geogenic and anthropogenic sources for the ion concentration in groundwater. The health risk assessment showed a higher non-carcinogenic risk for children and a higher carcinogenic risk for adults, respectively, due to the daily intake of As contaminated groundwater. Overall, this study represents the first systematic investigation of the distribution, geochemical behavior, and release process of As in groundwater in the study area and provides a strong base for future research in the alluvial aquifers of the upper Gangetic plain.

Vulnerability of groundwater to pollution at the Dabiss bauxite mining area, Boké Prefecture, Republic of Guinea

ABSTRACT Boké Prefecture has become a popular mining location, with various extractive corporations competing for bauxite extraction. Water samples were obtained from eighteen water wells across the Dabiss study area. All Physico-chemical parameters and major ions of groundwater were compared with World Health Organization (WHO) standard. Furthermore, using Excel and the Inverse Distance Weighted (IDW) interpolation technique in Arc GIS software, bi-plots of Physico-chemical parameters and spatial variations of water quality maps were generated respectively. A vulnerability study of groundwater pollution by mining activities was conducted by applying the standard DRASTIC method. It was found that the drinking water samples of the study areas were usually within the water quality standards of WHO. According to physicochemical analysis, most of the groundwater in the study area appears to be acidic. An equilibrium was set up in the aquifer between the chemical composition of the water and that of the rocks. The DRASTIC method enabled us to show a low vulnerability index to groundwater pollution. The results of this study could prevent diseases linked to the consumption of water contaminated and improve the quality of life of the population and will serve as a reference document in other mining areas.

Identifying the geochemical evolution and controlling factors of the shallow groundwater in a high fluoride area, Feng County, China.

Understanding how groundwater is formed and evolves is critical for water resource exploitation and utilization. In this study, hydrochemistry and stable isotope tracing techniques were adopted to determine the key factors influencing groundwater chemical evolution in Feng County. A total of fourteen wells and five surface water samples were investigated in November 2021. The δD and δ18O compositions show that both surface water and groundwater are recharged from atmospheric precipitation. The dominating order of cations and anions in groundwater appears to be Na+ > Mg2+ > Ca2+ > K+ and HCO3- > SO42- > Cl- > NO3- > F-, respectively. The groundwater hydrochemical facies are mainly characterized by HCO3-Ca-Mg and SO4-Cl-Na types. The chemical evolution of groundwater is dominated by water-rock interaction and cation exchange reactions. The major ions in groundwater are mainly controlled by various geogenic processes including halite, gypsum, calcite, dolomite, Glauber's salt, feldspar, and fluorite dissolution/precipitation. Furthermore, the abundant fluoride-bearing sediments, together with low Ca2+, promote the formation of high F- groundwater. Approximately 85.7% and 28.6% of groundwater samples exceeded the permissible limit for F- and NO3- respectively. Apart from geogenic F-, human interventions (i.e., industrial fluoride-containing wastewater discharge and agricultural phosphate fertilizer uses) also regulate the F- enrichment in the shallow groundwater. Nitrate pollution of the groundwater may be attributed to domestic waste and animal feces. Our findings could provide valuable information for the sustainable exploitation of groundwater in the study area and the development of effective management strategies by the authorities.

Groundwater Quality Affected by the Pyrite Ash Waste and Fertilizers in Valea Calugareasca, Romania

The aim of the study was to assess the groundwater quality in a rural area affected by the abandoned pyrite ash waste dumps. The abundance of major ions in groundwater depends largely on the nature of the rocks, climatic conditions, and mobility. To evaluate geochemical processes, 30 groundwater samples collected from Valea Calugareasca, Prahova County, Romania, were analyzed for the major anions (NO3−, SO42−, Cl−, HCO3−, and F−) and cations (Ca2+, Mg2+, Na+, and K+), which are naturally highly variable due to climatic and geographical location conditions. Ca2+, Na+, Mg2+, and K+ varied between 118 and 275 mg/L, 32 and 160 mg/L, 12.2 and 78.4 mg/L, and 0.21 and 4.48 mg/L, respectively. NO3− levels exceeding the World Health Organization (WHO) limit of 50 mg/L were identified in 17% of the groundwater samples, mainly as result of fertilizers applied to agricultural activities. The hydrogeochemical study identified dolomite dissolution and halite precipitation as natural sources of ions as well as the presence of pyrite as a source of SO42− ions in 60% of the samples. The sulfate content varied between 125 and 262 mg/L. Bicarbonate and chloride concentrations varied between 202 and 530 mg/L and 21 and 212 mg/L. The saturation index indicates the contribution of Ca2+ ions in the groundwater samples came from some processes of dissolving rocks such as aragonites (values between 1.27 and 2.69) and calcites (values between 1.43 and 2.82). Negative halite values indicated that salt accumulation results from precipitation processes. Only 10% of the analyzed groundwater samples were suitable for human consumption, the samples being situated on the hill, far away from the pyrite ash waste dumps and agricultural land.

