Triclosan (TCS) and triclocarban (TCC) are antimicrobials found in U.S. surface waters. This dissertation assessed the effects of TCS and TCC on early development and investigated their potential to bioaccumulate using Xenopus laevis as a model. The effects of TCS on metamorphosis were also investigated. For 0-week tadpoles, LC50 values for TCS and TCC were 0.87 mg/L and 4.22 mg/L, respectively, and both compounds caused a significant stunting of growth. For 4-week tadpoles, the LC50 values for TCS and TCC were 0.22 mg/L and 0.066 mg/L; and for 8-week tadpoles, the LC50 values were 0.46 mg/L and 0.13 mg/L. Both compounds accumulated in Xenopus. For TCS, wet weight bioaccumulation factors (BAFs) for 0-, 4- and 8-week old tadpoles were 23.6x, 1350x and 143x, respectively. Lipid weight BAFs were 83.5x, 19792x and 8548x. For TCC, wet weight BAFs for 0-, 4- and 8-week old tadpoles were 23.4x, 1156x and 1310x. Lipid weight BAFs were 101x, 8639x and 20942x. For the time-to-metamorphosis study, TCS showed an increase in weight and snout-vent length in all treatments. Exposed tadpoles metamorphosed approximately 10 days sooner than control tadpoles. For the hind limb study, although there was no difference in weight, snout-vent length, or hind limb length, the highest treatment was more developed compared to the control. There were no differences in tail resorption rates between the treatments and controls. At relevant concentrations, neither TCS nor TCC were lethal to Xenopus prior to metamorphosis. Exposure to relatively high doses of both compounds resulted in stunted growth, which would most likely not be evident at lower concentrations. TCS and TCC accumulated in Xenopus, indicating that the compound has the potential to bioaccumulate through trophic levels. Although TCS may increase the rate of metamorphosis in terms of developmental stage, it did not disrupt thyroid function and metamorphosis in regards to limb development and tail resorption.

Triclosan (TCS) and triclocarban (TCC), widely used antimicrobial agents found in numerous consumer products, are incompletely removed by wastewater treatment plant (WWTP) processing. Methyl-triclosan (M-TCS) is a more lipophilic metabolite of its parent compound, TCS. The focus of this study was to quantify bioaccumulation factors (BAFs) for TCS, M-TCS, and TCC in Pecan creek, the receiving stream for the City of Denton, Texas WWTP by using field samples mostly composed of the alga Cladophora sp. and the caged snail Helisoma trivolvis as test species. Additionally, TCS effects on E. coli and Arabidopsis have been shown to reduce fatty acid biosynthesis and total lipid content by inhibiting the trans-2 enoyl- ACP reductase. The lipid synthesis pathway effects of TCS on field samples of Cladophora spp. were also investigated in this study by using [2-14C]acetate radiolabeling procedures. Preliminary results indicate high TCS concentrations are toxic to lipid biosynthesis and reduce [2-14C]acetate incorporation into total lipids. These results have led to the concern that chronic exposure of algae in receiving streams to environmentally relevant TCS concentrations might affect their nutrient value. If consumer growth is limited, trophic cascade strength may be affected and serve to limit population growth and reproduction of herbivores in these riparian systems.

Chorine is used by the Village Creek Waste Water Treatment Plant to kill pathogenic microorganisms prior to discharge of the effluent into the Trinity River. The residual chlorine in the river impacted aquatic life prompting the U.S. Environmental Protection Agency in December 1990 to require dechlorination using sulfur dioxide. One pre-dechlorination and four post-dechlorination assessments of phytoplankton, periphyton, and zooplankton communities were conducted by the Institute of Applied Sciences at the University of North Texas. Dechlorination had no effect on the phytoplankton community. The periphyton community exhibited a shift in species abundance with a more even distribution of organisms among taxa. No change occurred in zooplankton species abundance, however, there was a decrease in zooplankton density following dechlorination.

