Use of fuzzy synthetic evaluation for assessment of groundwater quality for drinking usage: a case study of Southern Haryana,India

A method based on concept of fuzzy set theory has been used for decision-making for the assessment of physico-chemical quality of groundwater for drinking purposes. Conventional methods for water quality assessment do not consider the uncertainties involved either in measurement of water quality parameters or in the limits provided by the regulatory bodies. Fuzzy synthetic evaluation model gives the certainty levels for the quality class of the water based on the prescribed limit of various regulatory bodies and opinion of the experts from the field of drinking water quality. In this paper, application of fuzzy rule based optimization model is illustrated with twenty groundwater samples from Sohna town of Gurgaon district of Southern Haryana, India. These samples were analysed for 15 different physico-chemical parameters, out of them nine important parameters were used for the quality assessment using fuzzy synthetic evaluation approach. From this study, it has been concluded that all the water samples are in acceptable category whose certainty level ranges from 44 to 100%. Water from these sources can be used for the drinking purposes if alternate water source is not available without any health concern on the basis of physico-chemical characteristics.     

Suitability assessment of shallow and deep groundwaters for drinking and irrigation use in the El Khairat aquifer (Enfidha, Tunisian Sahel)

The El Khairat aquifer is an important groundwater aquiferous system, which is considered a major source for drinking and irrigation water in Enfidha in Tunisian Sahel. The analysis of groundwater chemical characteristics provides much important information useful in water resources management. Assessing the water quality status for special use is the main objective of any water monitoring studies. An attempt has been made for the first time in this region to appreciate the quality and/or the suitability of shallow and deep groundwater for drinking and irrigation. In order to attend this objective, a total of 35 representative water samples were collected during February 2007 from both boreholes (17) and wells (18); and analyzed for the major cations (sodium, calcium, magnesium and potassium) and anions (chloride, sulphate, bicarbonate, and nitrate) along with various physical and chemical parameters (temperature, pH, total dissolved salts, and electrical conductivity). Based on the physico-chemical analyses, irrigation quality parameters like sodium absorption ratio (SAR), residual sodium carbonate (RSC), percentage of sodium (Na%), and permeability index (PI) were calculated. In addition to this, iso-concentration maps were constructed using the geographic information system to delineate spatial variation of qualitative parameters of groundwater samples. The correlation of the analytical data has been attempted by plotting different graphical representations such as Piper, Wilcox, and US Salinity Laboratory for the classification of water. The suitability of the water from the groundwater sources for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with World Health Organization guideline values for drinking water. A preliminary hydrochemical characterization shows that most of the groundwater samples fall in the field of calcium–magnesium–chloride–sulphate type of water. Majority of the samples are not suitable for drinking purposes and far from drinking water standards. The high EC value and the percentage of Na in most of the groundwater render it unsuitable for irrigation. Wilcox classification suggested that around 50% of both deep and shallow groundwater samples are unsuitable for irrigation. According to the US Salinity Classification, most of the groundwater is unsuitable for irrigation unless special measures are adopted.     

Suitability assessment of deep groundwater for drinking and irrigation use in the Djeffara aquifers (Northern Gabes,south-eastern Tunisia)

