The design and synthesis of novel fluorescent coumarin-based derivatives as chemosensory for the application of toxic metal ion detection
- Authors: Schoeman,Stiaan
- Date: 2023-04
- Subjects: Fluorescent polymers -- South Africa , Polymerization , Chemosensory
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61270 , vital:69851
- Description: The rise of humankind has caused pollution, increasing damage to the environment. The actions of humans over hundreds of years have led to an increase in the release of heavy metal cations in concentrations that are toxic to plants, animals and humans. These toxic metals can find their way into humans’ diets through water sources or bioaccumulation in plants and animals such as fish. Heavy metals such as lead and mercury are known to cause serious health issues when consumed, affecting the functioning of the circulatory and nervous systems and causing developmental disorders. Other metal cations, such as iron and copper, can be found in the human body. However, detrimental health issues can occur when normal concentrations are disturbed (either too high or too low). Iron, for example, can be toxic if in excess in the human body, causing damage to the liver and heart and can cause neuroinflammation and Alzheimer’s disease. Many methods have been employed to detect and measure the concentrations of toxic metal cations. However, these methods are performed in a laboratory and need skilled operators using expensive equipment. This results in long and tedious sample collection, long feedback time and costly analysis. Chemosensors have been researched and proposed as a cost-effective, on-site, real-time alternative for use as metal detectors. Chemosensory can selectively detect specific metal cations and can be sensitive up to the nanomolar range. Various chemosensors have been synthesised and screened for their colourimetric and fluorometric abilities. Colourimetric chemosensors can be used to visually detect cationic and anionic analytes, whereas fluorometric chemosensors are used to detect anions using their emission properties which handheld devices can measure. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Schoeman,Stiaan
- Date: 2023-04
- Subjects: Fluorescent polymers -- South Africa , Polymerization , Chemosensory
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61270 , vital:69851
- Description: The rise of humankind has caused pollution, increasing damage to the environment. The actions of humans over hundreds of years have led to an increase in the release of heavy metal cations in concentrations that are toxic to plants, animals and humans. These toxic metals can find their way into humans’ diets through water sources or bioaccumulation in plants and animals such as fish. Heavy metals such as lead and mercury are known to cause serious health issues when consumed, affecting the functioning of the circulatory and nervous systems and causing developmental disorders. Other metal cations, such as iron and copper, can be found in the human body. However, detrimental health issues can occur when normal concentrations are disturbed (either too high or too low). Iron, for example, can be toxic if in excess in the human body, causing damage to the liver and heart and can cause neuroinflammation and Alzheimer’s disease. Many methods have been employed to detect and measure the concentrations of toxic metal cations. However, these methods are performed in a laboratory and need skilled operators using expensive equipment. This results in long and tedious sample collection, long feedback time and costly analysis. Chemosensors have been researched and proposed as a cost-effective, on-site, real-time alternative for use as metal detectors. Chemosensory can selectively detect specific metal cations and can be sensitive up to the nanomolar range. Various chemosensors have been synthesised and screened for their colourimetric and fluorometric abilities. Colourimetric chemosensors can be used to visually detect cationic and anionic analytes, whereas fluorometric chemosensors are used to detect anions using their emission properties which handheld devices can measure. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
The co-evolution of Africa’s eastern margin and its primate fauna: implications for hominin evolution
- Authors: Mambalu, Philasande
- Date: 2022-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59755 , vital:62418
- Description: I investigated potential links between the diversification of African primate lineages and the physical evolution of the continent. I compared published phylogenetic trees based on mitochondrial and nuclear DNA for five clades: (a) Lorisoidea (galagos and pottos); (b) arboreal guenon monkeys (Cercopithecus and its allies); (c) living apes (including humans); (d) Papionini (baboons); and (e) savanna or “vervet” monkeys (Chlorocebus). I compared primate divergence dates with the ages of tectonic events, patterns of climatic change, and their palaeo-vegetational consequences. Based on present primate distributions, I estimated likely geographic locations of the divergence events. Finally, I compared the phylogenetic patterns of the primate clades with hominin evolutionary scenarios. Phylogenetic comparisons indicated three time periods when rates of speciation increased across the five primate clades: the Eocene – Oligocene transition (34 – 32 Ma); the mid-late Miocene (10 – 5 Ma); and the Pliocene – Pleistocene transition (2.7 – 2.3 Ma). Concentrated bursts of lineage splitting indicate a broadscale causal relationship between environmental change and lineage divergence. Human evolution followed similar biogeographic patterns to those of other primate clades. Tectonic events, climatic changes and palaeo-vegetational shifts are intimately connected, and have synergistic effects on biotic diversity. Tectonic events influence climatic change through their effects on oceanic circulation, planetary temperatures and rainfall patterns. Additionally, tectonic uplift and erosion may create geographic barriers to organismal dispersal across the continent, increasing the likelihood of geographic separation of populations and speciation. Recently evolved primate species show high levels of hybridisation for several generations after their initial divergence. Genus Homo generated ~10 species over 2.5 Ma. The emergence of these taxa likely involved substantial hybridisation, as demonstrated by the presence of Neanderthal genes within the H. sapiens genome. I suggest that this hybridisation contributed to the difficulties palaeoanthropologists often experience in distinguishing fossil hominin taxa. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Mambalu, Philasande
- Date: 2022-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/59755 , vital:62418
- Description: I investigated potential links between the diversification of African primate lineages and the physical evolution of the continent. I compared published phylogenetic trees based on mitochondrial and nuclear DNA for five clades: (a) Lorisoidea (galagos and pottos); (b) arboreal guenon monkeys (Cercopithecus and its allies); (c) living apes (including humans); (d) Papionini (baboons); and (e) savanna or “vervet” monkeys (Chlorocebus). I compared primate divergence dates with the ages of tectonic events, patterns of climatic change, and their palaeo-vegetational consequences. Based on present primate distributions, I estimated likely geographic locations of the divergence events. Finally, I compared the phylogenetic patterns of the primate clades with hominin evolutionary scenarios. Phylogenetic comparisons indicated three time periods when rates of speciation increased across the five primate clades: the Eocene – Oligocene transition (34 – 32 Ma); the mid-late Miocene (10 – 5 Ma); and the Pliocene – Pleistocene transition (2.7 – 2.3 Ma). Concentrated bursts of lineage splitting indicate a broadscale causal relationship between environmental change and lineage divergence. Human evolution followed similar biogeographic patterns to those of other primate clades. Tectonic events, climatic changes and palaeo-vegetational shifts are intimately connected, and have synergistic effects on biotic diversity. Tectonic events influence climatic change through their effects on oceanic circulation, planetary temperatures and rainfall patterns. Additionally, tectonic uplift and erosion may create geographic barriers to organismal dispersal across the continent, increasing the likelihood of geographic separation of populations and speciation. Recently evolved primate species show high levels of hybridisation for several generations after their initial divergence. Genus Homo generated ~10 species over 2.5 Ma. The emergence of these taxa likely involved substantial hybridisation, as demonstrated by the presence of Neanderthal genes within the H. sapiens genome. I suggest that this hybridisation contributed to the difficulties palaeoanthropologists often experience in distinguishing fossil hominin taxa. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-12
