|Year : 2016 | Volume
| Issue : 1 | Page : 25-29
Distribution of natural uranium in groundwater around Kudankulam
BS Selvi, B Vijayakumar, BK Rana, PM Ravi
Health Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India
|Date of Web Publication||1-Jul-2016|
B S Selvi
Environment Survey Laboratory, Health Physics Division, Koodankulam Nuclear Project, Kudankulam, Radhapuram, Tamil Nadu - 627 106
Source of Support: None, Conflict of Interest: None
A systematic study was carried out to estimate the uranium concentration in the ground water around Kudankulam in Southern Tamil Nadu. The uranium concentration in ground water varies from 0.2 to 6.6 μg/l, with a mean value of 2.0 μg/l. The Quantalase uranium analyzer was used to measure the uranium concentration. These groundwater samples were analyzed for the water quality parameters such as pH, conductance, total dissolved solids (TDS), salinity, chloride, and sulfate. An attempt has been made to correlate the uranium concentration with the water quality parameters. It is observed that conductance, TDS, salinity, chloride, and sulfate show positive correlation with uranium concentration.
Keywords: Groundwater, parts per billion, uranium
|How to cite this article:|
Selvi B S, Vijayakumar B, Rana B K, Ravi P M. Distribution of natural uranium in groundwater around Kudankulam. Radiat Prot Environ 2016;39:25-9
|How to cite this URL:|
Selvi B S, Vijayakumar B, Rana B K, Ravi P M. Distribution of natural uranium in groundwater around Kudankulam. Radiat Prot Environ [serial online] 2016 [cited 2020 Oct 30];39:25-9. Available from: https://www.rpe.org.in/text.asp?2016/39/1/25/185164
| Introduction|| |
About 96% of all unfrozen fresh water is found below the earth's surface and is known as groundwater. Groundwater systems globally provide 25-40% of the world's drinking water. In India, most of the people living in rural areas depend on groundwater for drinking purpose. Naturally, groundwater consists of major ions, minor ions, trace metals, heavy metals, radionuclides, organic matter, etc. The groundwater quality needs to be monitored periodically so as to check that the water quality parameters do not exceed the limits of drinking water quality standards. Uranium is one of the natural radionuclides present in groundwater in minute quantity. Due to its natural existence, uranium is present in all environmental matrices such as water, soil, sediment, food materials, and biota. On a global basis, its concentration in soil varies from 1 to 5 parts per million while in water, it varies from 1 to 3 parts per billion (ppb). 
The present study was carried out around Kudankulam (Latitude 8° 9' 52" N and Longitude 77° 42' 41" E) along the coast of Gulf of Mannar near the Southeastern tip of India. Groundwater is the major source of water for drinking, irrigation, and domestic purposes of the villages around Kudankulam. Environmental Survey Laboratory at Kudankulam site routinely monitors the major water quality parameters of the fresh water samples within 30 km radial distance from the nuclear plant. This study presents the natural uranium concentration in ground water samples collected around Kudankulam.
| Materials and methods|| |
Around 50 groundwater samples were collected in clean, plastic bottles from bore wells, open wells, and tube wells within 25 km radius around Kudankulam Nuclear Power Plant. [Figure 1] gives sampling locations around Kudankulam. Collected samples were filtered through 0.45 μm Whatman filter paper. U content in groundwater sample was measured by light-emitting diode (LED)-based ultraviolet (UV) fluorimeter (Model No. UA2, M/S Quantalase Enterprises Pvt. Ltd., Indore, Madhya Pradesh, India) which works on the principle of measurement of fluorescence of uranium complexes in the aqueous sample, in which a pulsed LED UV light was used to excite uranyl species at 405 nm. The instrument has a dynamic range from 0.2 to 500 ppb with 5% accuracy.
A standard stock solution of 973 mg/l (Sigma-Aldrich, Merck Company, India) was diluted to working concentrations for regular calibration and checking the performance of the instrument. Water sample analysis was carried out by standard addition method to avoid matrix effect and any other interference by different ions. Five percent sodium pyrophosphate solution was used as a fluorescence enhancing reagent that forms uranyl phosphate complexes which are more stable in the solution 5 ml water sample and 0.5 ml of 5% sodium pyrophosphate were taken in cleaned cuvette and subjected to fluorescence reading by the instrument. To get blank counts, a blank sample was prepared using double distilled water with the same amount of fluorescing reagent for measurement of U concentration. In standard addition method, U concentration in the sample was estimated by:
where Cs is the concentration of U in the sample (μg/l), Cst is the concentration of U standard solution (μg/l), Fs is the fluorescence due to sample only, Fmix is the fluorescence due to sample and spiked U standard solution, Vs is the volume of sample (ml), and Vst is the volume of U standard solution spiked (ml).
The water samples are analyzed for physicochemical parameters such as pH, conductance, salinity, and total dissolved solids (TDS) by using water and soil analyzer kit. Concentration of chloride and sulfate in water samples were estimated by Mohr's method and turbidimetric method, respectively.