The multilayered Djeffara aquifer system, south-eastern Tunisia, has been intensively used as a primary source to meet the growing needs of the various sectors (drinking, agricultural and industrial purposes). The analysis of groundwater chemical characteristics provides much important information useful in water resources management. Detailed knowledge of the geochemical evolution of groundwater and assessing the water quality status for special use are the main objective of any water monitoring study. An attempt has been made for the first time in this region to characterize aquifer behavior and appreciate the quality and/or the suitability of groundwater for drinking and irrigation purposes. In order to attend this objective, a total of 54 groundwater samples were collected and analyzed during January 2008 for the major cations (sodium, calcium, magnesium and potassium), anions (chloride, sulfate, bicarbonate), trace elements (boron, strontium and fluoride), and physicochemical parameters (temperature, pH, total dissolved salts and electrical conductivity). The evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium, chloride and sulfate contents as a result of leaching of evaporite rock. In this study, three distinct chemical trends in groundwater were identified. The major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories: (1) calcite precipitation, (2) gypsum and halite dissolution, and (3) ion exchange. Based on the physicochemical analyses, irrigation quality parameters such as sodium absorption ratio (SAR), percentage of sodium, residual sodium carbonate, residual sodium bicarbonate, and permeability index (PI) were calculated. In addition, groundwater quality maps were elabortaed using the geographic information system to delineate spatial variation in physico-chemical characteristics of the groundwater samples. The integration of various dataset indicates that the groundwater of the Djeffara aquifers of the northern Gabes is generally very hard, brackish and high to very high saline and alkaline in nature. The water suitability for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with World Health Organization (WHO) guideline values for drinking water. Piper trilinear diagram was constructed to identify groundwater groups where the relative major anionic and cationic concentrations are expressed in percentage of the milliequivalent per liter (meq/l), and it was demonstrated that the majority of the samples belongs to SO₄–Cl–Ca–Na, Cl–SO₄–Na–Ca and Na–Cl hydrochemical facies. As a whole, all the analyzed waters from this groundwater have revealed that this water is unsuitable for drinking purposes when comparing to the drinking water standards. Salinity, high electric conductivity, sodium adsorption ratio and sodium percentages indicate that most of the groundwater samples are inappropriate for irrigation. The SAR vary from medium (S2) to very high (S4) sodicity. Therefore, the water of the Djeffara aquifers of the northern Gabes is dominantly of the C4–S2 class representing 61.23 % of the total wells followed by C4–S3 and C4–S4 classes at 27.27 and 11.5 % of the wells, respectively. Based on the US Salinity Classification, most of the groundwater is unsuitable for irrigation due to its high salt content, unless certain measures for salinity control are undertaken.     

Hydrochemical investigation and quality assessment of ground water in rural areas of Delhi,India

The suitability of groundwater quality for drinking and agricultural purposes was assessed in the rural areas of Delhi based on the various water quality parameters. A total of 50 ground water samples were collected randomly from different sources viz. hand pump, tube well, boring and analyzed for major ion chemistry to understand the operating mechanism of geochemical processes for ground water quality. The quality analysis is performed through the estimation of pH, EC, TDS, total hardness, total alkalinity, Na, K, Cl, NO₃, SO₄, DO, BOD, Cu, Cr, Cd, Ni, Zn and Pb. Hydrochemical facies were identified using Piper, Durov and Chadha diagram. Chemical data were also used for mathematical calculations (SAR, %Na, RSC, PI, KI, and chloroalkaline indices) for better understanding the suitability of ground water for irrigation purposes. The results of saturation index shows that all the water samples were supersaturated to undersaturated with respect to carbonate minerals and undersaturated with respect to sulphate and chloride minerals. According to USSL diagram, most of the samples fall in the field of C₃S₁, indicating medium salinity and low sodium water which can be used for almost all types of soil with little danger of exchangeable sodium. Assessment of water samples from various methods indicated that majority of the ground water in the study area is chemically suitable for drinking and agricultural uses.     

Assessment and geospatial distribution mapping of fluoride concentrations in the groundwater of Al-Howban Basin,Taiz-Yemen

Groundwater is one of the most important natural resources of drinking water on the earth planet. In rural areas of Yemen, groundwater is the main resource for drinking as well as for domestic purposes. According to the World Health Organization, one of the most important elements that has to be found in drinking water is fluorine (fluoride) but within the range of concentration of 0.5 up to 1.5 mg/l. Otherwise, any concentration of fluoride out of that range may cause serious diseases in human’s body such as fluorosis, kidney chronic disease, and/or nephrotoxicity. Taiz City, the third important and largest city in Yemen, has been suffering from dental fluorosis for a few decades. The main resource for drinking water in this city and adjacent areas is Al-Howban Basin (the study area) from where 33 groundwater samples were collected from 33 stations. These samples were preserved and then chemically analyzed according to the American Public Health Association Standards. The results reflected high levels of fluoride concentrations up to 3.6 mg/l in groundwater of many stations. GIS mapping was used to produce a geospatial distribution map of fluoride concentrations using ArcGIS-inverse distance weighted (IDW) tool. As a result, three zones of risks were identified in the study area: mild risk zone which covers the major part of the study area, moderate risk zone, and zone of no risk (optimum level zone). The last two zones occupy small portions of the study area. Consequently, dental and skeletal fluorosis, kidney, and/or nephrotoxic diseases are highly expected to be detected in the study area. Groundwater treatment measurements and health precautions are strongly recommended to be taken by local authorities in the near future.     

