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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The concentration of ten metals in the tissues of shark species Squalus megalops and Mustelus mustelus (chondrichthyes) occuring along the Southeastern coast of South Africa

Erasmus, Christina Petronella January 2004 (has links)
The southeastern coast of South Africa is deemed unpolluted and with the exception of a few localized areas, is believed to be pristine. This study aimed to (1) assess the concentration of metals in the water and sharks (Squalus megalops, Mustelus mustelus) from different sites along the southeastern coast, (2) determine the effects that metals have on each other and investigate the accumulation and storage of metals in different shark tissues, (3) determine the effects of length and sex on metal concentration and the presence of metallothioneins in the liver. Metal concentrations in water from seven sites along the southeastern coast revealed concentrations below the detection limit of the extraction method, except for iron at St. Francis Bay which was below the recommended levels as supplied by DWAF. Met al concentrations in S. megalops from the seven sites revealed significantly elevated levels in individuals from Algoa and St. Francis Bay when compared to the other 5 sites. This was observed for all metals except manganese, which had a higher concentration at Cape Agulhas. After comparing the metal levels in muscle tissue (S. megalops) with data from the Department of Health it was concluded that the sharks caught at Algoa and St. Francis Bay were unsuited for human consumption. Liver and vertebral tissues from both S. megalops and M. mustelus were deemed unsuited for human consumption but further research should be conducted especially on vertebral metal concentrations. Comparing the metal concentration in different tissue types of S. megalops and M. mustelus significant difference were observed and attributed to differences in the maturity (thus age) of the two species. Significant differences in the metal concentration of males and females for both the species were observed. A higher number of differences were however observed in M. mustelus than in S. megalops, most probably due to the differences in maturity. Length and weight vs. metal concentration regressions in the males and females of both species revealed more negative than positive trends. This was found to be in accordance with other studies from around the world. Using the life stages of S. megalops, significant differences in the average concentration of metals were observed between the life stages, with embryos usually having the highest concentration. The metal concentration series determined for S. megalops were similar to that which have been reported in the literature in that iron and zinc occupied the highest concentration positions while cadmium, copper and manganese occupied the last three. The spleen usually had the highest metal concentration except for aluminium in skin and arsenic in muscle tissue. Pearson correlation revealed significant negative correlations between cadmium and the mentioned metals suggesting that cadmium replaces essential metals such as manganese, iron and copper as. Negative correlations between essential metals were observed most probably due to the competition for binding positions on ligands. Positive correlations were observed between metals in sp ecific tissue types and may be indicative of synergistic effects, e.g. aluminium may result in the accumulation of other metals such as cadmium. Positive and negative correlations between a specific metal and different tissue types have also been observed and it appears that there are movement of metals between tissue types. Positive correlation for essential metals between yolk and other tissue have been observed, although no correlations for non-essential metals were observed. This could potentially indicate a mechanism that prevents the accumulation of nonessential metals in embryos. Though no metallothioneins were isolated form the liver, the presence of cadmium in other proteins indicate that that cadmium is substituted for essential metals, and as this may result in deleterious physiological effects, further studies should be conducted. In conclusion it can be said that although some of the results were expected there are still quite a few unanswered question and further studies should be conducted.
2

The role of sulphate-reducing bacteria in mercury-contaminated estuarine sediments : a case study of Durban Bay

Simpson, Elizabeth Anne January 2003 (has links)
Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Durban Insititute of Technology, 2003. / Stimulated by the findings of international researchers, that the sulfate-reducing microorganism Desulfovibrio desulfuricans could be incriminated in the process of mercury bio-methylation, it was decided to test this hypothesis on sediments from selected areas of Durban Bay where elevated levels of the bio-hazardous heavy metal had previously been detected. The Environmentek Division of the Council for Scientific and Industrial Research (Durban) is involved in an ongoing chemical assessment of heavy metal contamination (including levels of mercury) in the sediments of this estuary, but nothing is currently understood about the form in which mercury exists or the biological processes that could be determining its fate. The purpose of this project was to attempt to answer some of these questions. The study involved attempting to isolate, identify and quantify microorganisms of the species Desulfovibrio desulfuricans, Escherichia coli and Clostridium perfringens in one hundred and eighty sediment samples taken from three designated sites in the bay. Each sample was additionally analysed for total and methyl mercury and sulfate content, as well as a number of physical parameters. Based on the outcome of the initial survey, it was envisaged that further laboratory experimentation would be conducted to determine whether or not isolates were responsible for the production of the highly toxic organic mercury and whether this process was occurring in situ in the sediments. The findings of this project were contrary to what had been expected. Total mercury concentrations (apart from one instance) did not appear to be appreciably elevated in the areas under study. Similarly, the levels of methyl mercury were fourrd to be either diminished or absent. Numbers of D. desulfuricans were low and not uniformly distributed throughout the sediments. Cl. perfringens was more in evidence, but counts were not perceptibly increased. Sulfate levels were consistently high, indicating significantly impaired rates of sulfate reduction. Difficulty experienced in sub-culturing / M
3

