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 a t numerous munitions production and storage facilities. The reductive trans formation of 2,4,6-trinitrotoluene (TNT) to aromatic (poly)amines and the c onsequent fate of these products were studied in anaerobic and aerobic sedi ment-water systems. Reduction of TNT was rapid under both anaerobic and aer obic conditions. Nitroreduction was regioselective, leading to the preferen tial formation of 4-amino-2,6-dinitrotoluene (4-ADNT) and 2,4-diamino-6-nit rotoluene (2,4-DANT). Subsequent sorption of 2,4-DANT was rapid under aerob ic conditions and resulted in nearly complete, irreversible retention by th e sediment phase. Under anaerobic conditions, the rapidly formed 2,4-DANT d isplayed little affinity for the sediment phase. Instead, 2,4-DANT was furt her transformed to products that remained in the aqueous phase. Sorption st udies in nontransforming sediments indicated increased irreversible sorptio n with replacement of nitro groups with amino groups. Covalent binding of t he DANTs was partially inhibited under anoxic conditions, but sorption of T NT and the ADNTs was unaffected by changes in redox conditions.