Drinking water quality in villages of southwestern Haryana,India: assessing human health risks associated with hydrochemistry

The chemical quality of groundwater of western Haryana, India was assessed for its suitability for drinking purposes. A total of 275 water samples were collected from deep aquifer based hand-pumps situated in 37 different villages/towns of Bhiwani region. The water samples were analyzed for different physico-chemical properties, e.g., pH, total dissolved solids (TDS), total harness (TH), total alkalinity (TA), calcium, magnesium, carbonate, bicarbonate, sulphate, chloride and fluoride concentrations. In this study, the average TDS content was greater ranging 1,692 (Bhiwani block) to 2,560 mg l⁻¹ (Siwani block), and other important parameters of water, e.g., TA (442–1,232 mg l⁻¹), TH (437–864 mg l⁻¹) and bicarbonate (554–672 mg l⁻¹), were also higher than maximum permissible limit by WHO or BIS. The fluoride appeared as a major problem of safe drinking water in this region. We recorded greater fluoride concentration, i.e., 86.0 mg l⁻¹ from Motipura village that is highest fluoride level ever recorded for Haryana state. The average fluoride concentration ranged between 7.1 and 0.8 mg l⁻¹ in different blocks of western Haryana. On the basis of fluoride concentration, Siwani block showed the maximum number of water samples (84% of total collected samples) unsuitable for drinking purposes (containing fluoride >1.5 mg l⁻¹) followed by Charki Dadri block (58%), Bhiwani block (52%), Bawani Khera block (33%) and Loharu block (14%). This study clearly suggest that some health deteriorating chemicals in drinking water were at dangerous level and; therefore, water quality could be a major health threat for local residents of western Haryana. The high fluoride level in drinking water has posed some serious dental health risks in local residents.     

Groundwater quality assessment for drinking purpose in Raipur city,Chhattisgarh using water quality index and geographic information system

An effort has been made to comprehend the groundwater quality of Raipur city for drinking purpose utilizing Water Quality Index (WQI) and Geographic Information System (GIS) techniques. In this study thirty four groundwater samples were collected during May, 2015. Standard methods has been adopted in groundwater sampling which are prescribed by the American Public Health Association (APHA, 1995). Eight water quality parameters have been considered to ascertained water quality index viz. pH, chloride, fluoride, calcium, magnesium, alkalinity, hardness and nitrate. The Bureau of Indian Standard (BIS, 2009) has been considered to assess the suitability of groundwater for drinking purposes and for the calculation of WQI. This study reveals that 76% area is falling under excellent, very good and good category and 24% area is falling under poor, very poor and unfit category as per the WQI classification. The predicted accuracy of the obtained result is around 97.05% reflecting capability of adopted techniques. Anthropogenic activities are influencing the groundwater quality of the study area. The present study is helpful in proper planning and management of available water resource for drinking purpose.     

Chemometric approach integrated with capillary electrophoresis for the investigation of public water system sources and quality

A chemometric approach coupled with capillary electrophoresis based on the hierarchical cluster analysis and principal component analysis has been applied for the investigation of the water quality in the Golcuk-Isparta region (Lake District of Turkey). In the research area, Egirdir Lake, Golcuk Lake and surrounding ground and domestic waters have been utilized as drinking water resources. Golcuk Lake is distinctive in terms of high fluoride content (3.50 ± 0.21 mg/mL) which is endemic in volcanic areas where the water flow through volcanic rocks and sediments. Based on the analysis of major anions chloride, sulfate, nitrate and fluoride with capillary electrophoresis, twenty-four drinking water sampling sites in the research area were classified into four classes using the hierarchical cluster and principal component analysis. Combining the research area investigation results of hierarchical cluster and principal component analysis, it was found that fluoride concentration is the major diagnostic variable to determine the quality of drinking waters, and all the other anions are the important classification factors to predict the resources of the drinking water samples, individually. To sum up, this study reveals the potential of the use of capillary electrophoresis in combination with chemometric techniques for the determination of the quality and origin of drinking waters.     

