Trilinear Diagram Research Articles

Processes and characteristics of hydrogeochemical variations between unconfined and confined aquifer systems: a case study of the Nakdong River Basin in Busan City, Korea.

This study is to assess the hydrogeochemical characteristics of groundwater at the deltaic region of the Nakdong River Basin in the Busan Metropolitan City of Korea. The study area is covered by the Quaternary sedimentary deposits and the Cretaceous granites associated with unconformity. The thick sedimentary deposits consists of two aquifers, i.e., unconfined and confined aquifers on the basis of clay deposit. Groundwater samples were collected from seven boreholes: two from unconfined aquifer and five from confined aquifer systems during the wet season of 2017year. ORP and DO indicates thatthe groundwater of the unconfined aquifer exists in the oxidization condition and that of the confined aquifer pertains in the reduction condition. Piper's trilinear diagram shows CaSO4 type for groundwater of the unconfined aquifer, and NaCl type for that of the confined aquifer. Ionic concentrations of groundwater increase in the confined aquifer because of direct and reverse ion exchange processes. Carbonate weathering and evaporation are other mechanisms in the water-rock interaction. Saturation indices of dolomite and calcite are observed as oversaturated, while halite reveals undersaturation. Hierarchical cluster analysis (HCA) exhibitsthat cluster 1 and cluster 2 represents the properties of groundwater in unconfined and confined aquifers, respectively. Factor analysis shows that groundwater of the confined aquifer is much influenced by seawater, and includes heavy metals of iron and aluminum. Groundwater samples in unconfined and confined aquifers are located at the rock weathering and evaporation zones in the Gibbs diagram. Inverse geochemical modeling of PHREEQC code suggests that carbonate dissolution and ion exchange of major ions are the prevailing geochemical processes. This comprehensive research provides the distinguished hydrogeochemical characteristics of groundwater in confined and unconfined aquifer systems of the Nakdong River Basin in Busan City, Korea.

Hydrogeochemical characteristics of groundwater and quality assessment for the purposes of drinking and irrigation in Bougaa area, Northeastern Algeria

In the northern part of Algeria, the intensive exploitation of groundwater resources and pollution has considerably affected the aquifer water quality, especially in rural areas where groundwater is the main source of water supply for most uses. This study was performed to evaluate the groundwater quality and its suitability for drinking and irrigation purposes through the hydrogeochemical study on the groundwater in Bougâa region (Northeastern Algeria). Fourteen groundwater samples were collected and analyzed for pH, T, EC, TDS, and major ions. Most samples are suitable for drinking based on the permissible limits of the Bureau of Indian standards (Indian standard specification for drinking water (IS 10500: 2012), but only 35 % of the samples are good enough for drinking purposes based on the water quality index of the groundwater. Assessment of groundwater samples from various parameters and methods such as “Electrical conductivity, Sodium adsorption ratio, Soluble sodium percentage, Magnesium adsorption ratio, Residual sodium carbonate, Permeability index, Kelly’s ratio, Wilcox’s diagram, and US salinity laboratory classification” showed that groundwater in the area is chemically suitable for irrigation uses. The Piper trilinear diagram suggests that the groundwater mainly belongs to the hydrochemical facies Ca–Mg–Cl and Na–Cl. The combination of ionic ratios, Gibbs plots, and saturation indices show that water–rock interaction, particularly the dissolution of carbonate, evaporation minerals, and ion exchange processes affects hydrogeochemistry of the area. Additional processes such as evaporation and anthropogenic pollution from various sources can also have major impacts on groundwater salinity.