The aesthetics of hegemony: a speculative design proposal exploring the convergence of surveillance capitalism and brain-computer interface technologies in the future
- Authors: Davies, James Tibbott
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54417 , vital:46517
- Description: This study examines the power dynamics of surveillance capitalism, and its role in shaping cultural hegemony. The research was expressed using graphic design to illustrate a (potential) future where Brain-Computer Interfaces (BCIs) and surveillance capitalism converge. The critique focused on Google and Facebook’s hegemony in the data-surveillance marketplace and what role this has in shaping global discourse. Both companies are funding the development of BCIs, with the aim of using brain signals as a means of interacting with the digital world, which would give the two biggest advertising companies in the world access to new sources of data. A speculative design framework was utilized to visually question the societal implications of this emerging technology and the funding behind its development. A theoretical investigation of the concepts underpinning critical theory and critical design was conducted to help clarify and critically inform this methodological approach, promoting the use of practice-based design as a critically reflective investigative tool. The resulting artefacts designed using this process were showcased in the form of a website and video that act as a visual embodiment the research, demonstrating the efficacy of this approach and the value of using communication design as a mechanism to question the status quo. , Thesis (MA) -- Faculty of Humanities, School of Visual and Performing Arts, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Davies, James Tibbott
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54417 , vital:46517
- Description: This study examines the power dynamics of surveillance capitalism, and its role in shaping cultural hegemony. The research was expressed using graphic design to illustrate a (potential) future where Brain-Computer Interfaces (BCIs) and surveillance capitalism converge. The critique focused on Google and Facebook’s hegemony in the data-surveillance marketplace and what role this has in shaping global discourse. Both companies are funding the development of BCIs, with the aim of using brain signals as a means of interacting with the digital world, which would give the two biggest advertising companies in the world access to new sources of data. A speculative design framework was utilized to visually question the societal implications of this emerging technology and the funding behind its development. A theoretical investigation of the concepts underpinning critical theory and critical design was conducted to help clarify and critically inform this methodological approach, promoting the use of practice-based design as a critically reflective investigative tool. The resulting artefacts designed using this process were showcased in the form of a website and video that act as a visual embodiment the research, demonstrating the efficacy of this approach and the value of using communication design as a mechanism to question the status quo. , Thesis (MA) -- Faculty of Humanities, School of Visual and Performing Arts, 2021
- Full Text:
- Date Issued: 2021-12
Testing alternative Pinus species and hybrids for the South African structural pole market
- Authors: Ndovela, Lisakhanya Sizo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52002 , vital:43435
- Description: According to the South African National Standards, only Pinus canariensis, Pinus pinaster and Pinus radiata are suitable to be used as structural softwood poles. Of the three Pinus species mentioned, only P. radiata is still planted in South Africa and its future and availability is uncertain. The lack of availability of structural pine poles necessitates the South African forestry industry to look at alternative softwood species to plant. The broad aim of this study was to determine whether there are alternative Pinus species or hybrids that can be planted in South Africa’s Western and Southern Cape areas that will have suitable properties to be used as a resource for structural poles. This document reports on the testing of the strength and stiffness, as well as other relevant properties, of poles from several Pinus species and Pinus hybrids. The poles were derived from thinned eight-year-old tree stands in Knysna, Western Cape. Poles were peeled, kiln dried and graded before bending tests were carried out. Species and hybrids were also assessed for differences within a tree along the length. Also, the correlation between modulus of rupture (MOR), modulus of elasticity (MOE) and wood grading properties was evaluated. The results showed that there was a highly significant effect of species and log position on the mean MOR of the poles. In general, poles from the bottom of the tree had a higher mean MOR than poles from the top of the tree. There was also a highly significant effect of species and pole position on the mean MOE of poles, with poles at the top of the trees generally having higher MOE values. A very concerning finding was that the 5th percentile MOR and mean MOE values of all the species were far lower than required by SANS 10163-1 (2003). Even for the best performing species, P. radiata, the MOR 5th percentile value was less than half the required value, while the mean MOE was also 39% lower than the required mean MOE. Apart from P. radiata, the P. maximinoi performed the best of all species and hybrids since it had a statistically similar mean MOR and MOE to P. radiata. P. elliottii and the hybrid P. elliottii x caribaea had statistically significant lower MOR and MOE than P. radiata. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Ndovela, Lisakhanya Sizo
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52002 , vital:43435
- Description: According to the South African National Standards, only Pinus canariensis, Pinus pinaster and Pinus radiata are suitable to be used as structural softwood poles. Of the three Pinus species mentioned, only P. radiata is still planted in South Africa and its future and availability is uncertain. The lack of availability of structural pine poles necessitates the South African forestry industry to look at alternative softwood species to plant. The broad aim of this study was to determine whether there are alternative Pinus species or hybrids that can be planted in South Africa’s Western and Southern Cape areas that will have suitable properties to be used as a resource for structural poles. This document reports on the testing of the strength and stiffness, as well as other relevant properties, of poles from several Pinus species and Pinus hybrids. The poles were derived from thinned eight-year-old tree stands in Knysna, Western Cape. Poles were peeled, kiln dried and graded before bending tests were carried out. Species and hybrids were also assessed for differences within a tree along the length. Also, the correlation between modulus of rupture (MOR), modulus of elasticity (MOE) and wood grading properties was evaluated. The results showed that there was a highly significant effect of species and log position on the mean MOR of the poles. In general, poles from the bottom of the tree had a higher mean MOR than poles from the top of the tree. There was also a highly significant effect of species and pole position on the mean MOE of poles, with poles at the top of the trees generally having higher MOE values. A very concerning finding was that the 5th percentile MOR and mean MOE values of all the species were far lower than required by SANS 10163-1 (2003). Even for the best performing species, P. radiata, the MOR 5th percentile value was less than half the required value, while the mean MOE was also 39% lower than the required mean MOE. Apart from P. radiata, the P. maximinoi performed the best of all species and hybrids since it had a statistically similar mean MOR and MOE to P. radiata. P. elliottii and the hybrid P. elliottii x caribaea had statistically significant lower MOR and MOE than P. radiata. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Synthesis of coumarin based fluorescent chemosensors for the detection of metal ions.
