Anions In Groundwater Research Articles

Evaluation of some anions in groundwater in Riyadh, Saudi Arabia, and human health risk assessment of nitrate and fluoride.

Groundwater is a vital source of water for human and agricultural use in many parts of the world. The purpose of this research was to establish the quality of groundwater in Riyadh, Saudi Arabia, as well as the human health concerns associated with it. We collected and examined groundwater samples for pH, EC, TDS, CaCO3, fluoride (F-), chloride (Cl-), sulfate (SO42-), and nitrate (NO3-). The ion chromatography conductometric detection method was constructed to determine fluoride, chloride, sulfate, and nitrate in groundwater. The suggested method worked well for the anions that were being studied; it had a high coefficient of determination (r2 > 0.998) and average recoveries for all analytes that were between 97.5% and 99.0%, with a range of error of 0.77 to 2.37%. Fluoride concentrations were detected between 0.001 and 0.14mg/L, which are within the acceptable limit by several organizations. Chloride was measured in the range of 17.1 to 966.5mg/L, with some samples above the limits. The influence on sulfate ranged from 2.0 to 1136.0mg/L, with several samples exceeding the limits. In contrast, with nitrate levels ranging from 1.4 to 5.0mg/L, the majority of the samples fall within the acceptable range. The overall intake of fluoride, chloride, sulfate, and nitrate is 0.00605, 138.911, 65.515, and 1.19, respectively, which is lower than the recommended daily consumption except for chloride. The groundwater sample contains fluoride and nitrate with HQ values less than one: 0.000064-0.0641 and 0.033654-0.120192. Humans in Riyadh, Saudi Arabia, do not pose a health risk when digesting or absorbing groundwater fluoride or nitrate.

Assessment of Groundwater in Erbil Central Basin, N Iraq

The present effort is expected to consider the groundwater quality of the Erbil Central Basin. In this study, we compared the physiochemical properties and distribution of major cations and anions in groundwater to evaluate the quality assessment as a special usage (drinking and irrigation) and identify the sources and types of water quality variation and pollution. The mean richness of major cations are Ca2+ > Mg2+ > Na+ > K+, whereas the major anions are HCO3- > SO42- > NO3- > Cl-. The quality of water was evaluated using SAR, sodium (%), PI, TH, MH, PS, and WQI. When the chemical and physical characteristics were compared to Iraqi and public health standards (IQS) for drinking water, it was discovered that the majority of the wells' groundwater during both periods was within the acceptable range, and suitable for all human drinking and domestic purposes except for three wells exceed the maximum permissible limit of NO3-, which are Newroz, Rizgari, and Birayaty, while HCO3ˉ is showed a maximum in Newroz, and in Rizgari well the total hardness (TH) doesn’t lie within recommended standards. The Ca and Mg- Bicarbonate type was the predominant form for the groundwater classified for both seasons, with only one well (Zanko) being Ca- Chloride type for the dry season. The majority of ionic species originated from alkaline earth metals that originate from interactions between weak acidic anions in groundwater and soil or rock. All samples were suitable for drinking water according to the WQI, only the Zanko well had poor water during the dry season.

Insights into the potential applications of permanganate/peroxymonosulfate systems: enhancement via amorphous MnO2, effects of water matrices, and optimization using response surface methodology.

In this study, we developed a novel self-catalytic oxidation system involving peroxymonosulfate (PMS) and permanganate (KMnO4), named as CUPP, to efficiently mineralize sulfamethoxazole (SMX) in groundwater. It was found that amorphous MnO2 derived from the in situ reduction of KMnO4 can directly adsorb HSO5-, a complex hydroxyl group, mediate the internal disproportionation reaction of HSO5- with the manganese complex, and effectively activate PMS, thereby promoting the oxidation of SMX and its degradation intermediates through sulfonate radiation. Furthermore, by using electron spin resonance (EPR), HPLC/MS full scan, and response surface methodology, the coexistence of HO˙, SO4-˙, O2-˙, 1O2, and active chlorine (Cl2, HOCl) in the CUPP system was confirmed. A total of 24 intermediate products were detected, and four possible degradation pathways were identified for SMX. In addition, it was found that the CUPP system has a strong impact resistance to pH variations, groundwater anions, and natural organic matter stress. Undoubtedly, the CUPP system presents an innovative approach for the degradation of various emerging organic pollutants in groundwater.