Mechanisms controlling groundwater chemistry and assessment of potential health risk: A case study from South India

Protection and management of groundwater resources depends on full understanding of the processes controlling the groundwater chemistry and associated health risks. In view of this, the rural part of Wanaparthy district, Telangana State, India was chosen for the present study and the groundwater samples collected from there were chemically analyzed. Quality of groundwater is of alkaline nature and mostly fresh water type. According to Trilinear Diagram, the change of groundwater quality from Ca2+- HCO3− type to Na+- Cl− type through mixed water type suggests the gradual influence of anthropogenic activities on the aquifer system. Gibbs Diagrams demonstrate that the chemistry of groundwater is mainly controlled by rock-water interactions and the rest by evaporation due to impact of anthropogenic sources. Bivariate Diagrams (Na+vsCl−, Ca2++Mg2+vsSO42−+ HCO3− and Ca2++Mg2+- SO42−- HCO3−vs Na+- Cl−) clearly specify that the processes of weathering and dissolution of minerals, and ion exchange are the dominant controlling factors of groundwater chemistry. Hierarchical R-type Cluster Analysis illustrates that Group I (Cl−- Na+ and HCO3−) is considered natural contribution, Group 2 (SO42−- Mg2+- Ca2+) is natural or anthropogenic source and Group 3 (NO3−- K2+ - F−) is anthropogenic influence. As per the estimation of sources of ions in the groundwater body by Unmix Model, the Source 1 (NO3−, Cl−, SO42− and Na+) is related to the anthropogenic activities; Source II (Ca2+, HCO3−, Na+, SO42−, Mg2+ and Cl−) to the weathering of silicate minerals, dissolution of chloride and sulfate minerals; and Source III (K+, F−, Ca2+, HCO3− and Mg2+) to the weathering of fluoride, calcium, magnesium and potassium bearing minerals or the application of chemical compounds of potassium and fluoride ions. These sources lead to groundwater contamination in some locations, thereby causing unfit for drinking purpose. Health Risk Assessment with respect to NO3− and F− ions suggests that the Total Hazard Index of non-carcinogenic risk (> 1.0) is observed from 26.67%, 26.67% and 43.33% of the total groundwater samples and the threat is to children compared to men and women due to their smaller body weights. Therefore, the health risk reduction measures are recommended to improve the groundwater quality in the study region.

Experimental determination of yield in beam-to-column flange connections

The paper describes a universal test bench, designed to conduct full-scale studies of the strength and stiffness of joints of building structures. The paper present the results of full-scale tests of the joints of beam flanged connections with columns in the elastic and elastoplastic stage with the determination of the dependence of their yield on the value of static loads. The study was conducted on 12 models with both one-sided joining of the beam to the column, and with two-sided, for which the flange thickness, resistance class and the controlled tension of the bolts, loading scheme were varied. The experiments were carried out according to a multifactorial plan until the destruction of the models. According to test results, 4 characteristic trilinear diagrams were obtained for dependence of the angles of rotation versus bending moments. The obtained results can be used in the design of flange connections and during the verification of their design models.

Groundwater Quality Appraisal and its Hydrogeochemical Characterization — Mathura City, Western Uttar Pradesh

In order to understand the hydrogeochemistry of Mathura city, western Uttar Pradesh a total of 92, 34 and 22 groundwater samples were collected from shallow, intermediate and deep wells during post-monsoon 2017 and pre-monsoon 2018 respectively and analyzed for major cations and anions. The groundwater of the study area is found to be alkaline in nature and is categorized as hard to very hard water type. Dominant facies deciphered from Piper’s trilinear diagram of shallow, intermediate wells are Na-K-Cl-SO4 and Ca-Mg-Cl-SO4 while deep well samples are Ca-Mg-Cl-SO4 type facies in post-monsoon 2017. During pre-monsoon 2018, the ionic facies for shallow, intermediate and deep well samples is Na-K-Cl-SO4 type with the exception of 7 samples of shallow well which shows Ca-Mg-Cl-SO4 type facies. Based on the water quality index (WQI) classification, majority of samples of shallow, intermediate and deep well fall in poor water category in both seasons. According to pollution index of groundwater (PIG) classification, majority of samples of all three depths showed low to moderate pollution in both the seasons. Saturation indices of minerals was also calculated by employing geochemical program PHREEQC. Groundwater at shallow depth possesses excess concentration of Ca, Na, K, and SO4, followed by intermediate and deeper depth samples of both seasons. Trace elements like As, Mo, Sr, and Zn show higher concentration in shallow depth samples followed by intermediate and deeper depth samples, except As which shows a reverse trend. This demonstrates that the groundwater from shallow wells is definitely more vulnerable to contamination. The study has revealed poor groundwater quality of Mathura city and noticeable influence of urbanization and industrialization on water quality.

