Orientadores: Meuris Gurgel Carlos da Silva, Sirlei Jaiana Kleinübing / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T10:55:13Z (GMT). No. of bitstreams: 1 Barros_ArielleMunizde_M.pdf: 2403867 bytes, checksum: 9d034ece43d77bf5fa23832c79a98b8c (MD5) Previous issue date: 2012 / Resumo: Pesquisas no campo da tecnologia têm buscado avaliar técnicas e/ou processos econômicos e eficientes para o tratamento de efluentes que contenham metal pesado. Atualmente a bioadsorção vem se apresentando como uma boa alternativa às tecnologias existentes. Este trabalho teve como objetivo a investigação da macrófita Azolla pinnata como bioadsorvente de cinco íons metálicos: Cd2+, Cu2+, Ni2+, Pb2+ e Zn2+ em soluções sintéticas. A caracterização do biomaterial foi realizada utilizando-se técnicas como Microscopia Eletrônica de Varredura (MEV) para análise da superfície do material; análise de Espectroscopia de Energia Dispersiva de Raios-X (EDX), que mostrou que qualitativamente a diminuição de íons de competição (Ca, Na e K) após o processo de adsorção, evidenciando que a troca iônica pode ser um dos mecanismos do processo; e análise de Infravermelho por Transformada de Fourier (FTIR), em que se pôde constatar que alguns grupos funcionais como carboxilas e grupos sulfonados são fundamentais no processo. A cinética de adsorção foi ajustada pelos modelos de pseudoprimeira e pseudossegunda ordem, sendo que o melhor ajuste variou de acordo com o íon estudado. O modelo de difusão intrapartícula mostrou que muitos mecanismos podem ser limitantes na taxa com a qual ocorre o processo. Os dados de equilíbrio foi ajustado pelos modelos de isoterma de Langmuir e de Freundlich em duas temperaturas, 25 e 45 ºC. O processo foi favorecido pelo acréscimo de temperatura para todos os íons. O modelo de Langmuir se ajustou melhor aos dados experimentais de todos os íons e o valor de capacidade máxima de adsorção (qmax) a 25 ºC foi de 0,359; 0,448; 0,254; 0,472 e 0,357 mmol/g para Cd2+, Cu2+, Ni2+, Pb2+ e Zn2+, respectivamente. Os eluentes HCl, EDTA e CaCl2 foram testados no processo de dessorção em batelada e o cloreto de cálcio se mostrou eficiente além de não causar danos ao material nem diminuir a capacidade de adsorção da macrófita. Ensaios dinâmicos em coluna de leito fixo foram realiados para os íons Cu2+ e Pb2+ com soluções mono e bicomponentes. Nos ensaios em sistema binários, pode-se constatar uma grande preferência pela adsorção de íons chumbo e, portanto, uma grande queda na adsorção de cobre. Foram testados ciclos de adsorção/dessorção em coluna utilizando o CaCl2 como eluente e, em três ciclos, a macrófita manteve suas propriedades adsortivas. Com estes resultados, pode-se constatar que a realização deste trabalho contribuiu para a avaliação deste material como bioadsorvente alternativo e que, especificamente, macrófita A. pinnata mostrou-se atrativa para utilização nos processos de tratamento e/ou estabilização de metais pesados presentes em baixas concentrações em efluentes industriais / Resumo: No processo Kraft para produção de papel e celulose, os cavacos de madeira são cozidos em um digestor com uma solução aquosa denominada licor branco, constituída de hidróxido de sódio (NaOH) e sulfeto de sódio (Na2S). Durante o cozimento uma pasta fibrosa é produzida. Esta pasta é filtrada e segue para o branqueamento. O produto filtrado chama-se licor negro, devido à mudança da sua cor nesta etapa. O licor negro possui aproximadamente 15 % de sólidos em massa. Ele é bombeado para a unidade de recuperação, na qual ele será concentrado em evaporadores de múltiplosefeitos até 75 % de sólidos em massa. Em seguida, ele é bombeado para uma caldeira onde é queimado, para recuperar os sais inorgânicos e, principalmente, fornecer calor para geração de calor. Durante a evaporação do licor negro, quando a porcentagem em sólidos ultrapassa 50 %, ocorre a precipitação de sais inorgânicos. Estes sais se depositam nas superfícies de troca térmica dos evaporadores diminuindo sua eficiência e causando prejuízos à indústria. Os principais sais que causam este problema são o carbonato de sódio (Na2CO3) e o sulfato de sódio (Na2SO4). O objetivo do presente trabalho foi testar e validar um método experimental para a determinação da quantidade de Na2CO3 presente em amostras industriais de licor negro. Além disso, também foram analisadas algumas propriedades físico-químicas do licor negro, como massa específica, teor de sólidos e viscosidade. Com os resultados obtidos, tentou-se obter uma correlação entre o teor de carbonato de sódio e as demais propriedades do licor que foram determinadas. Os resultados das análises das características físico-químicas demonstraram coerência e boa reprodutibilidade, porém, os resultados das análises de teor de carbonato de sódio não foram satisfatórios e mostraram que a técnica deve ser aperfeiçoada / Abstract: Research in the technology field has been looking for evaluating efficient and economic techniques and/or process for effluents that