The many researchers have developed various studies in the field of fluoride detection which are combined and presented in this chapter as a literature work. It includes the recent advances on fluoride detection in different parts of the world. This chapter also describes in brief about different methods applied to find the concentration of fluoride in laboratory and the sensitivity of these methods. Accurate determination of fluoride has increased its importance with the growth of the practice of fluoridation of water supplies as a public health measure. Maintenance of an optimal fluoride concentration is essential in maintaining effectiveness and safety of the fluoridation procedure.
2.1. FLUORIDE DETECTION METHODS
There are several existing methods for the detection of fluoride in laboratory and new detection techniques are continuously under research. Among the methods suggested for determining fluoride ion (Fâ») in water, the colorimetric and electrode methods are the most satisfactory. Because both methods are subject to errors due to interfering ions, it may be necessary to distill the sample before making the determination. When interfering ions are not present in excess, the fluoride determination may be made directly without distillation. Some of the existing technologies used for detection of fluoride in laboratory are given below:
2.1.1. Colorimetric Method
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Bellack et al (1968) have reported a rapid colorimetric determination of fluoride with SPADNS-zirconium Lake. This method is based on the reaction between fluoride and a zirconium-dye lake. Fluoride reacts with the dye lake, dissociating a portion of it into a colorless complex anion (ZrF62â») and the dye. As the amount of fluoride increases, the color produced becomes progressively lighter. The reaction rate between fluoride and zirconium ions is influenced greatly by the acidity of the reaction mixture. If the proportion of acid in the reagent is increased, the reaction can be made almost instantaneous. Under such conditions, however, the effect of various ions differs from that in the conventional alizarin method. The selection of dye for this rapid fluoride method is governed largely by the resulting tolerance to these ions.
A synthetic sample containing 0.830 mg Fâ»/L and no interference in distilled water was analyzed in 53 laboratories by the SPADNS method, with a relative standard deviation of 8% and a relative error of 1.2%. After direct distillation of the sample, the relative standard deviation was 11% and the relative error 2.4%. A synthetic sample containing 0.570 mg Fâ»/L, 10 mg Al/L, 200 mg SO42â» L, and 300mg total alkalinity/L was analyzed in 53 laboratories by the SPADNS method without distillation, with a relative standard deviation of 16.2% and a relative error of 7%. After direct distillation of the sample, the relative standard deviation was 17.2% and the relative error 5.3%. A synthetic sample containing 0.680 mg Fâ»/L, 2mg Al/L, 2.5 mg (NaPO3)6/L, 200mg SO42â»/L, and 300mg total alkalinity/L was analyzed in 53 laboratories by direct distillation and SPADNS methods with a relative standard deviation of 2.8% and a relative error of 5.9% (Schouboe, 1968).
2.1.2. Ion-Selective Electrode Method
The fluoride electrode is an ion-selective sensor. The key element in the fluoride electrode is the laser-type doped lanthanum fluoride crystal across which a potential is established by fluoride solutions of different concentrations. The crystal contacts the sample solution at one face and an internal reference solution at the other. The cell may be represented by:
Ag|AgCl, Clâ» (0.3M), Fâ» (0.001M) | LaF3| test
The fluoride electrode measures the ion activity of fluoride in solution rather than concentration. Fluoride ion activity depends on the solution total ionic strength and pH, and on fluoride complexing species. Adding an appropriate buffer provides a nearly uniform ionic strength background, adjusts pH, and breaks up complexes so that the electrode measures concentration (Frant & Ross, 1968).
A synthetic sample containing 0.850 mg Fâ»/L in distilled water was analyzed in 111 laboratories by the electrode method, with a relative standard deviation of 3.6% and a relative error of 0.7%. A second synthetic sample containing 0.750 mg Fâ»/L, 2.5 mg (NaPO3)6/L, and 300 mg alkalinity/L added as NaHCO3, was analyzed in 111 laboratories by the electrode method, with a relative standard deviation of 4.8% and a relative error of 0.2%. A third synthetic sample containing 0.900 mg Fâ»/L, 0.500 mg Al/L, and 200 mg SO42â»/L was analyzed in 13 laboratories with a relative standard deviation of 2.9% and a relative error of 4.9% (Harwood, 1969).
