PARENT SESSION
Biodegradation and Biotransformation.
John Knezovich, Tom Federle
Tuesday, November 14, 2000
1:20 PM to 5:20 PM
CC 108-109
(264) Microbial mineralization and transformation of Phenanthrene in coastal sediment microcosms.
Tidwell, Angela D.1, Aelion, C. Marjorie1, 1
ABSTRACT- Polycyclic aromatic hydrocarbons (PAHs) pose a significant threat to the environment and public health due to their widespread nature and carcinogenic potential. Due to their hydrophobicity, PAHs tend to bind tightly to sediment and sediment organic matter. The objective of this research was to examine to what extent indigenous microbes from 4 different coastal sediments degraded radiolabeled 14C-phenanthrene (PHE) to 14CO2 or transformation products. 14CO2 produced in sediment microcosms was trapped in NaOH and quantified using a liquid scintillation counter. The fate of the sediment-bound PHE and the formation of transformation products were determined through a series of solvent and organic matter extractions. Results indicated that up to 70% of the initial PHE added was mineralized within 50 days of incubation in golf course aquatic sediments. There was evidence that a significant fraction (20%) of 14C-PHE became incorporated into a bound residue with the organic matter as a result of a biological reaction. In contrast, bacteria from undeveloped estuarine sediments did not rapidly degrade PHE. Transformation products may be formed in some sediments and incorporated into a bound residue thereby immobilizing the remaining PHE. However, PHE may remain relatively unchanged in other sediments and thus have greater potential to migrate from the sediment and contaminant the water column when sorbed to colloids or other mobile particles.
Key words: PAH, mineralization, transformation, sediment