Natural phosphorus-ferromanganese ore-based composites for the simultaneous remediation of arsenic- and lead-co-contaminated groundwater: synergistic effectiveness, kinetics, and mechanisms.

Natural phosphorus-ferromanganese ore (NPO-NFMO) based composites by mechanical ball milling method, applying for the simultaneous remediation of arsenic (As) and lead (Pb) co-contaminated groundwater. Kinetic behavior adopted pseudo-second-order adsorption mechanism attaining equilibrium in 120min over a wide pH range (2.0-6.0). NPO-NFMO realized higher adsorption capacity for As(III) (6.8mgg-1) and Pb(II) (26.5mgg-1) than those of single NPO (1.7 and 7.8mgg-1) and NFMO (2.9 and 5.1mgg-1), indicating that synergistic effects of NPO and NFMO considerably enhanced the adsorption capacity in mixed adsorption system. Fresh and used NPO-NFMO were characterized, and indicated that NPO-NFMO formed stable minerals of PbAs2O6 and PbFe2(AsO4)2(OH)2. The underlying adsorption mechanism indicated that As(III) and Pb(II) removal was involved with multiple mechanisms, including electrostatic adsorption, oxidation, complexation, and coprecipitation. The effects of key reaction parameters including mass ratios of NPO and NFMO, initial metal ion concentration, dosage, solution pH, and co-existing anions in groundwater were systematically investigated. The novel designed NPO-NFMO-based composites can be deemed as a promising amendment for simultaneous immobilization of As(III) and Pb(II) in co-contaminated soil and groundwater.

Hydrogeochemical Characteristics and Human Health Risk Assessment of Fluoride Enrichment in Water in Faulted Basins of Qinghai-Tibet Plateau—A Case Study of Sanhe Plain in Guide Basin

Fluoride (F) is an essential element of drinking water for human health, especially for bone development and enamel creation. However, if the fluoride content in drinking water is higher than 1.5 mg/L or lower than 0.5 mg/L, it will cause endemic diseases, such as dental fluorosis. There are two main hydrogeological characteristics: the properties of the water-bearing rocks and groundwater conditions controlled the groundwater in guide basin. The geothermal water can be divided into fracture convection and sedimentary basin geothermal water according to its geological environment and heat transfer mode. Inductively coupled plasma spectrometry is a significant tool for groundwater quality analysis. The geochemical factors of fluoride enrichment in confined geothermal water mainly include pH, ion exchange, and mineral saturation. Both groundwater samples are slightly alkaline, while the phreatic water and surface water record pH values of 8.5, 7.78, and 7.8, respectively. The salinity of groundwater water is not high, but for confined geothermal water, phreatic water, and surface water measures 706.0, 430.1 and 285.9 mg/L respectively. The higher the pH of groundwater, the more beneficial it is to the enrichment of fluoride. In contrast, the main cations in phreatic water and surface water are calcium ions and magnesium ions. The anions in groundwater and surface water mainly include SO42− and HCO3−, followed by Cl−, indicating that the groundwater and surface water here is mainly leaching. Fluoride was shown to be positively correlated with sodium and bicarbonate. Moreover, the results indicate that F− enrichment is usually associated with high HCO3− and Na+ concentrations in water, while a high Ca2+ concentration tends to lower the F− concentration in water. This means that the ion exchange between calcium ions and sodium ions may lead to fluoride enrichment in natural water. As mentioned above, high-sodium and low-calcium water are favorable for fluoride enrichment. Moreover, saturation indices of fluorite, gypsum, dolomite, and calcite, as well as the saturation index of fluorite, represent a vital method to understand the fluoride enrichment. According to this study, fluoride as a pollutant poses great risks to human health overall, whether lower than or higher than the drinking water limit. Children face higher health risks than adults caused by confined geothermal water drinking intake. This study suggests that groundwater treatment should be conducted to reduce fluoride concentration in drinking water. It is suggested that when confined geothermal water is used as drinking water, it should be mixed with phreatic water and surface water in a certain proportion to make the fluoride in groundwater reach the range of safe drinking water.

