1994-10-24_HYDROLOGY - M1977378 (2)

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according to procedures contained in APHA/AWWA/WPCF (1985). A distillation was performed on the samples prior to titration. Alkalinity and hardness were determined according to procedures described in Hach Chemical Company(1978). Conductivity, dissolved oxygen, and pH probes were used to make these measurements. The tests followed the procedures in Weber et al. (1989). Effluent concentrations tested included 100%, 50%, 25%, 12.5%, and 6.25% mixtures. Individual Ceriodaphnia were placed in 30 ml plastic containers containing approximately 15 ml of exposure medium. Ten replicates at each concentration were used. The animals were fed daily with an aqueous mixture of trout chow/alfalfa/yeast and an equal volume of algae (Selenastrum capricormdum). Exposure medium was changed daily in each container and the number of young hatching overnight recorded. Young were removed from the containers daily and discarded. Routine measurements were made each day of temperature, dissolved oxygen, and Ph. Fathead minnows were exposed in 260 ml plastic cups to which 200 ml of media was added daily. Ten fish were placed in each jar and four replicates at each concentration were used. Fish were monitored for survival daily and fed live Artemia sp. at least twice daily. After seven days, the fish were removed from the jars and frozen. The fish were weighed on a four place analytical balance after drying in an oven for two hours at 1050C. Data Analysis Data from the test were analyzed on an IBM compatible personal computer using Fisher's Exact Test, Dunnett's Test, ANOVA with Bonferroni's T Test, Steel's Many One Rank, or Wilcoxon's Test These analyses were performed on the basis of the normality and heterogeneity of the data. The computer software was part of the TOXSTAT package developed at the University of Wyoming. RESULTS Ceriodaphnia Test Results Test results for Ceriodaphnia are summarized in Table 1 and provided on the lab data sheets in Appendix 2. A significant mortality was measured in the 100% effluent exposure as only 40% of the animals survived at that concentration. The remainder of the test had 100% survival, with 100% survival in the control. This produced an LC50 concentration of 91.6%. Average neonates per adult ranged from 4.1 in the 100% concentration to 23.9 in the 6.25% concentration. Average neonates per adult in the controls were 22.6. There was a statistically significant difference in the number of births between the controls and those animals exposed in the 100% concentration. Fathead Minnow Test Results Test results for the fathead minnows are summarized in Table 2. Survival was 100% In all effluent dilutions. Control survival was 100% also. Average weights of the fish after seven days ranged from 0.53 mg per individual