Geochemical evaluation of fluoride contamination of groundwater in the Thoothukudi District of Tamilnadu, India (original) (raw)
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Origin of high fluoride in groundwater of the Tuticorin district, Tamil Nadu, India
Applied Water Science, 2018
This paper reports the results of higher F − and HCO − 3 concentrations and its response to high pH level in a hard rock terrain in Tamil Nadu, India. About 400 groundwater samples from the study area were collected from a period of four different seasons and analysed for F − , HCO − 3 and other major cations and anions. The key rationale for the higher fluoride and bicarbonate in the study area is the soaring rate of the leaching fluoride-bearing minerals and weathering processes. Fluoride and HCO − 3 ranges from BDL to 3.30 mgl −1 and 12 to 940 mgl −1 , its concentrations are lower for the period of SWM and it increases during POM and reaches to a maximum in PRM. Higher dissolution is observed in the NEM season due to rainfall impact. Spatial distribution and factor score show that the higher concentrations of F − and HCO − 3 are eminent in the northern and central zone of the study area due to the impact of lithology. The higher values in pCO 2 versus HCO − 3 plot indicate higher residence time which favours more water-rock interactions, which further increase the F − concentrations in groundwater. HCO − 3 is linearly correlated with F − which indicates that these ions were consequent from the weathering influences. At the same time, poor correlation of F − with pH could possibly be due to the increase of alkalinity follow-on from the swell of bicarbonate level with very low Ca 2+ that promotes increase in F − concentration in the groundwater.
Water Science, 2017
High fluoride (F −) groundwater causes fluorosis which might at severe stages lead to deformation of bones, bilateral lameness. The concentration of F − ranged from 0.4 to 4.8 mg/L. This study suggests that high HCO 3 − and Na + in alkaline medium along with water-rock interaction plays important role in enrichment of F − in groundwater. Na-HCO 3 is the dominant water type followed by Ca-HCO 3 suggesting dominance of Na + , Ca 2+ and HCO 3 − ions in groundwater. Factor analysis of water quality parameters suggests that four principal components account for 74.66% of total variance in the dataset. Factor 1 shows higher positive loading for pH, HCO 3 − negative loading for F − , Ca 2+ , SO 4 2− depicting ion-exchange and HCO 3 dominant water type responsible for F enrichment in groundwater. Saturation index for selected minerals suggests that most of the samples are oversaturated with calcite and undersaturated with fluorite. Calcite precipitation leads to the removal of Ca 2+ from solution thus allowing more fluorite to dissolve. These released Ca 2+ ions combine with CO 3 2− ions to further enhance the precipitation of CaCO 3 .
Environmental Earth Sciences, 2012
Fluoride (F -) is an indispensable element for the human's skeletal and dental health at prescribed levels and becomes lethal at higher levels. Spatial-temporal variability of Fand its geochemical control/association with other dissolved ions in groundwater in the Dindigul district of Tamilnadu (India) were conducted to describe the geochemical dynamics of Fin response to seasonal variability. High concentrations of fluoride (C1.5 mg L -1 ) were observed in the northern region of the district. High levels of Fwere observed in non-monsoon periods and low levels in monsoon, because of dilution by precipitation. Bicarbonate was well correlated with Fwhich explains that both ions were derived from the weathering. While Fhas a very weak correlation with silica, this implies that the silicate weathering does not supply Fto the groundwater system. The Fpollution in Dindigul groundwaters is mainly driven by two factors: (1) the geogenic weathering inputs, the geology of this area mainly comprises fluoride bearing minerals (e.g. hornblende biotite gneiss and charnockite); (2) the anthropogenic inputs (agri-fertilizers and tannery waste). Further, Fin the study area is mainly attributed to geogenic sources during pre and postmonsoons and anthropogenic sources in monsoon periods.
