Microbial Degradation of Gasoline in Soil

Abstract

Abstract Forensic science analysis of soil samples for the presence of flammable liquids occasionally results in the detection of volatile mixtures that lack some of the diagnostic features of common petroleum products. The presence of these mixtures is not consistent with evaporation or with a chemical or physical process, but is reported in microbiological literature that addresses bacterial degradation. Microbiological research has shown that crude oil spilled in the environment is sometimes degraded by bacteria. A study was conducted to demonstrate how automotive gasoline is degraded. Gasoline was spiked into 36 containers of soil (12 were stored at −5°C; 12 were stored at room temperature; and 12 of the soil samples were sterilized prior to the addition of the gasoline and were then stored at room temperature). These samples were monitored, and the results were compared using static heated headspace sampling and capillary gas chromatography. The gasoline in the unsterilized samples stored at room temperature degraded rapidly, while the gasoline in the other two sets of samples was unaffected. This degradation followed trends that can be recognized in casework and can assist in the identification of affected petroleum product residues in soil.