Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima city, Fukushima prefecture, 960-1296, Japan; Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima city, Fukushima prefecture, 960-1296, Japan.
Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima city, Fukushima prefecture, 960-1296, Japan.
J Environ Radioact. 2022 May;246:106847. doi: 10.1016/j.jenvrad.2022.106847. Epub 2022 Feb 23.
Understanding the soil-to-plant transfer process of Cs is essential for predicting the contamination levels of plants in contaminated areas. The rooting depth is considered one of the key factors explaining the difference in the activity concentration of Cs in different plant species. In this study, the distributions of Cs and Cs in soils and plants were investigated, and the plants' rooting depth of Cs uptake was estimated using the Cs/Cs ratios in exchangeable fractions of soils and biological samples. The results showed that different plant species accumulate different levels of Cs and Cs. The Cs/Cs ratios were fairly constant in plants of the same species. The average Cs/Cs ratios in bamboo grasses and ferns were 0.015 ± 0.009 (n = 5) and 0.13 ± 0.04 Bq ng (n = 10) in Yamakiya, respectively. The percentage of Cs in the exchangeable fraction of the uppermost soil layer was lower than that in the deeper soil layers. The activity concentrations of Cs in the soil profiles decreased sharply with depth, whereas the depth distributions of Cs were uniform. Therefore, the Cs/Cs ratios were driven mainly by the Cs activity concentrations in soil. The plants' rooting depths of Cs uptake were estimated on the basis of the relationships between the averaged Cs/Cs ratio in the soil layer and the Cs/Cs ratio in the plant. The results indicate that the deeper-rooted species such as bamboo grasses have a lower accumulation of Cs than the superficial-rooting species such as ferns. The soil-to-plant transfer factors would be determined using rooting depth by calculating the averaged activity concentration of Cs within the estimated rooting depth.
了解 Cs 在土壤-植物间的迁移过程对于预测污染地区植物的污染水平至关重要。根长被认为是解释不同植物物种中 Cs 活性浓度差异的关键因素之一。本研究调查了 Cs 和 Cs 在土壤和植物中的分布，并利用土壤和生物样品可交换态中 Cs/Cs 比值来估算植物对 Cs 的根长吸收。结果表明，不同植物物种积累不同水平的 Cs 和 Cs。同一物种的植物中 Cs/Cs 比值相当稳定。在八木谷，竹类和蕨类植物中的平均 Cs/Cs 比值分别为 0.015±0.009（n=5）和 0.13±0.04 Bq ng（n=10）。最上层土壤中可交换态 Cs 的百分比低于深层土壤。土壤剖面中 Cs 的活度浓度随深度急剧下降，而 Cs 的深度分布则较为均匀。因此，Cs/Cs 比值主要受土壤中 Cs 活度浓度的驱动。根据土壤层中平均 Cs/Cs 比值与植物中 Cs/Cs 比值之间的关系，估算了植物对 Cs 的根长吸收。结果表明，竹类等深根物种比蕨类等浅根物种对 Cs 的积累量较低。通过计算估计的根长内 Cs 的平均活度浓度，可以用根长来确定土壤-植物转移因子。
