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The purpose of this project is to assess the organismal and ecological effects of episodic pollution events by characterizing contaminant concentration and exposure time toxicity relationships for differing pollutants and organisms. For this analysis, controlled laboratory experiments will be designed to subject common freshwater invertebrates to brief exposures of various contaminants over a range of contaminant concentrations. Exposures will be modeled after typical exposure periods observed in storm events, and will include 15, 30, 60, 90, 120, 180 and 240 minute durations. The organism used in this study will include the amphipod Hyalella azteca, the daphnid Ceriodaphnia dubia, and the rotifer Branchionus calyciflorus. After exposure, the organisms will be removed fro the contaminant and placed in a clean freshwater environment for a post exposure observation period. The concentration and exposure time toxicity relationship will be established for the common reference pollutants cadmium, zinc, phenol, and a contaminant mixture. A second component of this research will compare the results of these laboratory based time exposure toxicity tests to actual episodic pollution events. Analogous experiments will be conducted using stormwater samples collected from a moderately urbanized and industrialized area. Data analyzed during this phase of research will include discharge measurements, chemical characterization of pollutants, Microtex analysis, caged organism response, and real time monitoring using a Musselmonitor. The results of this project will be used to extend the scientific knowledge of the impacts of episodic discharge events such as agricultural runoff, accidental spillage, urban stormwater, and combined sewer overflows.
Last Updated: February 12, 1997