Using Piper trilinear diagrams and principal component analysis to determine variation in hydrochemical faces and understand the evolution of groundwater in Sidi Slimane Region, Morocco

The water quality of groundwater is one of the most important issues for development and life societies. The chemical parameters of the groundwater play a significant role in classifying and assessing water quality. In this study, twenty samples were collected from different locations in a rural region to determine the hydrochemical facies characteristics and understand the evolution of groundwater quality in the Sidi Slimane area in Morocco. Piper trilinear diagram and principal component analysis (PCA) were used to find out the major contributing parameters involved in groundwater samples. The results showed that the analytical values obtained when plotted on Piper’s plots revealed that the alkalis (Sodium, Potassium), are significantly dominant over alkaline earth metals (Calcium, Magnesium) and the strong acidic anions (Chlorides, Sulfates) dominant over the weak acidic anions (Carbonates and Bicarbonates). Piper trilinear diagram classified 90 % of the samples from the study area under Na+- K+ - Cl- - SO42- type and only 10 % samples under Ca2+- Mg2+- Cl--SO42- type. the Piper plots highlighted that the groundwater is dominant of Na–Cl type and the water types originating from halite dissolution (saline) in the study area. Also, correlation matrix showed that 95%, 100%, 65%, 75%, 65% and 55% of the examined groundwaters exhibit higher concentration of Sodium, Ammonium, Calcium, Electrical Conductivity EC, Chloride, and Nitrate respectively than the maximum acceptable limit of the Moroccan’s standards for drinking water. PCA suggests a significant mutual positive correlation between two main groups of parameters (EC, Ca2+, Mg2+, K+, Na+, HCO3- and Cl-) and (pH, NH4+, SO42-, and NO3-). The output of PCA analysis is in confirmation with that of the Piper trilinear diagram and the correlation matrix to identify the characteristics of the samples and aid to comprehend their spatial distribution.

Hydrochemical characterization of shallow and deep groundwater in Basement Complex areas of southern Kebbi State, Sokoto Basin, Nigeria

Groundwater under Basement Complex areas of southern Kebbi has been characterized in order to determine its suitability for drinking and irrigation use. Water samples were drawn from shallow groundwater (hand-dug shallow wells < 5 m) and deep groundwater (boreholes > 40 m). Physical parameters (i.e., temperature, TDS, pH, and EC), were determined in situ, using handheld meters. Discrete water samples were obtained for determination of chemical parameters. Results from several-sample ANOVA (Kruskal–Wallis test) suggested that heterogeneity in water table appeared to exert significant influence on groundwater chemistry which is characterized by a significant difference in pH, EC TH, Na+, Zn2+, Mg2+, PO43−, Cl−, HCO3−, SO42−, and NO3− concentrations. Also, ions including Fe3+, Zn2+, Mg2+, Na+, PO43−, and SO42− are above World Health Organization (2011) and National Standard for Drinking Water Quality (2007) reference guidelines. Most of the groundwater sources are moderately hard. Groundwater classification based on chloride, EC, and TDS revealed water of excellent quality for all types of uses. However, groundwater classification based on nitrate pollution revealed water of poor quality. Rock mineral is the major mechanism controlling water chemistry, as revealed by the Gibbs model. Most of the water sources have positive Scholler index, indicative of overall base exchange reactions in the underlying aquifers. Such condition was well explained by Piper trilinear diagram, which revealed two types of faces: Ca–Mg–HCO3 and Ca–Mg–SO4–Cl. The HCA categorized wells into three groups according to their hydrogeochemical physiognomies. Despite the significant difference in ions concentration and chemical indices, groundwater composition is more influenced by rock weathering than anthropogenic inputs. Groundwater evaluation for irrigation use indicates a significant difference in SAR level which is related to poor permeability index in shallow groundwater. Higher values of Kelly’s index and magnesium adsorption ratio threatened groundwater suitability for irrigation use in the study area.