Identification of the hydrochemical features, genesis, water quality and potential health hazards of groundwater in Dawen River Basin, North China

Groundwater resources fulfill a key role in socioeconomic development and residential water use in the Dawen River Basin (DRB). This study sampled and tested three types of groundwater in the DRB, including pore groundwater (PGW), fissure groundwater (FGW), and karst groundwater (KGW). Groundwater in the DRB was assessed for hydrochemical characteristics, quality, and hazards to human health by nitrate contents. Results identified the dominant groundwater anion and cation to be HCO3− and Ca2+, respectively, whereas groundwater was generally weakly alkaline hard-fresh water. The groundwater contents of main chemical components during wet season exceeded those in the dry season, with the rank of groundwater types by chemical component contents being: PGW > KGW > FGW. A Durov diagram indicated groundwater in the DRB to be mixed HCO3-Ca and HCO3·SO4–Ca·Mg types. Rock weathering (silicate and carbonate rocks) was found to be the predominant process regulating groundwater chemistry of the DRB, whereas human activities also had a significant impact, particularly for high NO3− related to agricultural activities. Groundwater quality of the DRB was relatively good overall, falling into the good and moderate classification grades, with that of the PGW the worst. Long-term human direct consumption or exposure to groundwater of DRB poses certain health risks due to groundwater nitrate, with the risk for children highest. The spatial variations in quality of groundwater and nitrate health hazard in the DRB were relatively consistent, with better quality and lower health risk of PGW and FGW in the east than in the west, and that of KGW better in the center than in the east and west. The present study can provide some reference for groundwater safety and protection management in DRB and other similar areas in the world.

Microbial contamination effects on the hydrochemical parameter in a Thettiyar watershed, Kerala, India, using GIS.

The present study has been carried out to assess the quality of groundwater and surface water resources of Thettiyar watershed, Kerala, India. Sixty-six water samples were collected during pre-monsoon (April, 2019) and monsoon (July, 2019) season, and analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness and major cations and anions and microbiological parameters as well. According to the piper diagram's plot, Ca and Mg dominate over Na among the cations, and Cl is the most prevalent anion in groundwater throughout both the studied seasons. The hydrochemical analysis of water samples revealed that all the parameters are within the permissible limit except for pH. For microbiological analysis, the samples were tested for total coliform and fecal coliform. Most of the groundwater samples collected have higher total coliform and fecal coliform (E. coli) content than the recommended count by BIS (2012). The pre-monsoon surface water samples owned a maximum number of 3700cfu/100ml (TNTC-too numerous to count) of total coliform and 1400cfu/100ml (TNTC) of fecal coliform. In monsoon, the number of total coliform and fecal coliform has increased to 3800cfu/100ml and 1900cfu/100ml respectively. E. coli and total coliform are effectively correlated with each other in both seasons, in accordance with the statistical study. Domestic, sewage dump, and other household wastes are the main sources of bacterial contamination in the study area, which in turn nourishes contaminant organisms. According to the results, the government or municipality should implement an appropriate system for managing solid waste and should take all necessary measures to clean up the study area.

Chemical Analysis of Groundwater and Wastewater in the Area of the Tengiz Deposit of the Atyrau Region of the Republic of Kazakhstan

This article analyzes the content of the chemical composition of groundwater and wastewater of the Tengiz deposit located in the Zhyloy district of Atyrau region of the Republic of Kazakhstan. This analysis is necessary to determine the deposition of inorganic salts in oilfield equipment. The analysis shows that the content of chloride anions and magnesium cations prevails in groundwater and wastewater. Thus, the content of chloride anions exceeds the content of other anions up to 2-3 times of sulfate anions in groundwater and wastewater and up to 2.5-5 times of bicarbonate anions in groundwater and 17-27 times in wastewater. Among the cations, the maximum values are characteristic of magnesium cations, whose content exceeds the calcium content by more than 3.5 times in wastewater and more than 6.5 times in groundwater. In addition, the magnesium content exceeds more than 5 times the content of the sum of sodium and potassium ions. Thus, according to the results of the study, it was determined that the main salts affecting the oilfield equipment at the Tengiz field are magnesium chloride salts.