Quality assurance and quality control
The quality of the data was assured by cross method analysis.  Ten water samples were analyzed by both laser fluorimeter and LED-based UV fluorimetry, which are the accepted and standard instruments and recommended method for ultratrace U analysis. The results were in good agreement with each other, and the correlation coefficient was observed to be 0.99 [Figure 2]. Quality assurance was made by analysis of standard reference material, replicate analysis, and cross method checking. All laboratory glassware used for sample processing was soaked in 10% nitric acid for 15 days and then rinsed thoroughly with distilled and double distilled water, respectively, before use. Reagent blank was taken along with each batch of sample preparation, and concentrations observed in the reagent blank were subtracted from the same batch of samples.
|Figure 2: Comparison of U concentrations in water samples by laser and light-emitting-diode-based fluorometry|
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| Results and discussions|| |
[Table 1] summarizes the prevalent natural uranium concentration in ground water samples and its physicochemical parameters at different locations around the plant site. The uranium concentration in water samples is found to vary from ≤0.2 to 6.6 ppb with an average of 2.0 ppb. It has been observed that there is no much variation in uranium concentration in different locations indicating that natural uranium is uniformly distributed within in the observed range.
Uranium content in groundwater shows a wide variation in India and throughout the world. Variation in uranium concentration mainly depends on the geology of the area and other meteorological parameters. Sahoo et al.  has been reported U concentration in the range of 0.1-19.6 ppb in the drinking water samples collected from Orissa, Andhra Pradesh, Maharashtra, Madhya Pradesh, Kerala, etc. Rana et al.  has been reported U concentration in the range of 0.38-79.7 ppb in the ground water samples collected nearby the Tummalapalle uranium mining and processing facility. Atomic Energy Regulatory Board (AERB)  recommended 60 ppb as the maximum permissible limit of uranium in drinking water. It is observed that the uranium concentration in all the samples collected around Kudankulam site lies well within the limit recommended by AERB.
Being a coastal site, groundwater samples around Kudankulam have higher conductance, salinity, TDS, and chloride. It is observed that some of the inland locations are showing lower conductance and other parameters. [Table 2] shows the values of the correlation coefficient of uranium with other physicochemical parameters determined in the present investigations in drinking water samples. It is observed that there is no correlation between the concentration of uranium and the pH. Positive correlation is observed in the case of conductance, TDS, salinity, chloride, and sulfate. Positive correlation of uranium with chloride and sulfate implies that uranium may be present in drinking water as a dissolved salt of these chemical precursors. [Figure 3],[Figure 4] and [Figure 5] show the relationship of conductance, chloride, and sulfate content with uranium concentration. Singh et al.  has been reported that there is a weak positive correlation of uranium with chloride, sodium, potassium, calcium, and TDS has been observed. The correlation of uranium with conductance, nitrate, hardness, and magnesium is found to be positive.
|Table 1: Uranium concentration and physicochemical parameters of groundwater samples around Kudankulam|
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|Table 2: Correlation coefficients for uranium physicochemical parameters|
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| Conclusions|| |
The natural uranium concentration in all the groundwater samples around Kudankulam is well within the limits prescribed by the AERB. Uranium concentration in ground water varies from ≤0.2 to 6.6 ppb with a mean value of 2.0 ppb and a standard deviation of 1.6 ppb. A positive correlation has been observed between uranium and other physicochemical parameters. Natural Uranium concentration is distributed uniformly in all zones within the observed range indicating the prevalence of natural uranium.
The authors would like to thank Dr. K.S. Pradeepkumar, Associate Director, Health, Safety and Environment Group, BARC, and Dr. R.M. Tripathi, Head, Health Physics Division, BARC, for their guidance and keen interest in this work. Authors are thankful to KKNPP Site authorities at Kudankulam for their full support and for extending all necessary infrastructures.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
World Health Organization. Guidelines for Drinking Water Quality, Health Criteria and other Supporting Information. 3 rd
ed. Geneva: World Health Organization; 2003.
Rana BK, Dhumale MR, Lenka P, Sahoo K, Ravi PM, Tripathi RM. A study of natural uranium content in groundwater around Tummalapalle uranium mining and processing facility, India. J Radioanal Nucl Chem 2016;307:1499-506.
Sahoo SK, Mohapatra S, Chakrabarty A, Sumesh CG, Jha VN, Tripathi RM, et al.
Distribution of uranium in drinking water and associated age-dependent radiation dose in India. Radiat Prot Dosimetry 2009;136:108-13.
AERB Safety Guidelines; Radiological Safety in Uranium Mining and Milling Guidelines No. AERB/FE-FCF/SG-2; 2007.
Singh S, Rani A, Mahajan RK, Walia TP. Analysis of uranium and its correlation with some physico-chemical properties of drinking water samples from Amritsar, Punjab. J Environ Monit 2003;5:917-21.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]
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