ABSTRACT

Radiocesium (¹³⁷Cs) contamination caused by the Fukushima Daiichi Nuclear Power Plant accident has posed a serious problem, especially for forest ecosystems. Phytoremediation is an effective decontamination method with less disturbance to the ecosystems than tree felling and soil removal. Eleutherococcus sciadophylloides is one of the ¹³⁷Cs-accumulating tree species in Japan. However, the accumulation mechanism is not well understood. Herein, we aimed to clarify the contribution of the colonization of arbuscular mycorrhizal fungi (AMF) to ¹³⁷Cs uptake by E. sciadophylloides based on both field and greenhouse experiments. In the greenhouse experiment, we used a growth pot system with a mesh partition, which enable to confirm separately the contribution of AMF hyphae from tree roots. In addition, because potassium (K) in the rhizosphere is related to ¹³⁷Cs uptake, we also aimed to clarify the role of AMF in ¹³⁷Cs uptake by E. sciadophylloides in the presence of K. Semi-quantitative analysis of the field survey revealed a significant and positive relationship between AMF colonization and radioactivity in the fine roots of E. sciadophylloides. The pot experiments with K treatment indicated that AMF contributes to ¹³⁷Cs uptake by E. sciadophylloides through its hyphae, and that the addition of K into the rhizosphere was effective in increasing the ¹³⁷Cs uptake synergistically by AMF colonization. These results could prove helpful to future applications of AMF and K for enhanced phytoremediation of ¹³⁷Cs by E. sciadophylloides.

摘要

福岛第一核电站事故造成的放射性铯（¹³⁷ Cs）污染已引起严重问题，尤其是对于森林生态系统。植物修复是一种有效的去污方法，与砍伐树木和去除土壤相比，对生态系统的干扰较小。拟南芥肠球菌是日本积累的¹³⁷种Cs树种之一。但是，积累机制还没有被很好地理解。在这里，我们的目的是明确的丛枝菌根真菌（AMF）殖民化的贡献，以¹³⁷的铯摄入E. sciadophylloides基于野外和温室实验。在温室实验中，我们使用了带有网状隔板的生长罐系统，该系统能够分别确认树根的AMF菌丝的贡献。此外，由于根际中的钾（K）与¹³⁷ Cs的吸收有关，我们还旨在阐明AMF在存在K的情况下对E. sciadophylloides吸收¹³⁷ Cs的作用。对田间调查的半定量分析显示sciadophylloides细根的AMF定植与放射性之间存在显着的正相关关系。用钾处理的盆栽实验表明，AMF有助于二十碳五倍体大肠杆菌吸收¹³⁷ Cs通过其菌丝，以及在根际中添加K可以有效地通过AMF定植协同增加¹³⁷ Cs的吸收。这些结果可能有助于今后利用AMF和K来增强二十碳糖藻对¹³⁷ Cs的植物修复作用。