- Authors: Hamukoshi, Simeon Shiweda
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic compounds--Synthesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52041 , vital:43422
- Description: The study focused on the synthesis of three coumarin-based chemosensors; hydrazone fluorescent chemosensor , azo-benzothiazole dye and azo-quinoline dye. The hydrazone fluorescent chemosensor was synthesised through multiple reaction steps were the azide functionality at position 8 of the coumarin backbone was replaced with the hydrazone group in the last reaction step. The azo dyes were synthesised through a two step reaction process. The photophysical properties of all three chemosensors were investigated. The hydrazone chemosensor and azo-benzothiazole dye presented high absorption and emission, while the azo-quinoline only presented absorption properties. The chemosensing ability of the three products were investigated through absorption and emission. The hydrazone chemosensor was found to be highly selective towards Fe3+ in water and the dyes were found to be selective towards Hg2+. The mechanisms of interaction between the chemosensors and their selective metal ions were investigated via computational analysis and 1H NMR analysis. All of the chemosensors where characyerised using 1H NMR, Fourier Transform Infrared Spectrometer (FTIR) and the X Ray Chrystal structure for the hydrazone chemosensor was obtained via X ray Chrystallography. Finally, the electron density distribution of the all synthesised compounds their predicted stable metal ion complexes was determined using Density Functionaly Theory (DFT). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Hamukoshi, Simeon Shiweda
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Organic compounds--Synthesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52041 , vital:43422
- Description: The study focused on the synthesis of three coumarin-based chemosensors; hydrazone fluorescent chemosensor , azo-benzothiazole dye and azo-quinoline dye. The hydrazone fluorescent chemosensor was synthesised through multiple reaction steps were the azide functionality at position 8 of the coumarin backbone was replaced with the hydrazone group in the last reaction step. The azo dyes were synthesised through a two step reaction process. The photophysical properties of all three chemosensors were investigated. The hydrazone chemosensor and azo-benzothiazole dye presented high absorption and emission, while the azo-quinoline only presented absorption properties. The chemosensing ability of the three products were investigated through absorption and emission. The hydrazone chemosensor was found to be highly selective towards Fe3+ in water and the dyes were found to be selective towards Hg2+. The mechanisms of interaction between the chemosensors and their selective metal ions were investigated via computational analysis and 1H NMR analysis. All of the chemosensors where characyerised using 1H NMR, Fourier Transform Infrared Spectrometer (FTIR) and the X Ray Chrystal structure for the hydrazone chemosensor was obtained via X ray Chrystallography. Finally, the electron density distribution of the all synthesised compounds their predicted stable metal ion complexes was determined using Density Functionaly Theory (DFT). , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Synthesis of cannibigerol, an antibiotic for methycillin resistant staphylococcus aureus, in continuous flow system
- Authors: Koeberg, Bryce
- Date: 2022-04
- Subjects: Drug resistance in microorganisms , Cannabis -- Therapeutic use -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55866 , vital:54395
- Description: This study focuses on the development of a synthetic version of the cannabinoid cannabigerol (CBG) through continuous flow systems. The compound has exhibited antibiotic properties that have been proven to be a potent killer of gram-positive methicillin-resistant Staphylococcus aureus that drive repeat infections. The cannabinoid kills the superbug by disrupting the cell wall integrity of cells that are drug resistant. Research suggests that CBG is not effective against gram-negative multi-drug resistant bacteria. However, when CBG is administered with polymyxin B, an antibiotic that disrupts the outer membrane of gram-negative bacteria the cannabinoid compound wipes out the drug-resistant gram-negative bacteria, thus revealing the extensive medicinal potential of cannabigerol. Cannabinoids, such as CBG, are present in low yields in the plant, depending on the extraction method, usually less than 5% in most strains. Natural medicines have a low amount of active ingredients due to the lab intensive and time-consuming extraction and isolation process; this has hindered the application of natural products in drug development. A major health concern of the human consumption of cannabis plant extracted cannabinoids is that the plant may be contaminated with microbes, heavy metals and pesticides due to the lack of regulation. Thus, it is proposed that these cannabinoids are synthetically produced through the integration of microfluidic technology, eliminating the presence of pesticides, microbes and heavy metals. The proposed method would even further speed up the rate of production at a lowered cost, produce greater yields of the product compared to extraction procedures / in batch reactions and improve the purity of cannabinoid compounds. This was achieved in flow chemistry whereby the key intermediates (olivetol, a derivative of methyl 6-n-pentyl-2-hydroxy-4-oxo-cyclohex 2-ene-l-carboxylate and cannabigerol) were produced at high conversions (67%, 100% and 34% respectively) in LTF glass microreactors. Cannabigerol was successfully synthesized in flow at high yields compared to literature, however, it was further discovered that the formation of side products was a hindrance to further improvement of the obtained yield in flow. , Thesis (MSc) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Koeberg, Bryce
- Date: 2022-04
- Subjects: Drug resistance in microorganisms , Cannabis -- Therapeutic use -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55866 , vital:54395
- Description: This study focuses on the development of a synthetic version of the cannabinoid cannabigerol (CBG) through continuous flow systems. The compound has exhibited antibiotic properties that have been proven to be a potent killer of gram-positive methicillin-resistant Staphylococcus aureus that drive repeat infections. The cannabinoid kills the superbug by disrupting the cell wall integrity of cells that are drug resistant. Research suggests that CBG is not effective against gram-negative multi-drug resistant bacteria. However, when CBG is administered with polymyxin B, an antibiotic that disrupts the outer membrane of gram-negative bacteria the cannabinoid compound wipes out the drug-resistant gram-negative bacteria, thus revealing the extensive medicinal potential of cannabigerol. Cannabinoids, such as CBG, are present in low yields in the plant, depending on the extraction method, usually less than 5% in most strains. Natural medicines have a low amount of active ingredients due to the lab intensive and time-consuming extraction and isolation process; this has hindered the application of natural products in drug development. A major health concern of the human consumption of cannabis plant extracted cannabinoids is that the plant may be contaminated with microbes, heavy metals and pesticides due to the lack of regulation. Thus, it is proposed that these cannabinoids are synthetically produced through the integration of microfluidic technology, eliminating the presence of pesticides, microbes and heavy metals. The proposed method would even further speed up the rate of production at a lowered cost, produce greater yields of the product compared to extraction procedures / in batch reactions and improve the purity of cannabinoid compounds. This was achieved in flow chemistry whereby the key intermediates (olivetol, a derivative of methyl 6-n-pentyl-2-hydroxy-4-oxo-cyclohex 2-ene-l-carboxylate and cannabigerol) were produced at high conversions (67%, 100% and 34% respectively) in LTF glass microreactors. Cannabigerol was successfully synthesized in flow at high yields compared to literature, however, it was further discovered that the formation of side products was a hindrance to further improvement of the obtained yield in flow. , Thesis (MSc) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Synthesis and characterization of iron doped sodium and potassium titanates using the pechini sol-gel method
- Authors: Guga, Aluwani
