Influence of Soil on Detection of Buried Explosives and Tunnels by Trace Gas Analysis
Detection of mines, explosives, and tunnels may be accomplished by sensing associated volatile effluvia. This investigation was undertaken to provide a basis for predicting the diffusion of volatile compounds from underground sources into the atmosphere. Diffusion of a volatile compound was studied for a range of soil conditions utilizing soils from the mine detection sites in Puerto Rico. A new mathematical analysis based on the Monte Carlo method was developed for predicting vapor diffusion through soil into the atmosphere. It was determined that diffusion in soil can be reliably predicted if soil porosity, moisture content, and affinity for the compound are known. Appearance in the atmosphere is also dependent on accumulation of the compound in air at the soil/atmosphere interface. Diffusion of volatile compounds through soil into the atmosphere is not likely to be an important factor in tunnel detection due to depth of overburden. However, adsorption of compounds at tunnel walls is likely to significantly reduce the amount of vapor appearing in the atmosphere through entrances and vents. Detection in the atmosphere of TNT vapor from mines and explosives buried in moist, porous soil should be possible under ideal sample collection conditions. (Author)
Print Book, English, JUN 1971
Defense Technical Information Center, Ft. Belvoir, JUN 1971