A toxicological study was initiated because of concerns about allegations that the Texas Water Commission that effluent from the Dallas Central Wastewater Treatment Plant, which discharges into the Trinity River, was affecting downstream water quality. Monthly, flow-weighted composite effluent samples were collected. Grab samples were also collected upstream and downstream from the effluent from April 1989 to August 1991. Toxicity tests were conducted on these samples using Ceriodaphnia dubia as the test organism. Samples were collected four times during this study in which rainfall occurred prior to sampling. In every instance, this "first flush" of the watershed during a rising hydrograph was toxic to C. dubia upstream. Analyzing toxicity by season resulted in a statistically significantly lower neonate production in the effluent than in the river samples during the months of June, July, and August. This impact on neonate production was suspected of being caused by organic pesticides which are used for insect control on lawns. The effluent was never acutely toxic to C. dubia. Primarily, toxic occurrences in either the effluent or the river samples were primarily of a chronic nature. Overall, survival of C. dubia was affected more frequently at the upstream site than in the effluent or the downstream site. Because EPA's Phase I Acute Toxicity Identification Evaluations (TIEs) methods were designed for identifying acute toxicity, two alternative strategies were attempted to identify chronic toxicity. The first attempt was the modification of the phase I acute TIE methodologies. This was done by processing more sample through the phase I characterization tests. This approach was inadequate due to toxicity that occurred during the last several days of the seven-day C. dubia reproduction test. The second strategy for identifying chronic toxicity within a TIE involved the use of freeze concentration. During this preliminary investigation ofthe efficiency of freeze concentration, four metals and two organic compounds were freeze concentrated.

by Wong On Nei. / Thesis submitted in: October 2004. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 101-116). / Abstracts in English and Chinese. / ABSTRACT --- p.ii / 摘要 --- p.iv / ACKNOWLEDGEMENTS --- p.vi / TABLE OF CONTENTS --- p.vii / LIST OF TABLES --- p.xi / LIST OF FIGURES --- p.xiii / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Lethal and sublethal effects of SS on fish --- p.2 / Chapter 1.2.1 --- Biological effects --- p.2 / Chapter 1.2.2 --- Molecular biomarkers --- p.3 / Chapter 1.2.2.1 --- Acetylcholinesterase activity inhibition assay --- p.4 / Chapter 1.2.2.2 --- Induction of cytochrome P450 mRNA --- p.5 / Chapter 1.2.2.3 --- Induction of metallothionein mRNA --- p.6 / Chapter 1.2.3 --- Study on CYP1A and MT expression / induction --- p.8 / Chapter 1.2.3.1 --- Reverse Transcription (RT) --- p.8 / Chapter 1.2.3.2 --- Polymerase chain reaction (PCR) --- p.8 / Chapter 1.3 --- Objectives --- p.11 / Chapter CHAPTER TWO --- MATERIALS AND METHODS --- p.13 / Chapter 2.1 --- Study sites --- p.13 / Chapter 2.2 --- Sediment --- p.15 / Chapter 2.2.1 --- Sediment samples collection --- p.15 / Chapter 2.2.2 --- Sediment handling --- p.15 / Chapter 2.2.3 --- Sediment dry-wet (w/w) ratio measurement --- p.15 / Chapter 2.2.4 --- Heavy metal content analysis --- p.16 / Chapter 2.2.5 --- Organic