An assessment of selected metal pollutants in Durban Harbour

Paul, Vimla January 2001 (has links)
Submitted in partial fulfillment of the requirements for the Degree of Master of Technology in Chemistry, M.L. Sultan Technikon, 2001. / The purpose of this study was to determine the concentration of selected metals in Durban Harbour water and sediments. Four sites were selected for the investigation. The water and sediment samples were collected from July 1998 to July 1999 to accommodate seasonal changes / M
4

Characterization of polychlorinated biphenyl residues in the North End lake and Port Elizabeth harbour, South Africa

Kampire, Edwige January 2015 (has links)
Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) are widespread in aquatic systems, they can bioaccumulate in the tissues of aquatic organisms, especially fish as they occupy a position near the top of the aquatic food web. PCBs are among the most toxic substances and have been shown to cause many adverse effects to humans and wildlife. High health risks are associated with populations that follow a diet high in fat content such as fish and shellfish in which PCBs bioaccumulate. Given the importance of industries and the potential health concerns of exposure to PCBs, the lack of information on environmental levels of PCBs in South Africa (SA) is significant and concerning. Less attention has been directed to analysis of PCBs in the South African environments due to high cost and lack of appropriate equipment. This study was the first conducted in order to assess the levels of PCBs in the environment of Nelson Mandela Bay Municipality (Port Elizabeth). The research was directed at determining the PCB levels in water, sediments, fish and mussels collected in the Nelson Mandela Bay Municipality. The sampling sites, North End Lake (NEL) and Port Elizabeth Harbour (PEH) were selected based on their location and the importance of activities taking place in these areas. In total 456 samples of water (dissolved and particulate phases), sediments, mussels and tissues of fish were analysed. Suitable analytical methods were based on the equipment and materials available at the Nelson Mandela Metropolitan University. Gas chromatography-mass spectrometry (GC/MS) was used to quantify PCBs in the samples using the internal standard method. Six indicator congeners (PCB nos. 28, 52, 101, 138, 153, 180) were chosen because they are mainly present in most PCB mixtures in environmental samples and they are recommended for regular monitoring. These congeners represent about 50% of the total non-dioxin like (NDL) PCBs in food. All these congeners were detected in the samples analysed. The total PCB concentrations in the sediments from the NEL and PEH ranged from 1.60 to 3.06 and from 0.56 to 2.35 ng g-1 dry weight, respectively. The concentrations of total PCBs in Mytilus galloprovincialis ranged from 14.48 to 21.37 ng g-1 wet weight and from 20.84 to 31.34 ng g-1 wet weight in Perna perna. Total PCBs in water ranged from 0.18 to 0.355 ng L-1. The concentrations of total PCBs in the liver, gonads, gills and muscle were 95.69, 57.49, 44.63, 34.14 ng g-1 lipid weight in Cyprinus carpio and 119.73, 59.21, 49.78, 34.63 ng g-1 in Oreochromis mossambicus, respectively. Fish liver was the most contaminated organ due to its high lipid content compared to other parts of fish analysed. The NEL was found to be more contaminated than the PEH. The main potential sources of PCB pollutants in both areas of this study are industrial and municipal discharges. The NEL is surrounded by many industries and serves as a potential pollutant sink due to wastewater and inflow entering into this lake. Four 0.227 kg meals of the edible part of fish (muscle) per month were recommended based on the non-cancer health endpoint and one 0.227 kg meal per month was recommended based on the cancer health endpoint. This research contributed to notify the public and relevant governmental departments on the PCB pollution status of sediments, water and aquatic life in the PEH and NEL.
5

Waste and port reception facilities.

