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Integration of digital media and pedagogy in the twenty first century classroom: a survey of selected high schools in Eastern Cape, South Africa
Get PDFThe essence of this thesis was to study the effectiveness of integrating digital media technologies within the pedagogical approaches adopted and implemented in private and public high schools in a comparative manner. The study looked closely at private and public high schools of the Eastern Cape Province, to study the gaps of accessibility to technology by schools. The study identified the Eastern Cape Province as having a problem of poor performance in matric results at the end of each year as compared to other South African provinces. In order to select the relevant sample for the study, the researcher has utilized two secondary schools private and public in Makhanda Grahamstown and one public secondary school in Alice. The pragmatic paradigm was used to inform the study and used the mixed methods approach to data collection. The researcher distributed closed ended questionnaires to the learners in the three selected secondary schools and semi-structured interviews for the principals of the schools. The key findings reveal that the digital media tools are used for the teaching and learning purposes as well as communication to the schools’ stakeholders. The findings also revealed that various online platforms are utilized for teaching and sharing of information. For example, D6 and Ibambisa School Communicator app, WhatsApp groups for learners, Facebook, Instagram and School website for potential stakeholders. Hence, the results of this study should contribute to the field of ICTs and education in the country to solve the problems facing the teaching and learning systems of private and public schools of the Eastern Cape. Most schools (especially the public) do not have access to digital media tools in their classrooms. Thus, they still depend heavily on the textbooks, which may be outdated or not enough for all learners. In response to the issues faced by the Eastern Cape secondary schools and the findings, the researcher has suggested a model named the Digital Media and Pedagogy Integration DMPI Model of Communication. This model will contribute to the body of knowledge by providing advice to the Department of Basic Education on how teachers and learners can utilize digital media tools effectively. Also, the study has recommended that there is a need for provision of computer literacy training for teachers in secondary schools in this digital age.Thesis (PhD) -- Faculty of Social Sciences and Humanities, 202
The enforcement of settlement of agreements and arbitration awards
Get PDFThe Labour Relations Act (LRA) recognises settlement agreements and arbitration awards as mechanisms by which the rights of parties in troubled employment relationships can be asserted. Commission for Conciliation Mediation and Arbitration (CCMA) is a statutory body empowered to make and pronounce on such rights through settlement agreements and arbitration awards. The CCMA caters for those earning within the stipulated ministerial threshold falling outside the existing bargaining forums. However, not much empirical evidence is available to indicate the challenges experienced by parties when attempting to enforce those CCMA rulings to get defaulters to comply. South African law accepts settlement agreements as part of dispute resolution mechanism, but the experience of some who hold settlement agreements is such that they are exposed to prejudice when they are required to have the settlement agreement converted to arbitration awards which essentially requires alteration of the very settlement agreed upon. The broad objective of taking matters to the CCMA for resolution with the possibility of having them resolved at conciliation phase cannot be achieved if a settlement agreement is not worth the paper written on and must be made an arbitration award for enforceability. The two are not the same, nor should they be made to be and trying to give them a similar status for enforceability purposes brings about a myriad of unintended challenges. While it could be argued that there also exists section 158 (1) (c) of the LRA if the requirements of section 142A are challenging, it could also be said that such a provision is inaccessible to indigent individuals who may only be able to invoke that provision at the mercy of legal practitioners willing to take cases pro bono for those parties to even stand a chance at enforcing compliance with a settlement agreement that was entered into voluntarily. Such a system allows for employers to bail out on settlement agreements without consequence make a mockery of the CCMA. To a serious degree, this suggest lack of certainty on the part of CCMA and its ability to bring matters to finality which is an important element to realisation of justice. This study sought to examine the way settlement agreements and arbitration awards are enforced, with dedicated focus on the requirement that must be satisfied in