content analysis --- p.16 / Chapter 2.3 --- Test organism --- p.17 / Chapter 2.4 --- Bioassays --- p.17 / Chapter 2.4.1 --- 10-day exposure treatments --- p.17 / Chapter 2.4.1.1 --- Experimental setup --- p.17 / Chapter 2.4.1.2 --- Procedure --- p.21 / Chapter 2.4.1.3 --- Tissue sample collection --- p.22 / Chapter 2.4.2 --- 30-day exposure treatments --- p.22 / Chapter 2.4.2.1 --- Behavioural observations --- p.23 / Chapter 2.4.2.2 --- Tissue sample collection --- p.23 / Chapter 2.5 --- Molecular Biomarkers --- p.25 / Chapter 2.5.1 --- Tested samples --- p.25 / Chapter 2.5.2 --- Acetylcholinesterase activity inhibition assay --- p.25 / Chapter 2.5.2.1 --- Acetylcholinesterase activity assay --- p.25 / Chapter 2.5.2.2 --- BioRad Bradford assay --- p.26 / Chapter 2.5.2.3 --- Calculation of specific enzyme activity --- p.26 / Chapter 2.5.3 --- Study on CYP1A and MT expression / induction --- p.27 / Chapter 2.5.3.1 --- Gill and liver tissue samples --- p.27 / Chapter 2.5.3.2 --- Preparation of ribonuclease free reagents and apparatus --- p.27 / Chapter 2.5.3.3 --- Isolation of total RNA --- p.27 / Chapter 2.5.3.4 --- Spectrophotometric analyses of DNA and RNA --- p.28 / Chapter 2.5.3.5 --- First strand cDNA synthesis --- p.28 / Chapter 2.5.3.6 --- Cloning and sequencing of CYP1A and MT gene --- p.29 / Chapter 2.5.3.7 --- RT-PCR co-amplification of CYP1A and 18S rRNA --- p.34 / Chapter 2.5.3.8 --- Real-time RT-PCR --- p.36 / Chapter CHAPTER THREE --- RESULTS --- p.39 / Chapter 3.1 --- Sediment chemistry --- p.39 / Chapter 3.1.1 --- Sediment dry-wet (w/w) ratio --- p.39 / Chapter 3.1.2 --- Heavy metal content of sediments --- p.39 / Chapter 3.1.3 --- Levels of total PCBs and PAHs in sediment --- p.39 / Chapter 3.2 --- Monitoring of test conditions --- p.42 / Chapter 3.3 --- Bioassays --- p.42 / Chapter 3.3.1 --- Survivorship --- p.42 / Chapter 3.3.2 --- Growth --- p.46 / Chapter 3.3.3 --- Feeding rate --- p.51 / Chapter 3.3.4 --- Behaviour --- p.54 / Chapter 3.3.5 --- Sediment clogging --- p.59 / Chapter 3.3.6 --- Body lesions --- p.59 / Chapter 3.3.7 --- Abnormal behaviour --- p.59 / Chapter 3.4 --- Molecular biomarkers --- p.63 / Chapter 3.4.1 --- Acetylcholinesterase activity inhibition assay --- p.63 / Chapter 3.4.2 --- Cloning and sequencing of CYP1A and MT gene --- p.66 / Chapter 3.4.3 --- RT-PCR co-amplification of CYP1A and 18S rRNA --- p.73 / Chapter 3.4.4 --- Real-time RT-PCR --- p.77 / Chapter CHAPTER FOUR --- DISCUSSION --- p.84 / Chapter 4.1 --- Sediment chemistry --- p.84 / Chapter 4.2 --- Biological responses --- p.85 / Chapter 4.3 --- Molecular biomarkers --- p.91 / Chapter 4.3.1 --- Acetylcholinesterase activity inhibition assay --- p.91 / Chapter 4.3.2 --- Cloning and sequencing of CYP1A and MT gene --- p.93 / Chapter 4.3.3 --- RT-PCR co-amplification of CYP1A and 18S rRNA --- p.93 / Chapter 4.3.4 --- Real-time RT-PCR --- p.95 / Chapter 4.4 --- Recommendations --- p.99 / Chapter 4.5 --- Conclusions --- p.100 / REFERENCES --- p.101 / APPENDIX --- p.117

