AQUATIC TOXICITY VARIABILITY FOR FRESHWATER AND SALTWATER SPECIES IN REFINERY WASTE-WATER EFFLUENT

The U.S. Environmental Protection Agency (EPA) has established test requirements for toxicity reduction or toxicity identification evaluations (TR/TIE) of wastewater effluents. Interpretations of test results are complicated by factors other than toxicity when essentially freshwater wastewaters flow into estuaries and the effluent permit requires marine organisms for testing. This paper reports the results of an investigation of potential freshwater surrogate species, and Microtox(R), for use in such a TLE. Of the five species tested, mysid shrimp were found to be most sensitive to unidentified toxicants in petroleum refinery wastewater. No strong correlations of this sensitivity to that of other organisms, or to several wastewater constituents, were identified. The two marine species specified in the effluent permit were more sensitive to the toxicants than were the freshwater species.