order to have force and effect. With the above in mind, chapter one dealt with how settlement agreements and arbitration awards are given force and effect through the LRA as envisaged in section 142A. The chapter explored challenges brought by the enforcement process and what that may mean to the objectives intended by the legislation. Chapter two encapsulates the framework under which the CCMA operates and enforces its decisions, a framework envisaged to be less formal and non-legalistic for the expedient resolution of labour disputes. Chapter three touches on the challenges met with section 143 implementation and highlights some case law prior and after the LRA amendments. Lastly chapter four looked into the enforcement of international or foreign arbitration awards within the South African context given the affiliation with international organisations such as International Labour Organisation (ILO). While it may be good for South Africa to align herself with international practices, it is worth noting that South Africa is still developing in international arbitration as a mode of alternative dispute resolution, but its prevalence as a preferred dispute resolution mechanism is without a doubt increasing.Thesis (LLM) -- Faculty of Law, School of Mercantile Law, 202
The use of Police force in crowd management
Get PDFSouth Africa has a violent and oppressive past. They are various historical incidents1 of extreme cruelty perpetrated by the previous apartheid regime. Much of the modern South African democratic state was forged by protests. During the 1970s and 80s, the legislator by passing unjust laws was used to assist the government to maintain the oppression of the people of South Africa. From the Soweto uprising in the 1970s to the current service delivery protests of the 21st century, gatherings have always had the potential for deadly violence. The motivation for this research started with the emotions evoked by the iconic picture of the body of Hector Pietersen2 being carried after being shot by the police. Strikingly the images of the killing by the police of Andries Tatane conjured further questions concerning the use of deadly force within crowd management situations. The research undertook an analysis of the use of force by the police during crowd management situations. A brief analysis of South African law relating to the use of force by the police prior to 1996 is provided. There are legislative prescripts for the use of force during the maintenance of public order. It must be noted that the legislation falls short on providing clear, concise authority for the use of deadly force. Normally, the use of force by the police and civilians for the purpose of arrest is regulated by the Criminal Procedure Act3 , whereas the Regulation of Gatherings Act4 providing the authority for the use of force by the police in crowd management situations to preserve public order. At first glance, section 49 of the CPA seems to validate arguments that it violates some constitutionally protected rights, among which are the right to dignity, life, to freedom and security of the person, against cruel, inhuman or degrading treatment or punishment and to a fair trial, which includes the right to be presumed innocent. Section 49 however, withstood Constitutional muster as set out in Re: S v Walters & another. As the right to life is a non derogable right.5 The limitation of this right may lead to constitutional scrutiny. The emphasis will thus be on ensuring that the balance with regards to proportionality in the use of deadly force is maintained. During the research it became apparent that the police, especially during crowd management situations, served political interests.6 This had the unintended consequence that the laws were applied to suit the political narrative and not the rule of law. The use of force in the policing arena is controversial. It is very clear that any misuse of force in crowd management situations will evoke the historical wounds associated with apartheid. However, within crowd management, the use of force and the authority to use deadly force is absolutely necessary. The Marikana massacre was used to highlight the mistakes that police have made during inappropriate use of force and its catastrophic consequences.7 It was observed that the legislative framework concerning the use of force, whether under section 49 of the CPA or section 9 of the RGA, is incoherent and too complex. The research argues for simplicity and accuracy within policy and applicable legislative alignment. The linkages from the applicable legislation to the institutional policies should never be outdated or incorrectly formulated. The violent rhetoric from politicians such as ex-president Jacob Zuma, 8 Minister Fikile Mbalula 9 and Bheki Cele10 fuels the argument that the police are susceptible to misdirected notions and may cause the police act unlawfully. The Constitution requires the police to “enforce the law”11 and as such there is an obligation on the police to do this within the constitutional parameters. The correct use of deadly force will only be achieved if the SAPS adequately resource, train and regularly refresh their members regarding the use of force when policing protests.Thesis (LLM -- Faculty of Law, School of Criminal and Procedural Law, 202