Pak Ah Pan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 149-158). / Abstracts in English and Chinese. / ABSTRACT --- p.ii / 摘要 --- p.vi / ACKNOWLEDGEMENTS --- p.vii / TABLE OF CONTENTS --- p.ix / LIST OF TABLES --- p.xiv / LIST OF FIGURES --- p.xvi / Chapter CHAPTER ONE --- LITERATURE REVIEWS --- p.1 / Chapter 1.1. --- Sediment pollution problems --- p.1 / Chapter 1.2. --- Effects of suspended sediments (SS) on aquatic biota --- p.3 / Chapter 1.3. --- Histopathological biomarkers in fish --- p.7 / Chapter CHAPTER TWO --- INTRODUCTION --- p.20 / Chapter CHAPTER THREE --- MATERIALS AND METHODS --- p.23 / Chapter 3.1. --- Sediments --- p.23 / Chapter 3.1.1. --- Sediment sampling sites --- p.23 / Chapter 3.1.2. --- Sediment collection and handling --- p.25 / Chapter 3.1.3. --- Chemical analysis of sediments --- p.25 / Chapter 3.2. --- Collection and maintenance of fish --- p.26 / Chapter 3.3. --- Sediment bioassays for groupers (E. coioides) --- p.28 / Chapter 3.3.1. --- Preparation of suspended sediments (SS) --- p.28 / Chapter 3.3.2. --- Experimental design --- p.30 / Chapter 3.3.2.1. --- 10-day exposure experiment --- p.30 / Chapter 3.3.2.2. --- 30-day exposure experiment --- p.31 / Chapter 3.3.2.3. --- Time-course and recovery experiment --- p.33 / Chapter 3.3.3. --- Measurement of oxygen consumption and ventilation rates --- p.33 / Chapter 3.4. --- "Tissue sample collection, preparation and examinations" --- p.35 / Chapter 3.4.1. --- Study of sediment clogging --- p.35 / Chapter 3.4.2. --- Scanning electron microscopy (SEM) study --- p.37 / Chapter 3.4.3. --- Histopathological investigations --- p.38 / Chapter 3.4.3.1. --- Histopathology of gills --- p.40 / Chapter 3.4.3.2. --- Histopathology of liver --- p.40 / Chapter 3.4.3.3. --- Histopathology of kidney --- p.41 / Chapter 3.5. --- Sediment bioassays for seabreams (A. schlegeli) --- p.42 / Chapter 3.6. --- Statistical analysis --- p.43 / Chapter CHAPTER FOUR --- RESULTS --- p.44 / Chapter 4.1. --- Chemical analysis of sediments --- p.44 / Chapter 4.2. --- Physicochemical parameters --- p.47 / Chapter 4.3. --- Sediment bioassays for groupers (E. coioides) --- p.49 / Chapter 4.3.1. --- Feeding rate --- p.49 / Chapter 4.3.2. --- Growth rate --- p.49 / Chapter 4.3.3. --- Sediment clogging --- p.53 / Chapter 4.3.4. --- Survival rates --- p.53 / Chapter 4.3.5. --- Oxygen consumption rate and ventilation rate --- p.56 / Chapter 4.3.6. --- SEM study --- p.56 / Chapter 4.3.7. --- Histopathological investigations --- p.64 / Chapter 4.3.7.1. --- Histopathology of gills --- p.64 / Chapter 4.3.7.2. --- Histopathology of liver --- p.82 / Chapter 4.3.7.3. --- Histopathology of kidney --- p.94 / Chapter 4.4. --- Sediment bioassays for seabreams (A. schlegeli) --- p.113 / Chapter 4.4.1. --- Survival rates --- p.113 / Chapter 4.4.2. --- Histopathological investigations of gills and liver --- p.113 / Chapter CHAPTER FIVE --- DISCUSSION --- p.122 / Chapter 5.1. --- Hypoxic effects of SS on histopathology --- p.122 / Chapter 5.2. --- Synergistic effects between SS and chemical --- p.126 / Chapter 5.3. --- Effects of gill impairment on biological responses --- p.131 / Chapter 5.4. --- Reparability of histopathological alterations --- p.135 / Chapter 5.5. --- Species differences in sensitivity to SS --- p.135 / Chapter 5.6 --- Recommendation --- p.136 / Chapter CHAPTER SIX --- CONCLUSION --- p.138 / APPENDICES --- p.140 / REFERENCES --- p.149

