Applied Radiation and Isotopes 64 (2006) 396–401 Behavior of 210 Po and 210 Pb in high background areas of coastal Kerala on the south west coast of India Y. Narayana à , P.K. Shetty, K. Siddappa Department of Studies in Physics, Mangalore University, Mangalagangothri, 574199, India Received 19 May 2005; received in revised form 6 August 2005; accepted 7 August 2005 Abstract This paper deals with the distribution and behavior of 210 Po and 210 Pb in beach sand and surface soil samples from the Quilon district of Kerala. Beach sand and soil samples were collected and analyzed for 210 Po and 210 Pb radionuclides using standard radiochemical analytical techniques. Mean activities of 210 Po and 210 Pb were found to be maximum in the samples collected at 20 m away from waterline. Among the beach sand samples, the activities of radionuclide were found to be maximum for samples from most of the regions of Chavara and few regions of Neendakara. The activity of 210 Po was found to vary from 2.4 to 20.5 Bq kg À1 with a mean value of 8.3 Bq kg À1 at the water line, 2.5–19.9 Bq kg À1 with a mean value of 10.2 Bq kg À1 at 20 m away from the waterline, and 2.1–6.7 Bq kg À1 with a mean value of 3.5 Bq kg À1 at 40 m away from waterline. The respective values found for 210 Pb were from 1.2 to 48.2 Bq kg À1 with a mean value of 14.9, 11.3–34.2 Bq kg À1 with a mean value of 19.8 Bq kg À1 and 2.3 to 18.3 Bq kg À1 with a mean value of 8.7 Bq kg À1 . The depth profile study indicated the mean activity of 210 Po to decrease with depth for samples collected 20 m away from waterline whereas the activity slightly increases with depth 40 m away from sea. The activity concentration of 210 Po and 210 Pb in surface beach sand shows good correlation, with a correlation coefficient 0.81. r 2005 Elsevier Ltd. All rights reserved. Keywords: Polonium-210; Lead-210; Kerala; Sand and soil 1. Introduction High natural background radiation areas are of special interest, indicating anomalous conditions in their geologi- cal features and consequently in the background radiation levels. One of the prime sources of high background radiation level is the presence of radioactive monazite. One of the regions in India within which high background radiation levels have been reported is from the coastal areas of Quilon district in Kerala. Monazite sands are known to contain thorium with some amount of 238 U and 40 K(Eisenbud, 1987). The radionuclides 210 Po and 210 Pb are the final radioactive members of the 238 U series and are widely present in the environment, due to the decay of 222 Rn in the atmosphere, contributing about 8% of the natural radiation exposure to humans (United Nations Scientific Committee on the Effects of Atomic Radiation, 1988). However data avail- able on the distribution of 210 Po and 210 Pb in sand and soils of high background radiation areas is sparse. In view of this, detailed studies on the radiation level and radionuclide activity concentration in different environmental matrices of high background area have been undertaken. As a part of this programme, the distribution and enrichment of 210 Po and 210 Pb were studied in the region identified above. The soil and beach sand samples collected from different depths in the Karunagapalli, Chavara, Neendakara and Kollam beach areas were analysed for 210 Po and 210 Pb activity. An attempt is made in this investigation to study the distribution, enrichment, vertical profile, and activity ratios of 210 Po and 210 Pb and the influence of organic matter content on these radionuclides in surface soil and beach sand samples. ARTICLE IN PRESS www.elsevier.com/locate/apradiso 0969-8043/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2005.08.016 à Corresponding author. Tel.: +91 824 2287363; fax: +91 824 2287367. E-mail address: narayanay@yahoo.com (Y. Narayana).