Sediment-Mediated Reduction of 2,4,6-Trinitrotoluene and Fate of the Resulting Aromatic (Poly)amines
2,4,6-Trinitrotoluene is a major surface and subsurface contaminant found at numerous munitions production and storage facilities. The reductive transformation of 2,4,6-trinitrotoluene (TNT) to aromatic (poly)amines and the consequent fate of these products were studied in anaerobic and aerobic sediment−water systems. Reduction of TNT was rapid under both anaerobic and aerobic conditions. Nitro-reduction was regioselective, leading to the preferential formation of 4-amino-2,6-dinitrotoluene (4-ADNT) and 2,4-diamino-6-nitrotoluene (2,4-DANT). Subsequent sorption of 2,4-DANT was rapid under aerobic conditions and resulted in nearly complete, irreversible retention by the sediment phase. Under anaerobic conditions, the rapidly formed 2,4-DANT displayed little affinity for the sediment phase. Instead, 2,4-DANT was further transformed to products that remained in the aqueous phase. Sorption studies in nontransforming sediments indicated increased irreversible sorption with replacement of nitro groups with amin...