ABSTRACT Following the Fukushima Daiichi Nuclear Power Plant accident of 2011, the potential for radiocesium transfer from contaminated soils, such as Andosols, to agricultural crops became a significant concern. Andosols account for up to 70％ of paddy soils in the northern and northwest areas of Tochigi Prefecture, where the radiocesium concentration is 1000 Bq kg−1 or greater in the soil of some fields. The present study was carried out in order to determine the phytoavailability of radiocesium in Andosols by comparing it with that of gray lowland soils in the first 3 years following the accident. The transfer factor (TF) tended to be higher in Andosols than in gray lowland soils, leading to higher radiocesium concentrations in brown rice grown in Andosols. The exchangeable potassium (Ex-K2O) in Andosols was highly and negatively correlated with TF, followed by clay. The Ex-K2O value was positively correlated with the clay/total carbon (T-C) value, suggesting that a high T–C ratio could weaken K2O adsorption on clay mineral sites; hence, the low clay/T-C values can partially explain the relatively large TF values of Andosols. Samples with Ex-K2O contents less than 200 mg kg−1 and with low clay/T-C values showed striking decreases in TF values from 2011 to 2012. However, the decrease from 2012 to 2013 was quite small; radiocesium in these samples was potentially available for rice uptake for a long time, likely due to the reversible adsorption and fixation characteristics of allophane. Most gray lowland soil samples showed very low TF values over the 3 years of the study, except for those with TF values greater than 0.1 due to low Ex-K2O and clay contents; the geometric mean (GM) value of TF was below 0.01 in 2012. The extraction of exchangeable radiocesium (Ex-Cs) with a 1 mol L−1 ammonium acetate solution may not be an appropriate method for explaining the variability in radiocesium TF in Andosols. This is because the Ex-Cs value was significantly correlated with Ex-K2O in Andosols, but not in gray lowland soils, indicating that Ex-K2O explained this variability in relation to Ex-Cs.

中文翻译：

---

2011 年福岛第一核电站事故后的前 3 年枥木县北部和西北部地区的放射性铯从 Andosols 转移到糙米

摘要 2011 年福岛第一核电站事故后，放射性铯从受污染土壤（如安多溶胶）转移到农作物的可能性成为一个重要问题。枥木县北部和西北部地区的稻田土壤中，安多溶胶高达 70％，其中一些田地土壤中放射性铯浓度达到 1000 Bq kg-1 或更高。进行本研究是为了通过在事故发生后的前 3 年将其与灰色低地土壤的放射性铯进行比较来确定 Andosols 中放射性铯的植物有效性。Andosols 中的转移因子 (TF) 往往高于灰色低地土壤，导致 Andosols 中生长的糙米中的放射性铯浓度更高。Andosols 中的可交换钾 (Ex-K2O) 与 TF 呈高度负相关，其次是粘土。Ex-K2O 值与粘土/总碳 (TC) 值呈正相关，表明高 T-C 比会减弱 K2O 对粘土矿物位点的吸附；因此，较低的粘土/TC 值可以部分解释 Andosols 相对较大的 TF 值。Ex-K2O 含量低于 200 mg kg-1 且粘土/TC 值较低的样品显示 2011 年至 2012 年 TF 值显着下降。然而，2012 年至 2013 年的下降幅度很小；这些样品中的放射性铯有可能在很长一段时间内被水稻吸收，这可能是由于水铝石的可逆吸附和固定特性。在 3 年的研究中，大多数灰色低地土壤样品显示出非常低的 TF 值，由于 Ex-K2O 和粘土含量低而 TF 值大于 0.1 的除外；2012 年 TF 的几何平均值 (GM) 值低于 0.01。 用 1 mol L-1 醋酸铵溶液提取可交换放射性铯 (Ex-Cs) 可能不是解释 Andosols 中放射性铯 TF 变异性的合适方法. 这是因为 Ex-Cs 值与 Andosols 中的 Ex-K2O 显着相关，但在灰色低地土壤中没有，这表明 Ex-K2O 解释了与 Ex-Cs 相关的这种变异性。