HIGH FLUORIDE CONCENTRATION IN THE GROUNDWATER OF UTTANGARAI TALUK, DISTRICT, SOUTH Sridhar.N1, Chandrasekar.N2, Subbarayan.M.R3 1,2,3Department of Civil Engineering &Earth sciences, Jayam College of Engineering and Technology, (India)

ABSTRACT The present study has been made to evaluate the Fluoride concentration of Groundwater collected from Uttangarai Taluk in of South India. Geochemical studies were carried out on 34 samples from 24 villages and they were analyzed for fluoride and other water quality parameters (EC, TDS, pH, TH, Na,

K, Ca, Mg, Cl, CO3, HCO3 and SO4). Groundwater is the only source of drinking water in this area, as due to depletion of surface waters, more and more people are using groundwater for drinking purpose and these are exposed to health vulnerability. This study reveals that fluoride concentration varies between 0.37ppm and 3.47ppm with an average of 1.79ppm. The dominance of cations and anions are as follows: Ca2+ > Na+> Mg2+> K+ and SO4 2-.- > HCO3 - > Cl - > CO3-.The source for high fluoride is found to be due to leaching of the ion from biotite rich segregations in the country rock particularly shear zones. The results indicate that the groundwater quality in the vicinity of shear zone needs to study in detail.

Key Words: Fluoride concentration, Electrical conductivity (EC), Total dissolved solids (TDS), pH.

I. INTRODUCTION Groundwater forms a major source of drinking water in urban as well as in rural areas. More than 90% of the rural Population uses groundwater for domestic purposes. The most widespread contamination in India is that of elevated levels of fluoride. It is widely prevalent in different parts of India, particularly in the state of Andhra Pradesh, , Uttar Pradesh, Gujarat, and Rajasthan, where 50-100% of the districts have drinking water sources containing excess level of fluoride (CGWB 2014). The occurrence of fluoride in groundwater is mainly due to natural or geogenic contamination and the source of contamination of often complex and site specific (Saxena and Ahmad 2003). Fluorspar is commonly known as an ore of mineral fluorite. Fluorite/Fluorspar occurs in many rocks in varied forms. The fluoride content of the rocks, due to repeated weathering, gets slowly dissolved in water, when the water acquires acidic nature. In this procedure, water gets contaminated by fluoride (Acharya & Mathi, 2010). A permissible limit of fluoride concentration in drinking water as per WHO (2011) guideline is up to 1.5 mg/L. (WHO, 2011 and BIS, Revised 2003). The excessive amount of fluoride in water and environment is poisonous. Excessive fluoride concentrations in ground water have been reported in India, where 17 states are facing fluoride problem (Yadav and Khan 2010). Endemic

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fluorosis remains a challenging and extensively studied national health problem in India. The high concentrations of fluoride in groundwater in India have resulted due to the dissolution of fluorite, apatite, micas, amphiboles with the OH, F group and topaz from the local bedrock (Chidambaram 2000). The occurrence of the fluoride in groundwater is predominantly geogenic. Fluoride enrichment in groundwater takes place mainly through leaching and weathering of the Fluoride bearing minerals present in the rocks and sediments which depends on several factors such as the origin of water, composition of water bearing medium, the length of time the water has been in contact with the medium, the temperature and pressure conditions, ion- exchange, rate of recharge and discharge. In groundwater, the natural concentration of fluoride depends on the geological, chemical and physical characteristics of the aquifer, the porosity and acidity of the soil and rocks, the temperature and the action of other chemical elements (Tahaikt et al. 2008). The important fluoride-bearing minerals are; fluorite (fluorspar), fluorapatite, cryolite, biotite, muscovite, lepidolite, tourmaline, hornblende series minerals, glucophane-riebeckite. Besides these, there are anthropogenic source of fluoride also, like phosphatic fertilizer, cowdung and urban waste. Fluoride is essential for the development of tooth enamel, dentin, and the bones. It is harmful when it exceeds the permissible limit of 1.5 mg l–1(WHO 2011) in water. The problems are most pronounced in the states of Andhra Pradesh, Bihar, Gujarat, Madhya Pradesh, Punjab, Rajasthan, Tamil Nadu and Uttar Pradesh (Pillai and Stanley, 2002). Low concentration of fluoride below 0.5 ppm causes dental caries (Acharya et. al.2008). Manikandan et al. (2012) higher concentration of fluoride was noted in hard rock terrain of this district. It is found that nearly 58 % of the samples have more fluoride corresponding to magnesium water types. This is due to the release of fluoride from the magnesium-bearing minerals like biotite, hornblende or reasons of weathering of apatite/hydroxyapatites that is observed in charnockites. Various studies have been reported about fluoride content in water bodies in different part of India. The increase of F− concentration with SI of dolomite also shows a closer affinity of this ion to Mg2+ (Manivannan et. al. 2010). Environmental hydrogeochemistry and genesis of fluoride in groundwater of Dindigul district, Tamilnadu in India (Chidambaram et al. 2012). The Krishnagiri district contains minerals with higher amounts of fluoride (CGWB 2009), (Manikanda et. al., 2011). The favorable factor which contributes to rise of fluoride in ground water is presence of fluoride rich rock salt system (G S Tailor et. al., 2010). F– ions released into the groundwater are considered to be controlled by the degree of saturation of fluorite and calcite, and the concentration of Ca2+, HCO3 –, and Na+ ions in groundwater, among other natural geochemical processes (Mamatha and Rao, 2010). Chemical weathering under arid to semiarid conditions may seem to have favoured high concentration of fluoride in ground water (Kausik Kumar Das et. al. 2012). Drinking water in the Krishnagiri district of Tamilnadu containing high level of fluoride as conformed by the prevalence of dental and skeletal flurosis among the people of the village in this region. It is of course well known that fluorosis is caused by the consumption of drinking water containing high fluoride. The prevalence of dental fluorosis in the village of the Uttangarai block of Krishnagiri district prompted us to determine the fluoride levels of all available drinking water sources in order to identify the fluoride endemic areas that require immediate adoption of remedial measure to prevent the problem of fluoride toxicity.

