Geospatial Analysis of Fluoride Contamination in Ground Water of Tamnar Area, Raigarh District, Chhattisgarh State
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GEOSPATIAL ANALYSIS OF FLUORIDE CONTAMINATION IN GROUND WATER OF TAMNAR AREA, RAIGARH DISTRICT, CHHATTISGARH STATE M.K. Beg January, 2009 GEOSPATIAL ANALYSIS OF FLUORIDE CONTAMINATION IN GROUND WATER OF TAMNAR AREA, RAIGARH DISTRICT, CHHATTISGARH STATE by M.K. Beg Thesis submitted to the International Institute for Geo-information Science and Earth Observation in partial fulfilment of the requirements for the degree of Master of Science in Geo-information Science and Earth Observation, Specialisation: (Geo-hazards) Thesis Assessment Board Thesis Supervisors Examiner 1 : Dr. Cees van Westen, ITC (Chairman) Dr.E.J.M.Carranza, ITC Examiner 2 : Dr. G. J. Chakrapani, IIT, Roorkie (External) Drs.J.B.de Smeth, ITC Member : Prof. R.C.Lakhera, IIRS S.K.Shrivastav, IIRS Member : S.K.Shrivastav, IIRS iiiirrss INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION ENSCHEDE, THE NETHERLANDS & INDIAN INSTITUTE OF REMOTE SENSING, NATIONAL REMOTE SENSING CENTRE, DEPARTMENT OF SPACE, DEHRADUN, INDIA Disclaimer This document describes work undertaken as part of a programme of study at the International Institute for Geo-information Science and Earth Observation. All views and opinions expressed therein remain the sole responsibility of the author, and do not necessarily represent those of the institute. Abstract The occurrence of dental/skeletal fluorosis among the population in the study area provided the motivation to investigate occurrence of fluoride in groundwater. The main objective of the present study is to gain insight into spatio-temporal variation of F- contents in groundwater and its relationship with fluorosis prevalence in the study area to answer the following two research questions – (1) What are the controls on spatial distribution of F- concentrations in groundwater (i.e. relation of F- concentration in groundwater vis-à-vis other hydrochemical parameters, lithology and electrical resistivity of subsurface, and plausible source(s) and geochemical processes leading to increase in F- concentration)?; and (2) Is there a temporal variation in F- concentration in groundwater in the area? Prior to this study, no systematic and scientific investigation has been conducted on F- contamination in groundwater in the area. For hydrochemical analysis, groundwater samples were collected from hand-pumps during three periods, pre-monsoon (N=83), mid-monsoon (N=20) and post-monsoon (N=81). The temperature, pH, electrical conductivity and depth to water level were measured in the field. The hydrochemical data, obtained through chemical analysis, have been subsequently analysed and interpreted using univariate and multivariate methods. X-ray diffraction (XRD) and petrographic analysis of rock samples collected from the high F- zone have been carried out for identification of minerals constituting the host rock. Geographic Information System (GIS) has been used for spatial analysis of geological and hydrochemical data. The F- concentration in groundwater varies from 0.09 to 8.8 mg/l in pre-monsoon and 0.0 to 7.1 mg/l in post-monsoon. The spatial distribution of F- concentration in the pre-monsoon and post-monsoon periods shows that about 60% of the total samples in the northern, southern and western parts of the study area have F- concentration below the minimum required level (0.6 mg/l); 15% samples in the eastern part of the area have F- concentration above the maximum permissible limit (>1.2 mg/l); and the remaining 25% samples in the eastern and central parts of the area have F- concentration within the optimum range (0.6–1.2 mg/l). Of the 39 villages where hydrochemical analysis has been carried out, five villages namely Muragaon, Pata, Kunjhemura, Saraitola and Dholnara are found to have F- concentrations higher than the maximum permissible limit, which match with the fluorosis prevalence in the area. The overall distribution of F- concentration in the study area during the three periods indicates slight dilution effect owing to fresh recharge on account of rainfall; however, in and around the high F- zone the effect of rainfall recharge is found to be negligible. With regard to the number of locations where elevated concentrations of F- in groundwater are recorded, it is found that at twelve locations F- values are consistently above the acceptable limit of 1.2 mg/l, whereas at one location F- concentration is high only during post-monsoon period. The number of affected villages, however, remains the same. Based on the geospatial analysis of the various geological and hydrochemical datasets, it has been observed that – (1) high F- concentration in ground water mainly occurs in Barakar Formation having a litho-assemblage of feldspathic sandstone/shale/coal; few places in Barren Measures Formation, adjacent to the contact between the Barakar and Barren Measures Formations in the groundwater i movement direction, also have high F- content; (2) the