Specific activity of natural and anthropogenic radionuclides and radiological hazard assessment in surface soil samples collected along the Andaman sea coast in southern region of Thailand

The specific activities of natural (K-40, Ra-226 and Th-232) and anthropogenic radionuclides (Cs-137) in 314 surface soil samples collected from three provinces (Phuket, Phang-Nga and Krabi) along the Andaman sea coast in southern region of Thailand were studied and evaluated. Experimental results were obtained by using a high-purity germanium (HPGe) detector and gamma spectrometry analysis system. It was found that the mean values of specific activities of K-40, Ra-226, Th-232 and Cs-137 were 2859.63 +/- 209.83, 157.10 +/- 8.06, 137.16 +/- 7.26 and 4.88 +/- 2.34 Bq/kg, respectively. Furthermore, four radiological hazard indices which are absorbed dose rate in air (D), radium equivalent activity (Raeq), external hazard index (Hex) and annual effective dose rate (AEDout) in the area under consideration were also calculated and came out to be 277.11 +/- 16.96 nGy/h, 575.16 +/- 34.67 Bq/kg, 1.55 +/- 0.09 and 0.34 +/- 0.02 mSv/y, respectively. The experimental results were also compared and found to be comparable with national and global radioactivity measurements and evaluations. Moreover, the radioactive contour maps of the investigated area were also created and presented in this paper.