First report on global fallout 236U and uranium atom ratios in soils from Hunan Province, China. (February 2019)

• Record Type: Journal Article
• Authors: Shao, Yang; Yang, Guosheng; Xu, Diandou; Yamada, Masatoshi; Tazoe, Hirofumi; Luo, Min; Cheng, Hangxin; Yang, Ke; Ma, Lingling
• Is Part Of: Journal of environmental radioactivity. Volume 197(2019)
• Page Start: 1
• Page End: 8
• Publication Date: 2019-02
• Subjects: 236U -- Uranium atom ratios -- Global fallout -- Soil -- ICP-MS/MS -- China; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2018.11.009
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: More nuclear power plants continue to be built in China. Due to its long half-life, radiotoxicity and potential application as an environmental tracer, 236 U is one of the most important artificial radionuclides deserving more study since activity data are important for risk assessment. However, the ultra-trace activity of 236 U and its dilution by natural uranium isotopes make it difficult to distinguish its sources and there are only limited global fallout 236 U data for present in Chinese environmental samples. In order to understand the background levels for uranium isotopes, especially 236 U, and clarify their sources, inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was applied to analyze uranium isotopes in 48 soil samples from Hunan Province, China. The 234 U, 235 U, 238 U and 236 U concentrations were measured as 9.91–33.7, 0.312–1.43, 6.63–28.7 Bq kg −1 and (1.61–21.3) × 10 7 atoms g −1, while, the 236 U/ 238 U, 234 U/ 238 U and 235 U/ 238 U atom ratios were (0.470–4.91) × 10 −8, (5.10–9.31) × 10 −5, and (7.11–7.82) × 10 −3, respectively. The uranium isotopic fractionation may be due to irrigation of the agricultural lands where the samples were collected. Considering the facts that neither previous nuclear tests nor nuclear accidents had occurred in Hunan Province and the present 236 U/ 238 U atom ratios were included in the range of global fallout values in other areas, it may be concluded that 236 U in soils from Hunan Province is mainly from global fallout. To the best of the authors' knowledge, the presence of global fallout 236 U in soil samples from China has been confirmed for the first time, and these values may be useful as background data for risk assessment in the future. Highlights: First 236 U data in soil samples from Hunan, China are presented. Fingerprint and database of uranium atom ratios were established. The 236 U present was mainly from global fallout.