Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Tokyo 171-8588, Japan.
J Environ Radioact. 2012 Nov;113:116-22. doi: 10.1016/j.jenvrad.2012.04.014. Epub 2012 Jun 12.
Atmospheric fallout samples collected from Tokyo between 1963 and 2003 were analyzed using accelerator mass spectrometry (AMS) in order to determine (129)I/(127)I ratios and to examine the deposition rate of (129)I and its secular variation in Tokyo. The (129)I/(127)I ratios in the atmosphere during 1963-1977 ranged from 1 × 10(-8) to 2 × 10(-8). This is roughly 4 orders of magnitude higher than pre-atomic levels, possibly due to atmospheric nuclear weapons tests. The calculated monthly atmospheric deposition rates of (129)I differed from those produced by nuclear fallout of (90)Sr and (137)Cs, indicating that the variations in (129)I deposition are not influenced exclusively by either nuclear bomb testing or by the Chernobyl accident. After 1978, high (129)I depositions (up to 0.13 mBq/m(2)/month) were observed. The (129)I depositions started to increase markedly at the latter half of the 1970s. The secular variation of the estimated annual (129)I deposition in Tokyo showed a close relationship between the annual atmospheric discharge of (129)I from the Tokai Reprocessing plant. Therefore, the atmospheric fallout collected from Tokyo after the late 1970s is influenced primary by the (129)I discharge from the Tokai Reprocessing plant.
采集自 1963 年至 2003 年的东京大气沉降物样本，通过加速器质谱（AMS）分析，以确定 129I/127I 比值，并检测东京地区 129I 的沉积速率及其长期变化。1963-1977 年期间，大气中 129I/127I 比值范围在 1×10(-8)至 2×10(-8)之间。这大致比原子时代前的水平高出 4 个数量级，可能是由于大气核武器试验所致。计算得到的 129I 每月大气沉降速率与 90Sr 和 137Cs 的核沉降产物不同，表明 129I 沉降的变化不仅受到原子弹试验的影响，也不受切尔诺贝利事故的影响。1978 年后，观测到了较高的 129I 沉降（高达 0.13 mBq/m2/月）。129I 沉降在 20 世纪 70 年代后半期开始显著增加。东京地区估计的年度 129I 沉积的长期变化与东海再处理厂每年大气 129I 排放量之间存在密切关系。因此，20 世纪 70 年代后期以后采集自东京的大气沉降物主要受到东海再处理厂 129I 排放的影响。
