Effects of Nitramine Explosive CL-20 on the Soil Microinvertebrate Community in a Sandy Loam Soil

We investigated the effects of nitramine explosive, CL-20, on the soil microinvertebrate community in Sassafras sandy loam (SSL) soil using a 12 week soil microcosm assay. Freshly collected SSL soil was amended with CL-20 to prepare multiple treatment concentrations ranging from 0 (acetone control) to 10,300 mg kg 1. The selected CL-20 concentration range adequately assessed the concentration response relationships for total microarthropods and for individual microarthropod groups. Based on the number of taxonomic groups present in the individual treatments after 12 weeks, the overall composition of microarthropod community in SSL soil was not affected by exposure to CL-20. However, community structure analysis revealed greater sensitivity to CL-20 by predatory mesostigmatid mites. Microarthropod and nematode communities showed contrasting sensitivities to CL-20 in SSL soil. Total numbers of nematodes were unaffected or significantly (p 0.05) increased in the CL-20-treated soil compared with the control. Only the predator group among nematodes was consistently adversely affected by exposure to CL-20. The abundance of predatory nematodes decreased in a concentration-dependent manner throughout the 12 week exposure. Microcosm assays with corresponding community structure analysis can be used to validate the ecotoxicity data from standardized laboratory tests and complement and expand upon the ecotoxicological significance of data from standardized single-species toxicity tests. The original document contains color images.