International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 4(3), 17-20, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 17 Studies on Radionuclides 226 Ra, 238U, 228Th and 40K in River Sediment Samples of Kanyakumari District, Tamil Nadu, India Eugin Shaji J., Kannan C. and Feroz Khan M.2 Department of Chemistry, Manonmaniam Sundaranar University, Tirunelveli, 627012, Tamil Nadu, INDIA PG and Research Department of Zoology, C. Abdul Hakeem College, (Autonomous) Hakeem Nagar, Melvisharam, 632509, Vellore, Tamil Nadu, INDIA Available online at: www.isca.in, www.isca.me Received 28th December 2014, revised 4th February 2015, accepted 18th March 2015 AbstractThe activity concentration of natural radio nuclides such as 226Ra, 238U, 228Th and 40K were determined in river sediment samples collected from Kanyakumari district. The measurements were carried out using a 3” × 3” NaI Gamma spectrometry. The mean radionuclide activity concentrations obtained for each of the radio nuclides expressed in Bq/Kg are18.85, 8.71, 18.75 and 148.10 for 228Ra, 238U, 228Th and 40K respectively. The mean absorbed dose rate is 21.77 nGy/h-1. The activity concentration was found to be less than the recommended level of international guide lines and would not pose any significant radiological impact on the environment. Keywords:Distribution, river sediments, radio nuclides, impact, Kanyakumari district. Introduction There are many natural sources of radiation which have been present since the formation of earth. It is not surprising to know that for an average person, the naturally occurring sources contribute about four to five times as much to the exposure as the man made sources. Environmental activity of238 U and232 Th concentration were studied in high background radiation area palong, Johr, Malaysia and their concentration in grass and water samples in the study area though insignificant the mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment. Ramsar, a northern coastal city of Iran, has high back ground radiation as well as over 50 hot springs with low and high radium contents, The average whole body dose received by population in these areas is about 5 times higher than the normal background radiation level. The concentration of uranium and thorium in Earth’s crust is in the range 1.1-10 ppm for uranium and 10 ppm for thorium. This corresponds to an activity concentration range of 13.5-123Bq/kg for 238U and 39.4 Bq/kg for 232Th 4-6. Study on radionuclide in terrestrial ecosystem in the vicinity of western ghats in India revealed proportionate uptake of radioactivity to the concentration of the radionuclides in the soil. The radioactivity of beach sands of Manavalakurichi region along the south - west coast of India in Tamil Nadu has revealed the high potency of the monazite sands spanning across the Kadiapattinam estuary on the eastern side of Manavalakurichi. The in situ radiometric surveys indicated that the beaches and immediate hinterlands in the west coast of southern Tamil Nadu have more radioactive when compared to the east coast. According to UNSCEAR report, the greatest contribution to mankind’s exposure comes from natural background radiation, and the worldwide average annual effective dose per capita is 2.4 mSv. Natural background radiation based on the above scenario determined by the concentration of natural radio activity in river sediments, collected from kanyakumari district. Material and Methods Sample collection: Sediment samples were collected using a metallic crib and samples were collected at random. Samples were collected from the shore as well as from the interior up to 1m depth. After collection the samples were weighed and dried in a hot air oven at 80 – 90 C. The dried samples were sieved using a mechanical sieve and the sediment particles below � 63µ were taken for analysis. The sediments were stored in plastic container sealed and kept for one month for the equilibration of daughter products. Radioactivity measurements: The radio nuclide activity concentration was measured using Gamma counting system. Cs137 and Co60 standard sources are used in the system. The concentrations of the various nuclides are determined using the count spectra. The peaks corresponding to 1.46Mev (40K), 1.76Mev (214Bi) and 2.614 Mev (208Tl) energies are considered to arrive at the activity levels of 40K, 238U and 232Th respectively. 300 grams of rock powder samples are placed on the NaI detector and measured for a period of 5000 s. Gamma activity were calculated using the given efficiency factor and formula: 228Ac (930 Kev) = 4.5 × 10-3 CPS Bq-140K (1410 Kev) = 1.46 × 10-3 CPS Bq-1240Bi (1700 Kev) = 7.6 × 10-3 CPS Bq-1208Tl (2500 Kev) = 8.78 × 10-4 CPS Bq-1 International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 17-20, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 18 Net value = Sample net integral value – Back ground value Net counts 100 1 = × × × 1000 Bq/kg T Efficiency Sample weight Absorbed dose rate: Radionuclide activity concentration in river sediment is one of the major determinants of the natural back ground radiation. All exposure rates originate from radioactive sources in the river sediment and the activity concentration corresponds to total absorbed dose rate in air at 1m above the ground level on the basis of guide lines reported by UNSCEAR10. Therefore radioactivity content in river sediment can be used to estimate the external gamma radiation exposure or dose rate. The gamma radiation absorbed dose rate in air D (nGy h-1) was calculated using the equation. = 0.462 Cu + 0.621 CTh + 0.0417 C (1) Where: CTh, U and CK are the average activity concentrations of 228Th, 238U and 40K in Bq/Kg, respectively. Results and Discussion The radio nuclides (226Ra, 228Th, 238U and 40K) activity concentration in river sediment samples were shown in Table 1. The activity concentrations for 226 Ra ranged from 10.79 to 28.56 Bq/Kg with an average activity of 18.85 Bq/Kg. Similar pattern has been reported in Cauvery river sediments at Tiruchirapalli11. 