Monitoring of Fluoride Concentration in Groundwater of Tosham Block, Bhiwani District, NW, India: Correlation with Physico-Chemical Parameters

Hydrogeochemical investigations were carried out in the eight villages of Tosham Block; district Bhiwani, Haryana to recognize the mechanism and sources of enrichment of fluoride in the groundwater. The results specify that concentrations of fluoride attain up to 1.9 mg/l in groundwater samples. In the soils, the overall fluorine contents vary between 1.1 and 2.7 mg/kg, which could have sufficient potential to released fluorine into the groundwater. In groundwater, the fluoride enrichment is primarily controlled by solubility of fluorite, intensity of evapotranspiration, residence time and the processes of weathering prevailing in Tosham area. Moreover, various other water quality parameters such as pH, electrical conductivity, total hardness, and total alkalinity as well as calcium, magnesium, carbonate, bicarbonate and chloride concentrations were also calculated. A logical calculation of correlation coefficients between different physico-chemical parameters was done. The 67% of groundwater samples do not comply with WHO standards of fluoride for drinking purposes. The excessive fluoride concentration in the groundwater of villages under study causes dental fluorosis among people especially the children. Except few of villages, without any prior treatment, the overall quality of water was found unacceptable for drinking purposes.

Open Journal of Geology most challenges of the twenty-first century. Constantly, the demand for water is on rise. The water resources are unevenly distributed over the earth's surface.
Moreover, the excellence of the water resources, which are disproportionately scattered over the surface of earth, is fading due to the anthropogenic and natural activities. In the near future, the countries even having gigantic water resources could experience water scarcity. The properties of groundwater have also been changing simultaneously corresponding to heavy use of fertilizers, dumping of industrial and municipal waste. Hence, to study the variation in quality parameters, the analysis of groundwater is essential. The groundwater quality could be rated for various uses, like industrial, drinking agriculture on the basis of the physico-chemical parameters. The groundwater pollution also governed by the geology of the area where widespread cavern systems are beneath the water table [1]. The changes in groundwater quality respond to the deviation in chemical, physical, and genetic environments through which it passes [2]. Fluoride with an optimum concentration within a narrow range between toxic exposure and beneficial ingestion is essential for human beings [3] [4] [5]. Due to long term intake of waterborne fluoride over the permissible limit of 1.5 mg/l set by the World Health Organization (WHO) and 1.0 mg/l by China, endemic fluorosis has been extensively reported in numerous areas such as Mexico, China, India and Africa [6]- [12]. The low concentrations of Ca 2+ , cation exchange, high pH, sometimes high concentrations of Na + and 3 HCO − , evapotranspiration, hydrolysis of silicate minerals are the most common factors behind the fluoride enrichment in groundwater [13]. The correlation between fluoride and other physical parameters has done in this study. A positive correlation coefficient of sodium with fluoride in ground water has reported in groundwater samples of study area. In the present investigation, the analysis of ground water samples of eight villages of Tosham block of Bhiwani District is presented. The correlation analysis of the physicochemical parameters, pH, EC, TH, Na + , Ca 2+ , Mg 2+ , Cl − , 2 3 CO − , F − and 3 HCO − measured in 19 samples collected from eight villages. The results obtained are presented and discussed in this paper. The purpose of this study is to elucidate the fluoride distribution in area under study and to establish a correlation between fluoride concentration and physico-chemical parameters of groundwater of Tosham block, Bhiwani district, NW, India. The present paper also tries to find the role of local geology in fluoride contamination in area under study.

Geology Setting of the Study Area
Malani Igneous Suite (MIS) representatives are well exposed in the Bhiwani dis-

Sampling and Analytical Methods
Nineteen groundwater and nineteen soil samples were collected from eight villages of Tosham area ( Figure 1). All of the groundwater samples were collected from boreholes and dugwellsafter filtration through 0.45 μm PVDF branes (Millipore) and sealed on the spot. Samples for the determination of major cations (Na + , Ca 2+ , Mg 2+ and K + ) were stock up in polyethylene bottles that had been soaked in 5% HCl and before collection three times rinsed by distilled water.

Results
The result of analysis of physico-chemical parameter and fluoride in groundwater is summarized in Table 1  proportional to concentration of fluoride in soil and thus establishing positive correlation. Khanak and Panjokhera are two villages that have highest concentration of fluoride both in soil and groundwater samples. Twenty percent of fluoride affected villages in the world are in India [18]. Although fluoride is essential for formation of dental enamel and normal mineralization of bones and is one of the important life elements to individual health with presence in small amount, however at a higher concentration might cause detrimental effects on individual health. The largest contributor to the daily intake of fluoride is drinking water. The food when derived from plants grown in the contaminated soil also becomes another source of fluoride intake when they are used as food. The prolonged experience to elevated concentration of fluoride is poisonous to bones, teeth and other organs. If present in high concentration in drinking water, it is also known to cause thyroid [19], neurological, kidney changes, gastrointestinal and endocrine problems. In its harsh form, dental fluorosis is characterized by yellowish brown to black stains, severe pitting and opaque areas on the tooth surface. It has been estimated that 20% of those who bear osteoporosis linked hip fractures die within six months. In comparison to males, females are at four times greater threat of osteoporosis. In bottle fed infants, intake higher than 50 mg/l are identified to have been linked with Open Journal of Geology    Table 2.

Geochemical Processes Influencing Fluoride Concentrations
The key hydrochemical types are Na-Cland Ca-HCO 3 in the area under study.
The groundwater samples having high concentration of TDS belong to Na-Mg-HCO 3 -SO 4 and Na-Mg-Cltypes, possibly due to dissolution [20]. Thus the variation in chemistry of groundwater advocate that in the host rocks of the TRC, there are tough geochemical reactions that occur, where hydrolysis reactions of silicate playing a leading role, e.g.,  [21]. The higher concentration of fluoride in groundwater is caused by presence of fluorine bearing minerals [22]. The dissolution of CaF 2 , is promoted by high alkalinity, liberate fluoride into groundwater because precipitation of dolomite and calcite can diminish the Ca 2+ concentration in groundwater (hydrolysis reaction) e.g. CaCO H Ca HCO By applying the law of chemical equilibrium constant (K 1 ) can be expressed as, Equilibrium constant (K 2 ) in dissolution of CaF 2 dissolved in water is given by Using Equations (2) and (3), The Equation (4) shows the relationship between bicarbonate, hydrogen ion and fluoride and interpret that the it the pH (hydrogen ion activity) of water is constant an increase in fluoride ion would be accompanied increases in bicarbonate ions while in Equation (2) shows that increase in the fluoride is accompanied by corresponding decrease in calcium ions and thus shows negative correlation. The interionic relationship of Fvs pH, Ca + , 2 3 CO − and 3 HCO − in the groundwater samples of area under study is depicting in Figures 6-9.

Conclusions
Fluoride concentration in most of the groundwater samples of Tosham area, Bhiwani, NW, India found to be higher than BIS standards. This study reveals that the fluoride bearing minerals are the foremost sources for fluoride in    Moreover, the parameters like bicarbonate, total alkalinity and carbonate exhibit the negative correlations with fluoride.