Hydrochemical properties and groundwater quality evaluation in Suzhou City, lower Yangtze Delta, China

Detailed study of the chemical analysis results of 49 groundwater samples collected from the region’s second confined aquifer were carried out in an attempt to identify the samples’ hydrochemical properties and to assess the quality and usability of groundwater in Suzhou city, China. The results revealed that sodium, calcium and bicarbonate were the dominant ions in the groundwater samples. Na-HCO3, mixed Na-Ca-HCO3, Ca-HCO3, and Na-Cl type were the four major hydrochemical facies identified by a Piper Trilinear diagram. It was observed that the concentration of ammonia and nitrite in most of the samples in study area exceeded the permissible limit values prescribed by the national (China) and international (WHO) drinking water guidelines. Anthropogenic activities have been shown to be largely responsible for groundwater contamination. Scatter diagrams and factor analysis suggest that natural weathering processes, along with anthropogenic activities, control the hydrogeochemistry of groundwater. On the basis of the analytical results of the 49 groundwater samples as compared to water quality standards, it was found that majority of groundwater samples were not suitable for drinking or for industrial uses directly. Toxic metals and high levels of ions must be removed to render the groundwater suitable for drinking and industrial purposes. However, salinity, sodium adsorption ratio (SAR), residual sodium carbonate (RSC) and sodium percentage (Na%) values indicate that most of groundwater samples were suitable for irrigation purposes.

Hydrochemistry and Arsenic Contamination of Shallow Aquifers in Bidyananda and Nazimkhan Unions, Rajarhat Upazilla, Kurigram, Bangladesh

ABSTRACT In this study, the spatial distribution and hydrochemistry of arsenic (As) in shallow alluvial aquifers of Bidyananda and Nazimkhan Union of Rajarhat opazilla, Kurigram district of Bangladesh have been evaluated. Nineteen groundwater samples (depth: 10 to 50 m) were collected from the studied area for physical and chemical analysis. Based on analytical data of chemical analysis, a Piper trilinear diagram have been prepared which revealed that the groundwater of the studied area is Ca-HCO3 type, where Ca is the dominant metal. Physical data and permeability index values indicate good quality of the groundwater for drinking and irrigation. The concentrations of Fe, Mn and As in almost all samples exceed the WHO and Bangladesh national standard indicating significant pollutions. Groundwater As concentrations in the aquifer (10–50 m of depth) ranged from &amp;lt;0.005 to 0.323 mgL-1 and geochemical conditions changed from oxidized to successively more reduced, higher As concentrations with depth. Correlation studies revealed a good correlation between As and Mn (R2=0.20) in groundwater implying that natural reductive dissolution of MnO(OH) and FeO(OH) may be responsible for As release into the groundwater. However, a poor correlation between As and Fe (R2 = 0.0084) in groundwater is probably due to the precipitation of dissolved Fe and Mn as siderite (FeCO3) and rhodochrosite (MnCO3), respectively, under reducing conditions. The poor correlations among dissolved As, Fe and SO42- concentrations (As vs. SO42- R2 = 0.0674; Fe vs. SO42-, R2=0.1542) in groundwater suggest that pyrite/sulfide oxidation is not the dominant process for As release. A high concentration of As, Fe and Mn indicate that the natural reductive dissolution of iron oxyhydroxides is probably the dominant process for As mobilization in the groundwater of the studied area.