A systematic risk management model for construction project management: a case study of the new infrastructure project in the University of Mpumalanga
Get PDFThe construction industry has become the significant player in the economy of many developed and developing countries in the world. The industry contributes to the Gross Domestic Product (GDP) and employment rate of many nations. As such, the industry is the engine for the economic development and growth across the world. Recently, African countries have received global attention due to its calls for massive infrastructure development and maintenance thereof. Accordingly, the South African government has adopted a National Infrastructure Development Plan (NIDP), which seeks not only to transform the economic landscape of the country, but also to support the integration of the African economies through infrastructure development. To ensure that the execution of these infrastructure projects is successfully delivered in terms of time, cost, and scope; project risk management in the construction industry has become an important area of interest in the execution and delivery of the infrastructure projects. However, the constantly increasing complexity and dynamics in the delivery of construction projects have serious effects on the risk management processes during the execution of the project. In practice, risk methods and techniques have proven to be unrealistic when using the traditional risk management approach in the context of the complexity and dynamic environments wherein construction projects are delivered. Worryingly, project management practitioners in engineering and construction projects still lack the holistic and systematic insight and understanding of construction projects when applying the risk management procedures in the complex and dynamic projects environments. As a result, there are growing reports of unsatisfactory delivery of construction projects in terms of time, cost, quality, and environmental objectives. In this regard, the call for embracing the systems thinking paradigm as the alternative approach that will provide more clarity in dealing with the complex management challenges and which will gradually substitute the traditional theoretical approach of dealing with construction project management, is becoming prominent. Against this background, this study uses a multiple case study approach to explore how a systematic risk management approach could be developed and applied towards successful delivery of construction projects, and subsequently to propose a systematic risk management model that is designed to depict and grasp the underlying complexities and dynamics embedded ix | P a g e in construction projects. The choice of the case study design is founded on its utility and appropriateness for in-depth investigations into phenomena in its context as well as its usefulness for exploratory studies. Therefore, to explore the risk management phenomenon in real-life settings, the unit of analysis in this study was based on three construction projects built in one of the new Institutions of Higher Learning in South Africa during the period between 2017 and 2019. Notwithstanding the unique characteristics of these projects, the complexity and dynamic environments of these projects also emanated from the facts that i) the successful delivery of the projects was a predecessor activity to the academic schedule and activities; ii) this was one of the first universities to be built by the democratic Republic of South Africa; and, iii) the construction contract used for the delivery of the construction projects is relatively new to the professionals in the country’s construction industry. This qualitative case study design has its backbone in the constructivism philosophical paradigm which is underpinned by the ontology that there are multiple realities as conceptualized, experienced, and perceived by the people in their real-life situations or natural settings. Accordingly, the construction professionals, projects’ documents as well as field work observations were purposively chosen as the essential and reliable methods of data collection for this case study. For analysis, a conventional content data analysis methodology was applied on the empirical data that was obtained from the multiple data sources to provide a clearer understanding of the contexts in which the risk management for construction projects is performed. Accordingly, a qualitative data analysis software system called MAXQDA was used to enable the performance of data coding, managing coding, and eventually the retrieving of the coded segments in a form of visual models and summary tables. Ultimately, the qualitative content analysis approach in this thesis was performed in terms of a ‘critical filter of thick description’ which involved a balanced approach