Difeto, Phyllis Motsatsi. January 2010 (has links)
Internationally, shipping, boating and ancillary services are seen as significant contributors to degradation of the marine environment, affecting water quality, habitats and coastal amenity. As a result, it is important to ensure good practice with regard to safety issues when discharging or handling such wastes while vessels are in the port's jurisdiction. The international standards for regulating the prevention of marine pollution through ship generated waste are clearly outlined primarily in the United Nations Convention on the Law of the Sea 1982 ("UNCLOS") and the International Convention for the Prevention of Pollution from Ships1973 as amended by the Protocol of 1978 ("MARPOL 73/78"). The proposed study will explore compliance to MARPOL 73/78 Convention's requirement for governments to ensure the provision of adequate port reception facilities capable of receiving ship board residues and mixtures, containing oil, noxious liquids or garbage, without causing undue delay. The paper further reviews the implementation of the Conventions in the European Union and South Africa as it aims to provide a profile of the availability of waste reception facilities to assess their effectiveness in addressing the problem of marine pollution through ship generated waste. It is concluded that a variety of South African legislation is also applicable to marine pollution, but inadequately enforced. Further, that there was a considerable range of legislation intended to protect the North Sea and European waters in general from marine pollution but marine pollution from vessels is still considered to be a significant problem. In conclusion, it is recommended that South Africa should urgently develop effective mechanisms to monitor the enforcement oflegislation adequately. / Thesis (M.Com.)-University of KwaZulu-Natal, Durban, 2010.
6

At low tide : an absence of water, and abundance of plastic

Obermeyer, Chloe 02 1900 (has links)
This project deals with the concepts of care, contentedness and self-reflection in light of the ecological plights that face our planet and the way that my artistic practice reflects this. It achieves this by focusing on marine forms of plastic pollution along Cape Town’s coastline as well as on the water resources during Cape Town’s water crisis that started in 2017. To unite these areas of interest, the conceptual platform and the visual associations of “a low tide” were used to navigate material and practical considerations of my chosen alternative photographic media and how they can best address such interests. / Art and Music / M.V.A.
7

Contamination levels in and cellular responses of intertidal invertebrates as biomarkers of toxic stress caused by heavy metal contamination in False Bay

