Effects and bioavailability of 2,4,6-trinitrotoluene in spiked and field-contaminated soils to indigenous microorganisms

✍ Scribed by Ping Gong; Steven D. Siciliano; Charles W. Greer; Louise Paquet; Jalal Hawari; Geoffrey I. Sunahara

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 196 KB
• Volume: 18
• Category: Article
• ISSN: 0730-7268
• DOI: 10.1002/etc.5620181205

✦ Synopsis

The response of potential nitrification activity (PNA), nitrogen-fixation activity (NFA), and dehydrogenase activity (DHA) in soil to 2,4,6-trinitrotoluene (TNT) was assessed. Two garden soils of contrasting texture (sandy loam vs clay loam) were spiked with TNT (25-1,000 mg TNT/kg). Soil microbial activities and TNT residues were analyzed 1 week later. The estimated IC50 (concentration causing 50% inhibition) ranged from 39 to 533 mg/kg of the acetonitrile-extractable (AE) TNT (1 week after spiking), depending on indicators and soils. The lowest LOEC (lowest-observed-effect concentration) was 1 mg AE TNT/kg. Field soil (0-15 cm) was collected from three known contaminated sites in an abandoned TNT manufacturing facility. Microbial toxicity significantly correlated to TNT levels in these soils. The LOEC and NOEC (no-observed-effect concentration) values were site and indicator specific, with the lowest LOEC being 1 mg AE TNT/kg and the lowest NOEC being 0.4 mg AE TNT/kg. The IC50 of the pooled field samples was 51 mg AE TNT/kg for PNA or 157 mg AE TNT/kg for DHA. These results indicate that microbial responses were consistent and comparable between the laboratory and the field and that TNT could significantly inhibit soil microbial activities at very low levels. Both AE TNT and deionized water-extractable (DW) TNT concentrations correlated well with microbial toxicity, but AE TNT provided a better evaluation of TNT bioavailability than did DW TNT.