Long-term TNT sorption and bound residue formation in soil
- Univ. of Nebraska, Lincoln, NE (United States)
Soils surrounding former munitions production facilities are highly contaminated with 2,4,6-trinitrotoluene (TNT). Long-term availability and fate of TNT and its transformation products must be understood to predict environmental impact and develop appropriate remediation strategies. Sorption and transport in surface soil containing solid-phase TNT are particularly critical, since nonlinear sorption isotherms indicate greater TNT availability for transport at high concentrations. Our objectives were to determine long-term sorption and bound residue formation in surface and subsurface Sharpsburg soil (Typic Argiudoll). Prolonged equilibration of {sup 14}C-TNT with the soil revealed a gradual increase in amount sorbed and formation of unextractable (bound) {sup 14}C residues. The presence of solid-phase TNT did not initially affect the amount of {sup 14}C sorbed during a 168-d equilibration. After 168d, 93% of the added {sup 14}C was sorbed by uncontaminated soil, while 79% was sorbed by soil containing solid-phase TNT. In the absence of solid phase, pools of readily available (extractable with 3 mM CaCl{sub 2}) and potentially available (CH{sub 3}CN-extractable) sorbed TNT decreased rapidly with time and coincided with increased {sup 14}C in soil organic matter. More {sup 14}C was found in fulvic acid than in the humic acid fraction when no solid-phase TNT was present. After sequential extractions, including strong alkali and acid, 32 to 40% of the sorbed {sup 14}C was irreversibly bound (unextractable) in Sharpsburg surface and subsurface soil. Results provide strong evidence for humification of TNT in soil. This process may represent a significant route for detoxification in the soil-water environment. 58 refs., 6 figs., 3 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 494216
- Journal Information:
- Journal of Environmental Quality, Vol. 26, Issue 3; Other Information: PBD: May-Jun 1997
- Country of Publication:
- United States
- Language:
- English
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