Differences in Remediation Effect of ~(137)Cs in Napiergrass (Pennisetum purpureum Schum.) under Different Land-Use Soil and Cutting Frequency Conditions

摘要

The present study reports the remediation of radiocesium-137 (~(137)Cs) using napiergrass in Cs-contaminated soils of Fukushima Prefecture. Two field experiments were performed to examine the remediation effects in two different land-use soils (lowland and upland soils) using two different cutting frequencies (cut once or twice a year). Plant growth in the upland soil was significantly greater than that in the lowland soil. The ~(137)Cs concentration (Bq kg~(-1) dry weight basis) in the aboveground parts and total Cs-removal ratio (CR) in the upland soil were also significantly higher than those in the lowland soil. In the lowland soil, cutting twice a year [at 12 and 24 weeks after transplanting (WAT)] was more effective for CR (P＜0.01) than cutting once a year (18 WAT); however, there was no significant difference of CR related to cutting difference in the upland soil as a result of the shading effect on the plants at second cutting. In the present study, above-ground dry matter weight was highly correlated with CR in both fields. Given the possibility to increase plant number per unit of land to increase aboveground bio-mass per unit of land, the potential Cs remediation effect could be much greater in a wide range of Cs-contaminated soils than the potential of napiergrass for Cs uptake demonstrated in the present study.