contains heavy metal. The biodsorption process has been seemed as a good alternative to the existing technology. This work had the aim to investigate the use of Azolla pinnata macrophyte as biosorbent of five metallic ions: Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+ in synthetic solutions. The biomaterial characterization was carried out by techniques as scanning electron microscopy (SEM) for the analyze of material superficies; the energy dispersive X-ray spectroscopy (EDX), which showed, qualitatively, a decreasing in the competitions ions (Ca, Na e K) after the sorption process, indicating that the ion exchange can be one o the process mechanism; and Fourier Transform Infrared Spectroscopy (FTIR), in which it was possible implied functional groups as carboxyl and sulfonate play a important role in the adsorption. The kinetics was adjusted by primer and second order models and the model which fit better depends on each ion. The intra-particle diffusion model showed that several mechanisms may be limiting to the process rate. The equilibrium data were adjusted by Langmuir and Freundlich models in two temperatures: 25 and 45 ºC. The process was favored by the increasing in the temperature for all five ions. The Langmuir model fit better the experimental data and the maximum adsorption capacity (qmax) were 0,359; 0,448; 0,254; 0,472 and 0,357 mmol/g for Cd2+, Cu2+, Ni2+, Pb2+ and Zn2+, respectively. The HCl, EDTA and CaCl2 eluents were tested in the desorption process and the calcium chloride was efficient and did not cause any damage in the biomaterial or decreasing the biosorption capacity. Dynamics runs were carried out in fixed-bed in mono and bi-components solutions. In the binary were found a great preference for lead instead of copper and as a result, a significant decrease in the removal of copper. Adsorption/desorption cycles were tested in fixed-bed system using CaCl2 as eluent. After three cycles no damage, weight lost or significant decrease in the biosorption capacity was noticed. These results indicating that the A.pinnata macrophyte is an attractive potential new biosorbent to be used in heavy metal removal especially in low concentrations effluents / Abstract: In the Kraft process for pulp and paper production, wood chips are cooked in a digester with an aqueous solution named white liquor, consisted by sodium hydroxide (NaOH) and sodium sulfide (Na2S). During this cooking process, wood chips are transformed generating a fibrous paste and a liquid solution. This paste is filtered and separated from the liquid solution, named black liquor due to its color. The paste goes to the bleaching stage to produce cellulose. Black liquor contains inorganic and organic (mainly lignin) compounds from wood. Initially this black liquor contains approximately 15 mass/% of solids and is sent to the recovery unit to have this concentration raised to approximately 75 mass/% to be burned in a recovery boiler in order to generate power and recover inorganic reactants, recycling them to the process. The concentration process of black liquor occurs in a multiple effect evaporators unit. During this process, when the concentration of solids exceeds 50%, the precipitation of inorganic salts (mainly Na2CO3 and Na2SO4) begins. These salts are deposited in the heat transfer surfaces of the evaporator tubes, reducing their efficiency, leading to a reduction in the production capacity. The scope of this work was testing and validate an experimental method to estimate the content of Na2CO3 present in industrial black liquor samples. Moreover, some black liquor's physical-chemical properties as density, solids content and viscosity were also analyzed. An attempt to develop a predictive model to evaluate sodium carbonate content from the other properties was made. The results obtained for physical-chemical properties have shown a good consistency. However, the results of sodium carbonate analyses were not satisfactory, showing that the technique must be improved / Mestrado / Engenharia de Processos / Mestra em Engenharia Química

M.Sc. / Aquatic toxicology is the qualitative and quantitative study of toxic effects of pollutants on aquatic organisms. The main goal in toxicity testing is to predict, in combination with other environmental factors, with known accuracy, a concentration of a specific toxicant that will not harm a system and to make this prediction in a responsible and cost effective manner. There are a variety of unique toxicity tests, with fish being one of the most popular organisms to work with, due to being the best-understood organism in the aquatic environment and its commercial importance. Zinc, copper and cadmium are three biologically important heavy metals that are commonly used in various industries. Low concentrations zinc and copper are essential micronutrients for both plants and animals, but in higher concentrations they become toxic to the environment and its biota. Cadmium has a chemical structure similar to