Mdzeke, Naomi Patience 03 1900 (has links)
Thesis (PhD) -- Stellenbosch University, 2004. / ENGLISH ABSTRACT:Heavy metals are persistent environmental contaminants whose sources of inputs into the environment are both natural and anthropogenic. The levels of heavy metals (cadmium, copper, nickel, lead and zinc) in the False Bay intertidal zone were measured in the water, sediments and invertebrate species between August 2000 and August 2001. The results of the water and sediment analyses revealed that most pollution was associated with the northern shore of the bay between Strand and Muizenberg, where the most populated and industrial catchments occur. Significant spatial variations occurred, indicating the presence of localised contamination, while seasonal variations may be related to changes in precipitation and runoff at different times of the year. The concentrations of cadmium, nickel and lead were occasionally higher than the levels recommended by the South African Water Quality Standards. The possible sources of pollution at the different sites are also discussed. The concentrations of the five metals in the different invertebrate species (Oxystele tigrina, 0. sinensis, Choromytilus meridionalis, Patella oculus, Patiriella exigua and Tetraclita serrata) also revealed significant seasonal and spatial variations, with both the soft tissues and shells accumulating heavy metals. The barnacle T serrata from Rooiels had the highest cadmium concentration (70.67 J.lg/g dry weight), which may be related to historic pollution inputs from the military activities which took place at a weapons testing site at this site between 1987 and 1994, although no evidence was found to confirm this. The periwinkle 0. tigrina from Strand had the highest copper concentration (70.25 J.lg/g) while the limpet P. oculus from the same site had the highest nickel concentration (35.75 J.lg/g). The shells of the mussel C. meridionalis from Muizenberg had the highest concentration of lead (25.75 J.lg/g). Since cadmium occurs as a constituent of phosphate fertilisers used widely in the False Bay catchments, the effects of cadmium exposure on the different species were investigated during 14-day laboratory exposures to 200 and 400 J.lg/LCdCh. The results revealed a general pattern of tissue metal increase in the exposed organisms, followed by slight reductions after decontamination in clean seawater. The viscera and kidneys of C. meridionalis accumulated most of the dissolved cadmium. The shells of the mussels also accumulated cadmium, indicating the possible use of shells as a detoxification matrix. / AFRIKAANSE OPSOMMING:Swaarmetale is persisterende omgewingskontaminante waarvan die insetbronne beide natuurlik of van menslike oorsprong kan wees. Die kontaminasievlakke van swaarmetale (kadmium, koper, nikkel, lood en sink) in die Valsbaai tussengetysone is in die water, sedimente en invertebraatspesies bepaal vanaf Augustus 2000 tot Augustus 2001. Voorlopige resultate van die water- en sedimentontledings het getoon dat die meeste besoedeling by die noordelikke oewer van die baai voorgekom het tussen Strand and Muizenberg, waar die mees digbewoonde en ge-industrialiseerde opvangsgebiede is. Betekenisvolle ruimtelike en seisoenale variasie het in die konsentrasies van swaarmetale voorgekom, met die ruimtelike variasie wat moontlik gelokaliseerde kontaminasie aandui terwyl die seisoenale variasies weer verband mag hou met veranderings in die neerslag en afloop gedurende verskillende tye van die jaar. Die konsentrasie van kadmium, nikkel en lood was somtyds hoer as die vlakke wat deur die Suid-Afrikaanse Waterkwaliteitsstandaarde voorgestel word. Die moontlike bronne van besoedeling in die verskillende areas is ook in bespreking genoem. Die konsentrasies van die vyf swaametale in die verskillende invertebraatspesies (Oxystele tigrina, 0. sinensis, Choromytilus meridionalis, Patella oculus, Patiriella exigua and Tetraclita serrata) het ook seisoenale en ruimtelike variasies vertoon, die swaarmetale het in die sagte weefsel en skulpe van die invertebrate geakkumuleer. Die hoogste gemiddelde konsentrasie van kadmium (70.67 ).lg/g droe massa) is in die heel-liggaam monsters van die eendemossel T serrata gemeet wat by Rooiels versamel is. Die vlakke mag verband hou met die oprigting en aktiwiteite van die wapentoetsingsaanleg in die opvanggebied van die Rooiels lokaliteit tussen 1987 en 1994, maar geen bewyse daarvan is gevind nie. Die tolletjie, 0. tigrina wat in die 10kaliteit by Strand versamel is het die hoogste gemiddelde konsentrasie koper gehad 70.25 pig droe massa), terwyl die klipmossel P. oculus by dieselfde versamelpunt die hoogste konsentrasie nikkel (35.75 ).lg/gdroe massa) gehad het. Eksperimentele studies is ook uitgevoer op vier invertebraat spesies wat vir 14 dae in akwaria blootgestel is aan see-water met 200 en 400 p,g/L CdCh, en daama gedekontamineer is in skoon seewater. / The NRF and the University of Stellenbosch, for funding this study.
8

The application of integrated environmental management to improve storm water quality and reduce marine pollution at Jeffreys Bay (South Africa)

Seebach, Rudi Dieter January 2006 (has links)
It is projected that by 2025 three-quarters of the world’s population will live in the coastal zone. This is an alarming statistic, with a consequently significant impact on small coastal towns and the adjacent marine environments. Developing communities within the coastal zone of South Africa have proved to be a significant pollution source of storm water. Studies have shown that storm water that is deposited in the ocean will be trapped in the near shore marine environment causing poor seawater quality over a large distance. Furthermore, this can pose a significant threat to the health of recreational users and important marine ecosystems. In Jeffreys Bay storm water quality is thought to pose a threat to the maintenance of the international Blue Flag status for its beach. The aim of the current project was to investigate the main sources of storm water and subsequent marine pollution at Jeffreys Bay and to develop an appropriate management strategy using the integrated environmental management framework. In order to achieve this objective, it was also necessary to determine the current quality of water at various points within the catchment and near shore marine environment. Even though the storm water was found to be severely contaminated no evidence existed for a negative impact on the marine environment. None the less, a precautionary approach was adopted and a risk assessment employed in order to consider potential impacts on the marine and aquatic environment, human health and socio-economic welfare within the town. Significant sources of storm water contamination included grey water, domestic solid waste disposal and informal ablution. These significant aspects were investigated further and it was found that solid waste management in the catchment was poor with significant quantities of waste, primarily (76%) from domestic sources, being disposed of illegally. A study of sanitation management showed inadequacies where up to 58% of the residents from the informal settlements disposed of their grey water into open spaces. The ratio of residents to toilets in these areas was 28:1, therefore supporting the outcome of the risk assessment. Due to the fact that all the significant aspects were related to anthropogenic waste, an integrated waste management plan (IWMP) was developed that would not only facilitate the reduction of pollution of storm water, but would also allow for sustainable community-based development.
9

