• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 16
  • 3
  • 1
  • Tagged with
  • 30
  • 30
  • 30
  • 30
  • 16
  • 16
  • 10
  • 6
  • 6
  • 6
  • 6
  • 6
  • 6
  • 5
  • 4
  • 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.
21

Metal ecotoxicology of the Upper Olifants River at selected localities and the effect of copper and zinc on fish blood physiology

Nussey, Gail 11 September 2012 (has links)
D.Phil. / The entire Olifants . River Catchment is subjected to increasing afforestation, agricultural, domestic, mining, industrial, irrigation and urbanisation activities. These activities have a profound effect on the water quality of the river and its tributaries. This is cause for concern for the water users in the upper catchment, and because the Kruger National Park, one of its downstream water users, is extremely dependent on water of a satisfactory quality to sustain its various ecosystems. It is therefore vitally important to determine to what extent activities in the Upper Catchment of the Olifants River (Mpumalanga), especially in the Witbank and Middelburg areas, influence the water quality of the river. Point sources of pollution in the upper reaches include mining and industrial activities as well as water care works located at various points along the river. These were addressed in a Water Research Commission Project (No. 608/1/97) titled "Lethal and sublethal effects of metals on the physiology of fish: An experimental approach with monitoring support". Although sixteen localities were chosen for the initial project, this study only focussed around the metal ecotoxicology at two localities (Steenkool Spruit and Witbank Dam) in the upper catchment and the effect of metals (copper and zinc) on fish blood physiology. In aquatic ecosystems water quality is an important variable and full assessment of water quality, of Steenkool Spruit (locality 3) and Witbank Dam (locality 7), included evaluation of the chemical, physical and biological characteristics at each of the localities. Water and sediment samples were collected seasonally during the study period, February 1994 to May 1995, and the chemical and physical water quality variables were measured. During the study period three metal bioaccumulation indicator species, Labeo umbratus, Clarias gariepinus and Labeo capensis, were captured from which tissue (gills, liver, muscle and skin) samples were collected. These samples as well as water and sediment samples, were analysed for aluminium, chromium, copper, iron, manganese, nickel, lead and zinc concentrations, using atomic absorption spectrophotometry. In the past routine monitoring of chemical and physical water quality characteristics left scientists and managers with a sizeable pool of data which is often difficult but not impossible to interpret. To standardise and summarise this collection of data an aquatic toxicity index (ATI), WATER2 was developed by Wepener et at (1992). The present study attempted to expand and refine WATER2, which has resulted in the establishment of a new ATI, RAUWater.
22

Evaluation of a health assessment index with reference to metal bioaccumulation in Clarias gariepinus and aspects of the biology of the parasite Lamproglena clariae.

Marx, Hazel Mary 14 August 2012 (has links)
M.Sc. / The catchment area of the Olifants River has, over a number of years, been exposed to extensive mining, agriculture and urbanisation activities in the Witbank-Middelburg and Phalaborwa regions which has largely contributed to the deterioration of water quality. Of major concern is the influence anthropogenic activities have on the aquatic ecosystem of the Olifants River within the Kruger National Park and how me health of fish residing In these waters is affected. To determine fish health, a biological monitoring method, the Health Assessment Index (H41), was tested for the first time In South Africa. Four surveys were conducted at Mamba and Balule In the Olifants River, Kruger National Park during 1994 (February, May, July and November). An additional survey was conducted in February 1995 at Loskop Dam. Samples of water and sediment were taken for analysis of metals and physical and chemical water parameters. A maximum of 20 Clarias gariepinus fish were sampled at each location. Evaluation of the fish was done according to guidelines set in the HAI and parasite population composition (prevalence, abundance, mean intensity) was determined. Organ and tissue samples including gills, liver, muscle and skin were analysed for the bioaccumulation of chromium, copper, Iron, manganese, nickel, lead, strontium and zinc, using atomic absorption spectrophotomeby. Metal concentrations in the water at Mamba and Balule were within guideline limits, whereas concentrations at Loskop Dam were above guidelines. As reflected by the application of the Aquatic toxicity Index, Loskop Dam presented with the poorest water quality followed by Mamba then Balule. It was found that certain physical and chemical variables namely fluoride, potassium, sulphate and total dissolved solids concentrations at Mamba and Balule were relatively high, particularly during drier months. Metals accumulated in organs and tissues, with the highest concentrations In the gills followed by the liver, skin and muscle. The discriminant analysis, utilising metal bloaccumulation, discriminates between water quality at Mamba and Balule, revealing a 100 % classification probability for each survey. Values obtained In the application of the HAI indicated that variables with good predictor accuracy were plasma protein, all parasites, endoparasites, liver, white blood cell counts, ectoparasites, skin, fins and gills. The discriminant function for the HAI generally Indicated variables similar to those exhibiting high predictor accuracy. The discriminant function showed relatively low classification probability for each survey. In case 1, where separate endo- and ectoparasite variables were Included in the determination of me discriminant function, probability for me entire study ranged between 47.5 % and 84.2 %. In case 2, where endo- and ectoparasite variables were given a refined score rating system, probability ranged between 62.5 % and 100 %. The low classification probability Indicates either the Importance of repetitive testing for this technique or a total departure from it. Results showed that fish populations with higher HAI values are found in water of poorer quality (Mamba), while healthier fish populations i.e. with lower RAI values are found In water of better quality (Balule). Parasite data shows a similar tendency by indicating that ectoparasites are abundant in water of higher quality, while endoparasftes increase in water of poorer quality. The HAI reflects the condition of fish populations in relation to their aquatic environment, therefore, the HA/ gives an indication of water quality and should be used as a first level screening tool. If complemented by a parasite survey, distinguishing between endoand ectoparasites, the results from the HAI will be enhanced.
23