between the deductive analysis and the inductive analysis processes. With the assistance of the MAXQDA, performing the multiple levels coding and analysis processes in this thesis has not only been efficient, but also more reliable. To shed insight into the empirical findings of the study, a hybrid theoretical framework has been applied in the discussion and interpretation of the findings. The theoretical framework of this study is underpinned by the complexity theory and the theory of systems engineering. The applicability of these theories in this study is essential in providing a x | P a g e systematic and logical explanation of the practices of risk management in construction projects and further helps to explain why particular events occurred in the processes of risk management. Eventually, the theoretical framework has enabled the designing and developing of a systematic risk management model that will assist in depicting and grasping the underlying complexities while supporting proactive decision making in the delivery of construction projects. To this end, this study has made several major contributions in three multiple folds in the body of knowledge. Firstly, this study makes theoretical contributions by developing an empirically underpinned systematic risk management model which provide more clarity on comprehending the multifaceted and complex risk factors embedded in construction projects. Secondly, the qualitative case study approach and the associated analysis methods thereof in this thesis provides novelty and lays the groundwork for future research and methodological replicability in another similar phenomenon elsewhere in the world. Thirdly, this study has gone some way towards expanding the understanding and the basis for managerial decision making in relation to front-end planning and proactive approach for risk management, and eventually to improve projects’ performances on cost, time, scope, and environmental sustainability. In this regard, the key practical implication for project management practitioners is that the adoption and embracing of the systematic and holistic thinking approach in the risk management processes could enhance the successful delivery of construction projects. In the literature, there is paucity and need for more research into the exploration and analysis of the integration and interplay between the systems engineering and complexity perspectives and the other knowledge areas in the PMBOK. In conclusion, this thesis therefore argues that to address the deficiencies in risk management practices during construction projects’ delivery, the solution requires a paradigm shift from the traditional linear approach which, by design, overlooks the complexities, non-linearity and interdependences of the elements that are underpinning and characterizing the nature of the contemporary construction projects. Therefore, this thesis supports the increasingly emerging debate on the discourse that the superior traditional and linear approaches do not solve the current problems, and as such they should be replaced with the systems and holistic thinking approach that will provide more clarity in dealing with the complex management challenges in contemporary construction projects.Thesis (PhD) -- Faculty of Engineering, Built environment and Information Technology, School of the built Environment 202
Delights and negation: analysis of feminine writing in some African Francophone novels
Get PDFFrom the onset, it is worthy to note that, nowadays, just as after the independence of most African countries, several writers from the African continent have been preoccupied with the fate of women. This is because, the African continent was since ancient times characterized by certain traditions and cultures which mainly have contributed to the plight of the women. This goes to emphasise that women in most cases are the victims of misdeeds such as early marriage, forced marriage, prejudices, violence, marginalisation, exploitation, discrimination; in short, vices that lead to devalorisation of African women in Africa. Over time, some contemporary French-speaking African writers have responded to the devaluation and valuation of women in their novels using 21st century objective view. With regard to the theme that we decided to address in this research, it is worth knowing that the preponderant task is based on the socio-critical theory, postulated by Claude Duchet. Meanwhile, recourse is also made to the comparative method by Rens, Bod et al. However, since the author’s message could be understood by the reader through the use of some expressions or terms that speak directly to the themes of the research, and that a reader’s role in reading experience cannot be overemphasised, we have been able to also lean on the Reader-response theory of Louise Michelle Rosenblatt. The three methods were used concurrently especially that the analysis of each text is based on how characters are being depicted leading us to realizing that our findings on how the African woman is devalued in the first part of the