An evaluation of the toxicity of contaminated sediments from Waukegan Harbor, Illinois, following remediation

Waukegan Harbor in Illinois was designated as a Great Lakes Area of Concern due to high concentrations of sediment-associated polychlorinated biphenyl s (PCBs). The objective of this study was to evaluate the toxicity of 20 se diment samples collected after remediation (primarily dredging) of Waukegan Harbor for PCBs. A 42-day whole sediment toxicity test with the amphipod H yalella azteca (28-day sediment exposure followed by a 14-day reproductive phase) and sediment toxicity tests with Microtox(R) were conducted to evalu ate sediments from Waukegan Harbor. Endpoints measured were survival, growt h, and reproduction (amphipods) and luminescent light emission (bacteria). Survival of amphipods was significantly reduced in 6 of the 20 sediment sam ples relative to the control. Growth of amphipods (either length or weight) was significantly reduced relative to the control in all samples. However, reproduction of amphipods identified only two samples as toxic relative to the control. The Microtox basic test. conducted with organic extracts of s ediments identified only one site as toxic. In contrast, the Microtox solid -phase test identified about 50% of the samples as toxic. A significant neg ative correlation was observed between reproduction and the concentration o f three polynuclear aromatic hydrocarbons (PAHs) normalized to total organi c carbon. Sediment chemistry and toxicity data were evaluated using sedimen t quality guidelines (consensus-based probable effect concentrations, PECs) . Results of these analyses indicate that sediment samples from Waukegan Ha rbor were toxic to H. azteca contaminated at similar contaminant concentrat ions as sediment samples that were toxic to H. azteca from other areas of t he United States. The relationship between PECs and the observed toxicity w as not as strong for the Microtox test. The results of this study indicate that the first phase of sediment remediation in Waukegan Harbor successfull y lowered concentrations of PCBs at the site. Though the sediments were gen erally not lethal, there were still sublethal effects of contaminants in se diments at this site observed on amphipods in long-term exposures (associat ed with elevated concentrations of metals, PCBs, and PAHs).