FACTORS AFFECTING MICROBIAL 2,4,6-TRINITROTOLUENE MINERALIZATION IN CONTAMINATED SOIL

The influence of selected environmental factors on microbial TNT miner alization in soils collected from a TNT-contaminated site at Weldon Sp ring, MO, was examined using uniformly ring-labeled [C-14]TNT. Microbi al TNT mineralization was significantly inhibited by the addition of c ellobiose and syringate. This response suggests that the indigenous mi croorganisms are capable of metabolizing TNT but preferentially utiliz e less recalcitrant substrates when available. The observed inhibition of TNT mineralization by TNT by concentrations higher than 100 mu mol /kg of soil and by dry soil conditions suggests that toxic inhibition of microbial activity at high TNT concentrations and the periodic dryi ng of these soils have contributed to the long-term persistence of TNT at Weldon Spring. In comparison to aerobic microcosms, mineralization was inhibited in anaerobic microcosms and in microcosms with a headsp ace of air amended with oxygen, suggesting that a mosaic of aerobic an d anaerobic conditions may optimize TNT degradation at this site.