The present study has been carried out covering two blocks—Suri I and II in Birbhum district, West Bengal, India. The evaluation focuses on occurrence, distribution and geochemistry in 26 water samples collected from borewells spread across the entire study area homogeneously. Quantitative chemical analysis of groundwater samples collected from the present study area has shown that samples from two locations—Gangta and Dhalla contain fluoride greater than the permissible limit prescribed by WHO during both post-monsoon and pre-monsoon sampling sessions. Significant factor controlling geochemistry of groundwater has been identified to be rock–water interaction processes during both sampling sessions based on the results of Gibb’s diagrams. Geochemical modeling studies have revealed that fluorite (CaF2) is, indeed, present as a significant fluoride-bearing mineral in the groundwaters of this study area. Calcite or CaCO3 is one of the most common minerals with which fluorite remains associated, and saturation index calculations have revealed that the calcite–fluorite geochemistry is the dominant factor controlling fluoride concentration in this area during both post- and pre-monsoon. High fluoride waters have also been found to be of ‘bicarbonate’ type showing increase of sodium in water with decrease of calcium. Keywords Groundwater Fluoride Geochemistry Suri
Applied Water Science, 2016
The present study has been carried out covering two blocks-Suri I and II in Birbhum district, West Bengal, India. The evaluation focuses on occurrence, distribution and geochemistry in 26 water samples collected from borewells spread across the entire study area homogeneously. Quantitative chemical analysis of groundwater samples collected from the present study area has shown that samples from two locations-Gangta and Dhalla contain fluoride greater than the permissible limit prescribed by WHO during both post-monsoon and pre-monsoon sampling sessions. Significant factor controlling geochemistry of groundwater has been identified to be rock-water interaction processes during both sampling sessions based on the results of Gibb's diagrams. Geochemical modeling studies have revealed that fluorite (CaF 2) is, indeed, present as a significant fluoride-bearing mineral in the groundwaters of this study area. Calcite or CaCO 3 is one of the most common minerals with which fluorite remains associated, and saturation index calculations have revealed that the calcite-fluorite geochemistry is the dominant factor controlling fluoride concentration in this area during both post-and pre-monsoon. High fluoride waters have also been found to be of 'bicarbonate' type showing increase of sodium in water with decrease of calcium.
Fluoride in the Groundwaters of Hard Rock Hirehalla Sub-basin, Karnataka, India
Hydrogeochemical analysis was carried out in and around parts of Hoovina Hadagali and Harapanahalli taluks, Karnataka, India where increasing fluoride risks were reported. 140 no. of representative water samples were collected for both seasons. Cations such as Ca, Mg, Na and K while anions such as CO 3 , HCO 3 , Cl, SO 4 and F were analysed along with physical parameters-pH, EC, TDS and H. Analyses were carried out following standard procedure of APHA. Ion selective electrode method was adopted to determine fluoride and compared with different standards such as BIS, ICMR and WHO. F ranged from 0.05 to 5.69 mg/lit. 25.71 % and 20% of water samples in the study area reported to be above allowable limit for both the seasons. Excessive amounts of fluoride ion concentration in drinking water lead to different forms of fluorosis-dental, skeletal and non-skeletal. ArcGIS v10 was used to depict spatial distribution of F samples. Correlation matrix of the study area revealed, HCO 3 and Na showed positive correlation with F, which increases the fluoride content in the water due to associated rock minerals and fertilizers. Thus Hirehalla Sub-basin has alarming fluoride contamination and it's necessary to study and suggest measures for proper management of water resources for drinking purpose and to elucidate fluoride endemic areas.
A study on the status of fluoride ion in groundwater of coastal hard rock aquifers of south India
Arabian Journal of Geosciences, 2013
India has an increasing incidence of fluorosis, dental and skeletal, with nearly about 62 million people at risk. High fluoride groundwaters are present especially in the hard rock areas of the country. This paper analyzes the most extensive database on fluoride and other chemical constituent distribution in the coastal hard rock aquifers of Thoothukudi district. A total of 135 samples were collected and analyzed for major cations and anions to assess the geochemical process. The fluoride concentration in drinking waters varied from BDL to 3.2 mgl −1 in the study area. Majority of the samples do not comply with WHO standards for most of the water quality parameters. The saturation index of fluorite saturation index was used to correlate with F − to identify their relationship to increase of fluoride levels. The correlation between the F − concentration and the water type was also attempted. Spatial distribution of fluoride in groundwater was studied to understand the influencing factors. The relationship of F − with HCO − 3, Na + and pH concentrations were studied and found that HCO − 3 , has good correlation with F − than the other parameters.
