Natural radioactivity in beach sands of Goa of south-west coast of india

Natural gamma radiation level measurements were carried out in the beaches of Goa environs covering an area of 100 kms along coastal belt. An external gamma dose rate in air was found to be ranging from 1.0 μR h-1 to 7.2 μR h-1. Sand samples were collected and analysed for their natural radionuclides such as 226Ra, 232Th and 40K employing 90 cc HPGE spectrometer. The activity concentration of 210Pb and 210Po was determined by radiochemical separation techniques. The activities of 226Ra, 232Th, 40K, 210Pb and 210Po were found to vary in the range BDL-17.5 Bq kg-1, BDL- 24.2 Bq kg-1, BDL-132.9 Bq kg-1, 1.9-7.8 Bq kg-1 and 0.9-3.7 Bq kg-1 with a median value of 4.4 Bq kg-1, 4.0 Bq kg-1, 40.1 Bq kg-1, 5.9 Bq kg-1 and 1.5 Bq kg-1 respectively. Grain size analysis reveals that the activity concentration of 226Ra and 232Th shows increasing trend towards fine grain size, whereas 40K shows decreasing trend towards fine grain size. All these results are discussed in detail and compared with the literature values reported to other environs. (author)