Toxicities of TNT and RDX to the Earthworm Eisenia fetida in Five Soils with Contrasting Characteristics

Abstract : Studies were designed to characterize soil physicochemical parameters that can affect the toxicities of 2,4,6- trinitrotoluene (TNT) or hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to Eisenia fetida earthworms and also to generate ecotoxicological benchmarks for development of ecological soil screening levels (Eco-SSLs) for ecological risk assessments of contaminated soils. Soils with varied physicochemical properties were tested, including Teller sandy loam (TSL), Sassafras sandy loam (SSL), Richfield clay loam (RCL), Kirkland clay loam (KCL), and Webster clay loam (WCL). Reproduction toxicity of TNT to E. fetida in freshly amended soils was in the order (greatest to least) of TSL SSL = KCL = RCL WCL. Weathering-and-aging of TNT in SSL, KCL, RCL, and WCL soils increased the toxicity to E. fetida compared with corresponding freshly amended treatments. Reproduction toxicity of RDX weathered-and-aged (W-A) in soil was comparable with that of TNT W-A in TSL, SSL, RCL, and WCL soils. No clear relationships were identified between TNT or RDX toxicities and the soil organic matter or clay contents or the pH levels. Toxicity benchmarks established utilizing TSL and SSL will be submitted to the U.S. Environmental Protection Agency Eco-SSL Workgroup for developing soil invertebrate-based Eco-SSLs for TNT and RDX.