by Tse Ching Yee Carol. / Thesis submitted in: September 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 75-90). / Abstracts in English and Chinese. / Abstract --- p.ii / 摘要 --- p.iv / Acknowledgments --- p.vi / Table of contents --- p.vii / List of tables X / List of figures --- p.xii / Chapter 1.0 --- Introduction --- p.1 / Chapter 1.1 --- Sediment pollution in Hong Kong --- p.1 / Chapter 1.2 --- Impact of suspended sediment on fish --- p.2 / Chapter 1.3 --- Biochemical responses to pollution --- p.3 / Chapter 1.3.1 --- Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) --- p.4 / Chapter 1.3.2 --- Creatine kinase (CK) --- p.5 / Chapter 1.3.3 --- Ethoxyresorufin O-deethylase (EROD) --- p.6 / Chapter 1.3.4 --- DNA damage --- p.8 / Chapter 1.4 --- Study of recovery --- p.10 / Chapter 1.5 --- Objectives and significances --- p.11 / Chapter 2.0 --- Materials and Methods --- p.13 / Chapter 2.1 --- Study sites --- p.13 / Chapter 2.2 --- Sediments collection and handling --- p.13 / Chapter 2.3 --- Measurement of heavy metals and organic contents of sediment --- p.15 / Chapter 2.4 --- Exposure tests --- p.16 / Chapter 2.4.1 --- Test organisms --- p.16 / Chapter 2.4.2 --- 10- and 30-day exposure experiments --- p.18 / Chapter 2.4.3 --- 20-day exposure and recovery experiment --- p.19 / Chapter 2.5 --- Biochemical responses --- p.19 / Chapter 2.5.1 --- "Aspartate aminotransferase (AST), alanine aminotransferase (ALT) and creatine kinase (CK) activities" --- p.19 / Chapter 2.5.2 --- Ethoxyresorufin O-deethylase activity (EROD) --- p.20 / Chapter 2.5.3 --- DNA damage --- p.21 / Chapter 2.5.4 --- Statistical analysis --- p.22 / Chapter 3.0 --- Results --- p.24 / Chapter 3.1 --- Physical and chemical parameters --- p.24 / Chapter 3.2 --- Pollutants in sediment --- p.24 / Chapter 3.3 --- Mortality --- p.28 / Chapter 3.4 --- Biochemical responses --- p.31 / Chapter 3.4.1 --- 10- and 30-day exposure experiments --- p.31 / Chapter 3.4.2 --- 20-day exposure and recovery experiments --- p.50 / Chapter 4.0 --- Discussion --- p.58 / Chapter 4.1 --- "Sediment pollution at Port Shelter, Mirs Bay and Victoria Harbor" --- p.58 / Chapter 4.2 --- Biochemical responses --- p.59 / Chapter 4.2.1 --- 10- and 30-day exposure experiments --- p.59 / Chapter 4.2.1.1 --- "AST, ALT and CK" --- p.59 / Chapter 4.2.1.2 --- EROD --- p.63 / Chapter 4.2.1.3 --- DNA damage --- p.67 / Chapter 4.2.2 --- 20-day exposure and recovery experiments --- p.69 / Chapter 5.0 --- Recommendations and conclusions --- p.73 / References --- p.75 / Appendix --- p.91

This study evaluated the effects of a major chlorine disturbance on fish communities in Pecan creek by the City of Denton's Pecan Creek Water Reclamation Plant. Fish communities in Pecan Creek were sampled using a depletion methodology during February, April, July, and November, 1999. February and April sampling events showed that the fish communities were severely impacted by the chlorine. Sampling during July and November showed fish communities recovered in Pecan Creek. The first-twenty minutes of shocking and seining data were analyzed to mirror an equal effort methodology. This methodology was compared to the depletion methodology to see if the equal effort methodology could adequately monitor the recovery of Pecan Creek after the chlorine disturbance. It was determined that the equal effort methodology was capable of monitoring the recovery of Pecan Creek, but could not accurately represent the fisheries community as well as the depletion method. These data using the twenty-minute study were compared to a previous study. Results of this study were similar to those found in a previous study, although fish communities were more severely impacted and took longer to recover.

