Frequency distribution of natural and anthropogenic radionuclides in surface beach sand samples from Sakom beach in Songkhla Province (Thailand) after the Fukushima Dai-ichi Nuclear Power Plant Accident in Japan

The frequency distribution of specific activities of natural (40K, 226Ra and 232Th) and anthropogenic (137Cs) radionuclides in 50 surface beach sand samples collected from Sakom beach in Thepha district Songkhla province (Thailand), have been studied and analyzed after the Fukushima Nuclear Power Plant Accident in Japan. It was found that the frequency distribution of specific activities of 40K, 226Ra, 232Th and 137Cs for Sakom beach was asymmetrical distribution with the skewness of 0.13, 1.20, 2.00 and 1.49, respectively. The median values of 40K, 226Ra, 232Th and 137Cs were 1028.92 ± 130.68 Bq/kg, 31.53 ± 3.18 Bq/kg, 24.98 ± 2.00 Bq/kg and 2.32 ± 0.69 Bq/kg. Furthermore, the median values of specific activities of 40K, 226Ra and 232Th were also used to evaluate four radiological hazard indices which are gamma absorbed dose rate (D), radium equivalent activity (Raeq), external hazard index (Hex) and annual external effective dose rate (AEDout) for the study area. The results were also compared with the Office of Atoms for Peace (OAP) annual report data, Thailand and global radioactivity measurement and evaluations. Moreover, the radioactive contour maps of the investigated area were also created and presented in this paper.