Visualizing the spatial water quality of Bentota,Sri Lanka in the presence of seawater intrusion

Seawater flows towards the inlands along with the rivers and canals, through the process of infiltration and leaks in the ground water characterized by high concentrations of soluble salts. High salinity concentrations can make groundwater unsuitable for public consumption and surface water unsuitable for irrigation and agricultural activities. This study envisages the fluctuations of ground and surface water quality of Bentota area in the presence of seawater intrusion. The temporal and spatial variations of eleven water parameters were monitored by collecting the water samples during one year period. Spatial distributions were assessed by applying the Inverse distance weighted (IDW) interpolation method in Arc GIS 10.5 software. Water quality is assessed on the integration of all parameters in terms of an index based on the World Health Organization (WHO) standards. The significant linear relationship between the considered parameters of surface water (SW) and groundwater (GW) were identified applying correlation analysis using SPSS software. All parameters of surface water were above the permissible limits of WHO standards. Surface water quality index values with respect to 60% of canals show very poor quality (>1 250) of surface water indicating their unsuitability for irrigation activities. Those surface water bodies indicated very highly saline conditions during dry months. The spatial distribution of ground water quality index with respect to the highest parameter values of each sampling location indicates that 52.2% of total land extent of Bentota Divisional Secretariat Division (DSD) has good quality of ground water which is suitable for drinking. Its 47.2% of total land extent has poor quality of ground water for drinking purpose and less than 0.5% of the area consists of excellent or very poor quality of ground water in each. This study helps to manage coastal aquifers by understanding the extreme water quality conditions and coastal salinity.     

Visualizing the spatial water quality of Bentota,Sri Lanka in the presence of seawater intrusion

Seawater flows towards the inlands along with the rivers and canals, through the process of infiltration and leaks in the ground water characterized by high concentrations of soluble salts. High salinity concentrations can make groundwater unsuitable for public consumption and surface water unsuitable for irrigation and agricultural activities. This study envisages the fluctuations of ground and surface water quality of Bentota area in the presence of seawater intrusion. The temporal and spatial variations of eleven water parameters were monitored by collecting the water samples during one year period. Spatial distributions were assessed by applying the Inverse distance weighted (IDW) interpolation method in Arc GIS 10.5 software. Water quality is assessed on the integration of all parameters in terms of an index based on the World Health Organization (WHO) standards. The significant linear relationship between the considered parameters of surface water (SW) and groundwater (GW) were identified applying correlation analysis using SPSS software. All parameters of surface water were above the permissible limits of WHO standards. Surface water quality index values with respect to 60% of canals show very poor quality (>1 250) of surface water indicating their unsuitability for irrigation activities. Those surface water bodies indicated very highly saline conditions during dry months. The spatial distribution of ground water quality index with respect to the highest parameter values of each sampling location indicates that 52.2% of total land extent of Bentota Divisional Secretariat Division (DSD) has good quality of ground water which is suitable for drinking. Its 47.2% of total land extent has poor quality of ground water for drinking purpose and less than 0.5% of the area consists of excellent or very poor quality of ground water in each. This study helps to manage coastal aquifers by understanding the extreme water quality conditions and coastal salinity.     

Geographic Information System and groundwater quality mapping in Panvel Basin,Maharashtra, India

Panvel Basin of Raigarh district, Maharashtra, India is the study area for groundwater quality mapping using the Geographic Information System (GIS). The study area is typically covered by Deccan basaltic rock types of Cretaceous to Eocene age. Though the basin receives heavy rainfall, it frequently faces water scarcity problems as well as water quality problems in some specific areas. Hence, a GIS based groundwater quality mapping has been carried out in the region with the help of data generated from chemical analysis of water samples collected from the basin. Groundwater samples show quality exceedence in terms of chloride, hardness, TDS and salinity. These parameters indicate the level of quality of groundwater for drinking and irrigation purposes. Idrisi 32 GIS software was used for generation of various thematic maps and for spatial analysis and integration to produce the final groundwater quality map. The groundwater quality map shows fragments pictorially representing groundwater zones that are desirable and undesirable for drinking and irrigation purposes.     

