research project details
Project Title: Analysis of soil samples containing residues of N15-labeled TNT by NMR spectroscopy
Investigator(s): J.-M. Bollag
Sponsor: Universitat Stuttgart, Germany
Environmental Problem Addressed:
TNT-contaminated soil and water.
Research Project Objectives:
Laboratory analysis of soil samples containing residues of N15-labeled TNT by NMR spectroscopy.
Summary:
Trinitrotoluene (TNT) was heavily used as an explosive during World Wars I and II. TNT is a carcinogen and is and is considered toxic at levels above 10 parts per million. The soil and groundwater near many military and manufacturing sites are heavily contaminated with high concentrations of TNT.
A new treatment process for cleaning up TNT-contaminated sites demonstrated that TNT and its metabolites bind to humic substances and clay minerals. Using carbon isotopes as a tracer, further extraction tests with various chemical showed that TNT remained bound to the soil and was not released into the environment.
Three different kinds of interactions between TNT and its metabolites are possible:
- physical sorption,
- sequestration, and
- covalent binding to soil organic matter.
If TNT and its metabolites are bound through covalent linkages, are they considered to be an integral part of humus and thus do not represent a threat to the environment. Structural characterization of bound residues will be examined by 15N NMR spectroscopy to evaluate the stability of the bound residues. The aim is to test the binding characteristics of TNT and its metabolites to humic substances and clay minerals.