Energetic Materials Effects on Essential Soil Processes: Decomposition of Orchard Grass (Dactylis glomerata) Litter in Soil Contaminated with Energetic Materials

Abstract

Abstract : We investigated the effects of individual nitrogen-based energetic materials (EMs) 2,4-dinitrotoluene (2,4-DNT), 2-amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), nitroglycerin (NG), and 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) on decomposition, an essential soil process, utilizing Orchard grass (Dactylis glomerata) straw in Sassafras sandy loam (SSL) soil. Three pieces of 5-cm long internodular sections of straw were used to form a straw cluster. Pre-weighed straw clusters were placed in the soil in each 900 mL volume test container containing approximately 200 g of loosely packed EM-amended soil or carrier (acetone) control soil. After 1, 2, 3, 4, 6, and 8 months of exposure, one straw cluster was harvested from a set of randomly selected replicate containers from within each treatment to quantify the decomposition rates. The exposure concentrations of each EM in soil were analytically determined soils using the U.S. Environmental Protection Agency Method 8330A. The results showed that soil contamination with 2,4-DNT or NG can inhibit litter decomposition rates based on the EC50 values of 1122 mg/kg and 860 mg/kg, respectively. Exposure to 2-ADNT, 4-ADNT or CL-20 did not significantly affect litter decomposition in SSL soil at 10000 mg/kg. These ecotoxicological benchmarks can help identify concentrations of contaminant EM in soil that present an acceptable ecological risk for biologically-mediated processes in soil.