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Show PMX-1061 Page 5 of 13 l!. OBJECTIVES objective of this study is to determine the chronic toxicity of selenate to the alga, Dunaliella viridis. In this chronic test, algae undergoing logarithmic growth will be exposed to selenate in a. known concentration gradient for 96 hours. Growth in the test chambers will then be calculated based on the cell density. At test conclusion, comparisons will be The made to determine whether the addition of selenate to the nutrient medium caused statistical differences in algal growth rate. These results will be used for defining a concentration-response curve, and the No Observable Effect Concentration (NOEC) and the Lowest Observed Effect Concentration (LOEC) for the test material. Where the dose response will be linear (i.e. no growth enhancement occurs as a result of exposure to lower test concentrations), selenate's 96 hour EC50 and its 95% confidence limits will also be calculated. 2. TEST MATERIAL The test substance used in this study will be reagent grade sodium selenate (CAS #S-0882) obtained from Sigma Chemical Company located in St. LOuis, MO. The stock solution will nominal concentration and prepared the day of test initiation. be based on a 3. TESTING FACILITY 3.1 Physical Plant Toxicity testing win be conducted at Parametrix' Environmental Toxicology Laboratory, located at 5808 Lake Washington Blvd. NE, Seattle, Washington 98033. Parametrix' feet and includes both wet and laboratory occupies 5,000 sq. dry laboratories, culture facilities, and offices. Analytical confirmation of selenate test concentrations will be performed by a local analytical laboratory. 3.2 Dilution Water The dilution water for the' chronic toxicity test will be water collected from a reference site the Great Salt Lake (GSL). Dilution water will be filtered through a 1 JLffi filter to remove particulate matter, algae, brine shrimp, brine shrimp cysts, and brine fly larvae. An of the GSL dilution water for analysis potential contaminants such as certain heavy metals will be conducted to monitor dilution water quality. at |