Assessment of water quality for drinking and irrigation purposes: a case study of Başköy springs (Ağlasun/Burdur/Turkey)

It is important to know the quality of water resources for drinking, domestic and irrigation in the rural area. Because, in recent times, there has been increased demand for water due to population growth and intense agricultural activities, so, hydrogeochemical investigations come into prominence for the groundwater use. The purpose of this paper is to evaluate water quality of Ba?köy springs for both drinking and irrigation purposes. The geochemical processes and quality of springs were followed as seasonal in the study area. In view of geochemical classification, springs are Ca-Mg-HCO₃ water type for both seasons. Comparison of geochemical data shows that majority of the spring samples are suitable for drinking water. On the other hand, chemical indexes of springs with various classifications were calculated for irrigation purposes. According to the classifications (electrical conductivity, total dissolved solids, total hardness, salinity hazard, percent sodium, sodium adsorption ratio, residual sodium carbonate, residual sodium bicarbonate, permeability index, potential salinity, soluble sodium percentage, magnesium ratio, and Kelly’s ratio), Ba?köy springs are suitable for irrigation purposes. However, water quality of Çaygözü spring is different the other springs due to the high electrical conductivity and total dissolved solids. Also, groundwater mineralization processes and rock–water interaction are controlled with bivariate diagrams of major elements.     

Geochemical assessment of groundwater quality in vicinity of Bhalswa landfill,Delhi, India,using graphical and multivariate statistical methods

A geochemical assessment of groundwater quality and possible contamination in the vicinity of the Bhalswa landfill site was carried out by using a hydrochemical approach with graphical and multivariate statistical methods with the objective of identifying the occurrence of various geochemical processes and understanding the impact of landfill leachates on groundwater quality. Results indicate that nitrate, fluoride and heavy-metal pollution are in an alarming state with respect to the use of groundwater for drinking purposes. Various graphical plots and statistical analyses have been applied to the chemical data based on the ionic constituents, water types, and hydrochemical facies to infer the impact of the landfill on groundwater quality. The statistical analysis and spatial and temporal variations indicate the leaching of contaminants from the landfill to the groundwater aquifer system. The concentrations of heavy metals in the landfill leachates are as follows: Fe (22 mg/l), Mn (~20 mg/l), Cu (~10 mg/l), Pb (~2 mg/l), Ni (0.25 mg/l), Zn (~10 mg/l), Cd (~0.2 mg/l), Cl⁻ (~4,000 mg/l), SO₄²⁻ (~3,320 mg/l), PO₄³⁻ (~4 mg/l), NO₃⁻ (30 mg/l) and fluoride (~50 mg/l); all were much higher than the standards. The study reveals that the landfill is in a depleted phase and is affecting groundwater quality in its vicinity and the surrounding area due to leaching of contaminants.     

Hydrogeochemistry and water quality assessment of shallow aquifers in the western flanks of Southern Western Ghats,SW India

The present study deals with the hydrogeochemistry and water quality of shallow aquifers in two important river basins—the Ithikkara and Kallada river basins—draining the south western flanks of Western Ghats in Kerala, South West India. Well water samples were collected from 20 dug wells with a depth range of 1 m below ground level (mbgl) to 18.2 mbgl during pre-monsoon, monsoon, and post-monsoon seasons of the year 2011–2012. These samples were analyzed for various physico-chemical parameters following standard methods and were evaluated for their interrelations and drinking water suitability. The pH of the water samples shows wide variation from highly acidic to highly alkaline water. About 80% of pre-monsoon samples recorded Fe²⁺ concentration above the permissible limit of drinking water standard. Water Quality Index (WQI) shows that majority of the well water samples fall in the category of excellent–good for drinking purpose. The results of the irrigation suitability assessment using the procedures like Percent Sodium, Sodium Absorption Ratio, Residual Sodium Carbonate, Kelly Index, Permeability Index, and Magnesium Hazard reveal that the well waters of the study area are fit for irrigation purpose. Na⁺/Cl^? ratio reflects the release of sodium to water due to silicate weathering. The samples have a Ca²⁺/Mg²⁺ ratio equal or greater than 2 indicating the effect of silicate minerals in contributing Ca²⁺ and Mg²⁺ ions to the well water. The saturation indices reveal that groundwater is supersaturated with SiO₂. Among the causative factors that determine the hydrochemical quality of well water samples, silicate weathering plays a pivotal role with significant input of ions from anthropogenic sources.     

