Research Product

Polychlorinated biphenyl (PCB)-contaminated sites are often co-contaminated with fossil fuels making biodegration more difficult. Our current studies examine biodegradation of the fossil fuel components of two PCB-contaminated sites: (1) a former racing Drag Strip soil contaminated with Aroclor 1242 and (2) a sediment from Silver Lake contaminated with Aroclor 1260. The sandy surface soil at the Drag Strip site contains 1.9% organic carbon and 1.5% fossil fuel component. Analysis of the solvent-extractable organic fraction, by alumina column chromatography, shows the distribution of organics to be 91.2% hydrocarbons, 7.8% polars, and 1.1% asphaltenes. This oil is extremely weathered and contains few readily biodegradable components. Enrichments have yielded undefined mixed cultures of bacteria capable of extensive degradation of components of both the Drag Strip and Silver Lake site materials. One culture, enriched from a creosote-contaminated soil adjacent to a utility pole, transformed approximately 28% and 37% (by weight) of the Drag Strip and Silver Lake oils, respectively. While the presence of fossil fuels has been shown to inhibit aerobic PCB degradation, our studies show that the presence of PCBs negatively impacts fossil fuel biodegradation. continuing studies will examine the nature of PCB inhibition of fossil fuel biodegradation.