Assessing the phytoremediation potential of tall fescue and sericea lespedeza for organic contaminants soil

摘要

The phytoremediation potential of using tall fescue IFestuca arundinacea Schreb.) grass and sericea lespedeza (Lespedeza cuneata [Dum. -Cours.]) legume species was assessed using three different groups of organic contaminants in soil. One hundred parts per million (ppm) each of a nitroaromatic compound (TNT), a polycyclic aromatic hydrocarbon (Pyrene), and a polychlorinated biphenyl (Aroclor 1248) were used to contaminate the soils. The experiments were conducted using soils with high and low organic-matter content The results indicate that recoveries of Pyrene and TNT were very low in all treatments in soil with high organic-matter content (6.3 percent) compared with recoveries in soil with low organic-matter content (2.6 percentl. In contrast, recoveries of PCB from soil were not dependent on the soil's organic-matter content Planting both the legume and grass species had significant effect on the transformations of TNT and PCB in the soil with low organic-matter content and did not affect the fate of Pyrene in both soils. The amount of TNT transformed in the four months of plant growth was 63 percent in the tall fescue and 46 percent in the sericea-planted soils, compared with only a 15 percent unaccounted loss in the unplanted control soils. Furthermore, the grass species, with its massive root system, was significantly better at causing TNT dissipation compared with the legume species, which has less root vegetative mass. The plant biomass, particularly the shoot weight of the tall fescue grass, was significantly increased as a result of TNT treatment Tall fescue and sericea biomass did not appear to have any significant effect on Pyrene transformation. Planting sericea provided a significantly high level of PCB transformation in soils with either high or low amounts of organic matter: Tall fescue did not appear to have any significant effect on PCB trans formation.