Impact of Flooding on Shallow Groundwater Chemistry in the Taklamakan Desert Hinterland: Remote Sensing Inversion and Geochemical Methods

Understanding the effect of flooding on groundwater quality is imperative for oasis vegetation protection and local ecological environment development. We used geochemical and remote sensing inversion methods to evaluate the effects of flood recharge on the groundwater hydrochemical and geochemical processes in the Daliyaboy Oasis. Groundwater samples were collected from 30 ecological observation wells in the study area before (PRF) and after (POF) the flood. Except for small changes in HCO3− and K+ and a decrease in pH, ion levels were higher POF than PRF, and the water chemistry was essentially unchanged. In the POF groundwater, HCO3− was correlated with Cl−, Na+, Mg2+, total soluble solids (TDS), and electrical conductivity (EC), but not with SO42−, Ca2+, K+, or pH, and was positively correlated with all other variables, while the remaining variables, except for pH, were strongly positively correlated with each other. PRF water chemistry was controlled by silicate and evaporite mineral weathering and evaporation processes, resulting in high groundwater TDS, EC, and a major ion content, while POF major groundwater ions were regulated by mineral weathering and flood recharge. We demonstrated the high accuracy of remote sensing inversion, confirming this as a reliable method for evaluating groundwater chemistry. The results of the study help to reshape and predict the history of the regional hydrogeological environment and hydrogeochemical development, and provide a theoretical basis for assessing the rational use of local water resources and protecting the ecological environment.

Factors controlling groundwater chemical evolution with the impact of reduced exploitation

The ongoing groundwater exploitation reduction (GWER) project in the North China Plain (NCP) is causing a series of aquifer changes in the both hydraulic and chemical signals. However, how groundwater chemistry will evolve with the impact of GWER is still unclear. In this context, this study aims to identify the impacts of natural factors and anthropogenic activities on groundwater chemistry in the Heilonggang region, a pilot area of GWER in the NCP. A total of 150 groundwater samples were collected and major ions were measured during four sampling campaigns (June 2019, December 2019, December 2020, May 2021). Results show that the shallow aquifers are dominated by Na+ and mixed anions, while the deep aquifers are mainly characterized by Na–Cl and Na–SO4 types. Groundwater chemical evolution is dominated by water–rock interaction, evaporation, and cation exchange. The major ions in groundwater are mainly derived from various geochemical processes, including the dissolution/precipitation of gypsum, halite, Glauber's salt, feldspars, calcite and dolomite. Human interventions (i.e., groundwater pumping reduction, industrial, agricultural activities and domestic sewage) also regulate the chemical compositions in the shallow groundwater. GWER indirectly improves the overall quality of the shallow aquifers, lowering ion concentrations (Na+, Mg2+, and SO42-) and salinity. Saline water largely evolves into brackish water with an increase in freshwater. This may be attributed to the shallow aquifers partly diluted by upward leakage flow from the deep aquifers. However, insignificant variation in the salinity of the deep aquifers suggests that GWER has little effects on its chemical evolution. This study facilitates the understanding of groundwater chemical evolution in such a region where groundwater exploitation reduction is under way, with important implications for groundwater sustainable management strategies in other similar basins worldwide.

Understanding the hydrogeochemical processes and physical parameters controlling the groundwater chemistry of a tropical river basin, South India.

Detailed investigation on hydrogeochemistry of hard rock terrains is important to identify the major geochemical processes and the source of ionic constituents in groundwater. The present study is carried out to understand the hydrogeochemistry of groundwater resources and the major hydrogeochemical processes, controlling the concentration of major ions in groundwater in the Kallada River Basin (KRB), South India. About 166 groundwater samples were collected from KRB during pre- and post-monsoon of 2016 for hydrogeochemical analysis. Most of the groundwater samples in KRB were within permissible limits of drinking water quality. The dominant groundwater types during pre-monsoon were Ca2+-Mg2+-Cl- which was changed to Na+-Cl- during post-monsoon. This is supported bythe inverse relationship of depth of wells and change in EC during pre- and post-monsoon periods. Rock-water interaction processes such as reverse ion exchange and silicate weathering are major geochemical processes responsible for the hydrogeochemical signatures of KRB. The shallower wells (< 10 m) show strongest relation with the water types Na+-HCO3- and Ca2+-Mg2+-Cl- which have been changed to Na+-Cl- and Ca2+-Mg2+-HCO3- during post-monsoon. However, in deeper wells, Na+-Cl- is the dominant type of water during both seasons. The hierarchical cluster analysis displays different hydrogeochemical associations representing diverse physicochemical parameters both spatially and temporally. This study could shed light on diverse hydrogeochemical processes which are responsible for the hydrogeochemistry in KRB. Major hydrogeochemical processes in the Kallada River Basi.

