Partitioning, toxicity and mutagenicity of in-place contaminants of sediments from the Grand Calumet River and Indiana Harbor, Indiana

The presence of a wide variety of in-place chemical contaminants in sediments from the Grand Calumet River-Indiana Harbor Canal, Indiana Area of Concern, their chemical partitioning between environmental compartments, and their potential toxicological effects were the primary focus of this study. The partitioning behavior of non-polar organic chemicals (NPOCs) present in both sediment and sediment pore waters was investigated to determine the importance of NPOC binding to dissolved organic carbon (DOC) in sediment pore water. Better concordance was observed between estimated and actual field partition coefficients with a three-phase partitioning model. These results highlight the potential importance of the DOC-binding phenomenon in determinations of the bioavailability and effects of NPOCs present in sediment pore waters.; The Microtox{dollar}spcircler{dollar} assay, 48 h Daphnia magna and Ceriodaphnia dubia tests and a 10-d Chironomus tentans test were used in a toxic units approach to assess the toxicity of sediments and sediment pore waters and to conduct a preliminary identification of the potential toxicants. Based on the results of these analyses, ammonia, polycyclic aromatic hydrocarbons, metals, petroleum hydrocarbons and bicarbonate ion were the major contaminants of concern to benthic invertebrates within the study area. Separate experiments to determine the mechanism of bicarbonate ion toxicity to D. magna suggested that toxicity was due to the inhibition of the active uptake of Cl{dollar}sp-{dollar} from water. Therefore, pore water alkalinity should be considered when interpreting the results of aqueous phase toxicity tests with cladocerans and, perhaps, other species of invertebrates and fish.; Evaluation of the comparative mutagenicity of solvent extracts of sediments from the study area was conducted with the Ames and Mutatox{dollar}spcircler{dollar} assays. Extracts were mutagenic with metabolic activation in both assays, however, few samples contained direct acting mutagens. The lack of mutagenicity in Mutatox{dollar}spcircler{dollar} assays of pore waters indicates that short-term human exposure to mutagens in pore waters and sediments is likely to be non-problematic. Greater concern is required for the potential ecological and human health effects due to food chain transfer of mutagenic compounds in sediments from the study area.