Assessment of the quality of groundwater from different parts of southeastern Nigeria for potable use

Groundwater samples from three different states of southeastern Nigeria were analyzed for a range of physicochemical parameters and heavy metal constituents in order to determine their potability as drinking water sources. The results indicate that the physicochemical parameters (pH, temperature, TDS, TH, electrical conductivity, Cl^?, NO₃ ^? and SO₄ ^2?) tested for have most of their values fall within the permissible limits given by the Nigerian and World Health Organization standards for drinking water quality. The results also reveal that apart from Cu and Pb the rest of the tested heavy metals (As, Zn, Ni, total Fe, Cd and Mn) recorded values that are significantly above the maximum permissible limits for drinking water purposes and therefore have the potential to cause health impacts for long-term potable use. On the basis of principal component analysis, the sources of the measured chemical constituents are likely to be predominantly geogenic (weathering of soluble minerals in the formations) and partly anthropogenic (industrial effluent, agricultural practices and mining activities). Single-factor ANOVA tests indicated insignificant differences in the datasets within/between states or geological units. Caution or adequate treatment is generally required when utilizing the groundwater from the area for drinking purpose due to the elevated metal concentrations and rating as poor to unsuitable water quality.     

Use of geographical information system and water quality index to assess groundwater quality in El Khairat deep aquifer (Enfidha, Central East Tunisia)

Groundwater is the most important natural resource used for drinking by many people around the world, especially in rural areas. In Tunisia, since the quantity and the quality of water available for different uses is variable from one place to another, groundwater quality in El Khairat deep aquifer was evaluated for its suitability for drinking purposes. To this end, an attempt has been made for the first time in order to determine spatial distribution of groundwater quality parameters and to identify places with the best quality for drinking within the study area based on: (1) an integrated analysis of physical?Cchemical parameters, (2) use of Geographical Information System, and (3) Water Quality Index (WQI) calculation. The physical?Cchemical results were compared with the World Health Organization (WHO) standards for drinking and public health, in order to have an overview of the present groundwater quality. According to the overall assessment of the basin, almost all the parameters analyzed are above the desirable limits of WHO. Using GIS contouring methods with Arcview 3.2a, spatial distribution maps of pH, TDS, EC, TH, Cl, HCO₃, SO₄, NO₃, Ca, Mg, Na, and K have been created. The spatial analysis of groundwater quality patterns of the study area shows that the TDS value increases from north-west to south-east following the general trend of the Khairat aquifer flow direction. The spatial distribution map of TH shows that a majority of the groundwater samples falls in the very hard category. WQI was used to assess the suitability of groundwater from the study area for human consumption. From the WQI assessment, over 82% of the water samples fall within the ??Poor?? and ??Very poor?? categories, suggesting that groundwater from the south-eastern of the El Khairat deep aquifer is unsuitable for drinking purposes.     

Distribution of fluoride in groundwater of Maku area, northwest of Iran

High fluoride groundwater occurs in Maku area, in the north of West Azarbaijan province, northwest of Iran. Groundwater is the main source of drinking water for the area residents. Groundwater samples were collected from 72 selected points including 40 basaltic and 32 nonbasaltic springs and wells, in two stages, during June and August 2006. The areas with high fluoride concentrations have been identified, and the possible causes for its variation have been investigated. Regional hydrogeochemical investigation indicates that water-rock interaction is probably the main reason for the high concentration of ions in groundwater. The concentration of F⁻ in groundwater is positively correlated with that of HCO₃ ⁻ and Na⁺, indicating that groundwater with high HCO₃ ⁻ and Na⁺ concentrations help to dissolve some fluoride-rich minerals. All of the water samples, collected from the basaltic areas do not meet the water quality standards for fluoride concentration and some other parameters. Hence, it is not suitable for consumption without any prior treatment. Inhabitants of the area that obtain their drinking water supplies from basaltic springs and wells are suffering from dental fluorosis. The population of the study area is at a high risk due to excessive fluoride intake especially when they are unaware of the amount of fluoride being ingested due to lack of awareness.     