Environmental Monitoring and Assessment, 2017
The present research work is confined to a rural tract located in the northwestern part of Birbhum district, West Bengal, India. Chemical analysis of the groundwater shows the cations is in the order of Na + > Ca 2 + > Mg 2 + while for anions it is HCO 3 ─ > Cl ─ > SO 4 2─ > NO 3 ─. The F ─ concentration was found to vary from 0.01 to 18 mg/L in the premonsoon and 0.023 to 19 mg/L in post-monsoon period. 86% of samples show low F ─ content (<0.60 mg/L) whereas, 8% exhibit elevated concentration of F ─ (>1.2 mg/L) mainly in the central and north-central parts of the study area at a depth of 46 to 98 m. The prime water type is CaHCO 3 succeeded by F ─-rich NaHCO 3 and NaCl waters. The suitability analysis reveals that the water at about 81% of the sampling sites is unsuitable for drinking and at 16% of sites unsuitable for irrigation. The alkaline nature of the water and/or elevated concentration of Fe, Mn and F ─ make the water unsuitable for potable purposes while the high F ─ and Na + contents delimit the groundwater for irrigation uses. Multivariate statistical analysis suggests that chemical weathering along with ion exchange is the key process, responsible for mobilization of fluoride in groundwater of the study area.
Fluoride in groundwater: a case study in Precambrian terranes of Ambaji region, North Gujarat, India
Fluoride is one of the critical ions that influence the groundwater quality. World Health Organization (WHO, 1970) and Bureau of Indian Standards (BIS, 1991) set an upper limit of 1.5 mg L −1 in F − concentration for drinking water purpose and above affects teeth and bones of humans. The presence of fluoride in groundwater is due to an interaction of groundwater and fluoride bearing rocks. Fluoride rich groundwater is well known in granitic aquifers in India and elsewhere. Generally, the concentration of F − in groundwater is controlled by local geological setting; leaching and weathering of bedrock and climatic condition of an area. The main objective of the present study is to assess the hydrogeochemistry of groundwater and to understand the abundance of F − in groundwater in hard rock terranes of Ambaji region, North Gujarat. A total of forty-three representative groundwater samples were collected and analyzed for major cations and anions using ICP-AES, Ion Chromatograph (Metrohm 883 Basic IC Plus) and titration methods. The F − concentration in groundwater of this study area ranges from 0.17 to 2.7 mg L −1. Among, twenty groundwater samples have fluoride exceeding the maximum permissible limit as per the BIS (1.5 mg L −1). It is also noticed that residents of this region are affected by dental fluorosis. The general order of the dominance of major cations and anions are Ca 2+ > Mg 2+ > Na + > K + and HCO − 3 > Cl − > F − respectively. Geochemical classification of groundwater shows most of the samples are the alkaline earth-bicarbonate type. The semi-arid climatic conditions of the region, the dominance of granitoid-granulite suite rocks and the fracture network in the disturbed and brittle zone has facilitated the development of potential aquifers and enrichment in F − concentration in this area. The concentration of fluoride is due to high evaporation rate, longer residence time in the aquifer zone, intensive and long term pumping for irrigation.
A total of 72 groundwater samples were collected from open wells and boreholes during pre-and post-monsoon periods in Tuticorin. Samples were analyzed for physicochemical properties, major cations, and anions in the laboratory using the standard methods given by the American Public Health Association. The fluoride concentration was analyzed in the laboratory using Metrohm 861 advanced compact ion chromatography. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.3. The fluoride concentration ranges between 0.16 mg/l and 4.8 mg/l during premonsoon and 0.2-3.2 mg/l during post-monsoon. Alkaline pH, low calcium concentrations, high groundwater temperatures, and semiarid climatic conditions of the study area may cause elevated fluoride concentrations in groundwater, by increasing the solubility of fluoridebearing formations (fluoride). Linear trend analysis on seasonal and annual basis clearly depicted that fluoride pollution in the study area is increasing significantly. Fluoride concentrations showed positive correlations with those of Na + and HCO 3 − and negative correlations with Ca 2+ and Mg 2+ . The alkaline waters were saturated with calcite in spite of the low Ca 2+ concentrations. Northwestern parts of the study area are inherently enriched with fluorides threatening several ecosystems. The saturation index indicates that dissolution and precipitation contribute fluoride dissolution along with mixing apart from anthropogenic activities.