Application of toxicity identification evaluation techniques to pore water from Buffalo River sediments

To identify contaminants responsible for toxicity of sediments from the Buffalo River, toxicity identification evaluations (TIEs) were conducted with interstitial (pore) water from several sites. Initial toxicity of the samples was determined using fathead minnows (Pimephales promelas) and the cladoceran Ceriodaphnia dubia, and TIE analyses were conducted with the most sensitive of the two species at a particular site. Fathead minnows were more sensitive than C. dubia to pore water from five surficial samples, and TIE results suggested that under our test conditions ammonia was the primary toxicant to the fish. In contrast, C. dubia were more sensitive than fathead minnows to pore water from a sample comprised of deeper sediments at a site that corresponded with one of the surficial samples. Pore water from the deep sediment also was significantly more toxic to both species than the five surficial samples. In this instance, metals (predominantly copper, zinc, and lead) appeared to be most important in determining pore water toxicity to the cladoceran. Based on these analyses, there appear to be both quantitative and qualitative differences in toxicity/toxicants between surficial and deep sediments in the Buffalo River. This is an important consideration in identifying possible remedial strategies involving removal/management of existing (surficial) sediments.