Comparison of Potentials of Higher Plants for Phytoremediation of Radioactive Cesium from Contaminated Soil

摘要

Sixteen plant species were tested for their potential to remove radioactive cesium from contaminated soil with the Fukushima Daiichi nuclear disaster. There was a large difference of transfer factor (TF) of radiocesium (~(137)Cs) from the soil to plants. Among the examined plants, Hollyhock belonging to Malvaceae showed the highest TF but the efficiency of phytoremediation, such as total ~(137)Cs absorption of a plant or ~(137)Cs removal from unit area, was not proportionally high. According to the evaluation criteria (uptake of ~(137)Cs per plant and/or area), Kochia was shown to be the best plant species among 16 plants investigated here. Analysis of correlation showed that there was positive relationship between the total ~(137)Cs absorption and plant biomass, and contribution rate of plant biomass in total ~(137)Cs uptake by plant was scored to be 91.3%. These results indicate that selection of plant species that shows high biomass on site is important for ~(137)Cs-targeted phytoremediation rather than the plants’ ability in ~(137)Cs-uptake. On the other hand, our results also suggested that the TF value should be considered in order to evaluate the plant ability for ~(137)Cs-targeted phytoremediation. From this point of view, the present study suggests that field-grown Kochia could be used as a potential candidate plant for phytoremediation of ~(137)Cs from soil.