Specific Activity and Radioactive Contour Maps of Natural (40K, 226Ra and 232Th) and Anthropogenic (137Cs) Radionuclides in Surface Soil Samples from Phang Nga Province, Thailand

The specific activity of the natural (40K, 226Ra and 232Th) and anthropogenic (137Cs) radionuclides have been studied and evaluated for 97 surface soil samples collected from 7 districts of Phang Nga province in the south of Thailand. High-purity germanium (HPGe) detector and gamma ray spectrometry analysis system were employed to measure and analyze the experimental results. It was found that, the ranges of specific activities of 40K, 226Ra, 232Th and 137Cs in surface soil samples are 251.50 – 15740.34, 15.21 – 791.42, 18.14 – 854.34 and < 0.33 – 16.91 Bq/kg with average values are 2886.77 ± 225.93, 165.71 ± 8.45, 160.36 ± 7.93 and 5.76 ± 2.49 Bq/kg, respectively. The results were also compared with some research data in national and global radioactivity measurement and evaluations. Furthermore, the radiological hazards of Phang Nga province were calculated through the radium equivalent activity (Raeq), the external hazard index (Hex), the gamma absorbed dose rate (D) and the annual effective dose rate (AEDout) and also compared with research data in the south of Thailand and the safety limits recommended values by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Moreover, the radioactive contour maps of the natural (40K, 226Ra and 232Th) and anthropogenic (137Cs) radionuclides have been also created for the investigated area.