Enzymatic Transformation and Binding of Labeled 2,4,6-Trinitrotoluene to Humic Substances during an Anaerobic/Aerobic Incubation
| Autor: | Errol Fernandes, S. Thiele, Jean Marc Bollag |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
chemistry.chemical_classification
Catechol Environmental Engineering Chromatography Metabolite Nitro compound Nuclear magnetic resonance spectroscopy Management Monitoring Policy and Law Biodegradation musculoskeletal system Pollution chemistry.chemical_compound chemistry Trinitrotoluene Humic acid Organic chemistry Organic matter Waste Management and Disposal Water Science and Technology |
| Zdroj: | Journal of Environmental Quality. 31:437-444 |
| ISSN: | 0047-2425 |
| DOI: | 10.2134/jeq2002.4370 |
| Popis: | Organic pollutants are degraded in soil and simultaneously non-extractable residues are formed. However, proof is lacking that this fixation has a detoxifying effect. We investigated the transformation and binding of 2,4,6-trinitrotoluene (TNT) with catechol or soil humic acid as cosubstrates. Carbon-14-labeled TNT and its reaction products were quantified by radiocounting; extractable compounds were identified by high performance liquid chromatography (HPLC). Bound and extractable residues of 15 N-labeled TNT and metabolites were studied by 15 N nuclear magnetic resonance spectroscopy ( 15 N NMR). Since TNT is not easily transformed under oxidizing conditions an anaerobic/aerobic treatment was used. Anaerobic microorganisms from cow manure were used to reduce TNT during the anaerobic phase and subsequently, a laccase from Trametes villosa was used in the aerobic phase to oxidatively couple the metabolites to humic matter. Seventy-four percent of TNT was immobilized with catechol as cosubstrate, but only 25% with humic acid. With catechol the main extractable component was TNT, while with humic acid it was mostly the metabolite 4-aminodinitrotoluene. For both co-substrates, the spectra of immobilized metabolites obtained by solid-state 15 N-cross polarization magic angle spinning (CP-MAS) NMR spectroscopy showed signals in the chemical shift region for protonated aromatic amino compounds. However, in the presence of catechol, an additional signal from non-extractable nitro groups was found, which could represent sequestered TNT. The partially reduced metabolites of TNT that formed non-extractable residues in humic acid are not likely to be remobilized easily and are thus regarded as detoxified. |
| Databáze: | OpenAIRE |
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