Transport of Explosive Chemicals in Fire-Affected Hawaiian Topsoil

Several areas in Hawaii have background concentrations of unexploded ordnance (UXO) as a consequence of past and current military training. The presence of UXO and the release of their chemical compounds can be of environmental concern. The complete and incomplete detonation of explosives can ignite vegetation fires that cause organics in the topsoil to burn, and therefore, impact the environmental fate of these compounds. The sorption and transport of two UXOs, HMX and RDX, were investigated in a surface soil that was previously exposed to a fire event. In addition, a control soil that had not been exposed to a fire event was used. The use of burned and unburned soil to simulate soil that has been directly impacted by the explosion of UXOs combined with the uniqueness of the soil properties in Hawaii represents the novelty of this study. The surface soil that had been previously exposed to a fire event showed greater adsorption than the control, which was possibly due to a reduction of macropores in the burned soil and the presence of fine charcoal particles. Regardless of the presence or absence of a fire event, HMX showed a greater sorption affinity than RDX. (c) 2020 American Society of Civil Engineers.