Source apportionment and natural background levels of major ions in shallow groundwater using multivariate statistical method: A case study in Huaibei Plain, China

Understanding the sources, natural background levels (NBLs), and threshold values (TVs) of the major ions in groundwater is essential for the effective protection of water resources. In this study, a total of 70 shallow groundwater samples were collected in Suzhou, Huaibei Plain, China. A variety of statistical methods and cumulative probability distribution techniques were performed to identify the sources, NBLs, and TVs of the major ions. The major ion concentrations found in decreasing order as follows: HCO3− > SO42− > NO3− > Cl− and Na+ > Ca2+ > Mg2+. Piper diagram for hydrochemical types shows that groundwater types were Mg–HCO3 (36%), Ca–HCO3 (34%), and Na–HCO3 (30%). According to the factor and the Unmix model analysis, anthropogenic (agriculture-related) and geogenic source (water–rock interactions-related) were identified to be responsible for the chemical composition of the groundwater in the study area, and their mean contributions for the major ion concentrations are 47.9% and 52.1%, respectively. The NBLs for Na+, Ca2+, Mg2+, Cl−, SO42−, and NO3− were determined to be 29.5–44.2, 26.2–38.9, 18.9–39.5, 1.0–9.9, 12.9–19.4, and 2.1–16.5 mg/L, respectively, and the TVs were calculated as 122.1, 169.5, 39.5, 129.6, 134.7, and 18.3 mg/L, respectively. Moreover, this study shows the feasibility and reliability of using these multivariate statistical methods and natural background levels to evaluate the status of groundwater quality.

Hyporheic zone geochemistry of a multi-aquifer system used for managed aquifer recharge in Beijing, China

Hyporheic groundwater geochemistry evolution depends on the interactions of surface water and groundwater (SW–GW). Hydrodynamic variations driven by the long-term managed aquifer recharge (MAR) practice could change hyporheic geochemical processes, which requires a better understanding for groundwater management. In this work, a geochemical survey was conducted in a multi-aquifer MAR system. The results showed great impact of the MAR practice on the hydrodynamics and major ion chemistry of groundwater in the hyporheic zone compared to natural recharge. Besides, related geochemical processes including rock weathering and ion exchange showed increased effect on hyporheic hydrochemistry with aquifer depth, depending on hydrogeological conditions in addition to river water infiltration. Combined with hydrochemical indicators and the end-member mixing model, the relative contribution of precipitation to groundwater was estimated to be 5% for the 30-m aquifer, 16% for the 50-m aquifer, and 64% for the 80-m aquifer. However, precipitation made small contributions (<5%) to the major ions of groundwater regardless of depth. Conversely, the relative contributions of river water infiltration decreased with aquifer depth (95%→84%→36%), and its proportional contributions to major ions showed a similar trend (90%→84%→39%), which suggests reduced SW–GW interaction intensity with depth in the hyporheic zone. The major ion compositions of hyporheic groundwater tend towards river water after the long-term MAR practice, reflecting comprehensive effect of mixing and related geochemical processes. This study demonstrates the relevance of detailed studies at regional scale to understand anthropogenic effects from projects such as MAR on groundwater geochemistry especially in multi-aquifer systems.