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53646 , vital:45683
- Description: Iron doped (Fe: 5Ti) sodium and potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the structure and morphology of the titanate nanomaterials. A quantitative XRD analysis using Rietveld refinement of the titanates confirmed the powders to consist of crystalline phases with the Na2Ti7O15 and K2Ti8O17 phases predominant for the sodium and potassium titanate, respectively. This was further confirmed using selected area electron diffraction (SAED) in the TEM. SEM and TEM analyses indicated that the titanates are consistent with a nanostructured material exhibiting rod-like morphology. The elemental compositions of the titanites were examined by SEM-EDS and TEM-EDS and found to agree well with the targeted Fe to Ti ratio from synthesis. Limited evidence for the segregation of iron in the titanate regions were found indicating the iron to be incorporated within the titanate lattice. Electron energy loss spectroscopy (EELS) fine-structure analysis of the Fe L2,3 core-loss edge was successfully used to match the Fe to a 2+ or 3+ valence state, consistent with its occupation at Ti lattice sites. Finally, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to study the vibrational modes of the functional group of the sodium and potassium titanates. Vibrational modes consistent with previously reported findings for the titanate phases identified were found with no evidence of isolated Fe related modes. , Thesis (MSc) -- Faculty of Science, Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Guga, Aluwani
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53646 , vital:45683
- Description: Iron doped (Fe: 5Ti) sodium and potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the structure and morphology of the titanate nanomaterials. A quantitative XRD analysis using Rietveld refinement of the titanates confirmed the powders to consist of crystalline phases with the Na2Ti7O15 and K2Ti8O17 phases predominant for the sodium and potassium titanate, respectively. This was further confirmed using selected area electron diffraction (SAED) in the TEM. SEM and TEM analyses indicated that the titanates are consistent with a nanostructured material exhibiting rod-like morphology. The elemental compositions of the titanites were examined by SEM-EDS and TEM-EDS and found to agree well with the targeted Fe to Ti ratio from synthesis. Limited evidence for the segregation of iron in the titanate regions were found indicating the iron to be incorporated within the titanate lattice. Electron energy loss spectroscopy (EELS) fine-structure analysis of the Fe L2,3 core-loss edge was successfully used to match the Fe to a 2+ or 3+ valence state, consistent with its occupation at Ti lattice sites. Finally, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to study the vibrational modes of the functional group of the sodium and potassium titanates. Vibrational modes consistent with previously reported findings for the titanate phases identified were found with no evidence of isolated Fe related modes. , Thesis (MSc) -- Faculty of Science, Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
Studies on seed germination and response to fertilization of Amaranthus accessions collected in the Eastern Cape Province, South Africa
- Ramangoele, Mpaballeng Alinah
- Authors: Ramangoele, Mpaballeng Alinah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54112 , vital:46307
- Description: Studies were conducted at Döhne Agricultural Development Institute (D.A.D.I.), geographically located between latitude 32°31'34.077"S and longitude 27°27'37.473"E in Stutterheim, Eastern Cape Province from summer 2018 until autumn 2019.The objectives were to determine seed germination and seedling vigour of four local Amaranthus accessions and to evaluate the effect of organic and inorganic fertilization on the growth, yield and nutrient composition. In the germination studies, herein referred to as Experiment 1,laboratory assessments were laid out in a Complete Randomized Design (CRD) replicated four times to test seed germination, seedling emergence and seedling vigour of four Amaranthus accessions namely: A. Hypochondriacus, A. Retroflexus 1, A. Hybridus and A. Retroflexus 2. Data collection included germination percentage, radicle length, co-efficient of velocity of germination and seedling vigour. A.Retroflexus2 gave the highest germination percentage in summer (85%) and autumn (87.75%).Seed weight resulted in the highest germination percentage and was observed to have shown a high positive correlation of {R2=0.91} in summer and{R2=0.92} in autumn respectively. The highest seedling vigour (p<0.001) in summer was attained from A. Hypochondriacus and A. Retroflexus2.In the greenhouse in summer, the highest emergence percentage was observed from A. Hypochondriacus(93.00%), whilst in autumn it was A.Retroflexus2 (88.38%).A. Retroflexus1 was the least performer in both seasons. In summer, A. Hypochondriacus and A. Retroflexus2 resulted in very high seedling vigour. In autumn A. Hypochondriacus, A. Retroflexus2 and A. Hybridus resulted in high seedling vigour and A. Retroflexus1 in moderate seedling vigour. The relationship observed between seed weight and seedling vigour showed a negative (inverse)correlation in summer {R2=0.58} and autumn {R2=0.62}.In Experiment 2, seedlings of A. Hypochondriacus and A. Retroflexus 2were transplanted in 5litrebasal perforated plastic pots which were filled with soil. The experimental layout was a CRD replicated four times. The treatments were: control (no amendment), goat manure, cattle manure and NPK fertilizer. Growth performance data were collected for plant height, the number of leaves and stem girth. In summer, when goat manure was applied both accessions resulted in the tallest plants (78.80cm) yet A. Retroflexus 2 and vA. Hypochondriacus gave the greatest stem girthand highest number of leaves respectively. In autumn, the tallest plants and highest number of leaves were observed from A. Retroflexus 2fertilized with NPK and the greatest stem girth was observed from A. Hypochondriacus fertilized with goat manure. The interaction of fertilization and accessions resulted in A. Retroflexus 2 fertilized with goat manure generating the greatest fresh shoot biomass (137.27g plant-1) and the least from the control. Both accessions fertilized with goat manure attained the greatest dry leaf biomass. Insummer, A.Retroflexus2 outperformed A. Hypochondriacus in calcium content despite the treatments. Unfertilized A. Retroflexus2 produced leaves with high potassium. Both unfertilized accessions showed the highest magnesium content. All A. Retroflexus2 treatments outperformed A. Hypochondriacus treatments on iron content except the control. The summer season was the best in terms of growth and yield of the tested accessions. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Ramangoele, Mpaballeng Alinah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54112 , vital:46307
- Description: Studies were conducted at Döhne Agricultural Development Institute (D.A.D.I.), geographically located between latitude 32°31'34.077"S and longitude 27°27'37.473"E in Stutterheim, Eastern Cape Province from summer 2018 until autumn 2019.The objectives were to determine seed germination and seedling vigour of four local Amaranthus accessions and to evaluate the effect of organic and inorganic fertilization on the growth, yield and nutrient composition. In the germination studies, herein referred to as Experiment 1,laboratory assessments were laid out in a Complete Randomized Design (CRD) replicated four times to test seed germination, seedling emergence and seedling vigour of four Amaranthus accessions namely: A. Hypochondriacus, A. Retroflexus 1, A. Hybridus and A. Retroflexus 2. Data collection included germination percentage, radicle length, co-efficient of velocity of germination and seedling vigour. A.Retroflexus2 gave the highest germination percentage in summer (85%) and autumn (87.75%).Seed weight resulted in the highest germination percentage and was observed to have shown a high positive correlation of {R2=0.91} in summer and{R2=0.92} in autumn respectively. The highest seedling vigour (p<0.001) in summer was attained from A. Hypochondriacus and A. Retroflexus2.In the greenhouse in summer, the highest emergence percentage was observed from A. Hypochondriacus(93.00%), whilst in autumn it was A.Retroflexus2 (88.38%).A. Retroflexus1 was the least performer in both seasons. In summer, A. Hypochondriacus and A. Retroflexus2 resulted in very high seedling vigour. In autumn A. Hypochondriacus, A. Retroflexus2 