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Long‐Term TNT Sorption and Bound Residue Formation in Soil
Author(s) -
Hundal L. S.,
Shea P. J.,
Comfort S. D.,
Powers W. L.,
Singh J.
Publication year - 1997
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1997.00472425002600030042x
Subject(s) - sorption , environmental chemistry , chemistry , soil water , environmental remediation , adsorption , humic acid , organic matter , soil contamination , humus , humin , contamination , residue (chemistry) , soil organic matter , soil science , environmental science , organic chemistry , ecology , fertilizer , biology
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 solidphase 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 14 C‐TNT with the soil revealed a gradual increase in amount sorbed and formation of unextractable (bound) 14 C residues. The presence of solid‐phase TNT did not initially affect the amount of 14 C sorbed during a 168‐d equilibration. After 168 d, 93% of the added 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 m M CaCl 2 ) and potentially available (CH 3 CN‐extractable) sorbed TNT decreased rapidly with time and coincided with increased 14 C in soil organic matter. More 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 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.