2.1.3. Complexone Method
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Marked to Standard
The sample is distilled in the automated systems, and the distillate is reacted with alizarin fluorine blue-lanthanum reagent to form a blue complex that is measured colorimetrically at 620 nm. Interferences normally associated with the determination of fluoride are removed by distillation. This method is applicable to potable, surface, and saline waters as well as domestic and industrial wastewaters. The range of the method, which can be modified by using the adjustable colorimeter, is 0.1 to 2.0 mg Fâ»/L. In a single laboratory four samples of natural water containing from 0.40 to 0.82 mg Fâ»/L were analyzed in septuplicate. Average precision was Â±0.03 mg Fâ»/L. to two of the samples, addition of 0.20 and 0.80 mg Fâ»/L were made. Average recovery of the additions was 98% (Weinstein, Mandl, McCune, Jacobson, & Hitchcock, 1963).
2.1.4. Ion-Selective Electrode Flow Injection Analysis
Fluoride is determined potentiometrically by using a combination fluoride-selective electrode in a flow cell. The fluoride electrode consists of a lanthanum fluoride crystal across which a potential is developed by fluoride ions. The reference cell is an Ag/AgCl/Clâ» cell. The reference junction is of the annular liquid-junction type and encloses the fluoride-sensitive crystal. Ten replicate standards of 2.0 mg Fâ»/L gave a % relative standard deviation of 0.5%.
2.2. VARIOUS RESEARCH IN THE WORLD
Serious problems are faced in several parts of the world due to the presence of high concentration of fluoride in drinking water which causes dental and skeletal fluorosis to humans. Groundwater is the major source of freshwater on the earth. Groundwater containing dissolved ions beyond the permissible limit is harmful and not suitable for domestic use. Fluoride beyond desirable amounts (0.6 to 1.5 mg/l) in ground-water is a major problem in many parts of the world. Around 200 million people from 25 nations have health risks because of high fluoride in groundwater (Ayoob and Gupta 2006). In India too, there has been an increase in incidence of dental and skeletal fluorosis with about 62 million people at risk (Andezhath et al. 1999) due to high fluoride concentration in drinking water. Dental fluorosis is endemic in 14 states and 150,000 villages in India with the problem most pronounced in the states of Andhra Pradesh, Bihar, Gujarat, Madhya Pradesh, Punjab, Rajasthan, Tamil Nadu, and Uttar Pradesh (Pillai and Stanley 2002). Fluoride in groundwater has been studied in Guntur district (Subba Rao 2003), Varaha River Basin (Subba Rao 2008), Ranga Reddy district (Vijaya Kumar et al. 1991), and Nalgonda district (Ramamohana Rao et al. 1993) of Andhra Pradesh, India. Earlier studies in Nalgonda district (Ramamohana Rao et al. 1993) have indicated elevated concentration of fluoride up to 20 mg/l.
2.2.1. Assessment of Fluoride
A study was carried out to understand the status of groundwater quality in Nalgonda and also to assess the possible causes for high concentration of fluoride in groundwater. Samples from 45 wells were collected once every 2 months and analyzed for fluoride concentration using an ion chromatograph. The fluoride concentration in groundwater of this region ranged from 0.1 to 8.8 mg/l with a mean of 1.3 mg/l. About 52% of the samples collected were suitable for human consumption. However, 18% of the samples were having less than the required limit of 0.6 mg/l, and 30% of the samples possessed high concentration of fluoride, i.e., above 1.5 mg/l. Weathering of rocks and evaporation of groundwater are responsible for high fluoride concentration in groundwater of this area apart from anthropogenic activities including irrigation which accelerates weathering of rocks (K. Brindha et al. 2010).
A study was also conducted to work out seasonal variation in fluoride content of ground water from different sites in Patan district of North Gujarat region. Water samples were collected from dug well bore well and water-harvesting structures of selected sites during different seasons. Seasonal variations in fluoride concentration in groundwater have been studied during the period from December 2006 to November 2007. Maximum value of fluoride was recorded during summer (May-June) and minimum during post monsoon (September-November) period. The physico-chemical and microbiological analysis of groundwater was performed by employing standard water analysis methods. The physico-chemical parameters tested were DO, BOD, COD, pH, conductivity, TDS, nitrate, nitrite, sodium, potassium etc. The fluoride values ranged from 1.88 ppm to 6.80 ppm in winter, 1.89 ppm to 6.84 ppm in summer, 1.88 ppm to 6.84 ppm in Monsoon and 1.82 ppm to 6.81 ppm in Post Monsoon. Maximum value was observed during summer and minimum value was observed during post monsoon in mostly all the groundwater samples (Patel Paya & S.A. Bhatt, 2010). Seasonal variation of fluoride is shown in the Figure2.1.
Figure2.1.Seasonal variation of fluoride in Patan
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Attempts were also made to find out the fluoride content of groundwater of Jind district, Haryana and its relationship with the quality determining factors of irrigation waters. In March 2004, 446 representative tube-well water samples from 62 villages of two blocks of Jind district, Haryana were collected and analyzed for fluoride and various other water quality parameters. The analytical results indicated considerable variations among the analyzed samples with respect to their chemical composition. Results showed that fluoride content of these waters varied from 0.33 to 13.0 mg Lâ»1 with an average value of 2.08 mg Lâ»1 in Julana block and 0.22 to 5.8 mg Lâ»1 with an average value of 1.77ppm in Pillu Khera block, 55.4% of the tested water samples were having fluoride content more than 1.5 mg Lâ»1 and hence unsuitable for drinking purpose, only 1% of the tube-well waters have fluoride content above 10 mg Lâ»1 (Mohammad Shahid et al., 2008).
Sixteen states in India- Andhra Pradesh, Bihar, Delhi, Gujarat, Haryana, Jammu & Kashmir, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Manipur, Orissa, Punjab, Rajasthan, Tamil Nadu and Uttar Pradesh have already been identified endemic to fluorosis (Mariappan et al., 2000). Arsenic contamination of ground water in eight districts of West Bengal is well documented and more cases are also reported from eastern part of Bihar, Gorakhpur, Balia, Western part of Uttar Pradesh and Chattishgarh (Singh, 2006). The intensive farming belt of Western U.P., Haryana, Punjab, and parts of Rajasthan, Delhi and West Bengal have been reported to contain high NO3 in groundwater (Malve and Dhage, 1996). Information on water quality of North Eastern India is scanty. Available literature shows that groundwater of Assam valleys is highly ferruginous (Aowal, 1981; Singh, 2004). The presence of excess fluoride and endemic of Fluorosis was reported in the year 1999 in Karbi Anglong district of Assam, though the disease was prevalent for last twenty years. Subsequently, because of intensified water quality testing and health survey conducted, excess iron and fluoride is getting detected in more and more areas of the region (Akoijam, 1981; Sushella, 2001). Problem of arsenic has been detected in North Eastern India recently (Singh, 2004; Mukherjee et al., 2006; Singh, 2006). A research study has been done which illustrates the distribution and contamination of Arsenic, fluoride, nitrate and heavy metals in drinking water of North Eastern India (A.K. Singh et al.) and results of the study is shown in Table 2.1.
Table 2.1: Fluoride concentration in water samples of North-Eastern states of India
*N.D. Below detection limit
Though there has been tremendous progress in rural water supply infrastructure after setting up of the Rajiv Gandhi National Drinking Water Mission in 1986, the goal to provide safe drinking water to all is still to be achieved. Ever increasing population and the increased need for agriculture and industries has resulted in water scarcity. The country thus faces a series of threats to the management of water resources. This leads the rural population and even urban also to depend upon water from local tanks and tube wells and the consumption of untreated water for all purposes. In view to look into the aspects of water quality and related health problems, the water quality data from nine following States (a) Jammu and Kashmir (J&K), (b) Himachal Pradesh, (c) Rajasthan, (d) Haryana, (e) Bihar, (f) West Bengal, (g) Chhattisgarh, (h) Orissa and, (i) Maharashtra, covering almost the entire nation has been collected and analyzed (Dr. S.K. Sharma, 2003). The surface, subsurface and thermal water sample analysis indicate the fluoride concentration ranging from < 0.2 to 18ppm in the States of Jammu & Kashmir, <0.2 to 6.5ppm in Himachal Pradesh, > 1.5ppm in Rajasthan, 0.2 to 0.6ppm in Haryana, 0.35 to 15ppm in Bihar, on an average 12ppm in West Bengal, 15 to 20ppm in Chhattisgarh, 8.2 to 13.2ppm in Orissa and 0.7 to 6.0 in Maharashtra, indicating that except in Haryana, the concentration of fluoride is very high up to 20ppm. The results of chemical analysis of water are summarized in Table 2.2.
