Soil-based phytotoxicity of 2,4,6-trinitrotoluene (TNT) to terrestrial higher plants

Seed germination and early stage seedling growth tests were conducted to de termine the ecotoxicological threshold of 2,4,6-trinitrotoluene (TNT) in tw o soils of different properties. Soils were amended up to 1,600 mg TNT kg(- 1) soil and four representative species of higher plants, two dicotyledons (Lepidium sativum L., common name: cress; and Brassica rapa Metzg., turnip) and two monocotyledons (Acena sativa L., oat; and Triticum aestivum L., wh eat), were assessed. Cumulative seed germination and fresh shoot biomass we re measured as evaluation endpoints. Phytotoxicity of TNT was observed to b e affected by soil properties and varied between plant species. Cress and t urnip showed higher sensitivity to TNT than did oat and wheat. The lowest o bservable adverse effect concentration (LOAEC) of TNT derived from this stu dy was 50 mg kg(-1) soil. In contrast to high TNT concentrations, low level s of TNT, i.e., 5-25 mg kg(-1) soil for cress and turnip and 25-50 mg kg(-1 ) for oat and wheat, stimulated seedling growth. Oat was capable of tolerat ing as much as 1,600 mg TNT kg(-1) and demonstrated a potential ability of TNT detoxification in one of the soils tested, suggesting that this plant m ight be useful in the bioremediation of TNT contaminated soils.