HR: 15:40h
AN: B43B-03    [Abstracts]
TI: Development of Physical Systems for Fate and Transport Measurements of TNT and DNT in Variably-Saturated Soils
AU: * Padilla, I Y
EM: padillai@uprm.edu
AF: Department of Civil Engineering, University of Puerto Rico, Mayaguez, PO Box 9041, Mayaguez, PR 00681,
AU: Hwang, S
EM: shwang@uprm.edu
AF: Department of Civil Engineering, University of Puerto Rico, Mayaguez, PO Box 9041, Mayaguez, PR 00681,
AB: Transport of chemicals from buried explosives in soils influences their detection at the surface. The transport of these chemicals in soils is controlled by fate and transport processes, which are influenced by environmental and soil factor. These processes are often studied though the development of models that simulate the conditions found in the field. Laboratory-scale physical models are attractive for this purpose because they can be controlled to isolate specific parameters and minimize interferences from unknown conditions. These model, however, must be developed properly to be representative of processes and conditions found in the field. This research focuses on the development of physical transport models to simulate the fate and transport processes that occur in the field under variable environmental conditions. To achieve this, field lysimeters (soil tanks) have been designed and developed. The lysimeters are exposed to outdoor conditions, which are variable and uncontrolled but measurable. Transport experiments in these lysimeters are supported by a wide range of laboratory-scale models, ranging in size and dimensions, that simulate transport of DNT and TNT subjected to controlled environmental conditions. The development of the scalable systems and methods involved proper reproduction of soil composition, lithology, and structures, appropriate placement of boundary conditions, suitable simulation of representative environmental conditions, and the use of representative sampling systems. All systems developed use the same field soils, which are packed to similar properties. Flow and transport boundaries were developed to simulate free or no flow, capillary-controlled, constant concentration or temporally- variable point source conditions. Representative environmental conditions in the laboratory-scale models are imposed through temperature-controlled transfer, lighting systems, and rainfall simulators. Simulated processes include advective and dispersive transport under infiltration and evaporation conditions, rate-limited dissolution and vapor transfer, surface retention, degradation, vegetation uptake, and daily radiation and precipitation. This presentation addresses the development of the physical models and the results obtained on the experimental work conducted to determine and quantify the effect of environmental factors on fate and transport of TNT and DNT from buried explosive devices.
DE: 0499 New fields (not classifiable under other headings)
DE: 1832 Groundwater transport
DE: 1875 Vadose zone
SC: Biogeosciences [B]
MN: 2007 Joint Assembly