Evaluation of phytoremediation of pentachorophenol using eleven tree and three native grass species

Pentachlorophenol (PCP), a potent biocide used mainly for wood preservation, occurs as a soil and water contaminant due to point source pollution and leaching from treated lumber. Older wood treatment sites are often small and nestled among residential areas. The use of plants to stabilize, degrade or concentrate contaminants, known as phytoremediation, is a feasible option for such sites since it is a relatively low-cost in situ technology. The objective of this study was to determine which species of trees and grasses indigenous to the southeastern region could be used to stimulate degradation of PCP in contaminated soil. Trees and grasses were planted in different levels of contaminated and clean soil and monitored for survival, growth and root development. The PCP contaminated soil came from a test site located in the Southeast and contained very high concentrations of PCP. Very few of the trees and grasses evaluated were able to survive in this soil, even when it was diluted to 1,250 ppm of PCP. PCP is a potent plant toxin and the use of phytoremediation for PCP soils appears to be limited.; Planting trees of eleven different species with humus organic matter showed that species could survive in pentachlorophenol contaminated soil, however the organic humus material appeared to serve as a protective shield to the direct exposure of PCP. Trees planted bare root with no humus protecting the root structure did not survive in the PCP contaminated soil after three weeks. Herbaceous grasses did survive and grow in the PCP contaminated soil during an initial test planting (November 2002). However these grasses did not grow during any other planting. Further studies should be conducted on some of these species at lower concentrations.