by Tsui Tsz Ki, Martin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 119-138). / Abstracts in English and Chinese. / Acknowledgements --- p.I / Abstract --- p.III / Table of Contents --- p.VII / List of Tables --- p.XII / List of Figures --- p.XIV / Abbreviations --- p.XVI / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Research Background --- p.1 / Chapter 1.1.1 --- General description of glyphosate --- p.1 / Chapter 1.1.2 --- Physical and chemical properties of glyphosate --- p.2 / Chapter 1.1.3 --- Commercial formulations based on glyphosate --- p.3 / Chapter 1.1.4 --- Overview of ecotoxicological studies of glyphosate-based formulations --- p.4 / Chapter 1.1.4.1 --- Aquatic toxicity of glyphosate-based formulations --- p.4 / Chapter 1.1.4.2 --- Environmental fate of glyphosate-based formulations in waters --- p.12 / Chapter 1.1.5 --- Interaction of glyphosate and other substances --- p.14 / Chapter 1.2 --- Overview of Aquatic and Sediment Toxicology --- p.16 / Chapter 1.2.1 --- Aquatic toxicology --- p.16 / Chapter 1.2.2 --- Introduction to sediment toxicology --- p.19 / Chapter 1.3 --- "Significance, Outline and Objectives of the Present Study" --- p.20 / Chapter 1.3.1 --- Significance of the research --- p.20 / Chapter 1.3.2 --- Thesis outlines and research objectives --- p.22 / Chapter Chapter 2 --- Aquatic Toxicity of Glyphosate-based Herbicides to Different Organisms and the Effects of Environmental Factors / Chapter 2.1 --- Introduction --- p.25 / Chapter 2.2 --- Materials and Methods --- p.26 / Chapter 2.2.1 --- Test organisms --- p.26 / Chapter 2.2.2 --- Test chemicals --- p.27 / Chapter 2.2.3 --- Comparison between different organisms --- p.27 / Chapter 2.2.4 --- Environmental factors in modifying Roundup® toxicity --- p.30 / Chapter 2.2.5 --- Analysis of glyphosate concentration --- p.31 / Chapter 2.2.6 --- Validity of tests and statistical analyses --- p.32 / Chapter 2.3 --- Results --- p.32 / Chapter 2.3.1 --- Comparison between different groups of organisms --- p.32 / Chapter 2.3.2 --- Environmental factors in modifying Roundup® toxicity to C.dubia --- p.35 / Chapter 2.4 --- Discussion --- p.36 / Chapter 2.4.1 --- Toxicity of glyphosate to photo synthetic organisms --- p.36 / Chapter 2.4.2 --- pH-associated toxicity of glyphosate --- p.37 / Chapter 2.4.3 --- High potency of surfactant --- p.38 / Chapter 2.4.4 --- Effects of environmental factors on Roundup® toxicity --- p.38 / Chapter 2.5 --- Conclusions --- p.39 / Chapter Chapter 3 --- "Toxicity of Rodeo®, Roundup® Biactive and Roundup® to Water-column and Benthic Organisms and the Effect of Organic Carbon on Sediment Toxicity" / Chapter 3.1 --- Introduction --- p.41 / Chapter 3.2 --- Materials and Methods --- p.43 / Chapter 3.2.1 --- Test chemicals --- p.43 / Chapter 3.2.2 --- Test organisms --- p.43 / Chapter 3.2.3 --- Toxicities to water-column and benthic organisms --- p.44 / Chapter 3.2.4 --- Effect of sediment organic carbon --- p.45 / Chapter 3.2.5 --- Statistical analyses --- p.48 / Chapter 3.3 --- Results --- p.48 / Chapter 3.3.1 --- Toxicities to water-column and benthic organisms --- p.48 / Chapter 3.3.2 --- Effect of sediment organic carbon --- p.49 / Chapter 3.4 --- Discussion --- p.54 / Chapter 3.4.1 --- Different sensitivities between water-column and bethic animals --- p.54 / Chapter 3.4.2 --- Relative toxicities of three herbicides --- p.56 / Chapter 3.4.3 --- Route of exposure of herbicides in sediment to organisms --- p.57 / Chapter 3.4.4 --- Sediment toxicity of glyphosate-based formulations --- p.58 / Chapter 3.4.5 --- Effect of organic carbon on partitioning and toxicity --- p.60 / Chapter 3.5 --- Conclusions --- p.61 / Chapter Chapter 4 --- Joint Toxicity of Glyphosate and Several Selected Environmental Pollutants to Ceriodaphnia dubia / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- Materials and Methods --- p.65 / Chapter 4.2.1 --- Test organisms and toxicity tests --- p.65 / Chapter 4.2.2 --- Test chemicals --- p.66 / Chapter 4.2.3 --- Experiment I: Joint acute toxicity of Roundup® and nine toxicants --- p.66 / Chapter 4.2.4 --- Experiment II： Effect of IPA salt of glyphosate alone at EEC on toxicities of heavy metals --- p.67 / Chapter 4.2.5 --- Basic water properties and chemical analyses --- p.69 / Chapter 4.2.6 --- Statistical analyses --- p.70 / Chapter 4.3 --- Results --- p.70 / Chapter 4.3.1 --- General conditions and recovery for spiked chemicals --- p.70 / Chapter 4.3.2 --- Experiment I: Joint acute toxicity of Roundup® and nine toxicants --- p.71 / Chapter 4.3.3 --- Experiment II: Effect of IPA salt of glyphosate alone at EEC on toxicities of heavy metals --- p.73 / Chapter 4.4 --- Discussion --- p.75 / Chapter 4.4.1 --- Interactions of Roundup® and other toxicants --- p.75 / Chapter 4.4.2 --- Joint toxicity of dissimilar chemicals --- p.77 / Chapter 4.4.3 --- Complexation of glyphosate with metals interactions between liquid/solid phases --- p.79 / Chapter 4.5 --- Conclusions --- p.83 / Chapter Chapter 5 --- Environmental Fate of Glyphosate and its Nontarget Impact: a Case Study in Hong Kong / Chapter 5.1 --- Introduction --- p.85 / Chapter 5.2 --- Materials and Methods --- p.87 / Chapter 5.2.1 --- Description of study sites --- p.87 / Chapter 5.2.2 --- Physicochemical characteristics of different matrices --- p.88 / Chapter 5.2.3 --- Continuous weather monitoring --- p.89 / Chapter 5.2.4 --- Herbicide applications --- p.89 / Chapter 5.2.5 --- Experimental designs --- p.90 / Chapter 5.2.5.1 --- Estuarine enclosure experiment --- p.90 / Chapter 5.2.5.2 --- Freshwater pond experiment --- p.92 / Chapter 5.2.6 --- Schedule of sample collection and sample storage --- p.92 / Chapter 5.2.7 --- Sample preparation --- p.94 / Chapter 5.2.7.1 --- Water samples --- p.94 / Chapter 5.2.7.2 --- Sediment samples --- p.94 / Chapter 5.2.8 --- Sample determination --- p.95 / Chapter 5.2.8.1 --- Pre-column derivatization --- p.95 / Chapter 5.2.8.2 --- High performance liquid chromatography analyses --- p.95 / Chapter 5.2.8.3 --- Calibration of glyphosate and AMPA --- p.95 / Chapter 5.2.8.4 --- Recovery of glyphosate in spiked samples --- p.96 / Chapter 5.2.9 --- Statistical analyses --- p.96 / Chapter 5.3 --- Results --- p.96 / Chapter 5.3.1 --- Site characteristics --- p.96 / Chapter 5.3.2 --- Weather conditions during herbicide application --- p.99 / Chapter 5.3.3 --- Chemical analyses --- p.100 / Chapter 5.3.4 --- In-situ toxicity tests --- p.104 / Chapter 5.4 --- Discussion --- p.106 / Chapter 5.4.1 --- Site-specific factor affecting the environmental fate --- p.106 / Chapter 5.4.1 --- Site-specific factor affecting the environmental fate of glyphosate --- p.106 / Chapter 5.4.2 --- Glyphosate in water and sediment --- p.106 / Chapter 5.4.3 --- Homogeneity of glyphosate in surface water and sediment --- p.109 / Chapter 5.4.4 --- Effect of weather conditions on environmental fate of glyphosate --- p.109 / Chapter 5.4.5 --- Biological impact of Roundup® --- p.110 / Chapter 5.5 --- Conclusions --- p.112 / Chapter Chapter 6 --- General Conclusions --- p.113 / References --- p.119