that of zinc and is often found in association with it, but it is a very toxic substance. The effects of zinc, copper and cadmium on the free-embryo life stage (yolk sac phase) of Oreochromis mossambicus were examined, for evaluation as a possible ¡§early life stage¡¨ fish lethality assessment. ¡§Fish early life stage tests¡¨ are considered to be relatively quick, comparable and inexpensive screening tools for testing effluents and chemicals. The yolk-sac stage is considered the most sensitive life stage in fish. O. mossambicus free-embryos feed endogenously and are indigenous to southern Africa and are therefore a good choice for lethality testing. The effects of the same metals on randomly selected Culicidae (mosquito) larvae were also tested. The reason for randomly selected larvae was to determine the possibility of doing toxicity testing without a species-specific culture. Mosquitoes are very common and well known due to being vectors of various human diseases. Recommendations towards future studies, to determine the usefulness of both O. mossambicus embryos and Culicidae larvae as biological indicator organisms, were also looked at. / Prof. G.J. Steyn

Rivers all over the world have supported the growth of human civilization since the first towns appeared some 7000 years ago. As a result of this growth and the diversification of activities, most of the world’s rivers have been negatively affected. Freshwater is probably the most important resource of mankind. Not only is it vital for terrestrial life but we consume water in such a range of activities that it can aptly be regarded as a ‘pillar of our civilization’. The development of water conservation recycling and management plans is therefore seen as vital. Cohen (1995) has recently highlighted the importance of freshwater to the future of mankind and in this context it is becoming increasingly important to view water as an economic resource in its own right. Being a third world country, South Africa is a developing country with a constant increase in population size. With the increase in the population, it is accompanied by increasing and expanding mining and industrial sectors. Various metals resulting from these sector’s activities are common pollutants in the rivers of South Africa. Although some metals are essential elements that are necessary for normal growth and metabolism in organisms, all metals can become toxic at elevated levels and therefore the monitoring of the freshwater systems is necessary in order to protect the environment and ultimately to protect humankind. Aquatic invertebrates appear to be excellent biological monitors of heavy metal pollution. They are more tolerant of metals than fish, they accumulate metals in relative proportion to the metal concentration in the water, and they concentrate the metal by some predictable, reproducible factor. However the life cycle of aquatic insects are short which limits the value in bioaccumulation studies. In contrast, crabs are relatively long lived and form an integral part of the food chain, as they are vital components in the diet of several animal species including humans. In the present study an integrated approach was employed in order to investigate the metal pollution in the Klip River, Gauteng. Selected physico-chemical characteristics of the water and sediment were analysed, as were the levels of metals bioaccumulated by the freshwater crab, Potamonautes warreni. Different biological aspects were investigated to identify the natural course of the life cycle, including moulting and reproductive cycles, relative abundance and age structure, as well as several behavioural patterns of this crab species. Water and sediment samples were collected from the Klip River and Sedaven Dam (reference locality) every month from August 1997 up to August 1998. Water quality data revealed that although the quality of the water at all sampling localities were relatively high, Lenasia (locality 1) and Dirk Fourie Stadium (locality 4) appeared to be more impacted than the rest of the sampling localities including the reference locality. Results of the metal analysis in the water samples indicated that levels of zinc, iron, manganese and chromium were below the suggested South African guideline values (laid down for the protection of aquatic life) and that elevated levels of cadmium, lead and aluminium were recorded at localities 1,3 and 4. Results of the metal analysis in the sediment samples indicated that there were elevated levels of zinc, lead, iron, manganese, chromium and aluminium at localities 1 and 2. Potamonautes warreni individuals were sampled every month to coincide with the water and sediment samples and the metal concentrations were determined. The results of this investigation showed that elevated levels of zinc, cadmium, lead, iron, manganese, chromium and aluminium was recorded at locality 1 and this indicated that this locality is subjected to above standard discharge. At locality 3 elevated levels of