Assessment of fish as bio-indicators of river health in rivers of the southwestern Cape

Hayes, Johan Barnard 03 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: In this study, the Fish Assemblage Integrity Index (FAll) was applied on three rivers within the southwestern Cape. This index uses fish as indicators of biological aquatic integrity and is based on indigenous species expected to be present in biological fish habitats. Fish integrity classes were calculated for each of the sites in the three rivers studied. Sites 2 and 4 within the Lourens River were rated as Class C, whereas sites 1 and 3 were rated as Class F and Class D respectively. Sites 1, 2 and 4 within the Palmiet River were rated Class F, whereas sites 3 and 5 were rated as Class E and Class D respectively. Site 1 within the Hout Bay River was rated as a Class F site, in addition to sites 2 and 3 been rated as Class A. It is however, suggested that the FAll needs to be adjusted to accommodate the general low species richness experienced in the southwestern Cape. In addition to the FAll been applied, the effects of long-term exposure to subtle water quality changes associated with human activities, specifically potential estrogenic compounds in fish from the Lourens River were also investigated. The production of the yolk precursor lipoprotein complex, vitellogenin (Vtg) produced in the liver under estrogen control was employed as biomarker for environmental estrogen exposure. Male fish from the Lourens River were studied using SDS-PAGE gel electrophoresis. Results indicated that 60% of male fish showed the presence of Vtg in their plasma. Abnormal gonad morphology in male and female fish were also assessed using standard histological procedures. Results from this study indicated no observed abnormalities in either male or female gonads. The immediate presence of endocrine disrupters with estrogen activity was investigated by screening water samples from the Lourens, Palmiet and Hout Bay Rivers for estrogen activity. Results indicated that none of the samples appeared to be cytotoxic. In addition, estrogen activity of water samples was also investigated by in vitro culturing of water samples with frog, Xenopus laevis, liver slices. Results indicated that none of the water samples from the three rivers studied indicated estrogenic activity. Although cytotoxicity and estrogen activity results were negative, the production of Vtg in male fish suggests further research regarding the presence of estrogenic substances in these rivers. / AFRIKAANSE OPSOMMING: In die huidige studie is die 'Fish Assemblage Integrity Index' (FAIl) toegepas op drie rivere in die suidwes Kaap. Hierdie indeks gebruik visse as bioindikatore van biologies akwatiese integriteit en is gebasseer op die inheemse visspesies wat verwag word in biologiese vishabitatte. Integriteitsklasse is bepaal vir elke studieterrein in die drie rivere wat ondersoek is. 'n Klas C is bepaal vir studieterreine 2 en 4 in die Lourensrivier. Klas F en Klas D is bepaal vir studieterreine 1 en 3 in die rivier onderskeidelik. 'n Klas F is bepaal vir studieterreine 1, 2 en 4 en Klas E en Klas D bepaal vir studieterreine 3 en 5 in die Palmietrivier onderskeidelik. 'n Klas F is bepaal vir studieterrein 1 in die Houtbaairivier waar 'n Klas A bepaal is vir studieterreine 2 en 3. Dit word egter voorgestel dat die FAII aangepas moet word om die algemene lae spesierykheid wat ervaar word in die suidwes Kaap te akkomodeer. Die reaksie van visse, afkomstig van die Lourensrivier, op die langtermyn blootstelling aan estrogeniese stowwe is ook bestudeer. Spesifieke reaksies van endokriene versteuring, soos vitellogeen (Vtg) produksie in manlike visse is ondersoek deur middel van SDS-PAGE gel elektroforese. Resultate toon dat in 60% van die manlike visse Vtg in die plasma teenwoordig was. 'n Ondersoek na abnormale gonade morfologie in manlike en vroulike visse van die Lourensrivier is deur standard histologiese prosedures gedoen. Resultate hiervan dui op geen sigbare abnormaliteite in die gonades nie. Die onmiddelike teenwoordigheid van endokriene versteurders is bestudeer deur die sitotoksisiteit van watermonsters afkomstig van die Lourens, Palmiet en Houtbaai riviere te bepaal. Resultate dui aan dat geen monsters sitotoksies was nie. Die estrogeenaktiwiteit van die watermonsters is ook ondersoek deur van in vitro kulture van watermonsters saam met padda, Xenopus leavis, lewersnitte gebruik te maak. Geen estrogeniese aktiwiteit is in die watermonsters gevind nie. Al is die sitotoksisiteit en estrogeenaktiwiteit resultate negatief, dui die produksie van Vtg in manlike visse op die noodsaaklikheid van verdere navorsing ten opsigte van die teenwoordigheid van estrogeniese stowwe in drie riviere.
24