research, while in the second part of the thesis, our findings demonstrate that a lot of tributes are showered on the African woman due to her numerous outstanding qualities. In effect, our findings also reinforce a significant shift in the narrative that concerns the contemporary view on womanhood. Hence, moving from a dogmatic overconcentration on her lot to the new era woman whose lot is now redefined via the new wave feminist perspective on the negation of the African woman. This could be said to be in line with Amadiume Ifi’s contributions and pioneering work in feminist discourse towards new ways of thinking about sex and gender, the question of power, and women’s place in history and culture.Pour commencer, il est nécessaire de se souvenir qu’à l’époque actuelle, comme juste après les indépendances de la plupart des pays africains, bon nombre des écrivains venant du continent africain décident de se préoccuper des méfaits sociaux tels que le mariage précoce et/ou forcé, les préjugés, la violence, la marginalisation, l’exploitation, la discrimination, entre autres. Tous ces vices sont issus de la négation de la femme africaine. Ceci se justifie par le fait que le continent africain était depuis l’antiquité caractérisé par certaines traditions et cultures qui ont contribué principalement aux dégâts ci-dessus soulignés subis par les femmes. En effet, nous estimons que beaucoup de femmes sont victimes de ces méfaits qui sont encore pratiqués dans certaines parties de l’Afrique. Avec le temps, certains écrivains africains francophones contemporains représentent la dévalorisation et la valorisation de la femme dans leurs romans en se servant d’une vision contemporaine, celle du XXIe siècle. En ce qui concerne le thème que nous avons décidé d'aborder dans cette recherche, il faut savoir que la tâche prépondérante repose sur la théorie sociocritique, postulée par Claude Duchet. Parallèlement, on a également recours à la méthode comparative de Bod Rens Et ses coauteurs. Cependant, puisque le message de l’auteur pourrait être compris aussi par le lecteur à travers l’usage de certaines expressions ou termes qui sont directement liés aux thèmes de la recherche, le rôle du lecteur dans l’expérience de lecture ne peut pas être surestimé, nous avons également pu nous appuyer sur la théorie de la réponse du lecteur de Louise Michelle Rosenblatt. Les trois méthodes ont été utilisées simultanément d'autant plus que l'analyse de chaque texte est basée sur la façon dont les personnages sont représentés ; ceci nous a amené à tirer nos conclusions sur la façon dont la femme africaine est dévalorisée dans la première partie de la recherche, tandis que dans la deuxième partie de la thèse, nos résultats démontrent que de nombreux hommages sont rendus à la femme africaine grâce à ses nombreuses qualités exceptionnelles. En effet, nos résultats renforcent également un changement important dans le récit qui concerne la vision contemporaine de la féminité. Par conséquent, passer d’une surconcentration dogmatique sur son sort à la femme de la nouvelle ère dont le sort est maintenant redéfini via la perspective féministe par rapport à la négation de la femme africaine telle a été la démarche. On pourrait dire que cela est au diapason avec les contributions d’Amadiume Ifi et avec son travail dans le discours féministe vers de nouvelles façons de penser le sexe et le genre, la question du pouvoir et la place de la femme dans l’histoire et la culture.Thesis (PhD) -- Faculty of Humanities, School of Languages and Literatures, 202
Social Learning and Regenerative Sustainability: Unlocking value created in sustainability projects in higher education
Get PDFThis qualitative study considers two bodies of theory, regenerative sustainability and social learning theory, within a tertiary education context. Universities offer unique opportunities, across both the formal and informal curriculum, that engage with the two-fold socioeconomic and environmental crises. The study explores both the promise of unlocking value in an ex-linear economy; and the healing and regenerative benefits in moving toward greener practices. Through an embedded case study at Rhodes University, in the Eastern Cape of South Africa, this research explores the value that is being unlocked in campus-based sustainability projects, when considered through a social learning lens (Lave and Wenger, 1991). Invitations to participate in this study were extended to project-leads of sustainability initiatives originating from Rhodes University campus. Six projects, which have been active on campus in recent years, were selected and, through semi-structured interviews, the insights of 12 participants were captured and analysed using the associated Value Creation Framework (VCF) developed by Wenger, Trayner and De Laat (Wenger, Trayner, de Laat, 2011) and later Wenger-Trayner and Wenger Trayner (2014, 2015, 2020). The VCF consists of value cycles that interconnect dynamically, including Orientating, Strategic, Enabling, Immediate, Potential, Applied, Realised and Reframed or Transformative value