zinc, cadmium and chromium was recorded and at localities 4 and 5 elevated levels of iron and aluminium was recorded. The results of the present study indicates that metal levels in P. warreni are indicative of the environmental levels of metals to which these crabs are exposed. Higher metal levels as compared to the habitat were found in the organisms at all localities. Locality 1 had a higher environmental level than the rest of the localities. Therefore, these organisms are useful bioaccumulative indicators and should be incorporated into biomonitoring programs in conjunction with fish. It must be stressed that further studies be done on the mechanisms of regulation and elimination of certain metals from the body of P. warreni and on sublethal effects of metals on the physiological processes such as reproduction and growth, especially in juvenile crabs. / Prof. G.J. Steyn

M.Sc. / South Africa is a developing country in which the rapid increase in population size is accompanied by expanding mining and industrial sectors. All these factors have resulted in an increase in the demand for good quality water, but various anthropogenic activities continually result in pollution of the freshwater reserves in the country, via either diffuse or point sources. Metals resulting from both mining and industry are common pollutants of South African aquatic systems. Although some are essential elements that are necessary for normal growth and metabolism in organisms, all metals can become toxic at elevated levels, thus resulting in either lethal and sublethal effects. Aquatic organisms can also bioaccumulate metals thereby transferring them to their predators, including man. Monitoring of freshwater systems is thus necessary in order to protect the environment from these toxic substances, and ultimately to protect mankind. Most monitoring programmes should use an integrated approach in which both physico-chemical and biological aspects are monitored. The present study employed an integrated approach in order to investigate the state of metal pollution in two water bodies that are subjected to differential levels of metal contamination. Selected physico-chemical characteristics of the water and sediment were analysed, as were the levels of metals bioaccumulated by the Freshwater River crab, Potamonautes warreni. The specific object of this study was to assess the potential of P. warreni as a suitable bioaccumulative indicator of metal pollution in the aquatic environment. Water and sediment samples were collected from Germiston Lake and Potchefstroom Dam every alternate month between February 1995 and February 1996. Water quality data revealed that although the quality of the water at both sites was relatively high, Germiston Lake appeared to be more anthropogenically impacted than Potchefstroom Dam. Analysis of metal levels in the water and sediment indicated that while levels of copper, manganese, nickel, lead and zinc were higher in Germiston Lake, calcium and iron were present in higher concentrations in Potchefstroom Dam. Cadmium levels differed little between the two sites. With the exception of iron in Potchefstroom Dam, nickel in Germiston Lake, and zinc at both sites, all of the physical and chemical characteristics of the water from the two sites were within the boundaries of the South African guideline values laid down for the protection of aquatic life. Potamonautes warreni individuals were also collected every alternate month, and metal concentrations in these organisms were determined using atomic absorption spectrophotometry. The results of this investigation showed that metal levels in these organisms did tend to reflect those in the environment, with lower levels of calcium and iron and significantly higher (p < 0.05) levels of copper, manganese, lead, nickel, and zinc in P. warreni from Germiston Lake. Cadmium concentrations detected in these crabs were essentially the same at the two sites. All metals, except for cadmium, were influenced by the size of the crabs at one or other site, but never at both, thus suggesting that the presence of size-related trends is influenced by ambient metal levels in the system. Iron and lead concentrations in P. warreni from Potchefstroom Dam were the only metals that were influenced by the sex of the organisms, with higher levels found in female crabs. The results of the present study clearly indicate that metal levels in P. warreni are indicative of the environmental levels of metals to which these crabs are exposed since higher metal levels were found in the organisms from the site that had higher environmental metal levels. These organisms have proven to be useful bioaccumulative indicators of metal pollution in the aquatic environments from which they were captured, and they should therefore be incorporated into biomonitoring protocols. It must, however, be stressed that further research is required to increase our database on metal levels in these crabs from different aquatic systems.

