published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Acclimation temperature had a significant effect on the lethality of copper to fathead minnows in replicated 96-hour lethality tests. Lowest median lethal copper concentrations (LC50) were recorded at 12 and 22°C, with LC50s at 5 and 32°C at least 140 μg/1 higher. This research found LC50 copper concentrations in the 300 to 500 μg/1 range and a polynomial relationship between LC50s and acclimation temperature. Following a 24-hour exposure to three sublethal concentrations of copper, critical thermal maxima (CTMax) were tested in minnows acclimated to four temperatures. Sublethal exposure to copper significantly decreased the CTMaxs relative to controls at three of the four temperatures. Control CTMaxs ranged from 28.6 to 40.4°C and increased 0.46°C for each 1°C increase in acclimation temperature.

Graduation date: 1994

No description available.

The toxicity of methanol, atrazine, and copper to Pseudokirchneriella subcapitata (Korshikov) Hindák historically referred to as Selenastrum capricornutum Printz were determined following 96 hrs growth in a modified Goram's growth media. Methanol and atrazine inhibited fluorescence readings in the cultures by 50% (IC50) at concentrations of 2% and 82 µg/l respectively. These toxicity values compared favorably to other published reports. The IC50 for copper was 160 µg/l which is substantially higher than reported values. This is understandable because of the high chelating capacity of Goram's media. The use of stereologically derived relative volume in the chloroplasts, mitochondria, lipid bodies, phosphate bodies, and nucleus was investigated to determine if it could be used as a sensitive endpoint in toxicity tests. The volume fractions for the chloroplasts and mitochondria were normally distributed in control cells while the nuclei, phosphate bodies, and lipid bodies were not. The chloroplasts were the most dominate organelle occupying a mean relative volume of 46% and mitochondria occupied a mean relative volume of 3%. The nucleus and phosphate bodies occupied a median relative volume of 7% and 2% respectively. The lipid bodies were rare in section profile and no meaningful median relative volume could be calculated. Up to the 82nd percentile of sectioned profiles contained no recognizable lipid bodies. The use of relative volume was not a sensitive endpoint for use in toxicity tests. No significant differences in relative volume could be detected in the nucleus or phosphate bodies following any treatment. Limited differences were detected in the mitochondria, chloroplasts, and lipid bodies. The only significant differences that appear to be biologically significant occurred in methanol treated cells where an increase in the lipid bodies' relative volume was apparently concentration dependent. Significant differences in the relative volume of mitochondria and chloroplasts do not appear to be biologically significant.

A behavioral model for acute responses in bivalves, was developed using time series analysis for use in a real-time biomonitoring unit. Stressed bivalves closed their shell and waited for the stressful conditions to pass. Baseline data showed that group behavior of fifteen bivalves was periodic, however, individuals behaved independently. Group behavior did not change over a period of 20 minutes more than 30 percent, however, following toxic exposures the group behavior changed by more than 30 percent within 20 minutes. Behavior was mathematically modeled using autoregression to compare current and past behavior. A logical alarm applied to the behavior model determined when organisms were stressed. The ability to disseminate data collected in real time via the Internet was demonstrated.

The purpose of this study was to investigate the effects of copper on the treatment of an abandoned landfill leachate by a Modified Ludzack Ettinger (MLE) single-sludge, activated sludge treatment system. MLE systems are designed to accomplish nitrification and denitrification, and at least two systems were used: one to which copper was added, and one maintained as a control. The system that did not receive copper additions gave an indication of the treatability of the leachate by an MLE system. Copper was added at concentrations of 1.0, 2.0, 2.5, and 5.0 mgCu/L in the influent and the sludge age was varied from 8 to 30 day. It was determined that copper did inhibit nitrification and denitrification. A strong linear relationship was shown to exist between the specific copper loading on the system, that is the total copper entering the system within a day divided by the total biomass within the system, and the soluble copper concentration within the system. The adsorption of copper by the activated sludge, and the resulting soluble copper concentration in the mixed liquor, could be generally described by the Freundlich Isotherm. Intermittent inhibition of nitrification unrelated to copper addition also occurred during treatment of the landfill leachate which was obtained from the abandoned Dixie Caverns Landfill near Roanoke, Virginia. The inhibiting substance was not identified during this study. It did not significantly inhibit denitrification, but did cause elevated effluent suspended solids concentrations. An additional treatment step would be needed for reliable treatment of the leachate. Copper additions caused inhibition of both nitrification and denitrification. The degree of nitrification and denitrification inhibition was a strong function of the soluble copper to ML VSS ratio in the reactors, i.e., the toxin -to -microorganism (TIM) ratio. Nitrification and denitrification appeared to be equally sensitive to copper. Both were severely inhibited at a soluble copper to ML VSS ratio of 0.001 in aerobic and anoxic reactors, respectively. Nitrosomonas species were more strongly inhibited by copper concentrations than were the Nitrobacter species. The denitrifiers appeared to be as sensitive to copper as the Nitrosomonas species. / Master of Science