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.

Seasonal Differences in the Hydrochemical Characteristics of Karst Wetlands and the Associated Mechanisms in Huixian, China

The present study aimed to identify the seasonal changes in the hydrochemical characteristics of the Huixian karst wetland and the underlying mechanism. Conventional ions and isotopes of 130 groundwater samples collected during the wet and dry seasons were analyzed. The hydrochemical characteristics of groundwater in the Huixian karst wetland were clarified using mathematical statistics and hydrochemical methods, including Durov diagrams, ionic ratios, Gibbs diagrams, and H and O isotopes. The hydrochemical evolution and sources of major ions in the Huixian karst wetland were also investigated. The results showed that cations and anions in groundwater in the study area were dominated by Ca2+ and HCO3−, respectively, sourced mainly from calcite weathering. The ions of some groundwater samples were regulated by weathering of dolomite, dolomitic limestone, and pyrite, resulting in relatively high concentrations of Mg2+ and SO42−. K+, Na+, SO42−, NO3−, and Cl− in groundwater originated from precipitation, Na+ and Cl− originated from domestic sewage, K+ was related to the application of potassium fertilizer in agriculture, and NO3− mainly originated from chemical fertilizer. Groundwater ions were primarily controlled by rock weathering, followed by evaporative concentration. The sources of major ions were dependent on the dissolution and precipitation of carbonate rock, as well as the chemical weathering of silicate rock and evaporite. Samples from the various water sources were scattered on both sides of the local meteoric water line (δD = 3.13δ18O − 13.9), which indicated isotopic composition was affected by evaporation and precipitation.

Analysis of Groundwater Chemical Characteristics and Spatiotemporal Evolution Trends of Influencing Factors in Southern Beijing Plain

During the rapid urbanisation of Beijing in the past two decades, the original natural underlying surface has been changed, and the groundwater recharge and discharge processes had undergone great changes. Therefore, whether these natural and human factors affect the evolution of groundwater chemical composition, and how these influences evolve, need to be studied urgently. In this study, the Daxing District was taken as a typical area to understand the evolution rules of the chemical characteristics of shallow groundwater in the plain areas of Beijing. By collecting monitoring data on shallow groundwater from 2006 to 2016, the spatiotemporal evolution trends of the chemical characteristics and influencing factors of shallow groundwater in Daxing District were studied using the hydrochemical analysis methods and principal component analysis–partial connection number method. The results show the following: 1) The cations and anions of groundwater in the study area increased with time, indicating that the groundwater quality tends to deteriorate. 2) The hydrochemical type and anion and cation components changed accordingly with the change in NO3−, indicating the profound impact of NO3− on the evolution of groundwater components. 3) The groundwater has always been affected by human factors and natural factors. Natural factors have dominated, but the influence of human factors on hydrochemical components has been increasing. From the spatial distribution of the impact of human factors and natural factors on groundwater composition, regions with higher urbanisation degrees are highly affected by human factors and vice versa. This study can provide a theoretical and methodological reference for regional groundwater management and industrial layout.

Rapid and enhanced adsorptive mitigation of groundwater fluoride by Mg(OH)2 nanoflakes.

Fluoride is one of the most abundant anions in groundwater, posing a significant threat to the safe drinking water supply worldwide. Fluoride contamination in drinking water at levels greater than 1.5 mg L-1 causes a variety of serious health problems. To address this problem, the current study deals with the synthesis of Mg(OH)2 nanoflakes by a facile and simple hydrothermal method in the absence of any added template. The sizes of these nanoflakes are in the range of 90 to 200 nm. These nanoflakes are pure and crystalline, possessing hexagonal phase structures. The surface areas of Mg(OH)2 nanoflakes are varying from 75.8 to 108.1 m2 g-1. These Mg(OH)2 nanoflakes exhibit excellent adsorption performance for fluoride over a pH range of 2.0 to 9.0 with a maximum Langmuir adsorption capacity of 3129 mg g-1 at pH 7.0 at 313 K which is the highest for such kind of adsorbent reported so far. The adsorption process is spontaneous and endothermic which primarily follows pseudo-second-order kinetics. The adsorbent is effective in the presence of co-existing anions and is reusable up to the fifth cycle with a minimal loss of adsorption performance. The nanoflakes can effectively remove highly concentrated groundwater fluoride to a permissible limit within a short time which increases the versatility of using these nanoflakes for practical applications.