>Magister Scientiae - MSc / South Africa is one of two countries responsible for the production of approximately 80% of the world’s Zr. The increase in mining activity has detrimental effects on the environment, especially crop plants, as more pollutants are leached into the soil. Consequently, it is necessary to understand how plants respond to this form of abiotic stress. Therefore, this study focused on determining the physiological and biochemical responses of two genotypes of Brassica napus L (Agamax and Garnet) in response to Zr stress. The levels of cell death, lipid peroxidation and ROS were higher in Garnet, whereas the chlorophyll content was higher in Agamax. Furthermore, native PAGE analysis detected seven SOD isoforms and seven APX isoforms in Agamax, compared to 6 SOD isoforms and 7 APX isoforms in Garnet. The results thus indicate that Agamax is tolerant to Zr-induced stress, whereas Garnet is sensitive. An assay for the rapid quantification of Zr within plant samples was subsequently developed, which revealed that Agamax retained the bulk of the Zr within its roots, whereas Garnet translocated most of the Zr to its leaves. The ability of Agamax to sequester Zr in its roots comes forth as one of the mechanisms which confers greater tolerance to Zr-induced stress. As a consequence, our study sought to use the optical, physical and chemical properties of quantum dots to image the uptake and translocation of Zr in B. napus genotypes. ICPOES was also performed to quantify Zr levels in various plant organs. Data from the ICPOES revealed varying patterns of uptake and translocations between Garnet and Agamax. These patterns were similarly shown in IVIS Lumina images, tracing the transport of QD/Zr conjugates. This method ultimately proved to be successful in tracing the uptake of Zr, and could essentially be a useful tool for targeting and imaging a number of other molecules.

The thesis presents the development of polymer based electrospun nanofibers as diagnostic probes for the selective detection of toxic metal ions in water. Through modification of the chemical characteristics of nanofibers by pre- and post-electrospinning treatments, three different diagnostic probes were successfully developed. These were the fluorescent pyridylazo-2-naphthol-poly(acrylic acid) nanofiber probe, the colorimetric probe based on glutathione-stabilized silver/copper alloy nanoparticles and the colorimetric probe based on 2-(2’-Pyridyl)-imidazole functionalized nanofibers. The probes were characterized by Fourier transform infrared spectroscopy (FTIR), Energy dispersive x-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The fluorescent nanofiber probe was developed towards the determination of Ni²⁺. Covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymeric nanofibers were employed. The solid state Ni²⁺ probe exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 mg/mL based on the Stern-Volmer mechanism. The detection limit of the nanofiber probe was found to be 0.07 ng/mL. The versatility of the fluorescent probe was demonstrated by affording a simple, rapid and selective detection of Ni²⁺ in the presence of other competing metal ions by direct analysis without employing any sample handling steps. For the second part of the study, a simple strategy based on the in-situ synthesis of the glutathione stabilized silver/copper alloy nanoparticles (Ag/Cu alloy NPs) in nylon 6 provided a fast procedure for fabricating a colorimetric probe for the detection of Ni²⁺ in water samples. The electrospun nanofiber composites responded to Ni²⁺ ions but did not suffer any interference from the other metal ions. The effect of Ni²⁺ concentration on the nanocomposite fibers was considered and the “eye-ball” limit of detection was found to be 5.8 μg/mL. Lastly, the third probe was developed by covalently linking an imidazole derivative; 2-(2′-Pyridyl)-imidazole (PIMH) to Poly(vinylbenzyl chloride) (PVBC) and nylon 6 nanofibers by post-electrospinning treatments using a wet chemical method and graft copolymerization technique, respectively. The post-electrospinning modifications of the nanofibers were achieved without altering their fibrous morphology. The color change to red-orange in the presence of Fe²⁺ for both the grafted nylon 6 (white) and the chemically modified PVBC (yellow) nanofibers was instantaneous. The developed diagnostic probes exhibited the desired selectivity towards the targeted metal ions.

The potential of non-viable Azalia filiculaides for the removal of Cu and Ni from aqueous solutions and the possibility of scaling up existing lab scale Azalia column systems was investigated. The effects of factors such as metal starting concentration, pH and two metals in solution on the removal of Ni and Cu from aqueous solution by dried and crushed Azalia biomass were studied in batch systems. Aqueous solutions of Ni with starting concentrations between 1000 and 2000J.lmolll gave the most efficient Ni removal by Azalla biomass. For Cu the optimum starting concentration for adsorption was 50J.lmol/l. The adsorption capacity of both eu and Ni increased as the starting pH of the sorption media increased. The optimum pH for Ni adsorption was found at pH 7 and for Cu, at pH 5. - Awlla biomass had a higher. maximum binding capacity (qrnax) for Cu than for Ni at pH 5. The removal of both Cu allct Ni showed little or no variation with the presence another metal in solution. Kinetic studies show that both Cu and Ni adsorbed rapidly onto the Azalia biomass. The removal of Cu and Ni from aqueous solutions using non-viable Azalia biomass was investigated in a lab scale fixed-bed column and an upscaled 4L column system. The nonviable Azalla filiculaides biomass when dried and used in a column for adsorption of Cu and Ni showed good physical stability under many different conditions. Preparation of the biomass before it could be used in the columns was very simple and did not involve any significant pretreatment steps. Prolonged exposure to UV light decreases Azalia biomass capacity for Ni and Cu adsorption. Column adsorption of Cu and Ni from aqueous solutions was successfully upscaled approximately 100 times. Relative to the lab scale column, the 4L column performed better for the uptake of Cu and Ni per gram of biomass. The larger column was also able to operate at relatively higher flow rates. The biomass showed good reusability with little change in the amount of Ni adsorbed in 10 consecutive cycles. Electron micrographs showecf little or no change in the physical structure and integrity of the Azolla biomass after exposure to mineral acids, Ni solution and high flow rates over 10 consecutive adsorption and desorption cycles. As much as 80% Ni and 70 % Cu was recovered when desorption profiles were generated using O.lMHCI as a desorption agent. The 4L column system was also tested using a highly concen~rat:~ Ni plating bath solution.(Nicrolyte 1). Only 18 % of the Ni could be removed from the expended Nicrolyte 1 pla~Jng solution after treating only 25L, indicating that Azolla biomass is more suited for removal of metals from more dilute industrial effluents.

