Transport of explosive chemicals when subjected to infiltration and evaporation processes in soils

Abstract

Knowledge of Explosive Related Compounds (ERCs) fate and transport is necessary to assess contamination potential to protect drinking water supplies from toxic contaminants, develop remediation strategies, and facilitate the detection of buried explosives. In this study six experiments were developed to evaluate the effects of infiltration and evaporation events on explosive chemicals transport. These experiments were conducted in a 100 cm uniform cylindrical sand column packed with homogeneous sand, instrumented with air and water pressure sensors and sampling ports to monitor hydraulic conditions and ERCs concentration profiles in soil. This research studied the transport behavior of ERC in soil under different environmental conditions, when subject to advection (fluid movement). The results show that transport of TNT (2,4,6 trinitrotoluene) and DNT (2,4 dinitrotoluene) is influenced by dissolution (source-water), volatilization (water-air), and sorption (water-soil) mass transfer limitations. Downward movement with infiltrating water is generally retarded by sorption processes at soil and air-water surfaces. Upward movement of water during evaporation processes results in upward movement of ERCs toward the soil-atmospheric surfaces. Water evaporation near the soil surface results in increased ERCs concentrations near the soil surface after prolonged evaporation periods