Vapor Diffusion in Soil: Simulated Explosive Burials and Canine Trials – Presented by Emma Calabrese

Buried explosive devices have been used throughout history and remain a hazard in conflicts today. They are of particular concern as they persist after the conflict is resolved. Canines, and other biosensors, are used in landmine remediation efforts as their superior olfactory system enables them to detect the volatile organic compounds (VOCs) being emitted from a target with superior sensitivity and selectivity. When an explosive device is buried, VOCs must travel through the soil to the surface. This process introduces sources of vapor loss, notably sorption to the soil, limiting vapor availability. This study considers the impact of various conditions on the simulated burial of two explosive-related compounds: 2,4-dinitrotolune (DNT) a degradant and contaminant from TNT and 2,3-dimethyl-2,3-dinitrobutane (DMNB) a common taggant in C-4. Headspace solid phase microextraction (HS-SPME) was used to measure free volatiles at varying heights in the simulated burials over time, providing quantitative evidence of the gaseous diffusion process. A driving force of vapor transport was confirmed to be evapotranspiration, as conditions with moisture and sunlight resulted in higher concentrations of analyte present. Additionally, stronger adsorption to soil indicated that environments with a higher sand content are likely to have more successful detection of buried explosives. Complementary canine olfactory trials were conducted to validate the results of the laboratory study. This work points to environments where detection of a buried explosive device is more likely to be successful or limited.

Coming soon.