Hydrogeochemical framework of groundwater within the Asutifi-North District of the Brong-Ahafo Region, Ghana

Hydrogeochemical processes responsible for groundwater composition within the Asutifi-North district were assessed. The aim was to delineate the factors influencing groundwater within the district. Results show that the pH values of groundwater within the district are moderately acidic to neutral and ranged from 4.4 to 7.5 with a mean value and standard deviation of 6.1 ± 0.7 pH units. 67.4% of groundwater is acidic (pH 4–6.5) due principally to the influence of aquifer materials on the chemistry of groundwater. Acid mine drainage investigations in groundwater within the district shows that, when exposed, sulphides such as pyrites (FeS2) and arsenopyrite (FeAsS) react with water and oxygen to principally produce Fe(OH)3. The major ion concentrations are within the WHO (2004) Guideline values for drinking water. The relative abundance of cations and anions in groundwater within the district is in the order of: Ca2+ > Na+ > Mg2+ > K+ and HCO3− > Cl− > SO42−, respectively. The study further shows that, albite/anorthite-(plagioclase) and calcite/dolomite(carbonates) dissolution as well as ion-exchange reactions may have contributed significantly to major ion concentrations in groundwater within the district. Hydrochemical facies using Piper trillinear diagrams delineated two major water types, the Ca–Mg–HCO3 and Na–Cl water types, with Ca–Mg–Cl, Ca–Mg–SO4–Cl and Na–K–HCO3 as minor water types. Using principal component analysis (PCA), three (3) main principal components accounting for 73.1% of the total variance with eigenvalues > 1 were extracted. PCA delineated the main natural processes through which groundwater within the district acquires its chemical characteristics, the incongruent dissolution of silicate/aluminosilicates and the prevalence of pollution principally from the application of inorganic fertilizers such as nitrates and ammonia via agricultural activities within the district.

Groundwater defluoridation efficacy of manganese-oxide-coated alumina prepared via two-step heating

ABSTRACT Fluoride concentrations in groundwater can be high in some Brazilian aquifers and therefore these waters should be treated before consumption. This study assessed the properties of Mn-oxide-coated alumina (AM) prepared by two-step heating in water defluoridation. The release of secondary contaminants (e.g. Al3+ and Mn2+) from alumina was also examined, as their removal by vermiculite. The process of Mn-oxide coating changed some properties of the activated alumina (AA), decomposing the crystalline phases and reducing some parameters, e.g. specific surface area (from 295.90 to 94.51 m2 g−1) and pHPZC (from 7.34 to 5.74). These changes increased the efficiency and kinetics of alumina in removing F− from synthetic solutions and groundwater (from 80%/16 h to 100%/1 h). This efficiency was not affected by the presence of other anions in groundwater, such as HCO3 − and SO4 2−. The optimum rate of F− removal occurred at pH 5; however, during the F− removal, Al3+ and Mn2+ ions were released, respectively, from the AA (0.61 mg L−1 Al3+) and from the AM ( 52 mg L−1 Mn2+). Vermiculite used to remove these cations adsorbed about 86% Al3+ and 90% Mn2+. However, only Al3+ concentrations fell below the standard limit for drinking water of <0.5 mg L−1. Therefore, AA has the advantage of not containing Mn, and after 3 h kept F− concentrations in solutions 5 mg L−1F− below the standard limit of 1.5 mg L−1. This study revealed that, depending on the groundwater characteristics, AA may be more efficient and sustainable for defluoridation than coated alumina.

