Microscale Characterization of the Location and Association of TNT in Soils

INTRODUCTION: Numerous ammunition manufacturing facilities and ammunition testing sites across the world are faced with environmental problems associated with soils contaminated with trinitrotoluene (TNT) and other nitroaromatic compounds. Although a number of TNT treatment technologies have been developed recently [1,2], these techniques do not result in a high degree of mineralization of the explosive compounds present. Thus, a significant part of the contaminant mass remains in the soil as residues of the original contamination. The acceptance of costeffective treatment techniques depends on better understanding of the stabilization of TNT and its nitroaromatic transformation products in soil. The chemical and biological availability of TNT residues in soil is determined primarily by the physical and chemical form in which TNT remain in soils. Reduction of TNT produces aminonitrotoluenes, which may covalently bond irreversibly with quinones, and reversibly with hydroquinones. Such transformation of molecular structure is implicated in making TNT transformation products unavailable for further degradation [3]. However, TNT residue may also be present in a solid form in soils, especially at former production facilities. Solid TNT particles may create a toxic zone in the vicinity thereby making biodegradation difficult. Thus it is important to understand the microscale nature of TNT residues found in contaminated soils.