Plutonium isotopes in Northern Xinjiang, China: Level, distribution, sources and their contributions

• Published in: Environmental Pollution
• Main Authors: Zhao, Xue, Qiao, Jixin, Hou, Xiaolin
• Format: Report
• Language: English
• Published: ELSEVIER SCI LTD 2020
• Subjects: Pu-239,2(40); Cs-137; Radioactive pollution; Nuclear weapons testing; Northern Xinjiang; NUCLEAR TEST-SITE; SOIL-EROSION; PU ISOTOPES; LACUSTRINE SEDIMENTS; FALLOUT PU; ICE CORE; PU-239,PU-240; TRACER; I-129; Environmental Sciences & Ecology; Environmental Sciences; ice core
• Online Access: http://ir.ieecas.cn/handle/361006/15995; http://ir.ieecas.cn/handle/361006/15996; https://doi.org/10.1016/j.envpol.2020.114929

Plutonium in the environment has drawn significant attentions due to its radiotoxicity in high concentration and source term linked with nuclear accidents and contaminations. The isotopic ratio of plutonium is source dependent and can be used as a fingerprint to discriminate the sources of radioactive , Pu-239, Pu-240 contaminant. and Cs-137 in surface soil and soil cores collected from Northern Xinjiang were determined in this work. The concentrations of Pu-239,Pu-240 and Cs-137 are in the range of 0.06-1.20 Bq kg(-1), and <1.0-31.4 Bq kg(-1) (decay corrected to Sep. 2017), respectively, falling in the ranges of global fallout in this latitude zone. The Pu-240/Pu-239 atomic ratios of 0.118-0.209 and Pu-239,Pu-240/Cs-137 activity ratios of 0.039-0.215 were measured. Among the investigated sites, distinctly lower Pu-240/Pu-239 atomic ratios of 0.118-0.133 and higher Pu-239,Pu-240/Cs-137 activity ratios of 0.065-0.215 compared to the global fallout values were observed in the northwest part, indicating a significant contribution from other source besides the global fallout. This extra source is mainly attributed to the releases of atmospheric nuclear weapons testing at Semipalatinsk Nuclear Test Site, which was transported by the west and northwest wind through the river valley among mountains in this region. This contribution is estimated to account for 28-43% of the global fallout in the northwest part of Northern Xinjiang. The contribution from the Chinese atmospheric nuclear weapons testing to this region is negligible due to the lack of appropriate wind direction to transport the radioactive releases to this region. (C) 2020 Elsevier Ltd. All rights reserved.