PERGAMON Radiation Measurements 31 (1999) 683-685

Radiation Measurements

U R A N I U M E S T I M A T I O N I N W A T E R S A M P L E S C O L L E C T E D

FROM S O M E A R E A S O F H I M A C H A L P R A D E S H , I N D I A

BALDEV SINGH, GURINDER SINGH, A.S. SANDHU AND SURINDER SINGH

Department of Physics, G.N.D. University, Amritsar-143005, India

ABSTRACT

Fission track technique has been used to estimate Uranium concentration in water samples belonging to some areas of Bilaspur, Mandi and Kulu districts of Himachal Pradesh, India. The samples are collected from springs and streams falling in river Bias. Uranium concentration has been found to vary from 0.07 to 4.65 ppb with a mean value of 0.72 ppb. Spring water samples from Gamrolla (Distt. Bilaspur) and Jashni (Distt. Kulu) have yielded comparatively higher Uranium values.

KEYWORDS

Uramum; track; lexan; water.

INTRODUCTION

Uranium is a naturally occurring radioactive element present in soil, rocks, plants and waters. Most of the natural waters contain a few ppb of dissolved uranium with a range of 0-4 ppb in sea waters and up to 1000 ppb in surface and under surface continental waters (Rich et al., 1980; Scot and Barker, 1962). High uranium values are possible in aquifers containing uranium mineralization. Estimation of uranium concentration in water systems in India has been carried out by many workers (Singh et al., 1984; Rarnola et al., 1988; Sarin et al., 1992; Singh et al., 1995) with an aim either of hydrogeochemical prospecting of uranium or for health risk assessments, since an excess of uranium results in transient chemical damage to the kidneys in human beings. In the present work uranium concentration has been made in water samples collected from springs and streams belonging to Kulu, Mandi and Bilaspur districts of Himachal Pradesh. The area under investigation belongs to Siwalik Himalays. The rocks in Siwalik area comprise mainly of massive soft and grey micaceous sand stones and clays. In Kulu, the rocks are quartzite, schist and gneiss.

EXPERIMENTAL TECHNIQUE

The particle track etch technique developed by Fleischer and Lovett (1968) has been used for uranium analysis in water. The details of the technique is given elsewhere (Singh et al., 1995). A drop of water is dried on the lexan detector disc. The residue left behind is covered with another lexan detector of the same size. The system is got irradiated with a known dose of thermal neutrons from a nuclear reactor. The induced fission tracks due to 235U are recorded in lexan after etching with 6.25 N NaOH at 70°C for 25 min. The track density is counted using an optical microscope at a magnification of 400X. The Uranium concentration is determined using the formula:

C = TM/(VGNsfE)

where N = Avagadro number (6.023 x 1023), S = fission cross section (4.2 x 10-24cm2), M = atomic weight of uranium isotope (238), V = volume of one drop(cc), f is the total thermal neutron dose

13504487/99/$ - see front matter © 1999 Elsevier Science Ltd. All rights reserved. PII: S 1350-4487(99)00172-9

684 B. Singh et al. /Radiation Measurements 31 (1999) 683-685

(nvt), T = total number of tracks formed, G = the geometry factor and E = the etching efficiency factor taken as 0.96 for lexan plastic. In our case, we have used total thermal neutron dose of 2 x 10 ~5 (nvt) which has been determined using a standard glass dosimeter during irradiation. The value of U concentration in water samples are reported in Table 1.

Table 1. U concentration m water samples collected during the year 1996 from Himachal Pradesh.