cycles. The study identified instances of all these value cycles, within and across the six embedded case studies (project). Drawing on social learning theorists the analysis further focused on instances of collaboration, agency and boundary crossing. Additional themes that emerged across the majority of the embedded study projects, were a convergence of socio and eco; a whole-systems perspective shared by project leads; the importance of the social commons; language as an enabler; and problem solving for system change. A recommendation is proposed to further unlock the unbounded value created through such projects by reframing the informal curriculum opportunities offered on university campuses as social learning spaces where students can practice agency. To do so, would require formalizing various forms of system support, thus facilitating expanded learning in regenerative sustainability activities, for the common social and planetary good.Thesis (MEd) -- Faculty of Education, Education, 202
Top-down control by grapsoid crabs in South African estuarine salt marshes
No full textSalt marshes are one of the most productive ecosystems globally. These ‘blue carbon’ habitats are in many respects resilient to climate change effects, able to track sea level rise and act as carbon sinks. Since salt marshes are economically and ecologically essential habitats (for example providing foraging grounds for invertebrates, fish, birds and humans), understanding the processes that control their structure is crucial to best maintain ecosystem services provided by these habitats. For decades the importance of top-down forces, such as grazing, has not been recognised as being important in controlling salt marsh plant productivity. Rather, bottom-up forces, such as the availability of oxygen, was thought to be the main constraint to primary production. Therefore, a better understanding of salt marsh ecosystem dynamics and whether grazer control exists is needed. Although grazer top-down control has been demonstrated in salt marshes in locations such as the United States, this has not been investigated in South Africa. This is a crucial knowledge gap locally considering the importance of salt marsh ecosystems. The aim of this study was therefore to determine what role consumers play in structuring South Africa’s estuarine salt marsh vegetation, thereby also contextualising this process internationally. In order to achieve this, the abundance of grapsoid crabs was estimated and related to key salt marsh features, such as Spartina maritima stem height and stem density, which was quantified from observational surveys. Sampling took place at the beginning and end of the early-spring and late-summer growth period (September 2021 and April 2022) in the Knysna, Kromme and Swartkops estuaries. If a correlation was observed between crab density and salt marsh features, it was important to determine whether they consume the salt marsh vegetation or if the effect was due to their burrowing activities. Hence, the diet of grapsoid crabs was investigated using stable isotope and gut content analysis. To examine the importance of crab grazing in controlling the growth of salt marsh vegetation, crab abundance was manipulated in situ by means of exclusion cages. This experiment ran for five months in the Kromme Estuary, from November 2021 to March 2022 over the salt marsh growing season. An ex situ feeding experiment was also conducted on 30 crab specimens collected from the Kromme Estuary, during May 2022. These crabs were starved for 48 hours and thereafter fed different components of Spartina (growing and dead blades, and roots and rhizomes). The food consumed was quantified as the change in plant length and dry weight after 48 hours, which gave a maximum grazing rate for the different food sources. It was found that crabs are having a minimal impact on the salt marsh vegetation structure. Spartina maritima does form an important component of the diet of grapsoid crabs, however, this is not their only source of food, and possibly not their preferred source of food. They are however contributing to sediment properties through their burrowing activities. The iii ex situ feeding experiment showed that grapsoid crabs can consume all vegetative components of Spartina, with a significantly greater amount of roots and rhizomes consumed. There was no consistent effect in terms of the exclusion of grazers, indicating that other mitigating factors could be reducing the impacts of grapsoid exclusion in situ. Together, these findings contribute knowledge that can be used to inform conservation by quantifying what the salt marsh risks losing in the absence or overabundance of crabs, as has occurred elsewhere globally. These results influence how salt marshes are managed, and highlight how not recognising the importance of consumers, such as crabs, could misalign management objectives.Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 202
Evaluation of spatial distribution and health risk of pesticide residues in the environmental matrices of buffalo river estuary and their removal using nanosponges and modified cyclodextrins
