Applied Radiation and Isotopes 57 (2002) 109–119 Distributionofnaturalandanthropogenicradionuclidesinsoil and beach sand samples of Kalpakkam (India) using hyper pure germanium (HPGe) gamma ray spectrometry V. Kannan a, *, M.P. Rajan a , M.A.R. Iyengar a,1 , R. Ramesh b a Environmental Survey Laboratory, Health Physics Division, BARC, Kalpakkam–603 102, India b Institute for Ocean Management, Anna University, Chennai-600 025, India Received 25 April 2001; received in revised form 8 October 2001; accepted 6 November 2001 Abstract Pre-operational survey at Kalpakkam coast, indicated elevated gamma background radiation levels in the range of 100–4000nGyh 1 overthelargetractsofthecoastalsandsduetothepresenceofpocketsofmonazitemineralinbeach sands. In view of the prevalence of monazite, a systematic gamma spectrometric study of distribution of natural radionuclidesinsoilandbeachsandsamplescollectedfromtheterrestrialandcoastalenvironmentofKalpakkamwas performedandconcentrationsofprimordialradionuclidessuchas 238 U, 232 Thand 40 Kandanthropogenicradionuclide 137 Cs were determined. The concentrations of 238 U, 232 Th and 40 K in soil samples were 5–71, 15–776 and 200– 854Bqkg 1 dry, respectively. In beach sand samples, 238 U, 232 Th and 40 K contents varied in the range of 36–258, 352–3872 and 324–405Bqkg 1 dry, respectively. The total absorbed gamma dose rate in air due to the presence of 238 U, 232 Thand 40 KinKalpakkamsoilsamplesvariedbetween24and556nGyh 1 withameanof103nGyh 1 .The contribution to the total absorbed gamma dose rate in air in the decreasing order was due to the presence of 232 Th (76.4%), followed by 40 K (16.9%) and 238 U (6.7%) in Kalpakkam soils. However, in beach areas of Kalpakkam, the presence of 232 Th in beach sand contributed maximum (94.0%) to the total absorbed gamma dose rate in air followed by 238 U (4.7%) and minimum contribution was by 40 K (1.3%). 137 Cs in Kalpakkam soils ranged from p1.0to2.8Bqkg 1 dry,whichwas1–3orderofmagnitudelessthantheconcentrationofprimordialradionuclidesin soil. r 2002 Elsevier Science Ltd. All rights reserved. Keywords: Naturalandanthropogenicradionuclidesinsoilandbeachsand;HPGegammaspectrometry; 238 U; 232 Th; 40 K;and 137 Cs; Absorbed gamma dose rate in air 1. Introduction Radiation is present in every environment of the Earth’s surface, beneath the Earth and in the atmo- sphere. According to UNSCEAR (1993), about 87% of theradiationdosereceivedbymankindisduetonatural radiation sources and the remaining is due to anthro- pogenic radiation. There are few areas such as Austria, Brazil, China, France, India and Iran in the world, wherethebackgroundradiationlevelswerefoundtobe high, varying over an order of magnitude depending uponthesite-specificterrestrialradioactivity(Roserand Cullen, 1964; Brazilian Academy of Sciences, 1977; HansonandKomarov,1983;Suntaetal.,1982).Cosmic radiation, and terrestrial radiation arising out of earth’s crust and building materials used for construction of houses and buildings give rise to the external exposure and inhalation or ingestion of natural/man-made radio- nuclides that are present in the environment forms due tointernalexposure.Therefore,atthesiteofanynuclear *Corresponding author. Fax: +91-4114-803-16. E-mail address: vkannan@igcar.ernet.in (V. Kannan). 1 Former address (now retired). 0969-8043/02/$-see front matter r 2002 Elsevier Science Ltd. All rights reserved. PII:S0969-8043(01)00262-7