Discrete geochemical behavior of Sr and Ba in the groundwater of Southern Mor Range, Balochistan, a tracer for igneous and sedimentary rocks weathering and related environmental issues

A comparative study of Strontium (Sr) and Barium (Ba) along with associated major ions of groundwater was made from the Southern Mor Range, Balochistan, where both igneous and sedimentary rocks are exposed. In the studied samples, Sr2+ varies from 237 to 6,723 with a mean of 1,688 μg/l, while Ba2+ ranged from 40 to 1,332 μg/l with a mean of 207 μg/l. TDS and Sr2+ displayed moderate positive, while Ba2+ showed a slight negative relation. Majority (80.85%) of the samples have existed in the narrow pH range (7.5–8.5). The impact of water-rock interaction is evidenced from the Gibbs diagram; showed influence of igneous and sedimentary rocks on the release of Sr2+ and Ba2+. It is also evidenced from molar ratio of Sr2+/Ca2+, Mg2+/Ca2+, Na+/Cl−, Mg2+/Cl− of the groundwater. Strontium possessed fairly high relative mobility (RM, av. 0.349) and mobility index (MI, av. 4.38), while RM (av. 0.003) and MI (av. 0.04) of Ba2+ was very low. The saturation indices (SI) plots barite vs. celestite, showed saturation of Ba, while Sr2+ ions are unsaturated. The low Ba2+/Sr2+ (av. 0.208) indicated the existence of aquifer in low elevation areas and the HCO3−/Cl− ratio (>1) demonstrated a short flow path and speedy flow. The suitability of groundwater was assessed for drinking purpose as per World Health Organization (WHO) and Expanded Programme on Immunization (EPI) guidelines and possible environmental issues were discussed.

Coastal shallow aquifer characterization in Tiruchendur coastal district of Tuticorin, Tamil Nadu, India utilizing geophysical and geochemical approaches

Southeastern coastal inlands around the Gulf of Mannar in the Tiruchendur district are primarily areas of agriculture, salt pan, andindustry. Canals of Tamirabarani River are the main source of groundwater for irrigation and livestock purposes. Intrusion of saltwater can have a range of major economic and environmental effects, including decreased freshwater storage capacity, pollution of freshwater production wells, salinisation of soil and decreased freshwater discharge into marine environments. In the study area, geophysical and geo-chemical investigations were conducted to interpret geological subsurface formation and to assess intrusion by seawater. Electrical resistivity tomographic surveys conducted in the study area showed low resistivity formation in the coastal region, as the average soil thickness is about 3 m with low surface moisture retention. The fresh water in the study area is given by nearly 10–100 Ωm of resistivity. The 10–50 Ωm apparent resistivities indicate the sub-surface section consists of sand, clay, and caliche. The very low layer of resistivity (<5 Ωm) could be due to the encroachment of seawater in the study area. Twenty three sample were collected of water from the well drilled in the Coastal area was analysed going to allow for the determination of concentration levels of major ions in groundwater. Data were used to determine the seawater intrusion and coastal environment characteristics in the study area.

Assessment of ground water quality in the vicinity of Sylhet City, Bangladesh: a multivariate analysis

Water, the most naturally abundant and the simplest molecule on the earth, is crucial for the existence of all flora and fauna on this planet. Groundwater chemical composition can change the suitability of the aquifer system. The aim of the study was to provide an evaluation of water quality with respect to different water quality parameters in the north-east part of Bangladesh using multivariate techniques. It also tried to identify the vital sources that control the groundwater resources in the aquifer. All samples were collected during the pre-monsoon season in March 2019 from 20 pumps of Sylhet City Corporation area. Correlation analysis has been used to assess the overall groundwater quality and the degree of the linear relationship between parameters. Multivariate statistical techniques have been used to interpret the water quality of the selected pumps and to provide some meaningful results that are not possible while investigating the data at a glance. The average concentrations of major ions in groundwater of Sylhet City Corporation area are in the following order: cations—Magnesium (28.43) > Sodium (11.45) > Calcium (8.47) > Potassium (1.36); while, anions—Bicarbonate (87.70) > Chloride (37.20) > Sulfate (1.80) > Nitrate (0.95). The correlation matrix shows that the basic ionic chemistry is influenced by pH, EC, TDS, K+, Na+, Mg2+, and SO42−. These characteristics of the water samples indicate that, in addition to fresh recharge water of CaHCO3 type, the groundwater are dominated by the dolomite (CaMg(CO3)2), calcite (CaCO3) and halite (NaCl) rock-forming minerals. PCA extracted three components, which are accountable for the data composition explaining 71% of the total variance of the data set and allowed to set the selected parameters according to regular features as well as to evaluate the frequency of each group on the overall variation in water quality of Sylhet City Corporation area. The factors have been identified as “freshwater and halite minerals interaction”, “anthropogenic influences”, and “anthropogenic-rocks interaction effect”. Hierarchical cluster analysis grouped the 20 sampling stations into five groups, the values of pH and HCO3− concentration increase gradually from cluster 1 to cluster 5, i.e., from the eastern part to the western part of the city. The western part is relatively on the downward side and thus, the recharge water of CaHCO3 type is comparatively affluent in this area.