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

Abstract

The present study reports the remediation of radiocesium-137 (137Cs) 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 137Cs 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, aboveground 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 biomass 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.