and A. Hybridus resulted in high seedling vigour and A. Retroflexus1 in moderate seedling vigour. The relationship observed between seed weight and seedling vigour showed a negative (inverse)correlation in summer {R2=0.58} and autumn {R2=0.62}.In Experiment 2, seedlings of A. Hypochondriacus and A. Retroflexus 2were transplanted in 5litrebasal perforated plastic pots which were filled with soil. The experimental layout was a CRD replicated four times. The treatments were: control (no amendment), goat manure, cattle manure and NPK fertilizer. Growth performance data were collected for plant height, the number of leaves and stem girth. In summer, when goat manure was applied both accessions resulted in the tallest plants (78.80cm) yet A. Retroflexus 2 and vA. Hypochondriacus gave the greatest stem girthand highest number of leaves respectively. In autumn, the tallest plants and highest number of leaves were observed from A. Retroflexus 2fertilized with NPK and the greatest stem girth was observed from A. Hypochondriacus fertilized with goat manure. The interaction of fertilization and accessions resulted in A. Retroflexus 2 fertilized with goat manure generating the greatest fresh shoot biomass (137.27g plant-1) and the least from the control. Both accessions fertilized with goat manure attained the greatest dry leaf biomass. Insummer, A.Retroflexus2 outperformed A. Hypochondriacus in calcium content despite the treatments. Unfertilized A. Retroflexus2 produced leaves with high potassium. Both unfertilized accessions showed the highest magnesium content. All A. Retroflexus2 treatments outperformed A. Hypochondriacus treatments on iron content except the control. The summer season was the best in terms of growth and yield of the tested accessions. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
Spatial modelling of accessibility to tuberculosis treatment: the case of Ngaka Modiri Molema District
- Authors: Ramotsongwa, Karabo Naome
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55435 , vital:52000
- Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Ramotsongwa, Karabo Naome
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55435 , vital:52000
- Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
South African plantation forest nursery pesticide -use: current status, pesticide identification for management, and screening of fungicides for pathogen control
- Authors: Opperman, Ilke
- Date: 2023-04
- Subjects: Forest insects –Control – South Africa , Pesticides -- Environmental aspects , Pest management
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61370 , vital:70618
- Description: Forest nurseries are exposed to many challenges during the production of plant material, with pests and pathogens two of the most important. Management of pests and diseases require the use of multiple methods, including cultural, biological, and chemical control strategies in an integrated nursery pest management plan (IPM). In most nurseries, where hygiene practices and biological controls do not prevent the presence of pests and pathogens, they are managed through the use of pesticides. Forestry companies are regulated by both Government and Forestry Certification bodies. These include South African legislation pertaining to pesticides regulated by the Registrar Act 36 of 1947, the Forest Stewardship Council (FSC) and the Programme for the Endorsement of Forest Certification (PEFC). A limited number of pesticides, with an even more limited range of active ingredients, and not targeting all known plantation forestry pests/pathogens, are currently registered for use against pests and pathogens in plantation forestry in South Africa. Many of these have been in use for more than a decade, posing a serious risk in terms of resistance build-up. There is a major need for the identification and testing of additional/alternative products (biological natural or synthetic) for use against the range of pests and pathogens that occur on the various plantation tree species and hybrid combinations that are raised in nurseries. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science & Management, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Opperman, Ilke
- Date: 2023-04
- Subjects: Forest insects –Control – South Africa , Pesticides -- Environmental aspects , Pest management
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61370 , vital:70618
- Description: Forest nurseries are exposed to many challenges during the production of plant material, with pests and pathogens two of the most important. Management of pests and diseases require the use of multiple methods, including cultural, biological, and chemical control strategies in an integrated nursery pest management plan (IPM). In most nurseries, where hygiene practices and biological controls do not prevent the presence of pests and pathogens, they are managed through the use of pesticides. Forestry companies are regulated by both Government and Forestry Certification bodies. These include South African legislation pertaining to pesticides regulated by the Registrar Act 36 of 1947, the Forest Stewardship Council (FSC) and the Programme for the Endorsement of Forest Certification (PEFC). A limited number of pesticides, with an even more limited range of active ingredients, and not targeting all known plantation forestry pests/pathogens, are currently registered for use against pests and pathogens in plantation forestry in South Africa. Many of these have been in use for more than a decade, posing a serious risk in terms of resistance build-up. There is a major need for the identification and testing of additional/alternative products (biological natural or synthetic) for use against the range of pests and pathogens that occur on the various plantation tree species and hybrid combinations that are raised in nurseries. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science & Management, 2023
- Full Text:
- Date Issued: 2023-04
Seasonal changes of metals in the salt marsh and seagrass beds of the Swartkops Estuary
- Authors: Nel, Marelé Annette
- Date: 2022-04
- Subjects: Salt marshes--Effect of heavy metals on--South Africa--Swartkops River Estuary , Estuarine ecology --South Africa --Swartkops River Estuary
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55734 , vital:53411
- Description: Estuaries are historically convenient places to build industries, as it was deemed a suitable place to dispose of large quantities of urban and industrial waste into the ocean. At the time it was judged to be appropriate, as rivers can transport and deposit waste into the ocean, which was considered so vast that it is insurmountable. Therefore, metal pollution in estuaries is a well-known occurrence. Coastal wetlands play an important role in the cycling of metals, and act as effective metal sinks. They provide an important ecosystem service acting as accumulators and phytostabilisers, which make toxic levels of the metals unavailable to the rest of the food chain. The overall aim of this study was to assess the metal pollution in the salt marsh (Salicornia tegetaria and Spartina maritima) and seagrass (Zostera capensis) of the heavily developed Swartkops Estuary. Assessing the metals in the estuary will provide information on effective environmental management strategies. Metal concentrations were measured in the rhizosediment of the three wetland plants, bare sediment, and in the tissues (leaves, shoots, and roots) of the selected plant species. Sampling occurred during one seasonal cycle (2019-2020), and in 5 sites along the middle and lower reaches of the estuary. Metal concentrations were not the highest closest to the point sources in the middle reaches, but the metals rather accumulated downstream in Site 3 (Tiger Bay launch site close to the WwTW) and Site 4 (Tippers’ Creek), which were depositional sites. Although these two sites generally displayed the highest metal concentrations, they also had the most seasonal fluctuations in their metal concentrations and sediment characteristics. Flushing events in spring/summer were likely the determining factor of these fluctuations. The mouth of the estuary (Site 5) consistently had much lower metal concentrations, with distinctly more sandy, low organic content sediment, due to marine-influenced flushing. Thus, spatial differences were distinct in the estuary, however seasonal differences did not play an important role in the metal concentrations, indicating that seasonal sampling was not as important as sampling in different sites. Assessing the metal concentrations in different rhizosediment gave important insights on intertidal accumulation