| Résumé | Toxicity of 2,4,6-trinitrotoluene (TNT) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) using two terrestrial plant species, lettuce (Lactuca sativa) and barley (Hordeum vugare), was assessed in artificial soil (silica) and forest soil. Lettuce emergence was significantly decreased after 5 days of exposure to TNT nominal spiked concentrations S 1,040 mg/kg dry soil in silica. Barley emergence was significantly reduced after 14 days of exposure at initial (t = 0) TNT concentrations S 55.9 - 4.5 mg/kg dry soil in silica and at S 291.9 - 42.8 mg/kg dry forest soil. Biomasses of shoot and roots of barley seeds were significantly reduced after 14 days of exposure at TNT initial exposure concentrations S 55.9 - 4.5 (LOEC) mg/kg dry soil in silica. Results were similar with the forest soil (LOEC = 91.4 - 7.9 mg TNT/kg dry soil) using the root growth parameter, but the shoot biomass was reduced only at concentrations S 291.9 - 42.8 mg TNT/kg dry soil. Plants were not affected by an HMX exposure up to 3,320 - 1,019 mg/kg dry soil using silica or 1,866 - 438 mg/kg dry soil using a forest soil. During the 14-day experiments, TNT was partially transformed in the spiked soil samples, as indicated by the presence of its amino metabolites (2-ADNT and 4-ADNT). Higher quantities of metabolites were detected in forest soils having higher initial TNT concentrations (h 1,849.4 - 228.2 mg/kg) compared to silica (h 239.3 - 88.0 mg TNT/kg). After 14 days, TNT concentrations in spiked silica and forest soil were reduced up to 80.5% at 55.9 - 4.5 mg/kg initial concentration and 94.4% at 91.4 - 7.9 mg/kg initial concentration, respectively. Data indicate that TNT is the probable phytotoxicant because it decreased plant emergence and growth in the presence and absence of the ADNT metabolites. |
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