Investigating non-regulatory barriers and incentives to stakeholder participation in reducing water pollution in Pietermaritzburg's Baynespruit.

Neysmith, Jocelyn. January 2008 (has links)
The Baynespruit, a stream running through the city of Pietermaritzburg in KwaZulu-Natal, is blighted by chronic, severe solid and liquid waste pollution in the form of sewage, industrial effluent and household garbage. It drains a large residential area, then flows through the city's main industrial area before reaching a low-income neighbourhood whose residents are unable to use the water for recreation and small-scale agricultural irrigation due to its polluted state. Both the Department of Water Affairs and Forestry (DWAF) and the local Msunduzi Municipality have been largely unsuccessful in their attempts to use regulatory means to address the situation over the past two decades. Bodies such as the Msunduzi Catchment Management Forum (MCMF) have little representation from industry and have been equally unable to initiate effective action. One possible way to work toward reducing pollution problems is to involve all stakeholders in a co-operative participatory process; a key element is therefore the use of incentives and the removal of barriers to participation. The aim of this research was to analyse past initiatives that have tried to address pollution in the Baynespruit, gain an understanding of stakeholders’ views of the problems and their relative importance, and identify economic, situational, developmental and socio-cultural barriers and incentives to participation in a multi-stakeholder process. To accomplish this, the research methodology included a number of different qualitative techniques as part of a case study approach. The main research tool used was a semi-structured interview conducted with individual stakeholders from government agencies and parastatals, industry, local residents and members of NGOs; the use of historical print media coverage and both participant and direct observation complemented the interview data. Though the details of past initiatives were difficult to trace due to the loss of institutional memory at both the agency and NGO level, they appear to have suffered from a lack of communication, accountability and inclusiveness among key stakeholders. Most of the stakeholders interviewed have an understanding of the various pollution problems affecting the Baynespruit and the consequent threat to human health, and there was general agreement that a mix of education, monitoring and enforcement was necessary to solve these problems. There was also broad support for a multi-stakeholder process, with all subjects stressing the need for action, not just discussion, as well as real engagement on the part of their fellow stakeholders. For local residents, building a network of contacts and partnerships could address many of the economic, developmental and socio-cultural barriers they face, and strengthen their effectiveness in fostering participation among other stakeholders. While barriers to industry participation in pollution reduction included problems such as a lack of consequences for polluting, and the feeling that it was ‘not their problem’, powerful economic and situational incentives, such as pressure from corporate customers and the public, remain largely unexploited. A lack of resources in the form of time, staff and equipment, as well as unsuccessful past experiences which have created a reluctance to prosecute or release information, were the major impediments preventing staff at regulatory agencies and parastatals from motivating other stakeholders to participate, though they were aware of the potential for increase effectiveness offered by participatory processes. It is hoped that by recommending ways to maximise incentives and reduce barriers, this research will assist the recently-established Baynespruit Conservancy, which is involving all interested parties in an effort to address the serious pollution problems in the stream. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
25

Factors preventing the successful implementation of the polluter pays principle : a case study of the Bayne's Spruit.

