A Comprehensive Study of the Alteration of Ignitable Liquids by Weathering and Microbial Degradation.

The differing effects of weathering and microbial degradation are described here in a comprehensive study that involved 50 different ignitable liquids from the Ignitable Liquids Database and Reference Collection. Examples of ignitable liquid residues from each of the main classes established by the American Society of Testing and Materials are presented. Weathering was accomplished via evaporation, whereas microbial degradation was carried out on soil at room temperature for periods of up to 21 days. Major trends included the rapid degradation of long n-alkanes and monosubstituted alkyl benzenes (e.g., toluene, ethylbenzene, and propylbenzene). Surprisingly, some longer branched alkanes (e.g., trimethyloctanes) were also susceptible to microbial attack. Although all ignitable liquids examined suffered at least to some extent from microbial degradation, gasoline, petroleum distillates, and oxygenates were the most susceptible. Isoparaffinic and naphthenic-paraffinic products were the most resistant to microbial degradation.