HR: 1340h
AN: H53F-1502    [Abstracts]
TI: Effect of Cyclic Precipitation and Radiation on the Fate and Transport of TNT and DNT Near Soil-Atmospheric Surfaces
AU: * ANAYA, A
EM: angel.a.anaya@gmail.com
AF: UNIVERSIDAD DE PUERTO RICO, MAYAGUEZ, CARRETERA 108 Km. 1.0, mayaguez, PR 00681,
AU: PADILLA, I Y
EM: padillai@uprm.edu
AF: UNIVERSIDAD DE PUERTO RICO, MAYAGUEZ, CARRETERA 108 Km. 1.0, mayaguez, PR 00681,
AU: Hwang, S
EM: shwang@uprm.edu
AF: UNIVERSIDAD DE PUERTO RICO, MAYAGUEZ, CARRETERA 108 Km. 1.0, mayaguez, PR 00681,
AB: Many explosive-related compounds (ERCs) are found near the soil-atmospheric surface in sites containing buried explosive devices, such as landmines and unexploded ordnance, detonation-residual solid explosives, and munitions residues from explosive manufacturing facilities. Accurate assessment of the fate and transport processes is essential for predicting their movement to the surface, groundwater, or any other important environmental compartment. The dynamics of ERCs movement is complex, involving multiple, interrelated processes. The transport processes controlling the direction and magnitude of the movement, and chemical, physical, and biological processes controlling the fate of the chemicals vary with environmental conditions. This research addresses the effect of variable rainfall, evaporation, temperature, and solar radiation on fate and transport of 2,4,6-Trinitrotoluene (TNT), 2,4-Dinitrotoluene (DNT), and other related chemicals in partially saturated soil. Fate and transport experiments were conducted in a laboratory-scale geo-environmental system containing a 3D SoilBed packed with a sandy soil, and equipped with rainfall and solar radiation simulators, and temperature control settings. Experiments were conducted by burying a TNT/DNT source under the soil surface and applying cyclic rainfall and radiation over the surface of the soil. Aqueous and gaseous concentrations of tracers, TNT, DNT and other related ERCs were monitored through time at several distances from the source. Measured hydraulic conditions and tracer concentrations during the experiments indicate the existence of preferential flow paths during infiltration events and solute accumulation during evaporation periods. TNT, DNT and an undetermined chemical believed to be a degradation by-product of TNT were detected non-continuously in space and time. Concentrations of TNT and DNT were much lower than their solubility limits, indicating rate- limited mass-transfer, dissolution limitations, and dilution processes. Concentrations of the degradation by- product were measured at all sampling depths, but mostly in the upper segments of the SoilBed, suggesting greater degradation processes resulting from radiation-induced conditions near the soil-atmospheric surface. ERC vapors were mostly detected in the upper soil segments and above the soil surface toward the end of evaporation periods. In general, it is deduced that ERCs follow preferential flow path during infiltration periods but that the overall transport is further influenced by vapor transport, sorption, mass transfer, and degradation processes. Results indicate that the magnitude and direction of their transport were strongly influenced by changes in environmental conditions.
DE: 1842 Irrigation
DE: 1847 Modeling
DE: 1865 Soils (0486)
DE: 1866 Soil moisture
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting