M.Sc. / The study looks into the sediment-bound metals (Fe, Mn, Cu, Cr, Cd, Co, Pb, Ni, Zn and Hg) of the Leeu/Taaibospruit catchment, which is impacted by agricultural, industrial and urban development. A number of chemical procedures, including total metal determination, the Tessier-sequential extraction scheme, the BCR Protocol, evaluation of the % TOC and determination of AVS to SEM ratios were applied to sediment samples collected from eight sites along the two rivers in the study area. Samples were collected during both high flow (summer) and low flow (winter) conditions. Following the chemical characterisation, bioaccumulation testing was conducted by exposing chironomid larvae to the sediment samples collected in from the study sites and determining their metal uptake relative to control specimens in uncontaminated sediments. These bioaccumulation results were then considered in conjunction with the chemical parameters in an attempt to identify any trends and correlations. Significant spatial and temporal differences were found in the metal concentrations from the study area. The total extraction results indicated that abundant amounts of Cr and Fe are present throughout the system. This was expected based on the make-up of the underlying geology. In addition, one of the sites, which is in close proximity to the town of Sasolburg, was identified as a potentially contaminated site. This site had significantly higher concentrations of Zn, Cu, Pb and, most notably, Hg when compared to the other sites. The elevated metal concentrations are most evident in samples collected under low flow conditions, but are also seen in the high flow Hg concentrations. Sequential extractions showed that Fe and Cr are concentrated in the residual phases of the sediment. Copper is largely present in the oxidisable fraction under low flow conditions, but also has considerable residual and reducible chemical forms. Manganese and Zn are distributed among all the different chemical phases and are therefore likely to be readily available for uptake by benthic organisms. The TOC was found to be highest during low flow conditions and at those sites with observable amounts of organic debris from the surrounding reeds and other vegetation. The AVS/SEM ratios were used to predict that due to the formation of insoluble metal sulphides, Cd, Cu, Hg, Ni, Pb and Zn are unlikely to be bioavailable at certain sites, i.e. the contaminated site 1 and at site 5, which only has agricultural impacts. In general, the bioaccumulation of Fe, Co, Ni, Cr and Mn was higher in the test larvae than the control larvae. Bioaccumulation of Cu, Pb, Zn and Hg levels were only higher than the control worms at sites where contamination was suspected to have taken place. Average bioaccumulation factors indicated that Hg is the metal that is most readily available for bioaccumulation, followed by Cu, Zn and Mn. All of these metals were bioconcentrated in the tissues of the test chironomids, while levels of Fe, Ni, Cr and Pb were found to be lower in the organisms than in the sediments. Although many of the chemical fractions were found to correlate significantly with the uptake of the different metals, the best overall correlation existed between the bioaccumulated metal and the total non-residual fraction. In fact, the sum of the first four steps of the Tessier-scheme correlated significantly with the bioaccumulated metal for all elements considered in the calculation, except for Pb. Additionally, the predictions made by the AVS model were found to be useful in justifying the behaviour and accumulation patterns of Hg, Zn and Cu at certain sites. The correlations and bioavailability clearly differed spatially, temporally and among the different elements. It is therefore suggested that prediction of the bioavailability and subsequent uptake of sediment-bound metals will require as many chemical and environmental factors as possible, and should include bioaccumulation and toxicity testing in order to examine the validity and completeness of these predictions.

Water is one of the most important resources in South Africa. The increased pressure on river systems in SA as a result of human activities and industrial development is evident from the systematic deterioration of the Olifants River (Mpumalanga). While the number of water users grows daily, the river is seen as a convenient disposal site. It is necessary to continually monitor the river to be aware of its status. Regular monitoring also supplements the existing data on water quality, biotic communities and possible points of pollution. The study had the following aims: Firstly to contribute to a larger project on the effect of pollutants on the physiology of fish populations in the Olifants River. This study concentrates on the bioaccumulation of certain metals (i.e. chromium, copper, iron, manganese, nickel, lead, strontium and zinc), in the gills, liver and muscle of Labeo congoro. Standard methods were used to prepare the organs and tissues for metal analysis using atomic absorption spectrophotometry. The following conclusions were reached subsequent to statistical analysis of the results: • The highest mean concentrations of all metals were recorded in the liver of Labeo congoro. • The lowest mean metal concentrations were calculated in the muscle, except for chromium, the concentrations of which were the lowest in the gills. • The highest mean concentration of each metal was recorded in organs / tissues of fish sampled at locality 2. • None of the three localities can be singled out to indicate the lowest mean concentration of each metal. Summary iii The second aim of this study was to determine the 96-hr LC50 (lethal concentration at which 50% of the test population dies) of nickel. Oreochromis mossambicus was used as test organisms for these laboratory studies. A flow through system was used to ensure that the organisms were exposed to the same concentration of nickel for 96 hours. Subsequent to the 96-hr LC50 determination, test organisms were subjected to sublethal exposure of nickel to determine the effects of the various concentrations of the haematology and blood coagulation processes of fish. The following conclusions were drawn from the statistical data processing: • The 96-hr LC50 of nickel for Oreochromis mossambicus is 50 μg.l-1. • The exposure to sublethal concentrations of nickel did effect certain haematological variables • No statistically significant differences in the blood coagulation variables at different sublethal concentrations of nickel were confirmed The results of this study can be used to supplement the database on the water quality and general status of the Olifants River (Mpumalanga). The LC50 of nickel can be used as one of the variables in water quality studies. / Prof. Johan van Vuren

M-Tech. (Department of Chemistry, Faculty of Applied and Computer Science), Vaal University of Technology. / The commercial flake graphite was prepared into functionalized graphite oxide (GO) by adopted chemical treatment. After the exfoliation and intercalation of graphite into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate in a microwave at 35 oC for two hours. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, Ultra-violet visible (UV-vis), atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman microscopy and magnified optical microscopy that confirm the oxidation of graphite and reduction of graphene oxide into graphene sheets. Carbon nanomaterials were synthesized from Co-Sn, Co-Sr and Co-Zn as catalysts supported on Al2O3, CaCO3 and MgO. The as-prepared nanomaterials were characterized by thermogravimetric and derivative thermogravimetric analysis (TGA & DTA), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and the transmission electron microscopy. The intensity ratios (ID/IG) of the D- and G- bands were found to be the same that is averagely at 0.83. The TGA & DTA curves have shown Co-Sn/Al had significant weight loss, Co-Sr/Mg weight loss and decomposition, Co-Sr/Al decomposition and Co-Zn/Mg weight loss. However these weight losses were not significant. The EDS analysis showed all elements which took part in the reaction confirming the success of each synthesis. The SEM images show carbon nanotubes only on samples that have been synthesized on MgO as confirmed by TEM images. Finally the XRD showed some characteristic peaks at desired peaks except that they were other peaks attributed to impurities and armophous carbon. It was also observed that Co-Sn/Ca and Co-Sn/Mg XRD curves showed broad peaks at theta = 24.3o & 42.6o and theta = 23.9o & 43.1o respectively which are lattice structure characteristic peaks.

No description available.

No description available.

The goals of this study were to elucidate relationships between food habits and tissue accumulations of heavy metals in Chesapeake Bay waterfowl and to determine effects of chronic cadmium and lead ingestion on energy metabolism in waterfowl. Concentrations of cadmium, lead, copper, and zinc were measured in 774 livers, 266 kidneys, and 271 ulnar bones from 15 species of ducks obtained from the Chesapeake Bay region. Liver and kidney concentrations of cadmium were highest among two carnivorous sea duck species, Clangula hyemalis and Melanitta deglandi. In contrast, lead concentrations in three tissues were generally highest in largely herbivorous species, such as Anas platyrhynchos, Anas rubripes, and Anas strepera. Spent shot may be an important source for tissue burdens of lead in these ducks. No marked trends were observed between food habits and tissue concentrations of copper or zinc. Cadmium and lead concentrations were generally higher in benthic macrophytes than in soft tissues of clams collected from several locations in the Bay. These results suggest that the change that has occurred in the food habits of some Chesapeake Bay ducks, most notably Aythya valisineria to diets composed largely of clams rather than aquatic vegetation probably did not increase ingestion of these elements. In experiments conducted with A. platyrhynchos, chronic ingestion of equal dietary concentrations of cadmium and lead resulted in about 15 times greater accumulation of cadmium than lead in livers and kidneys. However, while ulnar bones accumulated lead, cadmium concentrations in bones remained below detection limits. Cadmium ingestion enhanced renal accumulation of copper and zinc, perhaps due to induction of metallothionein by cadmium. In combination with an imposed food restriction, cadmium ingestion appeared to alter some indices of energy metabolism, such as plasma concentrations of free fatty acids and triiodothyronine, at dietary cadmium levels far below those eliciting similar responses in the absence of a food restriction. Those results suggest the importance of considering interactions with other stressors when examining potential effects of environmental contaminants on wild animals. / Ph. D.

by Tsui Wai-chu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 161-171). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Abbreviations --- p.vii / Contents --- p.ix / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Literature review --- p.1 / Chapter 1.1.1 --- Metal pollution in Hong Kong --- p.1 / Chapter 1.1.2 --- Methods for removal of metal ions from industrial effluent --- p.4 / Chapter A. --- Physico-chemical methods --- p.4 / Chapter B. --- Biosorption --- p.7 / Chapter 1.1.3 --- Chitin and chitosan --- p.11 / Chapter A. --- History of chitin and chitosan --- p.11 / Chapter B. --- Structures and sources of chitin and chitosan --- p.12 / Chapter C. --- Characterization of chitin and chitosan --- p.17 / Chapter D. --- Applications of chitin and chitosan --- p.19 / Chapter 1.1.4 --- Factors affecting biosorption --- p.22 / Chapter A. --- Solution pH --- p.22 / Chapter B. --- Concentration of biosorbent --- p.24 / Chapter C. --- Retention time --- p.25 / Chapter D. --- Initial metal ion concentration --- p.26 / Chapter E. --- Presence of other cations --- p.26 / Chapter F. --- Presence of anions --- p.28 / Chapter 1.1.5 --- Regeneration of metal ion-laden biosorbent --- p.28 / Chapter 1.1.6 --- Modeling of biosorption --- p.29 / Chapter A. --- Adsorption equilibria and adsorption isotherm --- p.29 / Chapter B. --- Langmuir isotherm --- p.33 / Chapter C. --- Freundlich isotherm --- p.34 / Chapter 1.2 --- Objectives of the present study --- p.36 / Chapter 2. --- Materials and methods --- p.37 / Chapter 2.1 --- Biosorbents --- p.37 / Chapter 2.1.1 --- Production of biosorbents --- p.37 / Chapter 2.1.2 --- Pretreatment of biosorbents --- p.39 / Chapter 2.2 --- Characterization of biosorbents --- p.39 / Chapter 2.2.1 --- Chitin assay --- p.39 / Chapter 2.2.2 --- Protein assay --- p.40 / Chapter 2.2.3 --- Metal analysis --- p.41 / Chapter 2.2.4 --- Degree of N-deacetylation analysis --- p.43 / Chapter A. --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.43 / Chapter B. --- Elemental analysis --- p.43 / Chapter 2.3 --- Batch biosorption experiment --- p.44 / Chapter 2.4 --- Selection of biosorbent for metal ion removal --- p.45 / Chapter 2.4.1 --- Effects of pretreatments of biosorbents on adsorption of Cu --- p.45 / Chapter A. --- Washing --- p.45 / Chapter B. --- Pre-swelling --- p.46 / Chapter 2.4.2 --- "Comparison of Cu2+, Ni2+ and Zn2+ removal capacities among three biosorbents" --- p.46 / Chapter 2.4.3 --- Comparison of Cu2+ removal capacity of chitins with various degrees of N-deacetylation --- p.46 / Chapter 2.5 --- "Effects of physico-chemical conditions on Cu2+, Ni2+ and Zn2+ adsorption by chitin A" --- p.48 / Chapter 2.5.1 --- Solution pH and concentration of biosorbent --- p.48 / Chapter 2.5.2 --- Retention time --- p.48 / Chapter 2.5.3 --- Initial metal ion concentration --- p.49 / Chapter 2.5.4 --- Presence of other cations --- p.49 / Chapter 2.5.5 --- Presence of anions --- p.51 / Chapter 2.6 --- Optimization of Cu2+，Ni2+ and Zn2+ removal efficiencies --- p.53 / Chapter 2.7 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden chitin A" --- p.53 / Chapter 2.7.1 --- Performances of various eluents on metal ion recovery --- p.53 / Chapter 2.7.2 --- Multiple adsorption and desorption cycle of metal ions --- p.54 / Chapter 2.8 --- Treatment of electroplating effluent by chitin A --- p.54 / Chapter 2.8.1 --- "Removal and recovery of Cu2+, Ni2+ and Zn2+ from electroplating effluent collected from rinsing baths" --- p.54 / Chapter 2.8.2 --- "Removal and recovery of Cu2+, Ni2+ and Zn2+ from electroplating effluent collected from final collecting tank" --- p.55 / Chapter 2.9 --- Data analysis --- p.56 / Chapter 3. --- Results --- p.58 / Chapter 3.1 --- Characterization of biosorbents --- p.58 / Chapter 3.1.1 --- Chitin assay --- p.58 / Chapter 3.1.2 --- Protein assay --- p.58 / Chapter 3.1.3 --- Metal analysis --- p.58 / Chapter 3.1.4 --- Degree of N-deacetylation analysis --- p.62 / Chapter A. --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.62 / Chapter B. --- Elemental analysis --- p.62 / Chapter 3.2 --- Selection of biosorbent for metal ion removal --- p.67 / Chapter 3.2.1 --- Effects of pretreatments of biosorbents on adsorption of Cu2+ --- p.67 / Chapter A. --- Washing --- p.67 / Chapter B. --- Pre-swelling --- p.67 / Chapter 3.2.2 --- "Comparison of Cu2+, Ni2+ and Zn2+ removal capacities among three biosorbents" --- p.67 / Chapter 3.2.3 --- Comparison of Cu2+ removal capacity of chitins with various degrees of N-deacetylation --- p.70 / Chapter 3.3 --- "Effects of physico-chemical conditions on Cu2+, Ni2+ and Zn2+ adsorption by chitin A" --- p.70 / Chapter 3.3.1 --- Solution pH and concentration of biosorbent --- p.70 / Chapter 3.3.2 --- Retention time --- p.78 / Chapter 3.3.3 --- Initial metal ion concentration --- p.80 / Chapter 3.3.4 --- Presence of other cations --- p.93 / Chapter 3.3.5 --- Presence of anions --- p.93 / Chapter 3.4 --- "Optimization of Cu2+, Ni2+ and Zn2+ removal efficiencies" --- p.104 / Chapter 3.5 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden chitin A" --- p.104 / Chapter 3.5.1 --- Performances of various eluents on metal ion recovery --- p.104 / Chapter 3.5.2 --- Multiple adsorption and desorption cycle of metal ions --- p.109 / Chapter 3.6 --- Treatment of electroplating effluent by chitin A --- p.117 / Chapter 3.6.1 --- "Removal and recovery of Cu2+, Ni2+ and Zn2+ from electroplating effluent collected from rinsing baths" --- p.117 / Chapter 3.6.2 --- "Removal and recovery of Cu2+, Ni2+ and Zn2+ from electroplating effluent collected from final collecting tank" --- p.121 / Chapter 4. --- Discussion --- p.128 / Chapter 4.1 --- Characterization of biosorbents --- p.128 / Chapter 4.1.1 --- Chitin assay --- p.128 / Chapter 4.1.2 --- Protein assay --- p.129 / Chapter 4.1.3 --- Metal analysis --- p.129 / Chapter 4.1.4 --- Degree of N-deacetylation analysis --- p.130 / Chapter A. --- Diffuse reflectance Fourier transform infra-red spectroscopy --- p.130 / Chapter B. --- Elemental analysis --- p.132 / Chapter 4.2 --- Selection of biosorbent for metal ion removal --- p.133 / Chapter 4.2.1 --- Effects of pretreatments of biosorbents on adsorption of Cu2+ --- p.133 / Chapter A. --- Washing --- p.133 / Chapter B. --- Pre-swelling --- p.133 / Chapter 4.2.2 --- "Comparison of Cu2+, Ni2+ and Zn2+ removal capacities among three biosorbents" --- p.134 / Chapter 4.2.3 --- Comparison of Cu2+ removal capacity of chitins with various degrees of N-deacetylation --- p.136 / Chapter 4.3 --- "Effects of physico-chemical conditions on Cu2+, Ni2+ and Zn2+ adsorption by chitin A" --- p.137 / Chapter 4.3.1 --- Solution pH and concentration of biosorbent --- p.137 / Chapter 4.3.2 --- Retention time --- p.138 / Chapter 4.3.3 --- Initial metal ion concentration --- p.139 / Chapter 4.3.4 --- Presence of other cations --- p.141 / Chapter 4.3.5 --- Presence of anions --- p.143 / Chapter 4.4 --- "Optimization of Cu2+, Ni2+ and Zn2+ removal efficiencies" --- p.147 / Chapter 4.5 --- "Recovery of Cu2+, Ni2+and Zn2+ from metal ion-laden chitin A" --- p.148 / Chapter 4.5.1 --- Performances of various eluents on metal ion recovery --- p.148 / Chapter 4.5.2 --- Multiple adsorption and desorption cycle of metal ions --- p.149 / Chapter 4.6 --- Treatment of electroplating effluent by chitin A --- p.150 / Chapter 4.6.1 --- "Removal and recovery of Cu2+, Ni2+ and Zn2+ from electroplating effluent collected from rinsing baths" --- p.150 / Chapter 4.6.2 --- "Removal and recovery of Cu2+, Ni2+ and Zn2+ from electroplating effluent collected from final collecting tank" --- p.152 / Chapter 5. --- Conclusion --- p.154 / Chapter 6. --- Further studies --- p.156 / Chapter 7. --- Summary --- p.158 / Chapter 8. --- References --- p.161

by Sze Kwok Fung Calvin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 118-130). / Acknowledgement --- p.i / Abstract --- p.ii / Content --- p.iv / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Literature review --- p.1 / Chapter 1.1.1 --- Heavy metals in the environment --- p.1 / Chapter 1.1.2 --- Heavy metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Electroplating industry in Hong Kong --- p.6 / Chapter 1.1.4 --- Chemistry and toxicity of copper in the environment --- p.7 / Chapter 1.1.5 --- Methods of removal of heavy metal from industrial effluent --- p.9 / Chapter A. --- Physico-chemical methods --- p.9 / Chapter B. --- Biological methods --- p.9 / Chapter 1.1.6 --- Methods of recovery of heavy metal from metal-loaded biosorbent --- p.17 / Chapter 1.1.7 --- The physico-chemical properties of magnetites --- p.18 / Chapter 1.1.8 --- Magnetites for water and wastewater treatment --- p.19 / Chapter 1.1.9 --- Immobilized cell technology --- p.24 / Chapter 1.1.10 --- Stirrer-tank bioreactor --- p.26 / Chapter 1.2 --- Objectives of the present study --- p.28 / Chapter 2. --- Materials and Methods --- p.30 / Chapter 2.1 --- Selection of copper-resistant bacteria --- p.30 / Chapter 2.2 --- Culture media and chemicals --- p.30 / Chapter 2.3 --- Growth of the bacterial cells --- p.32 / Chapter 2.4 --- Immobilization of the bacterial cells on magnetites --- p.32 / Chapter 2.4.1 --- Effects of physical and chemical factors on the immobilization of the bacterial cells on magnetites --- p.34 / Chapter 2.4.2 --- Effects of pH on the desorption of bacterial cells from magnetites --- p.34 / Chapter 2.5 --- Copper ion uptake experiments --- p.35 / Chapter 2.6 --- Effects of physico-chemical and operational factors on the Cu2+ removal capacity of the magnetite-immobilized bacterial cells --- p.35 / Chapter 2.7 --- Transmission electron micrograph and scanning electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.36 / Chapter 2.7.1 --- Transmission electron micrograph --- p.36 / Chapter 2.7.2 --- Scanning electron micrograph --- p.37 / Chapter 2.8 --- Copper ion adsorption isotherm of the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.37 / Chapter 2.9 --- Recovery of adsorbed Cu2+ from the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.38 / Chapter 2.9.1 --- Effects of eluents on the Cu2+ removal and recovery capacity of the magnetite-immobilized cells --- p.38 / Chapter 2.9.2 --- Batch type multiple adsorption-desorption cycles of Cu2+ using ethylenediaminetetra-acetic acid (EDTA) --- p.39 / Chapter 2.10 --- Removal and recovery of Cu2+ from the electroplating effluent by a bioreactor --- p.39 / Chapter 2.10.1 --- Batch type multiple adsorption-desorption cycles using the copper solution and electroplating effluent --- p.39 / Chapter 2.10.2 --- Continuous type bioreactor to remove and recover Cu2+ from copper solution and electroplating effluent --- p.40 / Chapter 2.11 --- Statistical analysis of data --- p.43 / Chapter 3. --- Results --- p.44 / Chapter 3.1 --- Effects of physical and chemical factors on the immobilization of the bacterial cells on magnetites --- p.44 / Chapter 3.1.1 --- Effects of cells to magnetites ratio --- p.44 / Chapter 3.1.2 --- Effects of pH --- p.44 / Chapter 3.1.3 --- Effects of temperature --- p.44 / Chapter 3.2 --- Effects of pH on the desorption of bacterial cells from magnetites --- p.49 / Chapter 3.3 --- Copper ion uptake experiments --- p.49 / Chapter 3.4 --- Effects of physico-chemical and operational factors on the Cu2+ removal capacity of the magnetite-immobilized bacterial cells --- p.49 / Chapter 3.4.1 --- Effects of pH --- p.49 / Chapter 3.4.2 --- Effects of temperature --- p.53 / Chapter 3.4.3 --- Effects of retention time --- p.53 / Chapter 3.4.4 --- Effects of cations --- p.53 / Chapter 3.4.5 --- Effects of anions --- p.57 / Chapter 3.5 --- Transmission electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.62 / Chapter 3.6 --- Scanning electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.62 / Chapter 3.7 --- Copper ion adsorption isotherm of the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.68 / Chapter 3.8 --- Recovery of adsorbed Cu2+ from the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.68 / Chapter 3.8.1 --- Effects of eluents on the Cu2+ removal and recovery capacity of the magnetite-immobilized cells --- p.68 / Chapter 3.8.2 --- Batch type multiple adsorption-desorption cycles of Cu2+ using ethylenediaminetetra-acetic acid (EDTA) --- p.74 / Chapter 3.9 --- Removal and recovery of Cu2+ from the electroplating effluent by a bioreactor --- p.74 / Chapter 3.9.1 --- Batch type multiple adsorption-desorption cycles using the copper solution and electroplating effluent --- p.74 / Chapter 3.9.2 --- Continuous type bioreactor to remove and recover Cu2+ from copper solution and electroplating effluent --- p.81 / Chapter 4. --- Discussion --- p.89 / Chapter 4.1 --- Selection of copper-resistant bacteria --- p.89 / Chapter 4.2 --- Effects of physical and chemical factors on the immobilization of the bacterial cells on magnetites --- p.89 / Chapter 4.2.1 --- Effects of cells to magnetites ratio --- p.89 / Chapter 4.2.2 --- Effects of pH --- p.90 / Chapter 4.2.3 --- Effects of temperature --- p.91 / Chapter 4.2.4 --- Effects of pH on the desorption of bacterial cells from magnetites --- p.92 / Chapter 4.3 --- Copper ion uptake experiments --- p.93 / Chapter 4.4 --- Effects of physico-chemical and operational factors on the Cu2+ removal capacity of the magnetite-immobilized bacterial cells --- p.94 / Chapter 4.4.1 --- Effects of pH --- p.95 / Chapter 4.4.2 --- Effects of temperature --- p.96 / Chapter 4.4.3 --- Effects of retention time --- p.97 / Chapter 4.4.4 --- Effects of cations --- p.98 / Chapter 4.4.5 --- Effects of anions --- p.101 / Chapter 4.5 --- Transmission electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.101 / Chapter 4.6 --- Scanning electron micrograph of Pseudomonas putida 5-X loaded with Cu2+ --- p.102 / Chapter 4.7 --- Copper ion adsorption isotherm of the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.103 / Chapter 4.8 --- Recovery of adsorbed Cu2+ from the magnetite-immobilized cells of Pseudomonas putida 5-X --- p.104 / Chapter 4.8.1 --- Effects of eluents on the Cu2+ removal and recovery capacity of the magnetite-immobilized cells --- p.104 / Chapter 4.8.2 --- Batch type multiple adsorption-desorption cycles of Cu2+ using ethylenediaminetetra-acetic acid (EDTA) --- p.105 / Chapter 4.9 --- Removal and recovery of Cu2+ from the electroplating effluent by a bioreactor --- p.107 / Chapter 4.9.1 --- Batch type multiple adsorption-desorption cycles using the copper solution and electroplating effluent --- p.107 / Chapter 4.9.2 --- Continuous type bioreactor to remove and recover Cu2+ from copper solution and electroplating effluent --- p.108 / Chapter 5. --- Conclusion --- p.110 / Chapter 6. --- Summary --- p.112 / Chapter 7. --- References --- p.115

Ph.D. / The current study evaluated a bio-monitoring technique developed in the USA by Adams, Brown and Goede, 1993. This project was sponsored by the Department of Water Affairs and Forestry (DWAF), to enable testing of the Health Assessment Index (HAI) under South African conditions. Testing took place in the Olifants River system, one of the most polluted river systems . in South Africa. Initially two river points were tested using Oreochromis mossambicus (Robinson, 1996), Clarias gariepinus (Marx, 1996) and Labeo rosae (Luus-Powell, 1997). The current study re-tested the HAI at the same two sample sites, namely Mamba and Balule in the Kruger National Park, using 0. mossambicus and C. gariepinus respectively. Two additional sites were tested in the upper catchment area, namely Loskop Dam and Bronkhorstspruit Dam. The current study further enabled the comparison of HAI results collected during drought and flood conditions. Results obtained after deployment of the HAI were corroborated using chemical analysis of water, sediment and biota. Water and sediment analysis was carried out by the Institute for Water Quality Studies using standard techniques. Bio-accumulation of aluminium, copper, iron, lead, manganese, nickel, strontium and zinc was assessed in the gills, liver, skin and muscle tissue of sample fish using standard Atomic Absorption Spectrometry techniques. Modifications made to the original HAI involved the inclusion of variable ranking in the assessment of fish parasites, with endo- and ectoparasites evaluated separately. Testing of this parasite hypothesis lead to the development of a Parasite Index component to the HAI. Assessment of water, sediment and fish tissue determined that the Olifants River system is indeed exposed to macro and heavy metal pollutants, which negatively affect aquatic health. Constituents posing the greatest threat are chlorides, fluorides, phosphates, total dissolved solids, copper and iron concentrations. Testing the HAI and parasite hypothesis using C. gariepinus, provided the most meaningful results. During testing of the parasite hypothesis both endo- and ectoparasite numbers conformed to the suggested idea that higher endoparasite numbers will occur at highly impacted areas, whereby ectoparasite numbers will be low. This was particularly evident in the lower catchment area, whereby comparisons between drought and flood conditions were carried out. Subsequent decreases in water quality directly after the flood were noted using water and sediment analysis. This observation reflects the results gathered using the HAT and during testing of the parasite hypothesis at all four sample sites. During statistical analysis of the HAI, using logistic regression analysis, parasite numbers, more specifically endoparasite numbers, were the most indicative of fish health. Environmental stressors (flood conditions) result in immunological responses observed in fish, and are reflected statistically using the HAI as changes in WBC %. It is suggested that endoparasites and WBC % provide the best overall assessment of fish condition. These variables should thus not be eliminated, in order to streamline the HAI evaluation procedures. Testing of this bio-monitoring technique under South African conditions provided meaningful results. This indicates that the HAI can be used to assess water quality, with existing water monitoring programmes further benefiting from its incorporation.

Pollution of soil by trace metals has become one of the biggest global environmental challenges resulting from anthropogenic activities, therefore, restoration of metal contaminated sites needs due attention. The use of phytoremediation technologies as nature-based solution to pollution, could support successful implementation of green economic development strategies; with economically affordable and environmentally friendly benefits. The present investigation employed an exploratory study on the phytoremediation potentials of three selected native plants; Phytolacca dodecandra (L’Herit), Adhatoda schimperiana (Hochst) and Solanum incanum L, dominating areas close to heavy metal contamination sources; in metropolitan centers of Addis Ababa. In this work, concentration of six heavy metals of interest chromium (Cr), lead (Pb), cadmium (Cd), nickel (Ni) copper (Cu) and zinc (Zn) were examined in soil and in different tissues (leaves, stems and roots) of selected plants (both seedlings and mature plants), in dry and rainy seasons using atomic absorption spectrophotometer. Efficiency of phytoremediation is discussed based on calculated values of Bio-concentration Factor (BCF), Translocation Factors (TF) and Bioaccumulation Coefficient (BAC). Phytolacca dodecandra showed BCF, TF and BAC > 1 for Zn, Pb, Ni, Cu and Cd Adhatoda schimperiana gave BCF, TF and BAC > 1 for Zn, Cu, Ni and Cr; likewise, BCF, BAC and TF values of > 1 were noted in Solanum incanum for Zn, Cu, Pb and Ni. Based on these scenarios, the three plants could be utilized for phytoextraction of contaminated soil. Conversely, BCF and BAC for Cr levels in tissues of Phytolacca dodecandra were all < 1, which indicates unsuitability for phytoremediation of Cr in contaminated soils. Besides, Adhatoda schimperiana retained Pb and Cd in their roots showing root BCF > 1, while BAC and TF < 1, which highlights its suitability for phytostabilization. Moreover, BCF, TF and BAC values of < 1 noted for Cr and Cd in Solanum incanum reveal that Solanum incanum may not be a good candidate for remediation of Cr and Cd contaminated environments. In conclusion, results from this study revealed that the selected plants can accumulate substantial amounts of the above trace metals in their tissues and can serve as prospective phytoremediators of most of these metals. Phytoextraction and phytostabilization were the main mechanisms of remediation in this study. / Environmental Sciences / Ph. D. (Environmental Sciences)