Natural radionuclide distribution in soils of Gudalore, India.

The concentration of primordial radionuclides in soil samples of Gudalore Taluk in the Udagamandalam district has been measured from the gamma ray spectrum of the soil. The mean activities of 232Th, 238U and 40K are 75.3 +/- 44.1, 37.7 +/- 10.1 and 195.2 +/- 85.1 Bq kg-1 dry weight, respectively. The average outdoor absorbed dose rate in air at a height of 1 m above ground is 74.3 +/- 27.8 nGy h-1, corresponding to an annual effective dose equivalent of 455.6 microSv. The dose equivalent ranges from 168.3 to 1250.5 microSv. The results have been compared with other global radioactivity measurements and evaluations.