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II. STUDY AREA The study area is bounded by latitudes 12° 18’ N to 12° 25’ N and longitudes 78° 35’ E to 78° 32’ E and situated at an average height of 1000 m above mean sea level. Uthangarai is bounded by in the North and Thiruvannamalai district in the East, Pochampalli taluk in the West and in the South (Fig.1). Groundwater generally occurs under phreatic conditions in the weathered mantle and under semi- confined conditions in the fractured zones at deeper levels. The thickness of weathered zones in the district ranges from less than a meter to more than 15 m (CGWB 2009). A major portion of the Krishnagiri district consists of quartzofelspathic gneiss and followed by charnockites in the south western part of the district. The eastern part of the district is mainly composed of syenites, granite felsite and epidote hornblende gneiss. There are also patches of basic, ultrabasic and mafic rocks. Amphibolite patches are noted in the northern part of the district. Quartz reef is hosted by both hornblende schist of the region and the champion gneiss (quartzofelspathic gneiss) (GSI 2009). Ponnaiyar is the major river draining the district and is ephemeral in nature. The normal annual rainfall over the district varies from about 750 to about 900 mm.

Fig. 1. Study area map

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III. METHODOLOGY Thirty four groundwater samples were collected in one liter polyethylene bottles with airtight lids. pH was measured using portable pH meter and EC were measured by EC meter in the field itself. With respect to cations, Calcium and Magnesium were analyzed following volumetric method; Sodium and Potassium were analyzed using Flame photometer; and with respect to anions, Chloride and Bicarbonate were estimated by volumetric method; Nitrate, and Sulfate were estimated by turbidity method. All chemical analyses were carried out following APHA method (APHA, 1999). Fluoride content was determined using an ion analyzer (Orion modal 720 – pH-ise-FLURIMETRE, USA) equipped with a fluorine selective electrode. Chemical analyses of groundwater in this study were classified by a graphical technique described by piper (1944).

IV. RESULT AND DISCUSSION Water is an indispensable natural resource on earth. Two-third of the earth surface is covered by water. It is an essential and vital component for survival of all the living beings. It constitutes about 70% of the body weight of almost all living organisms. Potable water is the water that is free from disease producing micro-organisms and chemical substances. The scarcity of clean and potable drinking water has emerged as most serious environment issue of the twenty first century (Das N.C 2013). The sources of fluoride have been divided in two sections dealing with water and soil. Fluoride concentration in drinking water in various places of India is illustrated in Table 1. Table 1.Fluoride concentration in drinking water in various places of India. Locations Fluoride concentration (mg/l) References Andhra Pradesh 0.38 – 4.0 Sreedevi et al., (2006) Assam (Guwahati) 0.18 – 6.88 Dass et al., (2003) Bihar (Rohtas) 0.1– 2.5 Ray et al., (2000) Delhi 0.11– 32.5 Susheela et al., (2003) Maharashtra (Yavatmal district) 0.30–13.41 Madhnure et al., 2007 Gujarat (Mehsana) 0.1– 40 Chinoy et al., (1992) Karnataka 1.0 – 7.4 Sumalatha et al., (1999) Kerala (Palghat district) 1.51– 5.75 Shaji et al., (2007) Madhya Pradesh (Shivpuri) 0.2 – 6.4 Nawlakhe et al., (1995) Rajasthan (Dungapur) 0.1 – 10 Choubisa et al., (1996) Uttar Pradesh (Agra) 0.1 – 12.8 Gupta et al., (1999) West Bengal (Birbhum) 0.006 – 1.95 Gupta et al., (2006) Rajasthan 1.0-5.2 Choubisa, (2007) Uttar Pradesh (Sonbhadra) 0.48 -6.7 Raju et al., (2009) Andhra Pradesh (Visakhapatnam) 1.15-1.28 Rao, (2009) Rajasthan (Malpura Tehsil) 0.08 -11.3 Tailor & Chandel, (2010) Angul-Talcher, Orissa 0.2 – 2.4 Rizwan Reza & Gurdeep Singh(2013) Uttangarai(Tamilnadu) 0.37-3.48 Present study

