Assessment of Natural Radioactivity Levels in Soil of Bali Island, Indonesia

Bali is a popular resort and tourist destination in the world because of its culture and beautiful natural view. The purpose of this study is to investigate the natural radioactivity in soil samples collected from various locations in the area of Bali island and assess the radiological hazard due to its natural radionuclides. The soil samples were analyzed for natural radionuclides such as 226Ra, 232Th, and 40 by using gamma spectometry analysis. In order to evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity (Raeq), the absorbed dose rate (D), the annual effective dose rate (E), the external hazard index (Hex), and the internal hazard index (Hin) were calculated and compared with the internationally approved values. The natural radioactivity levels of 226Ra, 232Th and 40K measured from these samples were found to lie in the range 8.43 – 21.99, 11.37 – 27.84 and 106.04 – 360.53 Bq/kg respectively. The radioactivity concentrations of 226Ra, 232Th and 40K within the areas are lower than the world wide average values. The hazard indices calculated were all less than unity (≤ 1) and within the acceptable limit. The annual effective dose rate in the soil samples collected from the area estimated to be 0.03 mSv which is lower than the worldwide average value of 0.07 mSvy-1. The present work provides a background of radioactivity concentrations in the soil of Bali island.