This study analyzes the ¹³⁷Cs behavior in the ponds of Okuma Town from 2015 to 2019 in the Fukushima Dai-ichi nuclear power plant (FDNPP) exclusion zone. A decline in both particulate and dissolved ¹³⁷Cs activity concentrations was revealed. The decline rate constants for the particulate ¹³⁷Cs activity concentration were found to be higher than for the dissolved ¹³⁷Cs activity concentration. In terms of seasonality the dissolved ¹³⁷Cs concentrations were higher from June to October, depending on the specific pond and year, most likely due to temperature dependence of ¹³⁷Cs desorption from frayed edge sites of micaceous clay minerals. The apparent K_d(¹³⁷Cs) in the studied ponds, in absolute value, appeared to be much higher than that for closed and semi-closed lakes of the Chernobyl contaminated area; however, these were comparable to the values characteristic of the rivers and reservoirs of the FDNPP contaminated area. The apparent K_d(¹³⁷Cs) in the suspended sediment–water system was observed to decrease over time. It was hypothesized that this trend was associated with the decomposition of glassy hot particles. Relying on the theory of selective sorption and fixation, the exchangeable radiocesium interception potential, RIP^ex(K) was estimated using data on ¹³⁷Cs speciation in the surface bottom-sediment layer and its distribution in the sediment–water system. For the studied ponds, RIP^ex(K) was on the average 2050 mEq/kg, which is within the range of values measured in laboratory studies reported in the literature.

本研究分析了2015年至2019年福岛第一核电站（FDNPP）禁区中大沼町池塘中¹³⁷ Cs的行为。发现颗粒和溶解的¹³⁷ Cs活性浓度均下降。发现颗粒¹³⁷ Cs活性浓度的下降速率常数高于溶解的¹³⁷ Cs活性浓度的下降速率常数。就季节性而言，从6月到10月，溶解的¹³⁷ Cs浓度较高，具体取决于池塘和年份，这很可能是由于从云母黏土矿物的磨损边缘部位解吸的¹³⁷ Cs对温度的依赖性。表观K _d（¹³⁷ Cs）的在所研究的池塘，在绝对值，似乎是比用于切尔诺贝利污染区域的闭合和半封闭湖泊高得多; 但是，这些值与FDNPP污染地区的河流和水库的特征值相当。观察到悬浮泥沙-水系统中的表观K _d（¹³⁷ Cs）随时间降低。据推测，这种趋势与玻璃状热颗粒的分解有关。根据选择性吸附和固定的理论，使用^137上的数据估算了可交换的放射性铯截留电位RIP ^ex（K）表层底部沉积物层中的Cs形态及其在沉积物-水系统中的分布。对于研究池塘，RIP ^ex（K）平均为2050 mEq / kg，在文献报道的实验室研究中测得的值范围内。