Transport of TNT in munitions contaminated soils
- Univ. of Nebraska, Lincoln, NE (United States)
Past production practices at munitions ordnance plants have resulted in contamination of terrestrial and aquatic ecosystems. Efforts to date have documented the nature of contamination and attempted to estimate potential migration routes. To predict the fate of munitions in contaminated soils, an accurate prediction of the adsorption-desorption process is critical. Soils from drainage ditches at the abandoned Nebraska Ordnance Plant were found to be highly contaminated with TNT. Equilibrium soil solution concentrations were approximately 70 mg L{sup {minus}1} and relatively independent of soil to solution ratios, indicating the presence of solid phase TNT. Transport experiments were conducted using solute pulses of 70 mg TNT L{sup {minus}1} with uncontaminated soil and with soil columns containing contaminated and uncontaminated layers. Experiments were performed by displacing 27 or 53 pore volumes of TNT-{sup 3}H{sub 2}O pulse through disturbed soil columns at a pore water velocity of 11 cm d{sup {minus}1}. Results using uncontaminated soils indicated that breakthrough curves of TNT effluent concentrations never reached initial solute pulse concentrations. The equilibrium adsorption isotherm for TNT sorption on the uncontaminated soil was characterized as a nonlinear Freundlich type. Assuming local equilibrium and using a batch-determined distribution coefficient (K{sub d}) in the convection-dispersion equation resulted in an over estimation of elution times. These results indicate that errors can result by assuming a linear adsorption isotherm when predicting TNT transport in highly contaminated soils.
- OSTI ID:
- 491085
- Report Number(s):
- CONF-9406250--
- Country of Publication:
- United States
- Language:
- English
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