Phytoremediation of Soil Contaminated with Pentachlorophenol (PCP)

摘要

Pentachlorophenol (PCP) is a potent biocide mainly used for preservation of wood and occurs as a soil and water contaminant at many current and former wood-treating sites. The application of plants to stabilize, degrade, or concentrate contaminants, known as phytoremediation, is a possible clean-up 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. The PCP-contaminated soil came from a wood-treating site located in the Southeast and contained very high concentrations of PCP. Trees, grasses, and winter cover crops were planted in different levels of contaminated and clean soil and monitored for survival, growth, root development, and PCP decreases. In the initial study, eleven tree species were grown in 5,000, 2,500, and 1,250 ppm PCP-contaminated soil plus non-contaminated controls. The three best surviving tree species were then planted in 5,000 and 2,500 ppm PCP-contaminated soil. Of all of the trees planted in the PCP-contaminated soil, only those planted with organic humus surrounding the roots survived and grew. Switchgrass, gammagrass, and Indian-grass were planted in soil containing 1,250 ppm PCP. Within two weeks, all plants died. A screening of winter cover crops including hairy vetch, crimson clover, arrowleaf clover, rape, annual rye, and perennial rye was conducted. Of these only hairy vetch germinated and grew, while annual rye would grow if transplanted but would not germinate. PCP is a potent plant toxin and the use of phytoremediation for PCP-contaminated soils appears to be restricted to low PCP concentrations and would likely not be successful on wood-treating sites.