Ph.D. / Heavy metals like copper are toxicants commonly found in mining, industrial, agricultural and waste effluents in South Africa¡¯s riverine systems. In high concentrations these metals could have a negative effect not only on river systems, but also on fish populations. It is therefore important to determine the effect of these heavy metals on the fish at an early stage, before the fish show any sign of being exposed to the pollutants and before any bodily functions are affected. It is known that polluted water, especially heavy metal pollution like copper, can cause physiological and biochemical alterations in fish. Histopathology is a mechanism, which can provide an indication of fish health by determining early injury to cells and can therefore be considered an important tool to determine the effect of pollutants like copper on fish tissue. At present very little is known about the effect of toxicants on the histology of fish tissue of freshwater fishes in South Africa. This is important in gonads, where many variables not only in different fish species, but also in the number of developing germ cells in the testes exist. The large number of fish species and the variation in their anatomy and reproductive patterns make knowledge of the anatomy of all fish species difficult. In order to perform a histopathological analysis, it is important to be familiar with the normal histology of the fish organs that are being investigated. It was therefore necessary to describe the histology of selected organs in South Africa¡¯s freshwater fish species. The Mozambique tilapia, O. mossambicus was chosen as test organism and copper was selected as toxicant. The normal morphology and histology of the testes of O. mossambicus were described in order to serve as a baseline study and to provide histological parameters for further toxicological work on the gonadal histopathology of fish. Fish were exposed to sub-lethal concentrations of copper (CuCl2) for a short-term (96 hours) in experimental flow-through systems under controlled laboratory conditions (23 ¡¾ 1¨¬C). An external investigation of each of the 30 control and 40 copper exposed fish was performed. Standard length, body mass and gonadal mass were recorded and the maturity of each fish was obtained histologically. A light and electron microscopic examination was performed in order to describe the histology and histopathological changes. The histopathological changes were obtained by comparing the histology and ultrastructure of the testis of the control group with the information obtained for the testes that were exposed to copper. Fish obtained from the control group that were run simultaneously with every exposure group were used to describe the normal histology of the testes of O. mossambicus. The aim was to describe the normal morphology and histology of the testes of O. mossambicus so that the information obtained during this investigation could serve as a baseline study when dealing with toxicity studies. The different germ cells of the spermatogenesis process were also described with a view to assess not only the reproductive pattern, but also to provide histological parameters which might form a basis for any toxicological work on the gonadal histopathology of fish. Identification of reproductive biomarkers requires an understanding of all the principal cellular components of the testes and their normal range of variation. The cellular components that were described are the Sertoli and Leydig cells as well as the primary and secondary spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoa. The information on the GSI, gonad reproductive stages as well as the histological examination provided the baseline which was needed for comparison of the testes of fish that were exposed to copper. The cellular and sub-cellular responses at light and electron microscopic level were examined to determine early cell changes and damage in the testes which were caused by different sublethal exposures of copper. There were no differences in the gross structure of the testes of the control group and the group that were exposed to copper. The testes of the fish that were exposed to 0.16, 0.40 and 2.0 mg Cu/§¤ all revealed disorganisation of the lobules, disintegration of the spermatogonia as well as disintegration of the interstitial tissue. The exposure of fish to sublethal concentrations of copper induced histopathological changes in the testes of all three groups of fish that were exposed to copper. The results also showed that the intensity of the histopathological changes increased with an increase in the concentration of copper. As a biomarker of exposure to toxicants, histopathology represents a useful tool to asses the degree of pollution. The results from this investigation showed a decrease in the GSI after being exposed to copper, when compared with the control groups, which were not exposed to copper. The information on the effect of copper on the GSI, gonad reproductive stages as well as the histological examination also provides information on gonadal health and maturational stage. This information however provides structural, rather than functional information regarding gonadal health. The results showed that the GSI and gonadal staging should be used together with the gonadal histopathology in order to provide a baseline for comparison when dealing with other toxicological studies. The information obtained during this investigation showed that fish histology and histopathology could be used as a biomarker to provide information on the effect of heavy metals on fish health. It is however suggested that the information obtained during this investigation should be extended to field investigation in order to be validated as a reliable histopathological biomarker. / Prof. J.H.J. van Vuren Prof. G.J. Steyn

Silicalite-1 crystals and hollow tube structures were synthesized and functionalized with amine and sulfur containing groups. The adsorption behavior of metal ions (Pb2+, CrO4-) in aqueous solution was investigated on nanocrystalline zeolites functionalized with amines and thiols. Nanocrystalline zeolites with a diameter of 30-50 nm and external surface areas around 100 m2/g were functionalized with 3-aminopropyltriethoxysilane (3-APTES) and 3-mercaptopropyltrimethoxysilane (3-MPTMS). The materials were characterized by 29Si magic angle spinning nuclear magnetic resonance spectroscopy and x-ray diffraction. The adsorption of metal ions from aqueous solutions of Pb (NO3)2 and Na2Cr2O7 was measured by inductively coupled plasma-atomic emission spectroscopy. The effects of various conditions such as pH and concentration were studied to optimize adsorption. Adsorption on functionalized mesoporous silica (MS) was conducted for comparison to the functionalized zeolites. Magnetic zeolite/iron composites were prepared using nanoscale and commercial faujasite zeolites. The composites were functionalized with amine groups to facilitate chromate adsorption under acidic conditions. The materials were characterized using nitrogen adsorption, scanning electron microscopy, thermogravametric analysis, FTIR spectroscopy, and Mossbauer spectroscopy. The adsorption of chromium was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP/OES) to monitor solution chromium quantitatively. The removal of the composites with a magnet was demonstrated. The materials were then evaluated for the adsorption of Cr6+ using ICP-OES to detect chromium. Iron containing zeolite composites were prepared using nanoscale faujasite zeolites. The composites were functionalized with amine groups and Fe ions to facilitate arsenate(As V) adsorption under a variety of pH conditions. The materials were characterized using nitrogen adsorption, X-ray diffraction, thermogravametric analysis and FTIR spectroscopy, and Mossbauer spectroscopy. The adsorption of arsenic was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP/OES) to monitor solution concentration quantitatively. The removal of the composites with a magnet was demonstrated. Kinetics and pH dependence of the adsorption were studied.