Evaluate the Irrigation Water Quality in Salem District, Tamil Nadu, India

Water is one in all the foremost indispensable renewable assets and is that the elixir of life. In this present world population is increasing tremendously. Rate of technological development in industry and agriculture is also high. The mentioned top of the reason has enlarged the demand for water which is going to be a major crisis in next to the upcoming future. Quality of groundwater was assessed by collecting sixty-six sampling spots in January 2017(Post monsoon) and May 2017(pre monsoon) Irrigation water quality interpretation was done by using Sodium Adsorption Ratio (SAR), USSL classification, Doneen’s classification and Wilcox’s classification. The influence of anions and cations was done by Piper’s trilinear diagram. Groundwater quality for irrigation purpose during premonsoon season is in doubtful category in almost all parts of the study area.

Groundwater as an alternative source to irregular surface water in the O'Kiep area, Namaqualand, South Africa

Water insecurity is a growing concern globally and the role of groundwater and aquifers in buffering the effects of climate variability and change is increasingly acknowledged due to extended periods of drought in arid regions. Water security can only be fully realised with a more robust understanding of groundwater as a water resource, especially in the O'Kiep area which is in Namaqualand, South Africa. Results of analyses of groundwater samples (n = 8) indicated that pH values met acceptable standards for drinking, while the total dissolved solids (TDS) and electrical conductivity (EC) were however not within the recommended limits. The chemical composition of the groundwater indicated Eh values −34.1 to −87.2 mV, indicative of reducing geochemical conditions with the most abundant ions being Cl-, SO42-, NO3-, F-, Na+, Ca2+, Mg2+ and K+. Furthermore, some of the ions were not within the guidelines, i.e. Cl−, SO42+, Na+, Ca2+ and Mg2+, but all the potential toxic elements, namely: Al, S, As, Cd, Cr, Co, Cu, Fe, Mn, Hg, Ni, Se, V, Zn and CN, were within acceptable values for drinking groundwater as recommended by the SANS241-1 (2015) and WHO (2011). Hydrogeochemical characteristics of the water indicated that the continuous consumption of the groundwater without pretreatment might result in possible human health risk as the Groundwater Quality Index (GWQI) confirmed that the groundwater quality could be classified as being of moderate concern. Furthermore, the hydrogeochemical indices (CaCO3/Cl and Mg/Ca) and cationic exchange values indicated that the aquifer is of inland origin while the piper trilinear diagram revealed that the groundwater type in the area is categorised as sodium – potassium – chloride – sulphate- (Na–K–Cl–SO4), carbonate – chloride – sulphate- (CaCO3–Cl–SO4) and sodium – chloride (Na–Cl) type water. Additionally, the Sodium Adsorption Ratio (SAR) values up to 11.7 indicated that the groundwater is brackish and its excessive usage may have undesirable effect on plant growth. Therefore, this study recommends the consideration of suitable measures to improve the GWQI for the benefit of the community which have access to limited water resources.

Identifying the deep groundwater recharge processes in an intermountain basin using the hydrogeochemical and water isotope characteristics

Abstract The hydrogeochemical and stable isotopes of water (δD and δ18O) were combined to investigate the deep groundwater recharge processes in the geologically complex intermountain basin (Kathmandu Valley). Results of the stable isotopic composition of the deep groundwater compared with global and local meteoric water lines and d-excess showed the deep groundwater as a meteoric water origin which is insignificantly affected by evaporation. The analysis suggests the deep groundwater was recharged during high rainfall periods (wet season). Additionally, the control of seasonal variation was absent in the deep groundwater and in the spring water samples. The large range of isotopic composition distribution was due to the altitude affect, whereas variations are from the various geological settings of the infiltration encountered during the recharge processes. The tri-linear diagram showed Na-K-HCO3 and Ca-Mg-HCO3 as the two major water types. The distribution of water types in this intermountain basin was found to be unique compared to other basins. Ionic concentration of the samples was found to be higher in the central part than in the periphery due to the ion exchange processes. This study determines the spatial distribution of various recharge processes that depends upon the environment during rainfall and the geological settings.

