Potential for intrinsic bioremediation of a DNT-contaminated aquifer

Microorganisms indigenous to a shallow aquifer, which underlies an explosives-contaminated site, mineralized 28% of [U-ring-C-14] 2,4-dinitrotoluene to (CO2)-C-14 within 28 days under aerobic conditions. Approximately 20% of added 2,4-dinitrotoluene remained undegraded at the end of the incubation while approximately 22% and 6% were transformed to 4-amino-2-nitrotoluene and 2-amino-4-nitrotoluene, respectively. In aquifer microcosms containing 2,6-dinitrotoluene, approxinately 67% of the substrate remained undegraded and approximately 14% was transformed to 2-amino-6-nitrotoluene. The radiolabeled study indicated that about 8% of the 2,6-dinotrotoluene was mineralized to CO2. The demonstrated degradation and subsequent mineralization of dinitrotoluene compounds by aquifer microorganisms are consistent with the decline in dissolved dinitrotoluene concentrations observed along the general ground-water flowpath Pt the site. The results indicate that intrinsic bioremediation may be a viable alternative for remediating contaminated ground water at this site.