and contrasted with the unvegetated (bare) sediment. The metals generally accumulated more, higher up the intertidal range, due to less frequent tidal inundation and flushing — so that metal accumulated in the vegetation in the following order: Z. capensis > S. maritima > S. tegetaria. Moreover, unvegetated (bare sediment) showed much lower metal concentrations compared to the rhizosediment, indicating that the vegetation trapped small particles, and changes the physical environment to concentrate metals in their rhizosphere. Lastly, the plant species all displayed good accumulation of metals in their roots, while Z. capensis also showed remarkable uptake to its leaves. The study identified S. maritima and S. tegetaria as good phytostabilisers, particularly the latter with its vi high metal stocks and slow root turnover rate. The compartmentalization in these plants were unique to each species, corroborating previous assessments that compartmentalization cannot be compared between similar life forms and genera. These results contribute to local and international research on biogeochemistry in wetlands, and assessment of pollution in developed estuaries. Of note is Z. capensis, an endemic Southern African species, which has not been analysed for compartmentalization of metals before. All three of the studied species have potential as metal accumulators, and therefore a sink of metals. They localize the metals, limiting bioaccumulation to the rest of the food chain, which reduces the ecotoxic effect of metals in the environment. Higher accumulation in vegetated (rhizosediment) over bare sediment, make these habitats valuable metal sinks. This increases their importance in estuaries receiving high pollution loads, and they should be prioritized in conservation efforts. Two sites within the Swartkops Estuary, Tippers’ Creek (Site 4) and the Launch Site (Site 3), are potential sites for long-term monitoring due their capacity to trap and accumulate metals. The results of this study will inform local management on the state of metals in the Swartkops Estuary, providing crucial information on the importance of preserving local wetlands for the purpose of regulating toxic levels of metals in the ecosystem. , Thesis (MSc) -- Faculty of Science, Botany, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Nel, Marelé Annette
- Date: 2022-04
- Subjects: Salt marshes--Effect of heavy metals on--South Africa--Swartkops River Estuary , Estuarine ecology --South Africa --Swartkops River Estuary
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55734 , vital:53411
- Description: Estuaries are historically convenient places to build industries, as it was deemed a suitable place to dispose of large quantities of urban and industrial waste into the ocean. At the time it was judged to be appropriate, as rivers can transport and deposit waste into the ocean, which was considered so vast that it is insurmountable. Therefore, metal pollution in estuaries is a well-known occurrence. Coastal wetlands play an important role in the cycling of metals, and act as effective metal sinks. They provide an important ecosystem service acting as accumulators and phytostabilisers, which make toxic levels of the metals unavailable to the rest of the food chain. The overall aim of this study was to assess the metal pollution in the salt marsh (Salicornia tegetaria and Spartina maritima) and seagrass (Zostera capensis) of the heavily developed Swartkops Estuary. Assessing the metals in the estuary will provide information on effective environmental management strategies. Metal concentrations were measured in the rhizosediment of the three wetland plants, bare sediment, and in the tissues (leaves, shoots, and roots) of the selected plant species. Sampling occurred during one seasonal cycle (2019-2020), and in 5 sites along the middle and lower reaches of the estuary. Metal concentrations were not the highest closest to the point sources in the middle reaches, but the metals rather accumulated downstream in Site 3 (Tiger Bay launch site close to the WwTW) and Site 4 (Tippers’ Creek), which were depositional sites. Although these two sites generally displayed the highest metal concentrations, they also had the most seasonal fluctuations in their metal concentrations and sediment characteristics. Flushing events in spring/summer were likely the determining factor of these fluctuations. The mouth of the estuary (Site 5) consistently had much lower metal concentrations, with distinctly more sandy, low organic content sediment, due to marine-influenced flushing. Thus, spatial differences were distinct in the estuary, however seasonal differences did not play an important role in the metal concentrations, indicating that seasonal sampling was not as important as sampling in different sites. Assessing the metal concentrations in different rhizosediment gave important insights on intertidal accumulation and contrasted with the unvegetated (bare) sediment. The metals generally accumulated more, higher up the intertidal range, due to less frequent tidal inundation and flushing — so that metal accumulated in the vegetation in the following order: Z. capensis > S. maritima > S. tegetaria. Moreover, unvegetated (bare sediment) showed much lower metal concentrations compared to the rhizosediment, indicating that the vegetation trapped small particles, and changes the physical environment to concentrate metals in their rhizosphere. Lastly, the plant species all displayed good accumulation of metals in their roots, while Z. capensis also showed remarkable uptake to its leaves. The study identified S. maritima and S. tegetaria as good phytostabilisers, particularly the latter with its vi high metal stocks and slow root turnover rate. The compartmentalization in these plants were unique to each species, corroborating previous assessments that compartmentalization cannot be compared between similar life forms and genera. These results contribute to local and international research on biogeochemistry in wetlands, and assessment of pollution in developed estuaries. Of note is Z. capensis, an endemic Southern African species, which has not been analysed for compartmentalization of metals before. All three of the studied species have potential as metal accumulators, and therefore a sink of metals. They localize the metals, limiting bioaccumulation to the rest of the food chain, which reduces the ecotoxic effect of metals in the environment. Higher accumulation in vegetated (rhizosediment) over bare sediment, make these habitats valuable metal sinks. This increases their importance in estuaries receiving high pollution loads, and they should be prioritized in conservation efforts. Two sites within the Swartkops Estuary, Tippers’ Creek (Site 4) and the Launch Site (Site 3), are potential sites for long-term monitoring due their capacity to trap and accumulate metals. The results of this study will inform local management on the state of metals in the Swartkops Estuary, providing crucial information on the importance of preserving local wetlands for the purpose of regulating toxic levels of metals in the ecosystem. , Thesis (MSc) -- Faculty of Science, Botany, 2022
- Full Text:
- Date Issued: 2022-04
Rheology behaviour of slurries as a function of particle size and ion concentration
- Authors: Kondlo, Princess Kholiwe
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53333 , vital:45141
- Description: In this work, the rheological properties of alumina slurries milled to different particle sizes were investigated. Viscosity increases as the particle size decreases. When increasing amounts of calcium hydroxide, strontium hydroxide or barium hydroxide are added, the viscosity first goes down and then goes up. This can be explained in terms of changes in pH and changes in ionic strength impacting on the surface potential of the particles in suspension. Adding the same concentration of different cations results in different viscosities, with the order being (from high to low viscosity) Ba>Sr>Ca. Effects of partial dissolution of and structural changes to the alumina particles at high pH cannot be excluded. In order to better understanding the different effects, it was attempted to measure the zeta potential of the slurries at different pH values. This resulted in highly positive zeta potential values over the complete pH range, without the observationof an iso-electric point. This does not fit to the observed changes in rheology and contrasts withliterature data. One explanation would be that the measurement system used is unsuitable to yield correct zeta potential values for the materials under investigation. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Kondlo, Princess Kholiwe
