Please cite this article in press as: Kuperman, R.G., et al., An emerging energetic soil contaminant, CL-20, can affect the soil invertebrate community in a sandy loam soil. Appl. Soil Ecol. (2013), http://dx.doi.org/10.1016/j.apsoil.2013.09.011 ARTICLE IN PRESS G Model APSOIL-1944; No. of Pages 9 Applied Soil Ecology xxx (2013) xxx–xxx Contents lists available at ScienceDirect Applied Soil Ecology journal h om epage: www.elsevier.com/locate/apsoil An emerging energetic soil contaminant, CL-20, can affect the soil invertebrate community in a sandy loam soil R.G. Kuperman ∗ , R.T. Checkai, C.T. Phillips, M. Simini, J.S. Anthony Environmental Toxicology Branch, Edgewood Chemical Biological Center, 5183 Blackhawk Road, Aberdeen Proving Ground, MD 21010-5424, USA a r t i c l e i n f o Article history: Received 31 October 2012 Received in revised form 4 September 2013 Accepted 9 September 2013 Keywords: Nitramine explosive CL-20 Toxicity Soil Invertebrate community Microcosm a b s t r a c t We investigated the effects of nitramine explosive CL-20 (China Lake compound 20) on the indigenous soil invertebrate 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 concentration range of CL-20 adequately assessed the concentration–response relationships for total microarthropods, and for individual microarthropod groups. The overall composition of microarthropod community in SSL soil was not affected by exposure to CL-20, based on the number of taxonomic groups present in the individual treatments after 12 weeks. However, community structure analysis revealed greater sensitivity to CL-20 by predatory mesostig- matid mites. Microarthropod and nematode communities showed contrasting sensitivities to CL-20 in SSL soil. Total numbers of nematodes were either unaffected or significantly (p < 0.05) increased in CL-20 treatments compared with control. Only 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 assay with corresponding community structure analysis can provide the means for validating the ecotoxicity data from standardized labo- ratory tests, both complimenting and expanding upon the ecotoxicological significance of data from standardized single-species toxicity tests. Published by Elsevier B.V. 1. Introduction Preservation of soil fertility and structure is essential to pro- tecting and sustaining ecological integrity of terrestrial ecosystems at military installations. Understanding the potential impacts on the soil ecosystems of an accidental release of explosives and their byproducts during manufacturing, use in training, storage or disposal operations is important to achieving this goal. Soil con- taminated with energetic materials can affect soil biota directly or indirectly, by altering specific interactions among populations of soil organisms and by disrupting soil food webs. Populations of soil organisms are intimately linked and the effects of chemicals on any one species or group can impact the whole community. Ulti- mately, these effects can interfere with key soil processes that are important to the regulation, flow, and internal cycling of carbon and nutrients in ecosystems (Edwards and Bohlen, 1995; Kuperman and Carreiro, 1997; Kuperman et al., 1998; Parmelee et al., 1993). The use of multi-species tests in assessing soil contamination offers ∗ Corresponding author at: Environmental Toxicology Branch, Edgewood Chemi- cal Biological Center, RDCB-DRT-E E5641, 5183 Blackhawk Road, Aberdeen Proving Ground, MD 21010-5424, USA. Tel.: +1 410 436 4697. E-mail address: roman.g.kuperman.civ@mail.mil (R.G. Kuperman). holistic tools for risk assessment and can provide a much broader understanding of the mechanisms by which soil contamination can affect the structure and function of soil ecosystems (Kuperman et al., 2002). In spite of advances in soil ecotoxicological methodologies (Kuperman et al., 2002, 2009), only few studies investigated the community-level effects of soil contamination under controlled laboratory conditions (Bogomolov et al., 1996; Kuperman et al., 2007; Parmelee et al., 1993, 1997; Scott-Fordsmand et al., 2008). Soil microcosms can be used as tools for assessing the community level effects of chemicals while providing a large set of measure- ment endpoints from which an appropriate group can be selected for specific ecosystem structures and functions (Kuperman et al., 2002; Wentsel et al., 2003). Nevertheless, the current approach for assessing ecological risk in terrestrial ecosystems is to use limited data derived from standardized single-species laboratory tests and extrapolate these findings to contaminated sites without suffi- cient comprehensive regard to complexity of soil ecosystems in the field. Toxicity data established in standardized single-species tests can underestimate or overestimate the potential exposure effects on soil invertebrates in the field. For example, in a 7-d micro- cosm assay, total microarthropod numbers were reduced by 50% in the 30 mg kg -1 2,4,6-trinitrotoluene (TNT) treatment compared with numbers in control oak-beech forest silt loam soil (Parmelee 0929-1393/$ – see front matter. Published by Elsevier B.V. http://dx.doi.org/10.1016/j.apsoil.2013.09.011