Get PDFThe contamination of lotic ecosystems caused by agricultural, industrial, and anthropogenic activities has attracted the attention of researchers, authorities, and scientists because these waterbodies are of social and economic importance to human livelihoods. Pesticides and insecticides are a group of compounds that are toxic to pests and insects, respectively. Organophosphate pesticides (OPs) can be released into different environmental matrices through several sources including agricultural and urban runoff. They are one of the three main classes of synthetic organic pesticides that are used in agricultural sector and very often end up in other destinations than their target sites. In this study, four OPs, namely, ronnel, malathion, parathion and Durban were investigated. The Buffalo River Estuary, located in East London, is one of most popular areas and the river is a major source of raw water abstraction for three municipalities in the Eastern Cape Province, South Africa. Sediment samples were collected from six points in the estuary and soil samples were taken from a nearby dumpsite in winter and spring seasons of 2021. The physicochemical parameters of the samples including particle size, moisture content, oil and grease and organic carbon were determined. The samples were then extracted by ultra-sonication, the final extracts were analyzed using GC-μECD and the risk quotient (RQ) method was used to evaluate the risk of OP exposure to aquatic organisms. Polymer modified cyclodextrin (β-CD) for the removal of parathion in sediment and soil was synthesized and the morphology of the modified β-CD and vibrations of the synthesized material were determined using scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. The limit of detection (LOD) and the limit of quantification (LOQ) of the OPs investigated were in the range of 0.09 to 2.99 and 0.274 to 9.06 μg/L, respectively. OPs gave a good recovery except for malathion, which had a recovery percentage lower than 70%. Calibration curves were plotted for the four OPs and were linear with relative standard deviations (RSD) ranging from 1.02 to 3.50, and correlation coefficients (R2) ranging from 0.9935 to 0.9972. The mean concentrations for sediments and soil in both seasons varied from 0.00231 to 63.8 μg/g in winter and from 0.0017 to 36.6 μg/g in spring, with malathion being the predominant congener and dursban being the least dominant in both seasons. In winter, the particle size percentages of the sediment and soil samples ranged from 34.4 to 79.4 percentage, 15.4 to 23.9 percentage and from 7.77 to 38.3 percentage for coarse, medium, and fine fractions, respectively. While in spring, the particle size for the course, medium and fine mesh fractions ranged from 37.4 to 74.6 percentage, 14.1 to 25.1 percentage and 12.4 to 35.0 percentage respectively; the percentage moisture content varied from 43.0 to 73.1 in winter, and from 57.1 to 63.4 in spring. In the soil samples, the physicochemical properties were lower in winter except for the n- hexane extractable material (HEM), which significantly decreased in spring from 2.6 to 1.63 mg/kg; while for sediments, the oil and grease ranged from 1.77 to 10.3 mg/kg in winter and from 1.63 to 4.28 mg/kg in spring. The risk quotient method was used to determine the risk of OP exposure to sediment-dwelling organisms and the results obtained indicated that the levels of OPs in this study, especially dursban, can pose a high risk to the organisms in sediments, with RQs higher than ten (˃10) in both winter and summer. The Pearson product-moment correlation showed that parathion had a weak correlation with every other variable except for malathion in winter, whereas in spring, parathion correlated very weakly with malathion; suggesting that products containing parathion are mostly used to control pests found in crops, such as corn and mosquitos, which are most active in the spring season. There was a very strong correlation between dursban and ronnel in spring and winter, implying that an increase in dursban concentration resulted in an increase in the concentration of ronnel. To determine the efficiency of the synthesized adsorbent CD-chitosan-alginate for the removal of Parathion from soil and sediment, different parameters such as concentration, time, pH and dose were varied. The adsorption capacity was found to be highest at pH 2 (99.19 percentage), when 3 mL of the adsorbent was used for 30 minutes.Thesis (Msci) -- Faculty of Science and Agriculture, 202
Assessment of Pitman Model Capabilities in Modelling Surface Water-Groundwater Interactions in the Lake Sibaya Catchment, South Africa
