EVALUATION OF SOIL TOXICITY AT JOLIET ARMY AMMUNITION PLANT

Environmental toxicity testing and chemical analyses of soil were perf ormed as part of an ecological risk assessment at the Joliet Army Ammu nition Plant (JAAP), Joliet, Illinois. Soils were collected from an ar ea where munitions were loaded, assembled, and packed (area L7, group 1), and from an area where waste explosives were burned on unprotected soil (area L2). Control samples were collected from an adjacent field . Soil toxicity was determined using early seedling growth and vigor t ests, earthworm survival and growth tests, and Microtox(R) assays. Rel ative toxicity of soils was determined within each area based on stati stical significance (p = 0.05) of plant and earthworm growth and survi val, and the effective concentration at which luminescence of the bact erium Photobacterium phosphoreum was reduced by 50% (EC50) in the Micr otox assay. Samples were designated as having high, moderate, or no si gnificant toxicity. Son that had significant toxicity according to at least one test, and representative samples showing no toxicity, were a nalyzed for munitions via HPLC. Chemical residues found in soils were 2,4,6-trinitrotoluene (TNT); 1,3,5-trinitrobenzene (TNB); 2,4-dinitrot oluene (2,4-DNT); 2,6-dinitrotoluene; 2-amino-4,6-DNT; 4-amino-2,6-DNT ; 1,3,5-trinitro-1,3,5-triazine (RDX); and octahydro-1,3,5,7-tetranitr o-1,3,5,7-tetrazocine (HMX). All soils with no significant toxicity we re void of these chemicals. However, some soils void of munitions stil l showed toxicity that may have been caused by elevated levels of heav y metals. Linear regressions of toxicity test results vs. chemical con centrations showed that TNT and TNB accounted for most of the soil tox icity. Lowest-observable-effect concentrations (LOEC) of TNT were dete rmined from these data. This study presents a simple, relatively inexp ensive methodology for assessing toxicity of soils containing TNT, RDX , and other contaminants related to munitions production.