Oxidative pretreatment accelerates TNT metabolism in soils

The combined effect of ultraviolet (UV)-ozonation (O₃) of aqueous ¹⁴C-TNT solutions followed by direct addition of the solutions to aerobic soils was examined as a method of disposal. The effect of TNT concentration was studied on both UV-O₃ and soil metabolism. The amount of TNT degraded by either process decreased as the concentration increased. UV-O₃ of a 1 ppm solution of TNT using a laboratory 450 W lamp for 10, 20, and 30 minutes resulted in substantial fragmentation of the ring and an increase in polarity of the resultant products. Soil metabolism, as measured by metabolic CO₂ evolution, increased as the time of prior UV-O₃ increased. A large amount of the ¹⁴C associated with ¹⁴C-TNT recovered from soil was in the non-extractable fraction. When a , adapted to metabolize -nitrophenol or picric acid as a sole source of carbon and nitrogen, was substituted for the soil phase, about 25% of the added ¹⁴C appeared as ¹⁴CO₂. 1,3,5-Trinitrobenzene, 2,4,6-trinitrobenzaldehyde, 3,5-dinitrophenol, 3, 5-dinitrocatechol, 3,5-dinitrohydroquinone, and oxalic acid were identified as products of UV-O₃. Rapid destruction of TNT took place in a large 66 lamp unit, and the resultant distribution of ¹⁴C was similar to the results from the laboratory studies.