Pole, Adrian Leonard. January 2002 (has links)
Despite the pollution control provisions provided in national and local legislation that explicitly or implicitly give effect to the polluter pays principle (PPP), certain rivers continue to suffer from persistent industrial pollution. This research focuses on one such river, the Bayne's Spruit, as a case study. The Bayne's Spruit is a small river that is located within an urban catchment, and which has been subjected to wet industrial pollution for over a decade. Much of this pollution is associated with the Pietermaritzburg edible oil industry. This pollution impacts negatively on a downstream community that uses the river for irrigation of subsistence crops, for recreation and for subsistence fish harvesting. The pollution has also severely degraded the riverine ecosystem. This research commenced with a literature review of the PPP in its international, national and local context. It was noted that the current legislative framework for implementation of the PPP with regard to pollution of rivers in South Africa comprises primarily of the National Water Act 36 of 1998 (NWA), the National Environmental Management Act 107 of 1998, and the Pietermaritzburg-Msunduzi industrial effluent bylaws of November 1998. The case study was approached using a largely qualitative methodology, although quantitative data was also relied upon where feasible. The historical context of the case study was provided by conducting a review of newspaper reports, a review of. government inspection records, and a review of water quality data (including biomonitoring and chemical data). The current status of the Bayne's Spruit was then explored by conducting in-depth historical interviews with community members, and by conducting direct observation of the environmental status of the Bayne's Spruit. This data was supplemented by an analysis of the test results of sampled industrial effluent, and by information obtained from representatives of two edible oil companies. In-depth, purposively selected interviews were conducted with various role players. (local government, regional government and industry) to identify what factors are preventing the successful implementation of the PPP in the case study area. Factors identified include a lack of environmental ethic within the edible oil industry, with some of these companies free riding on the Bayne's Spruit to maximize their profits. At a local level, factors preventing implementation of the PPP include deficiencies in the local industrial effluent bylaws, failures to administer and implement provisions contained in the bylaws, capacity restrictions and institutional paralysis. National legislation is not being successfully implemented because the government agency empowered under the NWA is deferring primary responsibility for dealing with pollution to the local authority. Factors also include difficulties associated with monitoring of rivers, including lack of capacity to engage in monitoring, and confusion over the functions of the various spheres of government. Finally, enforcement complexities are a major factor preventing successful implementation of the PPP. These problems relate to inadequate penalties, enforcement arrangements, capacity problems, separation of authority to operate the municipal sewer works and to enforce the industrial effluent bylaws, difficulties in identifying the offending polluter (causation), problems with access to company premises, the open access character of the storm water drainage system, previous failed prosecutions and reliance on the criminal justice system. / Thesis (M.Sc.)-University of Natal, 2002.
26

Prevalence and antibiogram of some swine associated Shiga toxin producing Escherichia coli Serogroups and Salmonella species in Nkonkobe Municipality, Eastern Cape Province, South Africa

