Impact of Anaerobic Conditions and Microbial Activity on the Bioavailability of High Molecular Weight Polycyclic Aromatic Hydrocarbons in Soils. FY00-224

摘要

The influence of imposed anaerobic conditions on aqueous phase polycyclic aromatic hydrocarbon (PAH) fate was investigated. Highly aged, PAH contaminated soil was incubated with an oxygen scavenging titanium (III) citrate complex, or water, or water that contained nitrate or sulfate in combination with a H2(g), N2(g), or N2:CO2(g) (80:20) headspace. The anaerobic conditions imposed in this study resulted in increased aqueous concentrations of fluoranthene, pyrene, BenzAanthracene and benzoApyrene. BenzAanthracene and benzoApyrene were above a aqueous solubility limits, by as much as an order of magnitude for the latter. The mechanism for this increased PAH solubility is hypothesized to be a combination of oxidation-reduction potential and microbially mediated pH alteration resulting in enhanced solubility of organic material with associated PAH. Methanogenic organisms and sulfate reducing bacteria were seen to have the most significant effect on an increase in aqueous phase PAH. In addition, incubations that changed from anaerobic to aerobic conditions assessed the effect of anaerobiosis conditions on bioavailability. The solvating effect of formalin, used as a metabolic inhibitor, was also examined.