Evaluation of changes in groundwater quality caused by a water inrush event in Taoyuan coal mine, China

The effects of a water inrush event on the chemical composition of groundwater in a coal measures sandstone aquifer that is important for water supply was investigated at the Taoyuan coal mine in the Huaibei region in China. Changes in groundwater quality caused by the inrush event were investigated using statistical techniques, a Piper trilinear diagram, saturation index, ion combination ratios and a fuzzy comprehensive evaluation method. These investigations indicated that Na+ + K+ and SO42− were the main cation and anion, and the average contents were 272 mg/L and 732 mg/L before water inrush, and 394 mg/L and 779 mg/L after water inrush, respectively. The concentrations of anions in groundwater before the inrush event were in the order SO42− > HCO3− > Cl− and the cation concentrations were in the order Na+ + K+ > Ca2+ > Mg2+. The chemical composition of groundwater was mainly SO4·Cl–Ca·Mg before water inrush event, and SO4·Cl–Na and Na–HCO3–Cl after this event. According to the saturation index method, gypsum, calcite, magnesite, and aragonite controlling the chemical composition of groundwater were reactive minerals in groundwater system. The oxidation of pyrite, dissolution of sulfate and carbonate minerals were main geochemical process before and after the event; while the oxidation of pyrite and cation exchange were enhanced after the water inrush event. The fuzzy comprehensive evaluation results showed that the type V water accounted for a large proportion of poor-quality groundwater. Groundwater quality in the aquifer near the mine generally deteriorated after the water inrush event.

Arsenic removal from groundwater using an aerated electrocoagulation reactor with 3D Al electrodes in the presence of anions

Co-occurrence of arsenic and anions in groundwater causes a severe health problems and combine effects of these pollutants significantly affect performance of treatment process. Thus, this study has been conducted to examine the combine effects of anions on arsenic removal using aerated electrocoagulation (EC) reactor with 3D Al electrodes in groundwater. A 3-level, six factors Box-Behnken experimental design (BBD) was applied to investigate the individual and combine effect of anions and operating time: phosphate (x1: 1–10 mg L−1), silica (x2: 20–80 mg L−1), bicarbonate (x3: 130–670 mg L−1), fluoride (x4: 2–10 mg L−1), boron (x5: 5–10 mg L−1), and operating time (x6: 8–22 min) on desired responses. The specified responses were effluent arsenic concentration (Cf,As), removal efficiency of arsenic (Re), consumptions of energy and electrode (ENC and ELC), operational cost (OC), and adsorption capacity (qe). The optimum operating parameters predicted using BBD were found to be x1: 1.0 mg L−1, x2: 26.0 mg L−1, x3: 651.5 mg L−1, x4: 2.0 mg L−1, x5: 9.9 mg L−1, and x6: 10.5 min considering highest removal efficiency of arsenic and lowest operational cost. Under these operating conditions, the experimental values of Cf,As, Re, ENC, ELC, OC, and qe were found to be 2.82 μg L−1, 98.6%, 0.411 kWh m−3, 0.0124 kg m−3, 0.098 $ m−3, and 17.65 μg As (mg Al)−1, respectively. Furthermore, mathematical modelling was conducted using quadratic regression model and response surface analysis was performed to understand the relationship between independent parameters and responses.

Assessment of groundwater quality using water quality index (WQI): A case study of a hard rock terrain in Sri Lanka

Chronic Kidney Disease of uncertain etiology (CKDu) is a widespread health issue in rural dry zone regions in Sri Lanka. Monaragala region, located in eastern Sri Lanka is one of the hardest hit areas with CKDu. In order to investigate the possible relationship between the incidence of CKDu and drinking water quality, 99 groundwater samples from deep boreholes and shallow wells in hard rock aquifers in the Monaragala region, were collected and analysed for major cations and anions, and some selected trace element contents. The results revealed that over 65% of the groundwater samples from Monaragala area were alkaline. The anions in groundwater varied as HCO3− > Cl− > SO42− > F− while cations varied in the order of Na > Ca > Mg > K. The Majority of the samples (75%) belong to the Ca2+-Mg2+- HCO3− type. Among the studied parameters, electrical conductivity, chloride, sulphate, hardness, fluoride exceeded the WHO recommended values for drinking water in most cases. For instance, 76% of wells in the study area showed fluoride levels higher than the recommended levels (0.5 mg/L) for Sri Lanka. The higher ion contents in groundwater were mainly due to dissolution of aquifer minerals and a higher rate of evaporation. The calculation of Water Quality Index (WQI) indicated that over 50% of groundwater samples of the study area are poor in quality. The higher values of WQI also overlap with high prevalence areas of CKDu. This work revealed that groundwater quality has a direct effect on the etiology of CKDu in the region.