groundwater with high F- concentration is associated with Na-Ca-HCO3, Na-Ca-Mg-HCO3 and Na-Mg-Ca-HCO3 types of water; (3) the ratio of Na+ and Ca2+ increases with the increase in F- content; (4) F- has significant positive correlation with + 2+ 2+ - Na and SiO2, and significant negative correlation with Ca , Mg , HCO3 , alkalinity and total hardness (TH); additionally, F- also has poor but positive correlation with Li+, and negative but poor + - - correlation with EC/TDS, K , Cl and NO3; and (5) high F concentration in ground water is generally found in deeper (>110 m) wells. - + - The positive correlation of F with Na and SiO2 indicates the source of F in groundwater to be from weathering of silicate minerals. Further, the groundwater types and increase in Na+:Ca2+ values with the increase in F- concentration indicate dissolution of feldspars which can be attributed to the association of high F- zone with feldspathic sandstones. Since the increase in Na+ concentration increases the solubility of F- bearing minerals, the geochemical processes leading to increase in Na+ and decrease in Ca2+ concentrations play an important role in F- enrichment in ground water. The presence of Li+ in the high F- zone suggests that micas, forming an important constituent of Barakar sandstones (as observed in the outcrops, XRD analysis and thin sections) and which contain fluorine at the OH- sites, may act as an important source of F- in groundwater on dissolution. Cation exchange (Na+ for Ca2+) accompanied with anion exchange (OH- for F-) may also be the important processes by which micas and clay minerals (containing fluorine at the OH- sites) may contribute to F- enrichment in groundwater. The clay layers intercalated with sandstones in the Barakar Formation are likely to play an important role in the context of anion exchange as the wells are not completely cased and there is 3- an interaction of groundwater with them. The absence of PO4 in groundwater, in all the three periods, rules out the contribution from phosphate minerals (such as apatite and flour-apatite) and anthropogenic activities; high F- concentration in groundwater found in deeper wells also does not support the contamination from anthropogenic activities. Further, the negative correlation between F- and Ca2+ does not support the dissolution of fluorite which is considered to be an important source for releasing fluorine to groundwater. The lower values of the storativity and transmissivity and deeper wells are other important factors leading to increase in F- concentration in groundwater because of increase in temperature and residence time of groundwater. The spatio-temporal distribution maps of F- concentration in groundwater have been integrated in GIS to prepare the ‘health-risk map’ and to estimate the population at risk. The ‘health-risk map’ indicates that a large population in the area is at potential risk in addition to the already affected people. This will be useful for health officials to take up mitigation measures in the area so as to prevent the diseases caused due to either elevated or low F- concentration in groundwater. ii Acknowledgements I deeply give thanks to Dr. V.K.Dadhwal, Dean, IIRS, Dr.V.Hariprasad, In charge, Water Resource Division and programme coordinator, IIRS, Prof. R.C.Lakhera, Head, Geosciences Division, Dr. Cess van Westen (ITC), Dr. Michiel Damen, Course Coordinator, ITC-IIRS, Mr.I.C.Das (IIRS), Dr.Abbas Farshad and Dr. Druva (ITC) for their invaluable guidance, advice and support during my studies and research project at IIRS and ITC. Many thank to Dr. E.J.M. (John) Carranza, Drs. J.B. de Smeth my supervisor at ITC, who helped to sharpen my research question and explained how to do the interpretation of geochemical data and classify the maps using box and whisker plot. I am grateful to Mr. S.K.Srivastav, my IIRS, supervisor who always had the time to look in to my problem, whenever I was stuck at some stage during this research period. I am indebted to Dr.P.K.Bhat Director General, Chhattisgarh Council of Science and Technology, Raipur, Chhattisgarh, for forwarding my application and sponsoring me to attend this joint ITC-IIRS Geohazards M.Sc. Programme. I am thankful to Mr.Hingorani, Superintending Engineer, Public Health Engineering Department who took personal interest in Fluoride problem of Tamnar area of Raigarh, District and helped me to provide all support from office of the Executive Engineer, Raigarh Division. I must thanks to Mr.R.K.Tandan, Junior Engineer, Public Health Engineering Department, Tamnar for taking interest in Fluoride in groundwater, who personally accompanied me all the time during my pre-monsoon, mid-monsoon and post-monsoon, field campaign. I would like to give thanks to Dr.K.S.Patel, School of Studies in Chemistry, Pt. Ravishankar Shukla, University, Raipur for providing me all support for chemical analysis. Special thanks to Dhananjay Sahu, ph.D. Student of pt. Ravishankar Shukla University, Raipur for helping me in analytical analysis of pre-monsoon water samples at University lab.