| OCR Text |
Show 2. MATERIALS AND :METHODS 2.1 Physical System Testing was conducted in an enclosed light box placed inside an environmental chamber maintained at 25°C fluorescent bulbs. Continuous 400· ± 40 foot candles of illumination was provided by A platform shaker table inside the light 'chamber held ninety-six, 125-mL flasks circulating at a continuous rate of 100 rpm. An inverted 50 mL beaker was placed on each flask to provide cover but allow gas exchange. A Hach 3000 spectrophotometer calibrated with known 'cell density' D. viridis stocks was used for cell density determinations. The experimental design included six test treatments and a dilution water control each with 16 replicates. Test treatments were based on a 0.6 geometric dilution of the highest test treatment prepared immediately prior to testing from anhydrous sodium selenate (Na:zSe04). Replicates contained 49 mL of test solution and were inoculated with 0.743 mL of a 67.25 x 104 cells/mL algal stock prepared immediately prior to testing from a culture 4 to 7 days from renewal. Test chamber positions were randomized on the shaker table twice daily. Test Substance 2.2 The test substance, reagent grade sodium selenate, Na:zSe04 (CAS #13410-01-0), was received from Sigma Chemical Company located in St. Louis, Missouri. Following receipt at Parametrix, Inc. in Kirkland, Washington, the test substance was stored in the dark at room temperature. 1 Stock densities were determined by averaging multiple hemocytometer counts under lOx magnification on a Zeiss bifocal microscope. Parametrix, Inc. Final Report 2 March 1998 |
