Choi Y H, Lim K M, Choi H J, Choi G S, Lee H S, Lee C W
Nuclear Environment Research Division, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Daejon, 305-600, South Korea.
J Environ Radioact. 2005;78(1):35-49. doi: 10.1016/j.jenvrad.2004.03.036.
In order to study the plant uptake and downward migration of radiostrontium and radiocesium deposited on to a flooded rice field, 85Sr and 137Cs were applied to the standing water over an acidic sandy soil in planted lysimeters. The plant uptake was quantified with the areal transfer factor (TFa, m2 kg(-1)-dry plant). Following the spiking 14 days after transplanting, the TFa values for the hulled seeds were 3.9 x 10(-4) for 85Sr and 1.4 x 10(-4) for 137Cs, whereas those for the straws were 1.3 x 10(-2) and 3.2 x 10(-4), respectively. The 137Cs TFa from the spiking at the anthesis/milky-ripe stage was several times higher than that from the earlier spiking, whereas the difference was much less in the 85Sr TFa. Such an increase in the 137Cs TFa was attributed mainly to an enhanced plant-base uptake. The addition of KCl and lime after the spiking significantly reduced the TFa values of both radionuclides. The reducing effect was greater for the later spiking. An appreciable fraction of the applied activity leached out of the lysimeter for 85Sr, whereas a negligible fraction leached for 137Cs. The leaching was remarkably increased by the KCl and lime addition for both. A conspicuous localization of 137Cs with respect to the soil surface was observed. In a batch experiment, the 137Cs concentration in the standing water decreased more rapidly than that of 85Sr, both of which were fitted to the power functions of the elapsed time. To add KCl and lime slowed such decreases to lessen the distribution coefficients (Kd) of both 85Sr and 137Cs.
为了研究沉积在淹水稻田中的放射性锶和放射性铯的植物吸收及向下迁移情况，在装有酸性砂土的种植渗漏计中，将85Sr和137Cs施用于稻田的积水里。植物吸收量通过面积转移系数（TFa，m² kg⁻¹ - 干植物）进行量化。移栽14天后进行加标处理，去壳种子的85Sr的TFa值为3.9×10⁻⁴，137Cs的TFa值为1.4×10⁻⁴，而稻草的TFa值分别为1.3×10⁻²和3.2×10⁻⁴。在花期/乳熟期加标的137Cs的TFa比早期加标的高出几倍，而85Sr的TFa差异则小得多。137Cs的TFa增加主要归因于植物基部吸收增强。加标后添加氯化钾和石灰显著降低了两种放射性核素的TFa值。后期加标的降低效果更明显。对于85Sr，相当一部分施加的活度从渗漏计中淋溶出来，而对于137Cs，淋溶部分可忽略不计。添加氯化钾和石灰后，两者的淋溶量均显著增加。观察到137Cs在土壤表面有明显的定位。在批量实验中，积水里137Cs的浓度下降速度比85Sr快，两者均符合经过时间的幂函数关系。添加氯化钾和石灰减缓了这种下降，降低了85Sr和137Cs的分配系数（Kd）。