228Th ranged from 11.63 to 31.21 Bq/Kg with an average activity of 18.75 Bq/Kg. 238U ranged from 5.07 to 16.01 Bq/Kg with an average activity of 8.71 Bq/Kg. The activity of 40K has been recorded to vary in the range 111.42 – 151.13 Bq/Kg with an average activity of 148.10 Bq/Kg. The overall radionuclide activity has been recorded at Valliyar river sediment near Eraniel and in minimum at Sittar river sediment. The correlation between 228Th and 238U activity and also 226Ra and 40K activity in river sediments are shown in Figure 2 & 3.From the -absorbed dose rate of 228Th, 238U and 40K in river sediment samples were calculated using equation (1) and the calculated values are mentioned in the table (1). The calculated - absorbed dose rate for river sediments varied from 13.68 to 37.72 nGy-1 with an average value of 21.77 nGy-1. Which were much lower than the world average value of 55 nGy-112. Figure-1 Map showing the study area and sampling locations International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 17-20, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 19 Table-1 Gamma activity concentration of river sediment samples and the activity ratio of 228Th and 238U (Bq/Kg), absorbed dose rate S.No Locations 226Ra 228Th 238U 40K 228Th/238U Absorbed dose rate (nGy h-1) 1. Valliyar 28.56 31.21 16.01 262.42 1.9 37.72 2. Pazhayar 26.75 18.46 8.13 131.12 2.2 20.68 3. Kuzhithurai 13.46 22.34 7.48 121.56 2.9 22.39 4. Thirparappu 21.06 18.74 6.29 133.11 2.9 20.09 5. Marappady 16.77 23.23 9.07 151.13 2.5 24.91 6. Moovatumugam 20.58 18.55 7.99 133.98 2.3 20.79 7. Sittar 10.79 11.96 5.07 111.42 2.3 13.68 8. Kodayar 19.01 16.38 8.17 146.92 2.0 20.07 9. Mangadu 18.70 15.07 8.48 142.45 1.7 19.21 10. Sitharal 12.90 11.63 10.42 146.95 1.1 18.16 Figure- 2 Correlation between 238U and 228Th in river sediment samples (Bq/Kg) Figure-3 Correlation between 226Ra and 40K in river sediment samples (Bq/Kg) International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 4(3), 17-20, March (2015) Int. Res. J. Environment Sci. International Science Congress Association 20 Conclusion Gamma ray spectroscopy is used for studying the natural radiation. The river sediments of natural radio nuclides (226Ra, 228Th, 238U and 40K) activity concentration are very low which reflect to the values of their hazard indices that are below limits. However the overall activity level of 226Ra, 238U, 228Th and 40K activities in kanyakumari district river sediments level is very lower than the world average values. References 1.Hemming C.R. and Clarke R.H., A Review of Environmental protection standards, Clinton, NPRB-r 168, HMSO, London., (1984)2.Ghiassi-Nejad M., Beitollahi M.M., Asefi M. and Reza Nejad F., Exposure to 226Ra from consumption of vegetables in the high level natural radiation area of Ramsar, Iran, Journal of Environmental Radioactivity.,66, 215-225 (2003) 3.Termizi Ramli A., Wahab A., Hussein M.A. and Khalik Wood A., Environmental 238U and 232Th concentration measurements in an area of high level natural background radiation at Palong, Johor, Malaysia, Journal of Environmental Radioactivity., 80, 287-304 (2005) 4.Andrejeva O.S., Badjin V.I. and Kornilov A.N., Natural and depleted uranium, Atomizdat, Moscow (in Russian)., (1987)5.Kikoina I.K., Tables of physical constants, Atomizdat, Moscow (in Russian)., (1976) 6.Colmenerosujo L. et al., Uranium-228 and Th-232 series concentrations in soil, radon-222 indoor and drinking water concentration and dose assessment in the city of Aldama, Chihuahua, Mexico, J. Environ. Radioact., 77, 205-219 (2004)7.Saroja R.R.M. and Vetha Roy D., High background radiation sweeping along the south west coast of Tamil Nadu, India, Curr.Sci.,94, 1250-1251 (2008)8.Singh H.N., Shankar D., Neelakandan V.N. and Singh V.P., Distribution patterns of natural radioactivity and delineation of anomalous radioactive zones using in situ radiation observations in Southern Tamil Nadu, India., (2006) 9.UNSCEAR, United Nations Scientific Committee on effects of Atomic radiation Report to the general, assembly, Source and effects of ionizing radiation (New York: United Nations), , (2000) 10.UNSCEAR, United Nations Scientific committee on the Effects of Atomic Radiation, Report to the General Assembly (United Nations, New York), (1993) 11.Shahul Hameed P., Shaheed K., Somasundaram S.S.M. and Iyengar M.A.R., Radium-226 levels in the Cauvery river ecosystem India, J. Biosci., 22(2), 225–231 (1997)12.UNSCEAR, sources and effects of ionizing radiation. United Nations Scientific Committee on the Effect of Atomic Radiation, New York, (1988)