Biodegradation of Dissolved Aromatic Hydrocarbons in Gasoline-Contaminated Groundwaters Using Denitrification

The four aromatic hydrocarbons commonly found in gasoline—benzene, toluene, xylene, and ethylbenzene—are among the top 20 of those hazardous substances most often found in sites on EPA’s National Priority List. Many of the gasoline hydrocarbons are hydrophobic molecules, and hence possess low solubilities in water. They exhibit a marked tendency toward adsorption onto the soil phase of an aquifer, so the conventional removal of the “free product” from a contaminated site is largely ineffective at removing the majority of the spilled gasoline.