The ecological position of micro-algae at the base of the aquatic food web makes them critical components of aquatic ecosystems. Their short generation time also makes them useful biological indicators because they respond quickly to changes in environmental condition, enabling timely identification and assessment of water quality changes. The inclusion of micro-algae as indicators in water resource regulation and management in South Africa has started recently, their more extensive use in biomonitoring and ecotoxicology programmes for water resource management would contribute to the South African policy if water resource protection. The standard algal growth inhibition assay with the species Pseudokirchneriella subcapitata is currently used for monitoring toxicity of in-stream and industrial wastewater discharges to freshwater micro-algae. The relevance of the data generated by standard toxicity bioassays has been questioned, since micro-algae in particular are extremely variable in their sensitivity to a range of contaminants and these standard species used may not occur in the local aquatic environment. As a result, international regulatory agencies, have recommended algal growth inhibition tests be changed from a single standard species to tests with a number of species. One recommendation, in addition to the use of standard toxicity tests, is the use of species isolated from the local environment which may be more relevant for assessing site specific impacts. This study investigated the value and application of locally isolated South African freshwater micro-algae in toxicity tests for water resource management and was carried out in three phases. The first phase involved isolating micro-algae from South African aquatic resources. Micro-algae suitable for toxicity testing were identified and selected using as set of criteria. Three (Scenedesmus bicaudatus, Chlorella sorokiniana and Chlorella vulgaris) out of eight successfully isolated species satisfied the prescribed selection criteria and these were selected as potential toxicity test species. The second phase focused on refining and adapting the existing algal toxicity test protocol (the algal growth inhibition assay) for use on the locally isolated algal species. The refinement of the test protocol was achieved by exposing the locally isolated species to reference toxicants in order to assess and compare their growth and sensitivity to the toxicants under the prescribed toxicity test conditions with that of the standard toxicity test species (Pseudokirchneriella subcapitata) and a commercial laboratory species (Chlorella protothecoides). During this phase, one of the three local species (Scenedesmus bicaudatus) was eliminated as a potential toxicity test species due to inconsistent growth. The third phase of the study involved assessing the sensitivity of the two remaining species (C. vulgaris and C. sorokiniana) to a range of toxicants (reference toxicants, salts, effluents and a herbicide) and comparing it to that of the standard toxicity test species P. subcapitata and C. protothecoides. The toxicants were selected based on their relative importance in the South African context, as well as the practicality of using these local micro-algae to routinely determine the impact of these toxicants on local aquatic resources. The growth of the four micro-algae was stimulated by the selected effluents. The standard toxicity test species P. subcapitata was ranked the most sensitive and of the four species to two reference toxicants and two inorganic salts. Chlorella sorokiniana was ranked the most sensitive of the three Chlorella species to two reference toxicants and two inorganic salts. The herbicide stimulated the growth of C. vulgaris while inhibiting the growth of the other species. Pseudokirchneriela subcapitata and C. sorokiniana showed high intra-specific variability in growth, which made it difficult to determine the effective concentrations of the herbicide and therefore compare the sensitivity of the species. This varied response of micro-algal species to toxicants may result in the biodiversity shifts in aquatic ecosystems, and also supports the recommendation of using a battery of different species to support more informed decisions in water resource management.