Many heavy metals are essential for biological functions; however some of these metals, especially at high concentrations, can have serious adverse effects on humans. The main sources of heavy metal exposure are through agriculture, transport, mining and related operations. South Africa has a thriving mining industry and is known for its rich mineral resources, but due to the incorrect method of disposal of the waste from these mines, substances, including heavy metals, get into the water and air supply, affecting the people living in close proximity to these mines. Exposure is through inhalation of contaminated air and consumption of contaminated food and water. The most vulnerable to heavy metals are the developing fetus, because of the high rate of cell division and differentiation. In the current study, two heavy metals cadmium (Cd) and chromium (Cr) were chosen based on the possibility of being exposed to them in South Africa. Thus, the aim of this study was to investigate the possible cellular effects of the heavy metals Cd and Cr alone and in combination, at different concentrations, on brain, liver and kidney tissue by using a chick embryo model. This model was successfully implemented over a 14 day period after which the embryos were terminated and the brains, livers and kidneys removed and processed for light- and transmission electron microscopy (with energy dispersive spectroscopy and electron energyloss spectroscopy). In addition, the effect of Cd and Cr alone and in combination on DNA structure and micronuclei formation was evaluated. The levels of the major antioxidant component, glutathione was determined in the brains of the chick embryos. At low concentration of Cd and Cr alone and in combination, a hormesis effect was observed in the survival rates and weights of the chick embryos, while at x1000 physiological dose (PD) Cr and Cd alone and in combination the effects were toxic. The majority of viable embryos did not have any macro-anatomy abnormalities. Morphological evaluation of the brain, liver and kidney samples revealed that Cd caused severe alterations at its highest concentration with minor alterations at the lower concentrations. Cr and the metal combination groups on the other hand, only caused minimal alterations throughout the concentration ranges evaluated. The presence of Cd and Cr alone and in combination in the liver tissue was confirmed with the electron energy-loss spectroscopy analysis that detected these metals in the nuclei, mitochondria and Golgi complexes of the hepatocytes. This might contribute to the ultrastructural changes observed in this organ. The genotoxicity testing on the red blood cells revealed no substantial differences, as only a few micronuclei were present. Although heavy metals cause DNA damage through an indirect mechanism of oxidative damage, the presence of Cd and Cr in the nucleus and mitochondria indicates that these metals may have a direct effect on DNA structure. With DNA agarose gel electrophoresis it was found that Cd and Cr alone and in combination caused DNA fragmentation. In the brain, GSH levels were normal; however changes may be the result of Cd and Cr causing the depletion of other antioxidant elements such as glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase. In conclusion, this study indicates that Cd and Cr alone and in combination are toxic to the chick embryo. Cd is more toxic than Cr, and both metals accumulate in the nuclei and mitochondria where they induce damage either through oxidative and/or other mechanisms associated directly with DNA damage. / Dissertation (MSc)--University of Pretoria, 2014. / tm2015 / Anatomy / MSc / Unrestricted