Ecotoxicological characterization of energetic substances using a soil extraction procedure

The acetonitrile-sonication extraction method (US EPA SW-846 Method 8330) a nd aquatic-based toxicity tests were used on laboratory and field samples, to characterize the ecotoxicity of soils contaminated with energetic substa nces. Spiked soil studies indicated that 2,4,6-trinitrotoluene (TNT)-depend ent soil toxicity could be measured in organic extracts and aqueous leachat es using the 15-min Microtox (Vibrio fischeri, IC50=0.27 to 0.94 mg TNT/lit er incubation medium) and 96-h Selenasstrum ;capricornutum growth inhibitio n (IC50 = 0.62 to 1.14 mg/liter) toxicity tests. Analyses of leachates of c omposite soil samples [containing TNT and some TNT metabolites, 1,3,5-trini tro-1,3,5-triazacyclohexane (RDX), and 1,3,5,7-tetranitro-1,3,5,7-tetrazacy clooctane (HMX)] from an explosives manufacturing facility, indicated toxic ities similar to those found in the TNT-spiked soil studies and pure TNT in solution, and suggested that TNT was the major toxicant, Using TNT as a mo del toxicant in soils having different moisture contents (20% vs dry) and t extures (sandy vs clayey-sandy) but similar organic matter content (3-4%), multi-factorial analyses of Microtox test data revealed that these soil fac tors significantly influenced the TNT extractability from soil and subseque nt toxicity measurements. Taken together, data indicate that the modified M ethod 8330 may be used in conjunction with ecotoxicity tests to reflect the toxic potential of soils contaminated with energetic substances. (C) 1999 Academic Press.