Fate and metabolism of [15N]2,4,6-trinitrotoluene in soil.
The fates of the labels from [14C] and [15N] trinitrotoluene were analyzed in bioreactors under aerobic conditions in soil treated by a fungal bioremediation process with Stropharia rugosoannulata and in control soil. Up to 17.5% of the 15N label had a different fate than the 14C label. Three N-mineralization processes were identified in detailed experiments with [15N]TNT. About 2% of the 15N label was found as NO3- and NH4+, showing simultaneous processes of direct TNT denitration (I) and reduction with cleavage of the amino groups (II). The enrichment of NO2-/NO3- (up to 7.5 atom% 15N abundance) indicates the formation of Meisenheimer complexes with a denitration of [15N]TNT. A 1.4% of the label was found distributed between N2O and N2. However, the 15N enrichment of the N2O (up to 38 atom%) demonstrated that both N atoms were generated from the labeled TNT and clearly indicates a novel formation process (III). We propose, as an explanation, the generation of N2O by cleavage from condensed azoxy metabolites. In addition, 1.7% of the 15N label was detected as biogenic amino acids in the wheat straw containing the fungus. Overall, 60 to 85% of the applied [15N]TNT was degraded and 52 to 64% was found as nonextractable residues in the soil matrix. Three percent was detected as 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene.
Weiss
Martin
M
Department of Bioremediation, Centre for Environmental Research Leipzig-Halle UFZ, Permoserstrasse 15, D-04318 Leipzig, Germany.
Geyer
Roland
R
Russow
Rolf
R
Richnow
Hans H
HH
Kästner
Matthias
M
D001673:Biodegradation, Environmental; D019149:Bioreactors; D005658:Fungi / Q000502:physiology; D009587:Nitrogen Isotopes / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism*; D014303:Trinitrotoluene / Q000032:analysis* / Q000378:metabolism*
D009587:Nitrogen Isotopes; D012989:Soil Pollutants; D014303:Trinitrotoluene; D009609:Nitrous Oxide