Irreversible binding of biologically reduced 2,4,6‐trinitrotoluene to soil

Abstract

To analyze the fate of 2,4,6-trinitrotoluene (TNT) and its reduction products, a TNT-contaminated soil (350 mg TNT/ kg dry soil) was spiked with [ring-UL-14.C]TNT and treated in a laboratory slurry reactor. During an anaerobic/aerobic treatment, the total radioactivity measured in the supernatant and methanolic soil extracts decreased to 2 per cent. The decrease corresponded to an increase of strongly bound radioactivity to the soil. Throughout the whole treatment process, mineralization of TNT was not observed. During the reductive process, unidentified polar substances increased to a maximum amount of 23.2 per cent of the total radioactivity on the day after the start of the experiment. After the end of the anaerobic phase, still 9.7 per cent of the radioactivity was found in this fraction. Only during the aerobic phase did the polar substances disappear completely. The irreversible character of the binding of the reduced metabolites of TNT to the soil was indicated by the failure of desorption even under rigorous and longterm extraction conditions. A significant release of radioactivity could be measured only by using high concentrations of HCl (5.N) or EDTA (12.5 per cent and 5.9 per cent, respectively). However, in none of the extracts were TNT or any reduced metabolites detected by HPLC and 14.C-radiocounting. Size-exclusion chromatography of humic acids extracted from the treated soil indicated that the metabolites of TNT were evenly bound to the complete range of molecular size of the humic acids

Screening for Soil Toxicity and Mutagenicity Using Luminescent Bacteria—A Case Study of the Explosive 2,4,6-Trinitrotoluene (TNT)

“…Moreover, as proposed by Sunahara et al (1998), the analogous appearance of reduced metabolites in the well-described anaerobic and aerobic reductive (bio)transformation pathway of TNT (Blotevogel and Gorontzy, 2000) would re#ect a process of detoxi"cation of the TNT molecule, which is detectable by luminescent bacteria. These "ndings suggest the special suitability of luminescent bacteria assays as a screening tool to detect changes in soil toxicity in the context of bioremediation of TNT-contaminated soils, where reductive processes are expected to be of relevance Lenke et al, 1998;Achtnich et al, 1999).…”

Trinitrotoluene removal in a soil slurry and soil box systems by an oil-degrading mixed bacterial culture

“…While anaerobic treatment of TNT-contaminated soil allows for rapid removal of TNT, research has shown that high levels of reduced metabolites are typically produced during this approach, remediation of which may require a second aerobic degradation stage (Achtnich et al 1999). Ahmed & Hughes (2002), Wang et al (2002) and Lenke et al (1998) have shown that these reduced metabolites bind tightly to the humic substances in soil.…”

Toxicity and bioaccumulation of TNT in marine fish in sediment exposures

“…The differences between LSC-measured and HPLC-measured concentrations and between target and HPLCmeasured concentrations indicate that a large fraction of the spiked compound was rapidly transformed to extractable compounds that were non-identifiable using HPLC (i.e, compounds other than TNT, ADNTs and DANTs) or became so strongly associated to sediment particles that they were non-solvent extractable. Highly reactive aminated transformation products of TNT, either formed due to transformation of the parent compound or directly spiked to the sediment, have been reported to form covalent bonds with organic molecules in soil or sediment particles, especially humic acids, as has been observed in soils (Achtnich et al, 1999;Thorn and Kennedy, 2002;Eriksson et al, 2004).…”