Natural radionuclides distribution, depth profiles of caesium-137 and risk assessment for soil samples in west regions of China

An analysis of natural radioactivity in soils collected around Chinese Nuclear Test site is presented. The radioactivities of 238 U, 226 Ra, 232 Th, 40 K, and 137 Cs were determined by HPGe gamma-ray spectrometry, and potential radiological hazards were evaluated. The depth profiles of radionuclides in three selected areas of Gansu were analyzed, and a new method for detection of 137 Cs specific activities were measured using ultra-low background gamma spectrometer named GeTHU-II developed by Tsinghua University at China Jinping Underground Laboratory. The radioactivity concentrations of 137 Cs were significantly different in these three areas and gradually decreased from surface to underground 15 cm.