The potential impact of diving charges on the demand for diving and the diving industry in the Aliwal Shoal Marine Protected Area: a pilot study

Schmidt, Jadon January 2011 (has links)
This research is presented in three sections. Section 1 presents the research report in an Academic Paper format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed. Sustainable management of natural resources is a global imperative. It is particularly significant in a country like South Africa that is blessed with an abundance of biological diversity but faces many socio economic challenges that are associated with developing nations. Toward addressing these issues, diver permit fees were implemented in South Africa in 2005, making it a legal requirement for all scuba divers undertaking a dive in a Marine Protected Area (MPA) to purchase a permit. This pilot study is the first attempt since the inception of the dive permit fees to determine their impact on the demand for diving and the diving industry in the Aliwal Shoal MPA, one of the premier dive destinations in the country. In order to address key questions, qualitative data was gathered during interviews with 12 dive operators active in the MPA and 28 divers that utilised the operators to dive. In addition, independent quantitative data on the number of dive boat launches during the past 20 years was used in conjunction with mean paying diver data obtained from the operators to ascertain the demand for diving at the Aliwal Shoal during the past two decades. Results indicate that were no significant differences (at the 5% level of significance) between paying divers during 2005 compared to 2004 and 2006 [H =.1923366, N= 36, p =0.9083]. Paying diver data for the period 2000 - 2004 were compared to 2005 - 2010 and no significant differences were found at the 5% level of significance (U= 2040, Npost = 72, Npre= 60, p = 0.584981). Diver interviews revealed that only 36% of divers had paid for a permit, representing a loss of R7 438 499 during the past five years, enough to support the current budget of the MPA for 10.6 years. Operator interviews revealed that alternative destinations, economic climate and local competition had the most impact on their businesses, with permit fees having no impact on the 50% of the operators’ businesses. Operators also reported that there was little or no enforcement of the permit fees, 9 of the operators indicated that there has been no improvement in the MPA or its management since the inception of the fees and all were dissatisfied with the current management MPA. Operators and divers complained about the current purchasing and handling practices associated with the permits. Despite offering a world class diving opportunity, the dive operators currently have no incentive to enforce the permit system and due to price pressure in the local market, and have adopted a mute stance on diver permits. Consequently, there has been no significant impact on the demand for diving since the inception of the permits in 2005. The initial hypothesis that the increased costs to divers as a result of the permits would drive down the demand for diving is therefore rejected. If the permits are more strictly enforced, it is likely that more divers may seek alternative destinations due to the perception of poor value as a result of the Sappi Saiccor effluent discharge, existence of shark nets and poor management, in accordance with existing literature. The resultant decrease in demand will be detrimental to the diving industry at Aliwal Shoal. The second hypothesis, that the costs associated with the better enforcement of the MPA regulations-in terms of impacts on the diving industry- might outweigh the benefits, is therefore accepted. All the results produced by this study suggest that authorities may have been too enthusiastic to have all the boxes ticked in order to meet deadlines for international targets for marine conservation and paid little or no attention to lessons learnt from MPAs globally. Every negative aspect highlighted by existing international literature as symptomatic of MPA failure is occurring at Aliwal Shoal MPA, albatrossing it with “paper park” status. Due to the size and scope of this study, the results should be interpreted with caution and not be utilised to guide policy but rather encourage further research.

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