Iwu, Chinwe Juliana January 2015 (has links)
Gastrointestinal illnesses have continually become a global public health issue. Exposure to zoonotic food borne pathogens such as Salmonella and diarrhoegenic E. coli either by direct or indirect contact through the consumption of food producing animals is likely an important mode of infection to humans. More so, the use of antibiotics in farm animals similar to those used in humans can select for resistance in bacteria frequently harboured by them. These resistant strains can be passed on to humans through contaminated meat products and water leading to resistant infections with consequences such as prolonged illnesses, treatment failures, and increased morbidity and mortality. In animals, these can lead to reduced productivity. Monitoring the level of resistance among bacteria from animal isolates will help in generating data that could be used to create awareness of their presence in the environment and aid in preventing a potential epidemic in the community. In this study, we investigated the prevalence and antimicrobial resistance profile of Escherichia coli serogroups and Salmonella species in faecal samples collected from pigs in Nkonkobe Municipality in the Eastern Cape Province, South Africa between April – July, 2014. A total of 310 presumptive Shiga toxin producing Escherichia coli (STEC) were confirmed as E. coli spp using polymerase chain reaction (PCR) technique by amplification of the uidA gene, out of which 179 (58%) were confirmed positive. Approximately, serogrougs O157:H7, O145 and O26 made up 24% (n=43), 8% (n=14) and 20% (n=35) of the E. coli population respectively. Only E. coli O26 was positive for stx2 gene in 31% of the isolates harbouring the gene, while the other serogroups were non-pathogenic. Susceptibility of the isolates to 18 antibiotics was carried out in vitro by the standardized agar disc-diffusion method. All the isolates were susceptible to imipenem. Similarly, a relatively high susceptibility was observed in norfloxacin (83-100%), ciprofloxacin (63-100%), gentamycin (77-100%), and chloramphenicol (77-100%). However, all the isolates were resistant to tetracycline and its long acting counterpart oxytetracycline. Resistances observed against other antimicrobials are as follows: ampicillin (84-91%), streptomycin (14-100%), erythromycin (91-100%), ceftazidime (35%). Multiple antimicrobial resistance patterns and indices ranged from 3 to 12 and 0.2 to 0.7 to respectively. Genes encoding resistances to ampicillin (ampC), streptomycin (strA) and tetracycline (tetA) were frequently detected in 50-100%, 22-29% and 40-86% of the resistant isolates respectively. In the other arm of the dissertation, two hundred and fifty eight presumptive isolates of Salmonella were recovered from the faecal samples of pigs. Specific primers targeting serogroups A, B, C1, C2, and D were used to delineate the isolates into different serogroups using PCR. Only serogroup A (n=48) was detected. These isolates were examined for antimicrobial susceptibility by disc diffusion method using 18 antibiotics. The results showed that a large proportion of the isolates were resistant to tetracycline (100%), oxytetracycline (100%), ampicillin (75%), sulphamethoxazole/trimethoprim (75%) and streptomycin (75%). Majority of the isolates exhibited multidrug resistances with the predominant multiple antibiotic resistance (MAR) phenotype being against eleven antibiotics. A high multiple antibiotic resistance (MAR) index in a range of 0.3- 0.6 was observed. The incidence of genes encoding resistance against tetracycline (tetA), streptomycin (stra), and ampicillin (ampC) were 54%, 44% and 61% respectively. These findings reveal that pigs within the Nkonkobe Municipality in the Eastern Cape Province could harbour Shiga toxins and multidrug resistant serogroups of E. coli as well as resistant Salmonella which could be transmitted to humans through the food chain. To ensure public health safety, continuous monitoring and sufficient sanitation in swine industries must be ensured.
27

An assessment of water quality and endocrine disruption activities in the Eerste/Kuils River catchment system, Western Cape, South Africa

