Department of Radiation Chemistry, Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori, 036-8564, Japan.
Division of Nuclear Technology and Applications, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
Sci Rep. 2017 Nov 13;7(1):15369. doi: 10.1038/s41598-017-15714-w.
In the present study, I activities and I/I atom ratios were measured in 60 soil samples contaminated by the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. The I concentrations, I activities, and I/I atom ratios in dry-weight were observed to be 0.121-23.6 mg kg, 0.962-275 mBq kg, and (0.215-79.3) × 10, respectively. The maximum values of both I activities and I/I atom ratios in Japanese soil increased about three orders of magnitude due to this accident. The equation logy = 0.877logx + 0.173 (Pearson's r = 0.936; x, I concentration; y, I concentration; decay-corrected to March 11, 2011) instead of a simple constant may be a better way to express the relationship between I and I in Japanese soil affected by both global fallout and FDNPP accident fallout. In addition, a moderate correlation was observed between I and Cs (logy = 0.624logx + 1.01, Pearson's r = 0.627; x, I activity; y, Cs activity). However, I presented larger fractionations with less volatile radionuclides, such as U, Pu, and Pu. These findings indicated Cs could be roughly estimated from I or I; this is advantageous as fewer Cs data are available and Cs/Cs is being considered a promising tracer during radiocesium source identification.
在本研究中，我们测量了 60 个受福岛第一核电站（FDNPP）事故污染土壤样本中的碘-131（I）活度和 I/I 原子比。观察到这些土壤样本的干重中 I 浓度、I 活度和 I/I 原子比分别为 0.121-23.6mg/kg、0.962-275mBq/kg 和（0.215-79.3）×10。由于此次事故，日本土壤中的 I 活度和 I/I 原子比的最大值增加了约三个数量级。方程 logy=0.877logx+0.173（皮尔逊相关系数 r=0.936；x，I 浓度；y，I 浓度；校正到 2011 年 3 月 11 日的衰减值）可能比简单的常数更能表达受全球沉降和 FDNPP 事故沉降影响的日本土壤中 I 与 I 的关系。此外，I 与 Cs（logy=0.624logx+1.01，皮尔逊相关系数 r=0.627；x，I 活度；y，Cs 活度）之间存在中等相关性。然而，I 与不易挥发的放射性核素（如 U、Pu 和 Pu）的分馏较大。这些发现表明，可以从 I 或 I 大致估算出 Cs；由于 Cs 数据较少，且 Cs/Cs 正被考虑作为放射性铯源识别的有前途示踪剂，因此这具有优势。