The decline in mussel fauna of the Powell River has been attributed to extensive mining activities in headwater streams of Wise and Lee counties, Virginia. Surface mining causes erosion, sedimentation, and contamination of water with toxic substances from coal washing and waste piles. Historical water quality data of the Powell River have documented concentrations of metals at levels determined to be toxic to molluscs, specifically zinc (Zn) and copper (Cu). Acute toxicity tests with Zn, Cu, and mixtures of these two metals were conducted with glochidia and juvenile freshwater mussels. Effects of varying conditions such as water source, temperature, length of exposure, species, and lifestage were determined. Additionally, the effects of Powell River sediment on survival and growth of juvenile mussels were evaluated. The Cumberland moccasin shell (Wedionidus conradicus) was the most sensitive species tested, with 24-hr and 48-hr LC50 values for glochidia ranging from 423 to 725 μg Zn/L. Glochidia of the pheasantshell (Actinonaias pectorosa) exhibited LC50 values from 274 to 2886 μg Zn/L, depending on test conditions. Similar results were obtained for glochidia of the rainbow (Villosa iris), with LC50 values ranging from 577 to 4123 μg Zn/L. Juveniles were more sensitive, with 48-hr LC50 values ranging from 360 to 1885 μg Zn/L for A. pectorosa, and 339 to 1122 μg Zn/L for V. iris, depending on test conditions. Juvenile mussels were affected by Zn at lower concentrations as evidenced by valve gaping and a swollen and nonresponsive foot. Copper was 5 to 15 times more toxic than Zn, with 48-hr LC50 values ranging from 52 to 156 μg Cu/L, and ECS5O values ranging from 25 to 115 μg Cu/L for juveniles of A. pectorosa. Copper appeared to exert a different toxic mode of action, as evidenced by closed valves and reduced siphoning. In general, sensitivities of early life stages of mussels to Zn and Cu increased with higher temperature, soft water, and length of exposure. At certain concentrations, Zn seemingly had an antagonistic effect (less than additive) when mixed with Cu. This effect was evidenced by reduced mortality of juveniles in Cu solutions when Zn was added at concentrations of about 400 to 800 μg/L. However, this antagonistic effect was not reflected in the percent of juveniles affected, which increased continuously with increasing metal concentrations. Glass beads were found unsuitable as a control substratum for use in sediment testing with juvenile mussels. Results of sediment tests indicated that sediment in some areas of the Powell River may be toxic to juvenile mussels, and that toxicity may be linked to water quality. After 10 days, survival of juveniles in sediment collected downstream of a coal processing plant was significantly lower than survival in sediment upstream of the plant (p = 0.01). Further, survival in sediments with dechlorinated tap water was significantly higher than survival in sediment with river water (p = 0.0002). After 20 and 30 days, survival was similar among sites and water types. High metal concentrations in the river water appeared to contribute to toxicity, because juveniles in tap water displayed consistently better growth, and initially better survival than juveniles in river water and sediment. This toxicity was not apparent in sediments collected from the same sites less than two months later, suggesting the character of the sediments may change as new suspended sediment is deposited. The USEPA water quality criteria for Zn (adjusting for water hardness) are 174 μg/L (acute) and 158 μg/L (chronic), whereas copper criteria are set at 28 μg/L (acute) and 18 μg/L (chronic). Powell River water samples collected during 1991 contained concentrations of Zn and Cu exceeding these criteria, as well as concentrations shown to have adverse effects on mussel populations. Results suggest that some metals are introduced into the river system in runoff, whereas Cu is being introduced as an episodic event. Intensive monitoring of water quality is needed to identify specific sources of metal pollution. If levels of heavy metal concentrations remain high, then the declining mussel populations of the Powell River will not recover, and endangered species may be extirpated from Virginia. / Master of Science

by Janet Kwai-yu Cheung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 130-106). / ABSTRACT --- p.1 / ACKNOWLEDGEMENTS --- p.4 / TABLE OF CONTENTS --- p.5 / LIST OF TABLES --- p.7 / LIST OF FIGURES --- p.9 / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.11 / Chapter CHAPTER 2 --- LITERATURE REVIEW / Chapter 2.1 --- Toxicity of heavy metals to crustaceans --- p.13 / Chapter 2.2 --- Heavy metal pollution in Hong Kong waters --- p.20 / Chapter 2.3 --- Copper: its nature and occurrence --- p.27 / Chapter 2.4 --- General biology of Metapenaeus ensis --- p.32 / Chapter CHAPTER 3 --- ACUTE AND CHRONIC TOXICITY OF COPPER TO METAPENAEUS ENSIS / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Materials and Methods --- p.39 / Chapter 3.3 --- Results --- p.45 / Chapter 3.4 --- Discussion --- p.68 / Chapter CHAPTER 4 --- SUBLETHAL EFFECTS OF COPPER TO METAPENAEUS ENSIS / Chapter 4.1 --- Introduction --- p.76 / Chapter 4.2 --- Materials and Methods --- p.76 / Chapter 4.3 --- Results --- p.82 / Chapter 4.4 --- Discussion --- p.96 / Chapter CHAPTER 5 --- GENERAL CONCLUSIONS --- p.101 / REFERENCES --- p.103

The effect of variations in aluminum and copper concentrations on the growth rate and enzyme activity of the green alga Scenedesmus quadricauda was investigated. The goal was to determine which chemical species control the biological parameters. The computer program MINEQL (Westal et al 1976) was used to estimate chemical speciation. In the prevalence of both metals, algal growth rate and alkaline phosphatase activity could be correlated to cupric ion activity. The activity of isolated bacterial alkaline phosphatase was found to be a function of both total copper concentration and cupric ion activity. A model was developed to predicted the effects on alkaline phosphatase of perturbation in aquatic chemistry.