Fourie, Shani 04 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Water quality analysis forms the basis in assessing and monitoring catchments. As urban development continuously increase, pollution sources increase in either point source (wastewater treatment works, industrial effluents) and/or non-point source origin (storm water discharge, domestic pollutants), accumulating pollutants in the environment. It was only recently discovered that certain pollutants have subtle disrupting effects on the endocrine system resulting in health related problems associated with the reproductive system and thyroid system (growth and development) of animals and potentially humans. Natural water resource management proves to include limited biological assays measuring endpoints for cytoxicity, inflammatory activity and endocrine disruption. The broad objective of this study was therefore to include several bioassays, not normally used in municipal (City of Cape Town) monitoring programmes, along with water quality data collected by the City of Cape Town. The Eerste/Kuils River catchment system, Western Cape, under the auspices of the City of Cape Town was chosen, and although this catchment does not contribute to drinking water resources, is subjected to a range of anthropogenic influences (industrial effluents, household wastewater, agricultural runoff). Within the short time-frame available for this study (six months) two months, July (following a dry summer and autumn season) and October (following a wet winter and early spring season) were selected for water quality monitoring. Spatial variation (with relevance to specific point and non-point contamination) among sampling sites were also obtained by choosing several (n=10) along the catchment. Specific aim of the study therefore included: Firstly (Chapter 2), the use of in vitro bioassays, lactate-dehydrolises assay (LDH) for cytotoxic activity, pro-inflammatory hormone Interleukin-6 (IL-6) secretion by human blood cells and a specific Salmonella ELISA for faecal contamination, in conjunction with routine chemical and biological (mostly microbiological) monitoring activities. The study indicated significant variation among sites in all microbiological measures as well in IL-6 secretion and Salmonella presence. Between months, variations were also evident in certain variables. Secondly (Chapter 3), two bioassays using the yolk precursor protein, vitellogenin (Vtg) as endpoint was implemented in a) an in vitro Xenopus laevis liver slice assay (five day exposure) and b) an in vivo Zebrafish (Danio rerio) bioassay (seven day exposure) assessing estrogenic activity in the Eerste/Kuils River catchment. Although estrogen spiked positive control water samples stimulated Vtg production in vitro as well as in vivo, no dramatic estrogenic activity was measured at any of the selected sites. Thirdly (Chapter 4), a bioassay using the thyroid controlled metamorphosis in Xenopus laevis tadpoles to assess effects on the thyroid hormonal system was implemented. Thyroid stimulatory activity, compared with a negative control sample, was measured at two sites along the catchment. Although the practical implementation of the tadpole semi-static exposure protocol (water replacement) proved to be labour intensive, all the added bioassays proved to be valuable tools to add valuable information regarding water quality. It is clear that more research related to anthropogenic influences along the Eerste/Kuils River catchment system are needed, specifically in monitoring monthly variations to better understand annual variation in several of the endpoints studied. / AFRIKAANSE OPSOMMING: Waterkwaliteit vorm die basis vir die evaluering en monitering van opvangsgebiede. Voortdurende stedelike ontwikkeling gee aanleiding tot ‘n toename in die voorkoms van besoedelstowwe in die natuurlike omgewing deur gelokaliseerde (punt) bronne (rioolwerke/industriële uitvloeisel) en/of nie gelokaliseerde (nie punt) bronne (vloed uitlaat/huishoudelike uitvloeisels) van besoedeling. Dit het onlangs aan die lig gekom dat van hierdie chemise besoedelstowwe subtiel die endokriene sisteem versteur en so aanleiding gee tot gesondheidsprobleme in terme van die voortplantingsisteem en tiroied sisteem (groei en ontwikkeling) by diere en moontlik ook die mens. Daar is beperkte gebruik van biologiese toetse wat inligting verskaf oor sitotoksiteit, inflammatoriese aktiwiteit en endokriene versteuring. Die doel van hierdie studie was dus om van hierdie biologiese toetse, wat normaalweg nie deel uitmaak van die roetine munisipale (Stad van Kaapstad) opvangsgebied monitering nie, gebruik te maak. Die Eerste-, Kuilsrivier, Wes Kaap, onder beheer van Stad Kaapstad is gekies en alhoewel die opvangsgebied nie water bydra tot drinkwaterbronne nie, word die opvangsgebied beïnvloed deur verskeie mensgemaakte bronne van besoedeling (afloop vanuit omliggende lanbougebiede). Binne die kort tydsraamwerk van die projek (ses maande) is besluit om twee maande, Julie (volg ‘n droë somer en herfs seisoen) en Oktober (volg ‘n nat winter en vroeë lente seisoen) vir water kwaliteit monitering te kies. Ruimtelike variasie langs die loop van die opvangsgebied is ingesluit deur moniteringspunte (n=10), met in ag name van die potensiële besoedelingsbronne. Spesifieke doelwitte van die projek sluit in: Eerstens (Hoofstuk 2), om die in vitro biotoetse, laktaat hidrolise (LDH) vir sitotoksisiteit, proinflammatoriese hormoon Interleuikin-6 (IL-6) vir inflammatoriese aktiwiteit, vrygestel deur menslike bloedselle en ‘n Salmonella ELISA vir ontlasting besoedeling saam met bestaande chemise en biologiese (hoofsaaklik migrobiologiese) veranderlikes te gebruik. Die studie het getoon dat beduidende variasie in alle mikrobiologiese toetse asook IL-6 vrystelling en Salmonella voorkoms bestaan het tussen versamelpunte. Maandelikse variasie in sekere van die veranderlikes het ook voorgekom. Tweedens (Hoofstuk 3), is twee biotoetse wat die dooiervoorloperproteïen, vitellogeen (Vtg) as eindpunt gebruik geimplimenteer in a) ‘n in vitro Xenopus laevis lewersnit biotoets (vyf dag blootstelling) en b) ‘n in vivo Zebravis (Danio rerio) biotoets (sewe dag blootstelling) om estrogenisiteit in die Eerste-, Kuilsrivier opvangsgebied te evalueer. Alhoewel, die estrogeen behandelde positiewe kontrole water monsters Vtg produksie veroorsaak het in beide die in vitro lewer-kulture en in vivo vistoets, is geen dramatiess estrogeniese aktiwiteit by enige van die moniteringspunte gevind nie. Derdens (Hoofstuk 4), is ‘n biotoets wat die tiroïedbeheerde metamorfose in Xenopus laevis paddavisse gebruik om effekte op die tiroïedsisteem te evalueer. Die differensiële stimulering (versnelling), in vergelyking met ‘n negatiewe kontrole watermonster, van die tiroied sisteem is by twee moniteringspunte in die opvangsgebied waargeneem. Alhoewel die praktiese implementering van die paddavis semi-statiese (water word gereeld vervang) biotoets arbeidsintensief is, het alle bykomstige biotoetse waardevolle bykomstige inligting oor water kwaliteit verskaf wat ‘n belangrike bydrae tot ingeligte bestuursbesluite kan verleen. Dit is duidelik dat meer navorsing int verband met die menslike invloed langs die Eerste-, Kuilsrivier opvangsgebied nodig is, veral met maandlikse monitering vir seisoenale veranderinge.
28