Table 2.2: Average fluoride concentration detected in water from different parts of India
Manikaran (Him. Prad.)
0.35 - 4
2.70 - 6
<0.2 - 6.50
0.2 - 0.6
0.6 - 15.00
15.00 - 20.00
Reports on the occurrence of fluoride in natural water resources and the associated health hazards due to human consumption have been made from many parts of India during the last decade. With the objective of organizing a systematic scientific programme to understand the behavior of fluoride in natural water resources in relation to the local hydro geological and climatic conditions and agricultural use, a typical area constituting the lower Vamsadhara River basin was chosen for a detailed study (N. Srinivasa Rao, 1997).High fluoride concentrations in the groundwater reaching a maximum of 3.4 mg lâ» were observed to be associated with weathered formations of pyroxene amphibolites and pegmatite. The groundwater in the clayey soils contained much less fluoride as compared to the sandy soils. The complex depositional pattern of these sandy and clayey soils plays an important role in the uneven spatial distribution of fluoride in the groundwater. The contribution of fluoride from geological formations is far greater than that from agriculture: the maximum yield of fluoride by superphosphate fertilizer to irrigation water is observed to be 0.34mg lâ». The fluoride concentration is expected to be increased in the future as the groundwater is subsaturated with respect to fluorite. An inverse relationship between F and Ca and positive relationships of F with Na, HC03, P04 and electrical conductivity were observed. Best relationships were obtained in the fluoride range of 1.0-3.4 mg lâ» (N. Srinivasa Rao, 1997). The frequency distribution and the ranges of occurrence of fluoride (F) during the post-monsoon and the pre-monsoon periods are presented in Fig.2.2. (N. Srinivasa Rao, 1997).
Figure2.2. Frequency distribution of fluoride during the post-monsoon (November 1992)
And the pre-monsoon (April 1993)
High profile of fluoride in groundwater was observed in 4.6% geographical area (8900Â km2) of Karnataka. The incidence of very high levels of fluoride is in the eastern and southeastern belt of Karnataka, covering districts of Gulbarga, Raichur, Bellary, Chitradurga, Tumkur and Kolar and is scattered in rest of Karnataka. This study included 15 villages from each of the above mentioned six districts with noticeable levels of fluoride. The concentrations of fluoride vary from 1 to 7.4Â mg/l. Occurrence of fluoride is very sporadic and marked differences in concentrations occur even at very short distances, sometimes even less than 2 to 3Â km. Village Hathiguddur in Gulbarga district has a fluoride level of 7.4Â mg/l, while 5.75Â mg/l is seen in Farhatabad. Nimbala recorded 4.4Â mg/l while in other villages, the level was less than 3Â mg/l. District Raichur has non-permissible levels of fluoride prevailing in many villages. Gabbur and Lingasugu villages have 5Â mg/l while in the rest of the villages, levels ranged from 1.2 to 4Â mg/l. District Bellary showed a wide range of fluoride concentrations. Village Sanavaspur and Tekalakota have 7.4Â mg/l while Kurugodu and Verupayur have as low as 0.95Â mg/l. Fluoride levels are comparatively low in districts of Chitradurga and Tumkur. Bommianapalya has a high of 3.2Â mg/l while in the rest of the village levels range from 0.45 to 2.5Â mg/l. Villages in Kolar have comparable low levels of fluoride ranging from 1.5Â mg/l to 3.4Â mg/l (S. Suma Latha et al.).
Danish researcher KajRoholm published Fluorine Intoxication in 1937, which was praised in a 1938 review by dental researcher H. Trendley Dean as "probably the outstanding contribution to the literature of fluorine". Since that time, the fluoridation of public water has been widely implemented and has been hailed as one of the top medical achievements of the 20th Century. The effects of fluoride-rich ground water became recognized in the 1990s (T.H. Dean, 1938).
