CHEMICAL CHARACTERIZATION AND TOXICOLOGICAL TESTING OF WINDROW COMPOSTS FROM EXPLOSIVES-CONTAMINATED SEDIMENTS

Aerated and nonaerated windrow composts of explosives-contaminated sed iments at the Umatilla Army Depot Activity (UMDA, Hermiston, OR) were characterized chemically and toxicologically as a function of composti ng time. The concentrations of explosives in organic solvent extracts of the composts and in the aqueous leachates of the composts, the bact erial mutagenicity of organic solvent extracts from the composts, and the toxicity of aqueous leachates from the composts to Ceriodaphnia du bia all declined rapidly (<15 d) with composting. The nonaerated windr ow method of composting was slightly more efficient than was the aerat ed windrow method for reducing explosives concentrations in the compos ts (TNT, 99.9%; RDX, >99.7%; HMX, 98.5%) and in their leachates (>99.6 %, >98.8%, and >97.5%, respectively). Extractable mutagenicity decline d 99.7 and 97.9%, respectively, for strains TA-98 and TA-100 (without S-9 metabolic activation) in the nonaerated compost. The two types (ae rated and nonaerated) of windrow composts had about the same level of efficiency in lowering leachable toxicity (by 92% and 87%, based on re ductions in C. dubia survival and fecundity, respectively). Thus, wind row composting appeared to be at least as effective as static-pile and mechanically stirred composting evaluated previously. Windrow compost ing also appeared to be somewhat more effective for HMX transformation .