Vertical Distributions of Radionuclides (239+240Pu, 240Pu/239Pu, and 137Cs) in Sediment Cores of Lake Bosten in Northwestern China

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• 作者：Haiqing Liao ; Wenting Bu ; Jian Zheng ; Fengchang Wu ; Masatoshi Yamada
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：April 1, 2014
• 年：2014
• 卷：48
• 期：7
• 页码：3840-3846
• 全文大小：369K
• 年卷期：v.48,no.7(April 1, 2014)
• ISSN：1520-5851

文摘

Artificial radionuclides (¹³⁷Cs, ^239+240Pu, ²⁴¹Pu, ²⁴¹Am) deposited in lacustrine sediments have been used for dating as well as radionuclide source identification. In the present work, we investigated the vertical distributions of ^239+240Pu and ¹³⁷Cs activities, ²⁴⁰Pu/²³⁹Pu atom ratios, and ^239+240Pu/¹³⁷Cs activity ratios in sediment cores collected from Lake Bosten, which is the lake closest to the Lop Nor Chinese Nuclear Weapon Test site in northwestern China. Uniformly high concentrations of ^239+240Pu and ¹³⁷Cs were found in the upper layers deposited since 1964 in the sediment cores, and these were controlled by the resuspension of soil containing radionuclides from the nearby land surface. As the Chinese nuclear tests varied remarkably in yield, the mixing of the tropospheric deposition from these tests and the stratospheric deposition of global fallout has led to a ²⁴⁰Pu/²³⁹Pu atom ratio that is similar to that of global fallout and to a ^239+240Pu/¹³⁷Cs activity ratio that is slightly higher than that of global fallout. However, a low ²⁴⁰Pu/²³⁹Pu atom ratio of 0.080 and high ^239+240Pu/¹³⁷Cs activity ratio of 0.087, significantly different from the global fallout values, were observed in one sediment core (07BS10-2), indicating the inhomogenous tropospheric deposition from the Chinese nuclear tests in Lake Bosten during 1967鈥?973. These results are important to understand the influence of the CNTs on the radionuclide contamination in Lake Bosten.