PENTACHLOROPHENOL AND PHENANTHRENE BIODEGRADATION IN CREOSOTE-CONTAMINATED AQUIFER MATERIAL

Contamination of the subsurface environment at the Libby Superfund Sit e, Montana, includes polycyclic aromatic hydrocarbons and pentachlorop henol due to accidental spills and improper disposal of wood preservin g wastes, Biodegradation is a treatment technology gaining wide applic ation in the treatment of hazardous waste sites. A microcosm study was conducted to evaluate the effect of temperature, sampling depth, nutr ient addition, and oxygen on the biodegradation potential of phenanthr ene and pentachlorophenol in aquifer samples using radiolabeled chemic als. Mineralization of phenanthrene reached 14% but was less than 1% f or pentachlorophenol over the 56 day incubation period. Phenanthrene m ineralization in microcosms at 10 degrees C was not significantly diff erent from those at 20 degrees C. This may have been due to microbial community acclimation to lower temperatures at the site. Average volat ilization was less than 2% for both phenanthrene and pentachlorophenol . After 56 days, most of the radiolabeled chemical was either solvent extractable or soil bound. (C) 1998 Elsevier Science Ltd. All rights r eserved.