Groundwater purification using functionalised magnetic nanoparticles (electromagnetic separation)

Aigbe, Uyiosa Osagie 01 1900 (has links)
Most developing countries are faced with drinking water problems, with conditions becoming more severe due to water pollution. Meeting the growing demands for clean water in most countries, there are difficult challenges as the availability and supply of drinkable water are diminishing. Due to economic and environmental concerns, development of additional physical means for the removal of organic compounds from wastewater using permanent magnets, electromagnetic coils, electrodes and ultrasonic pretreatment is desirable. Improving the adsorption and separation process, magnetic field exposure method has progressively drawn consideration. Magnetic field exposure method has demonstrated its capacity for increasing the adsorptive elimination of contaminants from water as static magnetization is suitable, simple and cost-effective. The polypyrrole magnetic nanocomposite use for adsorption experiments influenced by exter-nal magnetic field was prepared using the in-situ polymerization method, which was charac-terized using TEM, SEM, EDX, XRD, BET, FTIR, VSM, and ESR spectrophotometers. The magnetic nanocomposite (PPy/Fe3O4) was observed to have an average particle size of 10 nm with the elementary composition of carbon, oxygen, nitrogen, chloride and iron. The magnetic nanocomposite had a crystalline structure of face-centred cubic lattice of Fe3O4, an adsorption-desorption isotherm shape indicating a typical type-IV mesoporous material with a surface area of 28.77 m2/g. Characteristic peaks of Fe3O4 and PPy were also observed using FTIR spectro-photometer. From the VSM and ESR characterization, the synthesized superparamagnetic ma-terial was shown to have a saturation magnetization of 23 emu/g and an effective g-value of 2.25 g which was attributed to Fe3+ spin interaction. An enhanced removal of Cr(VI), fluoride and congo red dye were observed under the influence of magnetic field, with parameters like pH, adsorbent dosage, the initial concentration of ad-sorbate, magnetic field and magnetic exposure time been varied. The enhanced adsorption of contaminants using magnetic field is attributed to the increase in the magnetic field induced on the particles over a magnetic exposure time, resulting in the rotating particles forming aggre-gates due to the increased magnetic force and torque on the particles from the PSV results. This leads to increase in the chain collision and area of particle interaction with the aqueous solution of hexavalent chromium, fluoride and congo red dye. / Physics / Ph. D. (Physics)
29

Project water (Grahamstown) : a case study of the development of an environmental education project

Ashwell, Alice Nicola January 1992 (has links)
Environmental education is an approach to education which emphasises the interrelatedness of people and their human and non-human environments and seeks to encourage environmental awareness, concern and action. This case study documents the implementation and development of Project WATER, Grahamstown, a practical environmental education project dealing with catchment conservation and water quality monitoring. The Grahamstown project is one of a number of local water quality monitoring initiatives affiliated to GREEN (the Global Rivers Environmental Education Network). Participants in the project included student teachers from the Department of Education at Rhodes University and pupils and teachers from three farm schools in the district and four high schools in the town. Project WATER, Grahamstown developed as an Action Research and Community Problem-Solving project. The study focuses on fragmentalist and holistic approaches to education, people's responses to Project WATER and the choice of action research as the research method.
30

Detection of aeromonas species in relation to the occurrence of estrogens and testosterone in various water resources in Limpopo Province, South Africa and Lusaka, Zambia