2.2.2. Assessment of Fluoride along with other Parameters
The incidence of fluoride above permissible levels of 1.5ppm occur in 14 Indian states, namely, Andhra Pradesh, Bihar, Gujarat, Haryana, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Orissa, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh and West Bengal affecting a total of 69 districts, according to some estimates. Some other estimates find that 65 per cent of India's villages are exposed to fluoride risk. High levels of salinity are reported from all these states except West Bengal and also the NCT of Delhi, and affects 73 districts and three blocks of Delhi. Iron content above permissible level of 0.3ppm is found in 23 districts from 4 states, namely, Bihar, Rajasthan, Tripura and West Bengal and coastal Orissa and parts of Agartala valley in Tripura. High levels of arsenic above the permissible levels of 50 parts per billion (ppb) are found in the alluvial plains of Ganges covering six districts of West Bengal. Presence of heavy metals in groundwater is found in 40 districts from 13 states, viz., Andhra Pradesh, Assam, Bihar, Haryana, Himachal Pradesh, Karnataka, Madhya Pradesh, Orissa, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, West Bengal, and five blocks of Delhi. Non-point pollution caused by fertilizers and pesticides used in agriculture, often dispersed over large areas, is a great threat to fresh groundwater ecosystems. Intensive use of chemical fertilizers in farms and indiscriminate disposal of human and animal waste on land result in leaching of the residual nitrate causing high nitrate concentrations in groundwater. Nitrate concentration is above the permissible level of 45ppm in 11 states, covering 95 districts and two blocks of Delhi. DDT, BHC, carbamate, Endosulfan, etc. are the most common pesticides used in India. But, the vulnerability of groundwater to pesticide and fertilizer pollution is governed by soil texture, pattern of fertilizer and pesticide use, their degradation products, and total organic matter in the soil. Pollution of groundwater due to industrial effluents and municipal waste in water bodies is another major concern in many cities and industrial clusters in India. A 1995 survey undertaken by Central Pollution Control Board identified 22 sites in 16 states of India as critical for groundwater pollution, the primary cause being industrial effluents. A recent survey undertaken by Centre for Science and Environment from eight places in Gujarat, Andhra Pradesh and Haryana reported traces of heavy metals such as lead, cadmium, zinc and mercury. Shallow aquifer in Ludhiana city, the only source of its drinking water, is polluted by a stream which receives effluents from 1300 industries. Excessive withdrawal of groundwater from coastal aquifers has led to induced pollution in the form of seawater intrusion in Kachchh and Saurashtra in Gujarat, Chennai in Tamil Nadu and Calicut in Kerala (M. Dinesh Kumar & Tushaar Shah).
Many Americans, especially those in metropolitan areas, take the availability and abundance of good water for granted. For many rural people, however, adequate and safe water supplies are not guaranteed. Approximately one sixth of all Americans rely on a groundwater supply that is continually threatened by increased demand and sources of contamination. A team of six Systems Engineering students under the direction of Professor Garrick E. Louis developed a model for ground water assessment (GWA) that could be used for planning development in rural areas that depend primarily on ground water for their water supply. The project was carried out on private wells in the Ivy subdivision of Albemarle County, Virginia. The Capstone team designed the test kit which consists of a laptop for ease of use, off-the-shelf nitrate and pH testing probes, compatible USB interfaces for the probes, software designed to work with the test probes, and a handheld GPS receiver (fig. 2.3.). The laptop-based kit can be expanded to accommodate probes that may be developed in the future. The kit includes a user's guide and instructional video (Garrick E. Louis, 2006).
Figure2.2. TEST KIT
Fuzzy mathematics method was used to evaluate the groundwater quality in Yang village, China. The groundwater quality of 18 villages belongs to V level water (GB/T14848-9 Quality standard for ground water) in the study area, where water pollution is very serious. Polluted area mainly includes the sandy soil region in northeast Yang village and east bank villages in western Beijing-Hangzhou Canal. Yinma village is I level water (GB/T14848-9), and Jiang Quan village is II level water (GB/T14848-9). Evaluating pollution degree of groundwater with fuzzy mathematics method objectively reflected water quality condition (XU Ying, 2010). Results were shown in Table 2.3.
