BASIC EXPERIMENTS OF CS UPTAKE CAPABILITY FOR Eleocharis acicularis

Soil in the Fukushima area has been polluted with the radioactive contaminants such as Cs by the accident of Fukushima Daiichi nuclear power plant in March 2011. Remediation of soil contaminated with radioactive Cs remains one of the most important problems. Phytoremediation is an environmental remediation technique that takes advantage of plant physiology and metabolism to remove radioactive contaminants. Eleocharis acicularis is well known as heavy metal hyperaccumulator aquatic plant and expected as the strong candidate for application to Phytoremediation of polluted water and soil. In this study, a laboratory experiment was carried out to investigate the potential of E.acicularis for Phytoremediation of radioactive Cs contaminated site.The plants were grown hydroponically and placed in solutions containing Cs and K at different concentration (Cs concentration: 5 mg/L, K concentration: 0, 0.2, 2, 5, 50, 100 mg/L) in a period of 21days.In the experimental results, the highest concentration of Cs was 1560 mg/kg-DW in E. acicularis after 21 days. The concentration of Cs in plants decreased with the increasing initial concentration of K in the solution. This results indicate that E. acicularis has the ability to accumulate radioactive Cs from radioactive Cs contaminated soil and water, making it a good candidate species for radioactive Cs Phytoremediation. Keywords : Fukushima, Eleocharis acicularis, phytoremediation, C

Establishment of an Aseptic Culture System and Analysis of the Effective Growth Conditions for Eleocharis acicularis Ramets for Use in Phytoremediation

Eleocharis acicularis, an aquatic macrophyte of the Cyperaceae family, has been shown to accumulate multiple heavy metals and has great potential for use in the phytoremediation of contaminated soil and water. To investigate the mechanism of accumulation of heavy metals in E. acicularis while excluding biotic and abiotic environmental effects and to acquire homogenous and sufficient populations of E. acicularis, we established an aseptic culture system and analyzed the applicability of this species for phytoremediation. Young ramet bases and stolon tips of E. acicularis grown in the field were sterilized, cultured, and established in an aseptic culture system, and the effective growth conditions of isolated ramets were determined. Isolated ramets grew remarkably well in a medium of pH 4.8 to 5.7 with 0.25 mg/L kinetin as a plant hormone. Furthermore, capacity for the accumulation of heavy metals was examined using E. acicularis subcultured with or without Si. Aseptically cultured E. acicularis showed a sufficient capacity for Cs and Zn accumulation and exceeded the criteria for hyperaccumulator plants in accumulating Pb, Cd, and In regardless of the addition or not of Si during its subculture. The aseptic culture of E. acicularis enhances its capacity for the accumulation of heavy metals and its applicability for phytoremediation