Sample No. Location Water Source Collection date Total No. U. Conc. of tracks (ppb)

(Distt, Kulu)

KW1 Jaslmi Spring KW2 Jashni Stream KW3 Sarsarri Spring KW4 Jan Spring KW5 Kasol Spring KW6 Manikam Hot Spring KW7 Manikarn Spring KW8 Manikarn Parbati Stream KW9 Shat Spring KW10 Nagar Spring KW I l Sarsay Spring KW12 Manali Spring KW13 Kulang Spring KW14 Solan Nala Valley Spring KW 15 Thagan Nala Stream KW 16 Dobhi Stream KWI7 Dobhi Spring KW18 Raison Spring KW19 Shivbag Spring

(Distt. Mandi) MW20 Dawarra Spring MW21 Randharra Spring MW22 Rewalsar Tap MW23 Mandi Bias river MW24 Mandi Stream MW25 Deot Sidh Spring

(Distt. Bilaspur) BW26 Gamrolla Spring BW27 Gamrolla Stream

March 22 2399 a 2.35 + 0.05 b March 22 351 0.34 + 0.02

March 22 366 0.35 + 0.02 March 22 2208 2.17 + 0.05 March 22 518 0.51 ± 0.02 March 23 105 0.10 + 0.01 March 23 643 0.63 + 0.02 March 23 881 0.86 + 0.03 March 23 80 0.08 + 0.01 March 23 193 0.19 + 0.01 March 23 147 0.15 + 0.01 March 24 202 0.21 + 0.01 March 24 69 0.07 + 0.01 march 24 226 0.22 + 0.01 March 24 474 0.47 + 0.02 March 24 380 0.38 + 0.02 March 24 364 0.35 + 0.02 March 24 90 0.09 + 0.01 March 25 720 0.71 + 0.03

March 25 265 0.26 ± 0.02 March 25 545 0.53 + 0.02 March 25 428 0.42 + 0.02 March 22 292 0.29 + 0.02 March 22 975 0.96 + 0.03 March 22 265 0.26 + 0.02

March 21 4742 4.65 + 0.07 March 21 1828 1.79 ± 0.04

aAverage of the two detectors b

Statistical counting error = l s , Is = 1/'~N Volume of water taken = 0.05cc (1 drop) (1 cc of water contains 20 drops)

B. Singh et al. /Radiation Measurements 31 (1999) 683--685 685

RESULTS AND DISCUSSION

Uranium concentration in water samples in Kulu district varies from 0.07 + 0.01 ppb (spring water from Kulang) to 2.35 + 0.05 ppb (spring water from Jashmi), in Mahdi district from 0.26 + 0.02 ppb to 0.96 + 0.03 ppb. Uranium concentration in spring water from Gamrolla in Bilaspur district has been found to be 4.65 + 0.07 ppb which is slightly above the normal value of 0 to 4 ppb (Rich et al. 1980). The values being low are not significant for uranium prospection. However the uranium concentration in water samples from the springs of Gamrolla, Jashni and Jan are above the recommended level of 1.9 mg (ICRP - 30) and thus may be unsafe for human use from the health hazard point of view.

Acknowledgement-Thanks are due to Prof. W. Enge, University of Kiel for the supply of lexan sheets. The irradiation facilities provided by BARC and the financial assistance provided by Ministry of environment and forests are gratefully acknowledged.

REFERENCES

Fleischer R. L. and Lover D. B. (1968) Uranium and Boron Content of Water by particle track etching. Geochim. Cosmochim. Acta 32, 1126-1128.

ICRP - 30(1979) Limits for the Intake of Radionuclides by Workers. International Commission on Radiological Protection. Pergamon Press, Oxford, U.K.

Rich R. A., Holland H. D. and Petersen U. (eds) (1980) Hydrothermal Uranium Deposits. Elsevier Scientific Publishing Company, Amsterdam.

Scott R. C. and Barker F. B. (1962) Data on Uranium and Radium in Ground Water in the United States. USGS paper 426, 115.

Singh N. P., Singh M., Singh S. and Virk H. S.(1984) Uranium and Radon Estimation in Water and Plants using SSNTDs. Nucl. Tracks Radiat. Meas. 8 (1-4), 483-486.

Singh J., Singh L. and Singh S. (1995) High Uranium Contents Observed in Some Drinking Waters of Punjab, India J. Env. Radioactivity 26, 217-222.

Sarin M. M., Krishnaswami S., Sharma K. K. and Trivedi J. R.(1992) Uranium Isotopes and Radium in the Bhagirathi Alakanda River Systems: Evidence for High Uranium Mobilisation in the Himalaya. Curr. Sci. 62 (12).