Table 2.3: Results of Wu Village Water Samples (mg/l)
Drinking water safety is an important part in water scientific field. The traditional living drinking-water quality assessment cannot evaluate wholly the impacts of groundwater quality on human body. Therefore, the groundwater health risk assessment was applied to evaluate the quality of groundwater of an important city in west of China in a study. The analysis shows that health risk super standard ratio caused by chemical carcinogens arsenic is 23.8% in groundwater. The cancer-making risk of Cr (VI) is in the acceptable limits. The nitrate is the major non-carcinogen chronic toxic substance for arsenic, nitrate, fluoride and manganese. Health risk assessment which assesses the carcinogen risk and non-carcinogen risk showed that 71.43% groundwater quality impacts drinking people's health directly or indirectly. The groundwater health risk assessment analyzes the impacts of chemical carcinogen and non-carcinogen in groundwater on human body, so it can provide more deeply scientific support for quality safety and pollution control on groundwater (Duan Lei et al., 2009).
Contamination of the shallow aquifer by elevated nitrate concentrations is a common problem in many rural regions of the world. An aquifer that has both aquifer intrinsic vulnerability and irrigated land uses is especially susceptible to this type of contamination. A study was carried out to evaluate an aquifer's intrinsic vulnerability and agricultural activity's impact on groundwater quality in the Dagu River in Qingdao, which is located in the eastern part of China. The Dagu River aquifer supplies 50 % - 60 % of total water usage for Qingdao. Groundwater hydrochemistry was investigated. Regarding sampling, 436 samples in groundwater and river water were collected from April of 2000 to September of 2006. Results indicate the main forms of contamination are NO3â»-N, CaCO3, TDS, Fâ», and Clâ» which exceed Chinese Groundwater Quality Standard III (GB/T14848-93) by 82%, 57%, 23%, 20%, and 11% respectively. Nitrate concentration is calculated as nitrogen concentration, i.e. NO3â»-N. In particular, nitrate contamination in the shallow aquifer was evaluated by comparing NO3â»-N concentration versus parameters affecting aquifer intrinsic vulnerability (i.e., depth to water table, impact of the vadose zone, etc.). Also, the effect of land use and fertilizer usage on NO3â»-N concentration in groundwater was analyzed. The results suggest intensive agricultural activities, especially an overabundance of fertilizer used in vegetable planting, is an important key factor for nitrate contamination. When much of the fertilizer nitrogen is not converted into harvested crops, it leaves a significant fraction available for leaching into the thin sandy vadose zone which is called the "infiltration window" (Youyuan Chen et al., 2010).
Another study was also carried out to assess exposure to unsafe rural drinking water quality which is the core problem of rural drinking water safety and evaluate the risk of rural drinking water quality among the Rain City District of Ya'an, Sichuan Province, China population. The study calculated the carcinogenic risk (R) and non-carcinogenic risk (hazard index, HI) by applying the health risk model recommended by the US National Research Council of National Academy of Science. Then, taking advantage of the geo-statistic spatial analysis function of ArcGIS, this study analyzed the assessment result data (R and HI), selected the proper interpolation approach and educed R and HI spatial distribution maps in the study area. The following conclusions can be drawn: most of the cancerous risk indexes belong to the unsafe extension, the main carcinogen in water sources were As, Cr (VI) and Pb, their concentrations are in the ranges of 0.004-0.005, 0.0005-0.015, 0.01mg/l respectively; the measured concentration values of fluoride, As, Hg and Nitrate of all the 12 water sources didn't exceed Guidelines for Drinking Water Quality of WHO (Third Edition, 2008) limit values; the total non-cancerous risk of 12 drinking water source investigation sites exceeded the drinking water management standard value of EPA (the limit value is 1), exceeded up to about 1.109-2.373 times. Hence there were tendency of producing non-carcinogenic, chronic and poisoning effects on drinking crowd, about 105757 residents are exposed to such drinking water environment. The effective way of decreasing the health risk and hazard was to control and dispose the rural drinking water containing Fe, Mn, and fluoride, Hg, Cd, Cr (VI) and Nitrate. The results provided important information of water quality control and the early warning for rural drinking water (NI Fu-quan et al., 2010).
A Database system based on VB was developed by collecting the investigation and testing data of endemic area in the West of Jilin Province. The water quality assessment module of the system was applied to assess the drinking water safety. The results show that the groundwater quality in this area is mainly level â…£ and â…¤, and taking up 68.99% of all the samples. The reason of the poor water quality is primarily high fluoride and arsenic concentrations. Establishment and application of database system provided an effective management tool for convenient and real-time monitoring of the disease condition and changes of geochemistry component and quantitative determining the groundwater quality condition (Li Zhao-yang et al., 2010).