Get PDFDifficulties arising from data scarcity, input data error or uncertainty, heterogeneous environments, lack of process understanding, and model structural uncertainty frequently constrain hydrological assessments of South African catchments. This research aimed to assess the usefulness of a “simpler” conceptual model for the conjunctive management of surface water and groundwater. The idea is that, to leverage the limited available data and information, a compromise between model complexity and data availability is required, which improves the use of models to produce reliable hydrological systems assessments. The research methodology focused on catchment-scale lake-groundwater dynamics to explore the limits of the groundwater components of the modified Pitman model (Hughes, 2004) in this type of environment, thus, determining the potential for using this model for integrated water assessments in South Africa. The Pitman model (Pitman, 1973; Hughes, 2013) is one of the most widely accepted models regarding surface water hydrology in South Africa; however, the newly incorporated groundwater components (Hughes, 2004) have not been applied as extensively as the surface water components. There remains uncertainty regarding their capability to adequately simulate groundwater processes and accurately represent surface and groundwater interactions in some environments. The model was assessed based on how well simulated water balance variables accurately reflected available evidence and expected catchment response (objective 1). Secondly, the research identified and addressed uncertainties as regards the structure and application of the model’s groundwater interaction components (objective 2). The model was set up for the Lake Sibaya catchment, which is a predominantly groundwater-driven system and, thus, provides an important opportunity to interrogate different aspects of uncertainty in both the conceptualizing and quantifying interaction processes. The study’s overall conclusion is that the model performed satisfactorily as it was able to simulate the lake’s water balance correctly enough such that the influences of dominating components were sensibly reflected in variations in streamflow and lake volumes. The following key findings were noted; (i) the lake volume shows a continuous decline, (ii) the lake volume decreased with increasing development (forestry and abstractions) in the lake catchment, (iii) there is significant rainfall uncertainty in the study area and the model showed high sensitivity to rainfall differences, (iv) robust conceptual knowledge of local catchment conditions was valuable for reducing some of the data related uncertainty in the study area and for producing realistic model simulations, (v) the Pitman model (Hughes, 2013) updated GW components can provide a valuable tool for modelling integrated hydrological processes; nevertheless, when applying the model to specific environments, implicit approaches may be necessary to account for processes that are not fully represented in the model.Thesis (MSc) -- Faculty of Science, Institute for Water Research, 202
Liposomal formulations of metallophthalocyanines-nanoparticle conjugates for hypoxic photodynamic therapy and photoelectrocatalysis
Get PDFThis thesis investigates new strategies to enhance the efficacy of photodynamic therapy (PDT) under hypoxic conditions using in-vitro cancer cell models. Phthalocyanines are chosen as viable photosensitizer complexes owing to the favourable absorption properties. To this end, this thesis reports on the synthesis and photophysicochemical properties of various zinc and silicon phthalocyanines (Pcs). To afford better photophysicochemical properties, the reported Pcs were conjugated to different nanoparticles (NPs) through chemisorption as well as amide bond formation to yield Pc-NP conjugates. All the studied Pcs showed relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yields. The various mechanisms for hypoxic response include (i) Type I PDT, (ii) PDT coupled with oxygen-independent therapy and (iii) in-situ oxygen generation using catalase-mimicking nanoparticles which serve to supplement in-vitro oxygen concentrations using MPcs or MPc-NPs conjugates. The mechanisms were assessed using electrochemical, computational techniques and catalase mimicking experiments. The as-synthesised Pcs or Pc-NPs were subjected to liposomal loading before PDT studies which led to enhanced biocompatibility and aqueous dispersity. The in-vitro dark cytotoxicity tests and photodynamic therapy activities of the fabricated Pc-liposomes and Pc-NPs-liposomes on either Henrietta Lacks (HeLa) or Michigan Cancer Foundation-7 (MCF-7) breast cancer cells are presented herein. This work further showed that folic acid (FA) functionalization of liposomes could be exploited for active drug delivery and herein led to an almost 3-fold increase in drug uptake vs non-FA functionalised liposomes in accordance with folate receptor (FR) expression levels between HeLa and MCF-7 cells. The in-vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates were accessed using MCF-7 and HeLa cell lines. The various mechanisms; (i) Type I PDT, (ii) PDT coupled with oxygen -independent therapy and (iii) in-situ oxygen generation using catalase-mimicking nanoparticles were shown to adequately compensate for the otherwise attenuation of PDT activity under hypoxia.Thesis (PhD) -- Faculty of Science, Chemistry, 202