Manavhela, Murendeni 18 May 2019 (has links)
MSc (Microbiology) / Department of Microbiology / Background: The occurrence of microorganisms and endocrine disrupting chemicals (EDCs) in water poses a serious concern due to their effects on humans, animals and environment. In recent years, EDCs have been increasingly reported in rivers that receive large amounts of wastewater effluents. Of all the EDCs, natural and synthetic hormones are among those that are recognized for their potential to mimic or interfere with normal hormonal functions of humans and animals. The present study aimed at assessing the occurrence of these hormones in relation to the molecular diversity of Aeromonas and evaluating the resistance of Aeromonas to antibiotics as well as to assess anti-bacterial activity of two selected traditional medicinal plants. Methods: Wastewater, water and fish samples were collected from various sources (rivers, wastewater treatment plants, taps, and dams) for the detection of hormones and isolation of Aeromonas species. The analysis of hormones from various organs of the fish and from water samples was conducted, after extraction using enzymelinked immunosorbent assays (ELISA). Different types of hormones including Estriol, Estradiol, Ethinylesradiol and Testosterone were detected, and their concentrations determined. Aeromonas spp were isolated rom the samples using microbiological methods and Conventional PCR was used for genotyping as well as for detection of the beta-lactamase genes. Kirby-bauer method was used to determine the susceptibility profiles of Aeromonas to different antibiotics. Microdilution assay was used to determine the Anti-bacterial activity of the plant (Annoniceae and Zornia milneana) extracts against Aeromonas species. Results: A total of 144 samples were collected from 23 different locations in two countries: South Africa and Zambia. These included wastewater and treated wastewater, River water, fish and tap water. 17α-ethinylestradiol (EE2) was detected in most of the samples (92.7%) with concentrations varying from 0.59 ng/ml to 65 ng/ml. The hormones were also detected from drinking water, with testosterone detected at high concentrations of up to 140 ng/ml in tap water. Most sewage treatment plants were not able to remove the EE2 from the wastewater as the concentration of this hormone in the final effluent was almost always higher than that in the influent. These homones were also detected in drinking water at high concentrations of up to 53.49 ng/ml in the tap water for EE2 and 1777 ng/ml for E2. The overall detection of Aeromonas species in the samples was 84.5%. A. caviae was the most prevalent species accounting for 73.6%, followed by A. veronii with 64.6%. The bacteria were completely resistant to cefuroxime accounting for 100% resistance. Aeromonas isolates also showed high resistance to trimethroprim (88.7% for A. hydrophila), cefazolin (highest 97.8% for A. cavie), and ceftazidime (83.9% for A. sobria). TEM was the most prevalent beta-lactamase gene with detection rate of 87%. All isolates lacked the presence of the CTX-M3 gene. Also, wastewater had the highest prevalence of A. veronni and A. caviae accounting for 87.5% and 82.5% respectively. Multiple antibiotic resistance was also observed with the Aeromonas isolates being resistant to up to 11 antibiotics. High prevalence of 77.1% of Aeromonas hydrophila was observed in the presence of ethinylestradiol (EE2). Aeromonas veronii and Aeromonas caviae were the most predominant species in the presence of total estriol, A. veronii had a prevalence of 57.1% and A. caviae had a prevalence of 52.8%. Aeromonas hydrophila and Aeromonas caviae had the lower prevalence in the presence of hormones with the percentages of 26.1% and 27.8% respectively. The methanol extracts of both Zornia milneana and Annona species showed good activity against the Aeromonas spp with the lowest MIC of 0.078 mg/ml. Ethyl acetate extracts were the least effective. Conclusion: This study has shown high occurrence of steroid hormones in all types of environmental samples tested. These included tap water, river water, wastewater and fish both in Zambia and South Africa. Therefore, steroid hormones constitute and important health problem in the Southern African Sub-Region. The incapacity of the wastewater treatment plants to remove EE2 is an important problem that needs to be tackled immediately. The prevalence of Aeromonas species is very high in our environmental water as well as in drinking water, with the highest prevalence observed in fish and wastewater. It was also revealed that there is relationship between steroid hormones and Aeromonas species, with the hormones supporting the growth of Aeromonas species. The presence of beta-lactamase genes which causes Aeromonas to be resistant to antibiotics was also noted. Methanol extracts of Zornia milneana and Annona spp were the most effective against Aeromonas spp and could serve as primary sources for the isolation of lead compounds. / NRF

Page generated in 0.1102 seconds