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Table 2.Sample results of maximum and minimum values (n=34) HCO EC TH F Na K Ca Mg Cl CO3 SO4 TDS pH 3 μS/cm mg/l Max 3.4 3650 8.9 546 171 10 210 73 660 44 970 2448 2336 8 Min 0.3 980 7.5 156 83 2 46 16 45 14 360 306 627 7 Avg 1950.0 7.9 344.8 1.8 125.8 5.1 114.8 36.2 215.8 25.3 665.6 1001.5 1247.9 0 1 9 0 9 4 6 5 1 1 9 0 4

4.1 Hydrogen ion concentration (pH) The pH value of water source is a measure of the hydrogen ion concentration in water and indicates whether the water is acidic or alkalinity. Most of the biological and chemical reactions are influenced by the pH of water system. In the present study all the ground water samples have pH values between 7.5 -8.9. The standard value of pH for drinking water by BIS is between 6.5 - 8.5 while, WHO is between 7.0-8.5.The samples S1 and S 10 have higher value of pH than the permissible limits. If pH is beyond the permissible limit, it damages the mucous membrane of cells (Koul Nishtha et al. 2012). 4.2 Electrical conductivity (EC) Electrical conductivity is the measure of the ability of water to conduct electrical current. This capacity depends on the concentration of ions, ionic mobility, valence of ions and temperature. Electrical conductivity of water is a direct function of its total dissolved salts. The WHO permissible limit for electrical conductivity in water is 600 μS/cm. Electrical conductivity values in the study area ranged from 980 to 3650 μS/cm, indicating the presence of high amount of dissolved inorganic substance in ionized form. When electrical conductivity exceeds 3000 μS/cm affected the germination of almost all the crops and it may result in very less amount of yield (L.Kalpana and L.Elango 2012). 4.3 Total dissolved solids (TDS) The total dissolved solids in water are due to presence of all inorganic and organic substances. The solids can be iron, manganese, magnesium, potassium, sodium, calcium, carbonates, bicarbonates, chlorides, phosphates and other minerals. The high values of TDS causes gastrointestinal irritation to the human beings but long time use of water with high TDS can cause kidney stones and heart diseases (Das N.C 2013). In the present analysis, the TDS values were observed from 627 to 2336 mg/l. The most desirable limit of TDS is 500 mg/l and maximum allowable limit is 1500 mg/l. The TDS value for all the ground water samples are well within the permissible limit of 1500 mg/l. 4.4 Total hardness (TH) Hardness of water is an aesthetic quality of water and is caused by carbonates, bicarbonates, sulphates and chlorides of calcium and magnesium. It prevents the lather formation with soap and increases the boiling point of water. The maximum permissible limit of total hardness for drinking purpose is 300 mg/l (BIS). The water