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53333 , vital:45141
- Description: In this work, the rheological properties of alumina slurries milled to different particle sizes were investigated. Viscosity increases as the particle size decreases. When increasing amounts of calcium hydroxide, strontium hydroxide or barium hydroxide are added, the viscosity first goes down and then goes up. This can be explained in terms of changes in pH and changes in ionic strength impacting on the surface potential of the particles in suspension. Adding the same concentration of different cations results in different viscosities, with the order being (from high to low viscosity) Ba>Sr>Ca. Effects of partial dissolution of and structural changes to the alumina particles at high pH cannot be excluded. In order to better understanding the different effects, it was attempted to measure the zeta potential of the slurries at different pH values. This resulted in highly positive zeta potential values over the complete pH range, without the observationof an iso-electric point. This does not fit to the observed changes in rheology and contrasts withliterature data. One explanation would be that the measurement system used is unsuitable to yield correct zeta potential values for the materials under investigation. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
Refining predator-prey preference at the prey demographic level for cheetah and lion
- Authors: Annear, Eleesha
- Date: 2022-04
- Subjects: Social behavior in animals --South Africa , Predatory animals –Behavior
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55800 , vital:53880
- Description: Traditional prey preference models estimate prey preference using a coarse species-specific body mass of three-quarters of the mean adult female body mass. This is widely assumed to estimate the average mass across prey populations, accounting for neonates, juveniles, sub-adults, and adults. However, this approach negates the models’ ability to predict demography-specific prey preferences, thus reducing our ability to predict the impacts of predation on prey populations. The objectives of this study were to 1) refine the prey selection models, using lion Panthera leo and cheetah Acinonyx jubatus as model species, by incorporating prey demographic classes and season and, 2) determine the influence of seasonal variability in availability of these prey demographic classes on cheetah reproduction. Lions preferentially killed adults of larger species (e.g., wildebeest, waterbuck, and zebra) irrespective of the season, as predicted by optimal foraging theory. Sub-adult, juvenile, and neonate prey were killed by lions relative to their abundance. Cheetahs preferred juvenile prey of large species, namely kudu, zebra, and wildebeest. Season influenced cheetah preference with neonates and juveniles being preferred during the wet season and adults of smaller species, and juveniles of larger species being preferred during the dry season. Thus, results support the alternative demographic class hypothesis. Furthermore, the availability of neonate and juvenile prey drives cheetah reproduction patterns with conception and cub independence coinciding with the peak availability of easy-to-catch neonates. Lactation coincided with the high availability of relatively larger juveniles to ensure that females obtain enough resources to sustain the most energetically costly reproductive phase. In addition, I suggest cheetah may be particularly vulnerable to disturbances that impact on prey reproduction (e.g., drought, fire, and flood), given their reliance on neonate and juvenile prey. My findings highlight that estimating species-level prey preference using a coarse species-specific body mass masks the level of prey use and potential preferences for the different prey demographic classes. The use of some prey species may be largely confined to juveniles by smaller predators, meaning that prey availability would vary seasonally, may influence reproductive patterns, and carrying capacity models would need to be revised in terms of the available demographic-specific prey biomass. , Thesis (MSc) -- Faculty of Sciences, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Annear, Eleesha
- Date: 2022-04
- Subjects: Social behavior in animals --South Africa , Predatory animals –Behavior
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55800 , vital:53880
- Description: Traditional prey preference models estimate prey preference using a coarse species-specific body mass of three-quarters of the mean adult female body mass. This is widely assumed to estimate the average mass across prey populations, accounting for neonates, juveniles, sub-adults, and adults. However, this approach negates the models’ ability to predict demography-specific prey preferences, thus reducing our ability to predict the impacts of predation on prey populations. The objectives of this study were to 1) refine the prey selection models, using lion Panthera leo and cheetah Acinonyx jubatus as model species, by incorporating prey demographic classes and season and, 2) determine the influence of seasonal variability in availability of these prey demographic classes on cheetah reproduction. Lions preferentially killed adults of larger species (e.g., wildebeest, waterbuck, and zebra) irrespective of the season, as predicted by optimal foraging theory. Sub-adult, juvenile, and neonate prey were killed by lions relative to their abundance. Cheetahs preferred juvenile prey of large species, namely kudu, zebra, and wildebeest. Season influenced cheetah preference with neonates and juveniles being preferred during the wet season and adults of smaller species, and juveniles of larger species being preferred during the dry season. Thus, results support the alternative demographic class hypothesis. Furthermore, the availability of neonate and juvenile prey drives cheetah reproduction patterns with conception and cub independence coinciding with the peak availability of easy-to-catch neonates. Lactation coincided with the high availability of relatively larger juveniles to ensure that females obtain enough resources to sustain the most energetically costly reproductive phase. In addition, I suggest cheetah may be particularly vulnerable to disturbances that impact on prey reproduction (e.g., drought, fire, and flood), given their reliance on neonate and juvenile prey. My findings highlight that estimating species-level prey preference using a coarse species-specific body mass masks the level of prey use and potential preferences for the different prey demographic classes. The use of some prey species may be largely confined to juveniles by smaller predators, meaning that prey availability would vary seasonally, may influence reproductive patterns, and carrying capacity models would need to be revised in terms of the available demographic-specific prey biomass. , Thesis (MSc) -- Faculty of Sciences, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Recreating a wetland at an abandoned saltworks : towards a rehabilitation plan
- Authors: Wasserman, Johan
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52146 , vital:43450
- Description: A saltworks at Swartkops Estuary was abandoned in 2018. While operational, the saltworks hosted some of the largest breeding colonies of several shorebird species in southern Africa and hosted thousands of Palearctic migrant waterbirds annually. The abandonment of the saltworks has resulted in the loss of the artificially managed hydrological regime and therefore the wetland function and habitat value of the site, and the rich and diverse avifauna that once occurred at the site have not returned. The rehabilitation of the saltworks as a wetland that functions as a waterbird sanctuary is currently being organised, and this research aimed to create a plan for implementing and monitoring the rehabilitation. In order to do so, the baseline environmental condition of the abandoned saltworks was established, the possible rehabilitation interventions necessary for rehabilitating the site were assessed, and the potential ecological implications of any interventions were investigated. The assessment of the saltworks’ baseline condition revealed that the site is now characterised by vast expanses of dry hypersaline sediment with sparse patches of monospecific vegetation and depauperate avifauna. The once rich and diverse waterbird communities have all but disappeared since the site was abandoned and are unlikely to return unless a managed hydrological regime is reinstated. Furthermore, it is improbable that salt marsh vegetation will cover the abandoned saltworks primarily due to the high sediment salinity that will persist unless the saltpans are flooded. The area will likely remain barren with little ecological value if no rehabilitation action is taken. Two potential rehabilitation options for reinstating a hydrological regime at the saltworks were identified: (1) pumping estuary water into all of the saltpans; or (2) pumping estuary water into some of the saltpans, while allowing the largest one to be filled with stormwater. Both options were deemed to be feasible; however, the second option will likely have lower running costs. The use of stormwater to fill the one saltpan is expected to result in brackish conditions initially, while the saltpans filled with estuary water would have salinity levels ranging from euhaline to slightly hypersaline. Both the stormwater and estuary water are rich in inorganic nutrients – the estuary water is rich in both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), while the stormwater has an exceptionally high DIN content. This raised concerns of creating eutrophic wetlands with detrimental conditions such as algal blooms and a hypoxic water column. