title: Assessment of radionuclide level in topsoil samples for partial areas of Tibet, China.
abstract: By using high-purity germanium gamma spectroscopy, specific activities of naturally occurring and man-made radionuclides were determined in topsoil samples collected from Nyingch, Lhasa and Xigazê of Tibet Autonomous Region, China. The average activity concentrations of (226)Ra, (232)Th and (40)K were 25.1 ± 0.7, 67.1 ± 2.8 and 608.6 ± 12.9 Bq kg(-1), respectively. The activity concentration of (137)Cs was found to vary from <0.3 (minimum detection concentration) to 46.2 Bq kg(-1) with an average of 4.3 ± 0.5 Bq kg(-1). By using the results of (226)Ra, (232)Th and (40)K in the sampled soils, the average outdoor gamma dose rate in air was calculated as 77.5 ± 23.2 nGy h(-1). Furthermore, the average outdoor annual effective dose from terrestrial radiation was 0.10 mSv. The external hazard index in this work varied from 0.20 to 0.70 with an average of 0.40 ± 0.14. The external exposure from terrestrial radiation will not pose any significant radiological threat to the population resident in the studied areas.
authors.affiliation: National Institute for Radiological Protection,  Chinese Center for Disease Control and Prevention, 2 Xinkang Street, Dewai, Beijing 100088,  China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.forename: Cuihua
authors.initials: C
authors.lastname: Xu
authors.forename: Fei
authors.initials: F
authors.lastname: Tuo
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Wenhong
authors.initials: W
authors.lastname: Li
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhou
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Xu
authors.initials: X
authors.lastname: Su
mesh_terms: D002681:China; D006801:Humans; D008297:Male; D011197:Potassium Radioisotopes / Q000032:analysis*; D011834:Radiation Monitoring; D011883:Radium / Q000032:analysis*; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D013910:Thorium / Q000032:analysis*
chemical_list: D011197:Potassium Radioisotopes; D012990:Soil Pollutants, Radioactive; D013910:Thorium; D011883:Radium