Practical methods for mitigating microbial degradation of ignitable liquids in soil samples

Abstract

In fire debris analysis, it is commonly accepted that soil samples can potentially cause degradation of ignitable liquids through microbial activity. Temperature- and solvent-based mitigation methods have been explored, but space and practical application limitations potentially cause problems for these mitigation methods. Alternate mitigation methods using carbon dioxide cartridges, dry ice, and oxygen-adsorbent pouches were cursorily explored as possible practical options to slow microbial activity through the displacement or removal of oxygen within the sample cans. Sample cans were left at room temperature, refrigerated, or treated with a mitigation agent and tested for up to four weeks after application of the gasoline, with cans prepared in triplicate for each time point and storage condition.The carbon dioxide cartridges were ultimately found to be unreliable and widely variable with respect to ignitable liquid contamination. Dry ice did not mitigate the microbial degradation and added additional safety concerns. The oxygen-adsorbent pouches prevented the degradation of gasoline for up to four weeks in the examined soil and did not introduce contamination or safety hazards. Further research is needed to more fully evaluate this potential mitigation method prior to introduction into the field.