Evaluation of Groundwater Quality for Domestic and Irrigation Suitability from Upper Bhima Basin, Western India: A Hydro-geochemical Perspective

Major ion constituents present in groundwater are studied for shallow unconfined basaltic aquifer in order to understand the quality of groundwater resources and its impacts on inhabitants and irrigation. 30 groundwater samples collected from dug wells located in upper Bhima basin were analyzed to measure major cations and anions for establishing water quality index (WQI) and irrigation indices. The concentration of pH, electrical conductivity, total hardness, total dissolved solids and major cations and anions were analyzed. Groundwater types were detected using Piper’s trilinear diagram as Ca2+-HCO3−, Ca2+-Na+-HCO3−, mixed Ca2+-Mg2+-Cl− and Ca2+-Cl− groups. High concentration (8 to 194 mg/L) of nitrate was found at some locations in the region. WQI shows 66% of the samples to be unfit for drinking purposes due to high nitrate content mostly introduced because of the anthropogenic activities. Suitability of groundwater for irrigation purposes was determined using of Sodium Adsorption Ratio (SAR), Permeability Index (PI), Kelly Ratio (KR), Magnesium Hazard (MH), Sodium (%) and Residual Sodium Carbonate (RSC). Groundwater in the region is suitable for irrigation.

Research on Piper-PCA-Bayes-LOOCV discrimination model of water inrush source in mines

The occurrence of mine water inrush constantly threatens the safety production of coal mines and causes serious financial losses in China. Existing water inrush source identification methods do not consider the mixing effect of aquifers and the complexity of discrimination indexes. To identify water inrush rapidly and accurately, an identification model that combines water chemistry and multivariate statistical methods is proposed. The Piper trilinear diagram was used to screen 48 water samples taken from a water inrush aquifer in a mining area. Forty-two typical water samples that represent the water inrush aquifers were obtained. They were selected as training samples with discrimination indexes (Ca2+, Mg2+, Na++K+, HCO3−, SO42−, Cl−). Principal component analysis (PCA) was used to extract three principal indexes. Then, with these indexes taken as factors of Bayesian discrimination, we established a model for determining the source of water bursting in Pingdingshan Mine. Finally, the prejudgment classification stability of the constructed model was evaluated by leave-one-out cross-validation (LOOCV), which reports 95.2% overall classification accuracy. The constructed model was used to obtain a prognosis of 10 samples collected from Pingdingshan Mine, and it reported one misjudgment on one sample. In addition to comparing the prediction results with fuzzy comprehensive evaluation and gray relational degree model, results indicate that the constructed Piper-PCA-Bayes-LOOCV discrimination model of the water inrush source in mines can increase the recognition accuracy effectively, thus guaranteeing the safety production of mines.

Assessing groundwater quality and health risks of fluoride pollution in the Shasler Vagu (SV) watershed of Nalgonda, India

The principal objectives of this study were to evaluate groundwater quality and human health risks of fluoride contamination in Shasler Vagu (SV) watershed of Nalgonda district, India. For this purpose, 107 groundwater samples were collected and analyzed various physcio-chemical parameters including fluoride, and Gibbs diagrams, Hill–Piper trilinear diagram, and groundwater quality index (GWQI) were applied to understand the groundwater chemistry and its suitability for drinking purpose. In addition to this, non-carcinogenic health risks of high fluoride intake were also evaluated using the US Environmental Protection Agency model for adults and children in the study region. Groundwater chemistry is mainly controlled by HCO3−-Ca2+-Mg2+ and Na+-HCO3− type, and rock weathering. Assessment of GWQI indicates that 76% of groundwater sources in the study region have poor quality for drinking uses. Results reveal that fluoride concentration ranged from 1.4 to 5.9 mg/L in the groundwater samples, which was significantly higher than the recommended limit of 1.5 mg/L for drinking uses. Results of hazard quotient (HQ) estimates are in the ranges of 0.90–3.78 and 1.21–5.11 in adults and children populations of the study region, respectively. About 98% of adults and 100% of children population of SV watershed are at very high risks of chronic toxicity by excess fluoride intake.