Hydrochemical and Isotopic Evolution of Groundwater Flowing Downstream of the Daqing River (Liaodong Bay, China)

Guo, Q.; Zhang, J.; Hu, Z., and Zhou, Z., 2020. Hydrochemical and isotopic evolution of groundwater flowing downstream of the Daqing River (Liaodong Bay, China). Journal of Coastal Research, 36(3), 608–618. Coconut Creek (Florida), ISSN 0749-0208.Hydrochemistry and specific environmental isotope ratios (δD, δ17O, and δ18O) were employed to investigate the hydrochemical and isotopic characteristics of groundwater in the downstream coastal plain of the Daqing River, China. The relative abundance of the major cations and anions of groundwater along the Daqing River changed from Ca2+, Mg2+ to Na+, Ca2+ and from to Cl–, respectively. The samples, divided into different groups on the basis of correlation coefficients, showed that the chemical composition of the groundwater samples near the Daqing River is approximately consistent with that of the Daqing River. The saturation indices calculated by PHREEQC software indicated that the main hydrogeochemical processes are evaporation and concentration along groundwater flow paths from the upper zone to the middle zone of the Daqing River basin. However, in the down zone, calcite, anhydrite, and dolomite become supersaturated. Isotopic data reveal that the groundwater is affected by the strong evaporation along the Daqing River. In the down zone of the Daqing River, the groundwater is polluted by the seawater.

Evaluating the suitability of groundwater for drinking purposes in the North Chengdu Plain, China

Groundwater is a significant and crucial component for all development activities of any life support system. In this study, the hydrochemical analysis and water quality index method (WQI) were used to assess groundwater quality for drinking purposes. Twelve groundwater samples were collected and analyzed into fourteen parameters which were considered as important indicators for assessing groundwater quality. A comparative study of these parameters with that of the Chinese Groundwater Standard (GB/T14848-2017) was conducted. It can be depicted from the results that groundwater quality is categorized as very hard, fresh water and slightly alkaline in nature. The major sequence of dominant cations and anions in groundwater are Ca2+ &gt; Mg2+ &gt; Na+ &gt; K+ and HCO-3 &gt; SO2-4 &gt; Cl- respectively. From the total 12 samples analyzed, the parameters of TH, NH+4, Fe and Mn of samples exceeded the limits set by (GB/T14848-2017) standard. Piper diagram illustrated that groundwater samples of the studied area are mostly of Ca-Mg-HCO3-SO4 type. WQI showed all samples fall between excellent to good category of water and suitable for drinking purposes. The quality of groundwater is mainly affected from anthropogenic activities and natural influence. The proposed method is reliable and effcient for groundwater pollution assessment and can be used in decision-making.

Hydrochemical characterization of shallow groundwater from the Mesta River basin

Groundwater is a valuable natural resource and an important source of drinking and domestic water supply. There are two types of groundwater in the Mesta River Basin: HCO3- &gt; Ca2++Mg2+ (1st type waters) and HCO3- &lt; Ca2++Mg2+ &lt; HCO3-+SO42- (2nd type waters). The waters of the first type formed in the silicate rocks, are widespread in the high mountain, mountain and low mountain area. These waters are attached to the region of regional fracturing of the Precambrian metamorphic complex represented by gneisses, granitogneisses, amphibolites and to the fractured environment of the southern Bulgarian granites and granitoids, quartzites, conglomerates and marls of the Paleozoic. The waters of the second type are characteristic of the valleys covered by Pliocene and Quaternary sediments with minimal precipitation. Groundwater from the Mesta River catchment area is mainly hydrocarbonate-calcium-magnesium with high sodium content in the southern part of the catchment area. The content of anions in groundwater is in the sequence: HCO3- &gt; SO42-&gt; Cl-. The cations are arranged in the order: Ca2++Mg2+ &gt; (Na++K+) or Ca2+ &gt; (Na++K+) &gt; Mg2+. Groundwater is very soft to moderately hard, fresh, with TDS content up to 0.5 g/l and chloride content below 10 mg/l.