Fate of 2,4,6-trinitrotoluene and its metabolites in natural and model soil systems

The sorption-desorption characteristics of 2,4,6-trinitrotoluene (TNT), 4-amino-2,6-dinitrotoluene (4-ADNT), and 2,4-diamino-6-nitrotoluene (2,4-DANT) within a natural topsoil, an illite shale, and a sanely aquifer material (Borden sand) were studied. The sorption capacity constant (K-d(s)) of the three nitroaromatic compounds (NACs) increased with the number of amino groups (i.e., 2,4-DANT > 4-ADNT > TNT) for topsoil, and there was significant sorption-desorption hysteresis. Traces of 4-N-acelylamino-2-amino-6-nitrotoluene (4-N-AcANT) formed during sorption of 2,4-DANT by nonsterile topsoil (22 h), but this did not account for the hysteresis. For longer contact times (66 h), 4-N-AcANT accounted for 26% of the biotic disappearance of 2,4-DANT, and traces of 2-N-acetylamino-2-amino-6-nitrotoluene (2-N-AcANT) were detected. For illite, the K-d(s) increased with the number of nitro groups (i.e., TNT > 4-ADNT > 2,4-DANT), and there was also sorption-desorption hysteresis. Most of the 2,4-DANT was neither desorbed nor extractable by acetonitrile from illite or topsoil. Sorption of the NACs by Borden sand was slight or nonexistent This study illustrates that soil and NAC type will have a significant effect on the K-d(s) as well as the formation of acetylated metabolites.