Understanding the hydrogeochemical characteristics of natural water for irrigation use around the hard rock mine in Maddhapara, Northwest Bangladesh

This study assesses the hydrochemical characteristics and water quality for irrigation use around the Hard Rock Mining area. The Hydrochemical analysis shows that there are wide variations of ions (e.g. pH, Sp. EC, turbidity, Fe3+, Na+, Cl−, Cd2+, soluble silica and others) which exceeded the acceptable limit of drinking as well as the irrigation uses. The concentration of SiO2 in the water is very high than the natural limit. It indicates a direct impact of granitic rock extracted from the mine. In fact, such rock contains a large quantity (50.17%–74.7% by weight) of silica. The WQI analysis shows that water samples are slightly marginal to excellent quality water. Where, the surface water samples possess comparatively good quality water than groundwater for irrigation purpose. The scatter graph of (Ca2+ + Mg2+) versus total cations (TZ+) plot suggests that some ions are produced due to the weathering of silicate minerals. The Trilinear diagram exhibits that 77.24% of samples are showing the CaHCO3 type of facies where 85.7% of surface water falls within this category. The Durov diagram illustrates the mixing of ion dissolution with reverse ion exchanging water type. The correlation matrix affirms the relationship, strength, and direction of multivariate data. In particular, the various classification of water such as SAR, Na%, salinity, and TDS values confirmed excellent to permissible use of water for agricultural purpose around the mining area.

Hydrogeochemistry and fluoride contamination in the hard rock terrain of central Telangana, India: analyses of its spatial distribution and health risk

Groundwater is the primary source for drinking uses in the hard rock terrain of central Telangana, India, where most of the people rely on it for daily uses. Therefore, this study was carried out to comprehend the fluoride contamination and its associated health risk assessment to local dwellers. For this study, 54 groundwater samples were collected from bore wells and hand pumps in the study region and were analysed for fluoride and other physicochemical parameters. The results indicated by statistical mean values of Na+, Ca2+, Mg2+ and K+ are 182.14, 59.79, 23.90 and 3.74 mg/L, respectively, while HCO32−, Cl−, SO42− and NO3− are 236.1, 230.8, 167.7 and 81.9 mg/L, respectively. The fluoride concentration ranged from 0.8 to 4.2 mg/L, with a mean of 2.21 mg/L. Eighty-one percent of the groundwater samples exceeded the World Health Organization’s water quality limit of 1.5 mg/L for fluoride. Piper trilinear diagram (PTD) signifies that groundwater quality in the study region is characterized by Na+–Cl−, Ca2+–Mg2+–Cl− and Na+–HCO3−–Cl− hydrochemical water types. Gibbs diagrams indicate that all the major ion chemistry of the groundwater in the study region is controlled by rock–water interactions, while evaporation plays a minor role. The health risk assessment results revealed that the associated hazard quotient (HQ) for the age range of 6 to 12 months within about 100% of the study area exceeded the acceptable HQ limits of 1. Furthermore, the HQ for age categories 6–11 years, 11–16 years and 16–18 years within 96.2, 68.5 and 50%, respectively, of the study locations were larger than 1. Results also indicate that age group 6 to 12 months was most prone to health risks in the study region. Therefore, in the study region, people should be taken necessary actions to abolish the groundwater contamination to protect the local dweller’s health.