Another study integrated conventional statistical tools with neighborhood linkage to propose the statistical diagnosis approach. Fourteen monitoring wells in Kaohsiung Science Park, Taiwan were selected as study case, and lab data of routine groundwater analysis including pH, EC, hardness, TDS, TOC, ammonia, nitrate, nitrite, chloride, sulphate, fluoride, phenols, Fe, Mn, As, and temperature were subjected to principal component and cluster analysis. Principal component analysis (PCA) was utilized to reflect those chemical data with the greatest correlation, and PCA results identified five major principal components (PCs) representing 74.6% of cumulative variance. Based on the monitoring data between 2005 and 2008, the extracted information from the PCA mirrored the potential sources of ground water contamination as acid leakage, arsenic dissolution, salinization, mineralization, and fluoride release (Ting-Nien Wu & Chen-Hsiang Huang, 2009).
On the basis of analysis of ash-water from Baoding power plant (China), chemical components of underground water and the condition of environmental hydrology the prediction on pollution from ash-water permeation was carried out by applying one-dimensional homogeneous mathematical model. The results show that ash-water will not take bad influence on the water quality of water source of Baoding city to ash-field 5000m in the short time. The result showed that when ash water seeps from coal ash layer, surface soil layer and unsaturated zone to aquifer, some contaminants can be degraded innocuous and harmless composition by series of physical, chemical and biological effect. Because of filter, adsorption and sediment another some contaminants are caught by surface soil layer. Still some contaminants are absorbed by various plants (such as water grass, reedy grass), especially the concentration of organic contaminant is significantly reduced, so there is few pollutants in area of aquifer. After major pollutants such as COD, BOD, As, Cr (VI), Fâ» enter aquifer, every concentration has reduced 90% except Clâ». It is said that soil can't absorb and decontaminate Clâ» and Clâ» is not attenuated in nature; because the migration rate of Clâ» is the same as water molecule, there isn't hysteresis phenomenon; if underground water isn't polluted, the concentration of Clâ» will change in a constant; if the concentration of Clâ» change sharply, it is shown that underground water has been polluted, so we choose Clâ» as marked indicator of having pollutant (Xu Peiyao et al., 2009).
2.3. RAJIV GANDHI NATIONAL DRINKING WATER MISSION
According to this mission provision of safe drinking water in the rural areas is the responsibility of the States. Funds are being provided for provision of the facility in the State budgets right from the First Five Year Plan period. The Accelerated Rural Water Supply Programme (ARWSP) was introduced in 1972-73 by the Government of India (GOI), to assist the States and Union Territories to accelerate the pace of coverage of drinking water supply. To ensure maximum inflow of scientific and technical input into the rural water supply sector to improve the performance, cost effectiveness of the on-going programmes and ensure adequate supply of safe drinking water, the entire programme was given a Mission approach. The Technology Mission on drinking water and related water management was launched in 1986. It was also called the National Drinking Water Mission (NDWM) and was one of the five Societal Missions launched by the Government of India. The NDWM was renamed Rajiv Gandhi National Drinking Water mission (RGNDWM) in 1991. It was realized that the objective of supplying safe water would not be achieved unless the sanitary aspects of water and the issue of sanitation are addressed together. The Centrally Sponsored Rural Sanitation Programme (CRSP) was launched in 1986 with the overall objective of improving the quality of life of the rural people. It is envisaged that the two programmes, the ARWSP and the CRSP, implemented simultaneously would help break the vicious circle of disease, morbidity and poor health, resulting from water borne diseases and insanitary conditions.
2.3.1. Control of Fluorosis
Excess fluoride in drinking water causes dental and skeletal fluorosis. The problem is prevalent in 150 districts of 16 states of the country, including Delhi. Control measures include providing alternate sources free from fluoride or treating fluoride contaminated water (to within permissible limit 1.5ppm) with the help of treatment processes such as Nalgonda technique or activated alumina process. So far 499 plants (fill and draw type and hand pump attached type) have been approved by the Mission, of which 427 plants have been installed up to December, 1998.