Mechanisms Underlying the Cone Penetrometer Detection of Energetic Materials in Soils

摘要

The Site Characterization and Analysis Penetrometer System (SCAPS) has demonstrated a variety of sensors for contaminants in soils. In this work, we focus on a sensor probe for the in situ detection of explosives. In a number of field tests, this probe has produced a very encouaging data set, including good comparisons with laboraotry and field chemical analyses of nearby soil samples. The components of each version of this probe have been an external pyrolyzer, a sweep gas flow which draws gases evolved from the soil into the probe, and electrochemical sensors (initially, a single sensor responding to nitric oxide, NO, a major decomposition product of all of the above energetic materials). We present results of a program of laboratory experiments, computer modeling and analysis of the SCAPS field data, with the goal of constructing an approximate predictive model capable of correlating observations of NO for a variety of soil heating parameters. We conclude that contact between soil and heatign element is required to reach soil temperatures adequate to produce observed signals, and that a low temperature, large area heatign element will require more sensitive NO detection than did previous, hgih temperature pyrolysis probes.