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having hardness up to 75 mg/l is classified as soft; 76 - 150 mg/l is moderately soft, 151- 300 mg/l as hard and more than 300 mg/l as very hard. Hardness more than 300 mg/l may cause heart and kidney problems (Bhattacharya et. al., 2012). The total hardness in ground water samples collected from the study area ranged from 156 -546 mg/l. In the study area 58 % ground water samples are have very hard and hence require suitable treatments before use. 4.5 Calcium (Ca2+) The rock, lime stone and industrial waste are the rich sources of calcium from where it is leached in the ground water. Calcium plays an important role for proper bone growth. According to WHO, the permissible limit of calcium is 100 mg/l. The concentration of calcium in the area varied from 46-210 mg/l. The high concentration of calcium in the ground water of the region is due to rapid industrialization and urbanization. 4.6 Chloride (Cl-) Chloride in ground water can be caused by industrial or domestic waste. The chloride concentration serves as an indicator of pollution by sewage. Soil porosity and permeability also has a key role in building up the chloride concentration. High chloride content in water bodies, harms agricultural crops, metallic pipes and injurious to people suffering due to heart and kidney diseases (Chapolikar et al 2010).The chloride content varied from 45- 660 mg/l. Most of the ground water samples show chloride concentration within the permissible limit (250 mg/l) of WHO, which indicates less contamination of chloride. The ground water samples S3 and S5 have slightly excess chloride concentration, which causes some physical disorders. 4.7Fluoride (F-) Fluoride is the 13th most abundant element on earth. It exists combining with other substances to become fluoride. The main source of fluoride in ground water is fluoride bearing rock such as fluorspar, fluorite, cryolite, fluorapatite and hydroxylapatite. High fluoride content in ground water causes serious damage to the teeth and bones of human body, diseases caused called dental fluorosis and skeletal fluorosis17. Hence excess fluoride should be removed from water and this process is called defluoridation. The sources of fluoride have been divided in two sections dealing with water and soil (Sakthi Thesai Annadurai et al 2014). The value of fluoride concentration in ground water samples lie between 0.37-3.48 mg/l. The high concentration of F in many parts of India is formed through evapotranspiration of groundwater with residual alkalinity ( Gunnar Jacks et al.2005). Except few sample locations, all the ground water samples have fluoride concentration more than the permissible limit (1.0 mg/l) of WHO and require suitable treatments before use. 4.8 Hydrogeochemical facies Hydrogeochemical facies interpretation is a useful tool for determining the flow pattern and origin of chemical histories of groundwater, and it is used to express similarity and dissimilarity in the chemistry of groundwater samples based on the dominant cations and anions (Piper 1953). The cations and anion fields are combined to show a single point in a diamond-shaped field, from which inference is drawn on the basis of hydrogeochemical facies. The combined piper plot shows dominant water types as (85%) Ca+ Mg cations and (74%) SO4+Cl are dominant anions. The lower base cation and anion triangles distribution of data points showing no dominant cations and (80%) sulfate type water (fig.2).

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Fig.2. Piper diagram

Table 3. Correlation matrix for the water samples (n=34)

F TH EC Ph Na K Ca Mg Cl CO3 HCO3 SO4 TDS

F 1

TH -0.304 1

EC -0.030 0.400 1

Ph 0.443 -0.252 -0.173 1

Na 0.900 -0.296 0.254 0.438 1

K 0.925 -0.156 -0.007 0.416 0.818 1

Ca -0.473 0.728 0.512 -0.371 -0.356 -0.338 1

Mg 0.947 -0.288 -0.008 0.452 0.847 0.900 -0.492 1

Cl -0.138 0.453 0.915 -0.256 0.092 -0.095 0.647 -0.162 1

CO3 0.925 -0.315 -0.036 0.418 0.835 0.888 -0.490 0.907 -0.140 1

HCO3 0.850 -0.217 -0.029 0.416 0.762 0.759 -0.375 0.791 -0.117 0.764 1

SO4 -0.293 0.242 0.375 -0.062 -0.146 -0.380 0.248 -0.258 0.284 -0.274 -0.180 1

TDS -0.031 0.401 1.000 -0.173 0.254 -0.007 0.512 -0.009 0.915 -0.037 -0.029 0.376 1

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The anomalous of TDS, EC, Na, HCO3 and SO4 in the study area are due to secondary hydrochemical processes such as cyclic salting, dissolution in the aquifer and ground water flow. (N. S. Robins and B. D. R. Misstear 2000), while investing the contribution of rock water interaction to groundwater chemistry in Loch fleet catchment area of U.K., found that the groundwater from aquifer at shallow depths over 90% of Ca2+,Mg2+,SiO2,F- and HCO3, are obtained from rock water interaction. However HCO3 shows good correlation with Ca indicating that the calc-granulites present in the area do not contribute much dissolution in to groundwater (Table.3). The higher concentration of HCO3, which have entered the input of atmospheric carbon dioxide to the soil zone, can be greatly enhanced by the respiration of bacteria acting upon decaying organic matter. The existence of soluble salt deposits within a regional aquifer system can have a profound effect on the groundwater chemistry. Gypsum and anhydride deposits are major sources of calcium and sulfate. However, there is no gypsum and anhydrite in the study area and they may have been derived from the fertilizer. In the study area a major shear zone is present and most of the samples were taken from locations along the zone. Biotite rich quartz veins are observed in many wells, which have intruded consequent to shearing of charnokite country rock. Its high weathering prone nature probably promotes it to be the principal source of fluoride in groundwater.

V. CONCLUSION The water quality in the study area is incompatible for drinking, domestic and irrigation purposes. The high concentration of fluoride in groundwater area is due to rock water interaction between the ground water and easily weathered fluoride bearing minerals of biotite and apatite formed due to shearing of the country rocks. The outcome warrants the need to observe ground water contaminants and, if likely, treatment should be given for fluoride rich water. Adjoining areas of shear zones also need to be observed for fluoride in groundwater.

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