Assessment of shallow groundwater in Lake Nyos catchment (Cameroon,Central-Africa): implications for hydrogeochemical controls and uses

In 1986, carbon dioxide gas exploded from Lake Nyos and killed about 1,800 people. After that disaster, various administrative and research activities have been conducted to mitigate subsequent disasters. However, none of those endeavors have characterized the groundwater chemistry to identify hydrogeochemical processes that control the water chemistry, and the quality of the water for domestic and agricultural uses that support the lives of un-official resettlers around Lake Nyos. Conventional hydrochemical techniques coupled with statistical and graphical analysis were therefore employed to establish the baseline hydrochemical conditions, assess processes controlling solutes distribution in shallow groundwater in the Lake Nyos catchment and explore its usability. Groundwater samples were analyzed for their physical and chemical properties. The wide ranges of electrical conductivity and total dissolved solid values reveal the heterogeneous distribution of groundwater within the watershed. The relative abundance of major dissolved species was Ca > Mg > Na > K for cations and HCO₃ >>> Cl > SO₄ > NO₃ for anions. Piper diagram classified almost all water samples into mixed CaMg–HCO₃ water type. Major ion geochemistry reveals that, in addition to silicates weathering (water–rock interaction), ion exchange processes regulate the groundwater chemistry. Principal component analysis supports the occurrence of water rock interaction. Hierarchical cluster analysis showed that the chemistry of groundwater in the study area is controlled by three main factors, and suggests no hydraulic connectivity between deep lake water and groundwater in the catchment. The quality assessment of the groundwater showed that groundwater parameters are within the acceptable limit of the World Health Organization and Nigeria guidelines for drinking and domestic uses, and water found to be good for irrigation.     

Assessment of groundwater quality with special emphasis on fluoride contamination in crystalline bed rock aquifers of Mettur region, Tamilnadu, India

Groundwater samples were collected from Mettur taluk of Salem district, Tamilnadu, India for two different seasons (pre-monsoon and post-monsoon) and analyzed for fluoride ion along with other chemical parameters. The major litho units of the study area are Charnockites, peninsular gneiss, and calc gneiss of meta-sedimentary group. The fluoride concentration ranges from 0.1 to 2.8?mg/L and 0.4 to 4.0?mg/L during pre-monsoon (PRM) and post-monsoon (POM) seasons, respectively. Results showed that collected water samples were contaminated by the presence of fluoride ion. During PRM and POM, 21% and 56% of samples recorded higher fluoride when compared with Indian Drinking Water Standard (1?mg/L) and (9% and 35%) of samples recorded higher fluoride when compared with World Health Organization tolerance limit (1.5?mg/L). The ratio of Na/Ca indicates high sodium content in groundwater enhances the dissolution of fluoride at higher pH. Hydrogeochemical facies indicates water-rock interaction as main source for high fluoride in groundwater. A positive correlation between pH, Mg, and F indicates high alkaline nature of water promotes fluoride leaching from source rocks into ground water. Factor analysis indicates hydro-geochemical processes like weathering, ion exchange, and anthropogenic contributes to groundwater chemistry. The saturation index indicates dissolution and precipitation contributes fluoride dissolution along with mixing.     

Hydrogeochemical parameters for assessment of groundwater quality in the upper Gunjanaeru River basin,Cuddapah District,Andhra Pradesh,South India

In the management of water resources, quality of water is just as important as its quantity. In order to know the quality and/or suitability of groundwater for domestic and irrigation in upper Gunjanaeru River basin, 51 water samples in post-monsoon and 46 in pre-monsoon seasons were collected and analyzed for various parameters. Geological units are alluvium, shale and quartzite. Based on the analytical results, chemical indices like percent sodium, sodium adsorption ratio, residual sodium carbonate, permeability index (PI) and chloroalkaline indices were calculated. The pre-monsoon waters have low sodium hazard as compared to post-monsoon season. Residual sodium carbonate values revealed that one sample is not suitable in both the seasons for irrigation purposes due the occurrence of alkaline white patches and low permeability of the soil. PI values of both seasons revealed that the ground waters are generally suitable for irrigation. The positive values of Chloroalkaline indices in post-monsoon (80%) and in pre-monsoon (59%) water samples indicate absence of base-exchange reaction (chloroalkaline disequilibrium), and remaining samples of negative values of the ratios indicate base-exchange reaction (chloroalkaline equilibrium). Chadha rectangular diagram for geochemical classification and hydrochemical processes of groundwater for both seasons indicates that most of waters are Ca–Mg–HCO₃ type. Assessment of water samples from various methods indicated that majority of the water samples in both seasons are suitable for different purposes except at Yanadipalle (sample no. 8) that requires precautionary measures. The overall quality of groundwater in post-monsoon season in all chemical constituents is on the higher side due to dissolution of surface pollutants during the infiltration and percolation of rainwater and at few places due to agricultural and domestic activities.