Assessment of surface–groundwater interactions using hydrochemical and isotopic techniques in a coalmine watershed, NW China

The Kuye River is located in Shenfu-Dongsheng coalfield which is the most important energy center in China. The region climate belongs to arid and semi-arid climate with vulnerable ecological environment. Groundwater dewatering for coal mining may cause stream flow reduction in the watershed. Therefore, the effects of coal mining on surface water–groundwater interactions are of great concern in the watershed. In this paper, descriptive statistical method, stable isotope measurements and Piper trilinear diagram are employed to analyze the interaction among river water, groundwater (both in wells used for drinking water and in mine water discharges) and rainwater. The chemical analysis of water samples shows that all the water sources are dominated by HCO3− as anions, by Ca2+ and Na+ as cations. River water has a chemical composition of the Na·Ca–HCO3·SO4 facies. The chemical composition of mine water discharges is similar to river water within the range of 5 km from the river course. Similarly, groundwater samples from drinking water wells that are less than 180 m deep and are located within 1 km of the river are similar to that of river water. Groundwater recharge analysis shows rainwater is the main source of drinking water recharge when drinking water wells are more than 180 m and also the main source for mine water discharge more than 5.5 km from the river course.

Hydrochemical Analysis and Fuzzy Logic Method for Evaluation of Groundwater Quality in the North Chengdu Plain, China.

Groundwater is a major water resource in the North Chengdu Plain, China. The research objective is to determine the quality and suitability of groundwater for drinking purposes within the vicinity of a shallow, unconsolidated aquifer of Quaternary age. In this study, a detailed investigation was conducted to define the hydrochemical characteristics that control the quality of groundwater, based on traditional methods. Considering the uncertainties linked with water resources and the environmental complications, the fuzzy logic method was used in the determination of groundwater quality for more precise findings that support decision-making. To achieve such an objective, sixteen water quality guidelines were used to determine groundwater quality status in six selected wells. The results showed that the groundwater is neutral, very hard, and fresh in nature. Dominating cations and anions are in the order of Ca > Na > Mg > K and HCO > SO > Cl. The Piper trilinear diagram demonstrates that the hydrochemical facies of groundwater are mostly of Ca-HCO type. Statistical analysis denotes a positive correlation between most of the chemical parameters. The study took the results of the fuzzy logic evaluation method into consideration, to classify the samples into five groups according to the Chinese groundwater quality standard (GB/T 14848-93) for their suitability for domestic use. The results demonstrated that the quality of the groundwater samples is within grade II and III, and is suitable for drinking purposes. The comprehensive evaluation of groundwater quality is critical to aid sensitive policy decisions, and the proposed approach can guarantee reliable findings to that effect. The results of this study would also be helpful to future researches related to groundwater quality assessment.

Relationship between Soil Salinization and Groundwater Hydration in Yaoba Oasis, Northwest China

Precipitation is scarce and evaporation is intense in desert areas. Groundwater is used as the main water source to develop agriculture in the oases. However, the effects of using groundwater on the ecological environment elicit widespread public concern. This study investigated the relationship between soil salinity and groundwater characteristics in Yaoba Oasis through in situ experiments. The relationship of the mineral content, pH, and main ion content of groundwater with soil salt was quantitatively evaluated through a gray relational analysis. Four main results were obtained. First, the fresh water area with low total dissolved solid (TDS) was usually HCO3− or SO42− type water, and salt water was mostly Cl− and SO42−. The spatial distribution of main ions in groundwater during winter irrigation in November was basically consistent with that during spring irrigation in June. However, the spatial distribution of TDS differed in the two seasons. Second, soil salinization in the study area was severe, and the salinization rate reached 72.7%. In this work, the spatial variability of soil salinization had a relatively large value, and the values in spring were greater than those in autumn. Third, the soil in the irrigated area had a high salt content, and the salt ion content of surface soil was higher than that of subsoil. A piper trilinear diagram revealed that Ca2+ and K+ + Na+ were the main cations. SO42−, Cl−, and HCO3− were the main anions, and salinization soil mainly contained SO42−. Fourth, the changes in soil salt and ion contents in the 0–10 cm soil layer were approximately similar to those of irrigation water quality, both of which showed an increasing trend. The correlation of surface soil salinity with the salinity of groundwater and its chemical components was high. In summary, this study identified the progress of irrigation water quality in soil salinization and provided a scientific basis for improving the oasis ecosystem, maintaining the healthy development of agriculture, managing oasis water resources, and policy development. Our findings can serve as a reference for other, similar oasis research.