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Wasserman, Johan
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52146 , vital:43450
- Description: A saltworks at Swartkops Estuary was abandoned in 2018. While operational, the saltworks hosted some of the largest breeding colonies of several shorebird species in southern Africa and hosted thousands of Palearctic migrant waterbirds annually. The abandonment of the saltworks has resulted in the loss of the artificially managed hydrological regime and therefore the wetland function and habitat value of the site, and the rich and diverse avifauna that once occurred at the site have not returned. The rehabilitation of the saltworks as a wetland that functions as a waterbird sanctuary is currently being organised, and this research aimed to create a plan for implementing and monitoring the rehabilitation. In order to do so, the baseline environmental condition of the abandoned saltworks was established, the possible rehabilitation interventions necessary for rehabilitating the site were assessed, and the potential ecological implications of any interventions were investigated. The assessment of the saltworks’ baseline condition revealed that the site is now characterised by vast expanses of dry hypersaline sediment with sparse patches of monospecific vegetation and depauperate avifauna. The once rich and diverse waterbird communities have all but disappeared since the site was abandoned and are unlikely to return unless a managed hydrological regime is reinstated. Furthermore, it is improbable that salt marsh vegetation will cover the abandoned saltworks primarily due to the high sediment salinity that will persist unless the saltpans are flooded. The area will likely remain barren with little ecological value if no rehabilitation action is taken. Two potential rehabilitation options for reinstating a hydrological regime at the saltworks were identified: (1) pumping estuary water into all of the saltpans; or (2) pumping estuary water into some of the saltpans, while allowing the largest one to be filled with stormwater. Both options were deemed to be feasible; however, the second option will likely have lower running costs. The use of stormwater to fill the one saltpan is expected to result in brackish conditions initially, while the saltpans filled with estuary water would have salinity levels ranging from euhaline to slightly hypersaline. Both the stormwater and estuary water are rich in inorganic nutrients – the estuary water is rich in both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), while the stormwater has an exceptionally high DIN content. This raised concerns of creating eutrophic wetlands with detrimental conditions such as algal blooms and a hypoxic water column. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Real-time feedback model for supporting individualised learning of programming students
- Authors: Keen, Charne
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53624 , vital:45691
- Description: Feedback is crucial to the enhancement of the learning and teaching environment, especially in those environments that suffer from a number of extrinsic challenges. The growing demands for educators to provide academic interventions throughout the lecture session and the need for continuous improvement of the quality of university education make it necessary to find and apply more effective and efficient educational technologies and practices based on the correlation of teaching with a student’s conceptual understanding and individual learning preference. Following a combination of Design Science Research (DSR) and Case Study Methodology, this research addresses this problem by designing a technology based real-time feedback (TBRTF) model that can easily be implemented in a South African University. The model designed followed a layered architecture pattern. The architecture describes the data, technology and user support layers of the model. The data support layer incorporates the collection of student academic data and learning preferences. The technology incorporates a machine learning component. The machine learning component covers two technological aspects: the prediction component and the clustering component. This TBRTF model provides the guidelines needed to develop a system that supports individualised real-time feedback in the learning and teaching environment of programming students. The aim of the model is that as the students partake in learning activities where the student data is updated, the monitoring component will fire, updating the probability of failure prediction and in turn the student clusters are regenerated. This will notify the educator of a change and provide decision making support. The student will be allocated individualised feedback in the form of learning materials based on the cluster that the student is allocated to. Through a demonstration and evaluation, this study showed that by following the proposed architecture of the TBRTF model, a model that supports individualised realtime feedback in the learning and teaching environment of programming students can be developed. The validation used an artificial neural network as the prediction component and a k-means clustering algorithm as the clustering component. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Keen, Charne
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53624 , vital:45691
- Description: Feedback is crucial to the enhancement of the learning and teaching environment, especially in those environments that suffer from a number of extrinsic challenges. The growing demands for educators to provide academic interventions throughout the lecture session and the need for continuous improvement of the quality of university education make it necessary to find and apply more effective and efficient educational technologies and practices based on the correlation of teaching with a student’s conceptual understanding and individual learning preference. Following a combination of Design Science Research (DSR) and Case Study Methodology, this research addresses this problem by designing a technology based real-time feedback (TBRTF) model that can easily be implemented in a South African University. The model designed followed a layered architecture pattern. The architecture describes the data, technology and user support layers of the model. The data support layer incorporates the collection of student academic data and learning preferences. The technology incorporates a machine learning component. The machine learning component covers two technological aspects: the prediction component and the clustering component. This TBRTF model provides the guidelines needed to develop a system that supports individualised real-time feedback in the learning and teaching environment of programming students. The aim of the model is that as the students partake in learning activities where the student data is updated, the monitoring component will fire, updating the probability of failure prediction and in turn the student clusters are regenerated. This will notify the educator of a change and provide decision making support. The student will be allocated individualised feedback in the form of learning materials based on the cluster that the student is allocated to. Through a demonstration and evaluation, this study showed that by following the proposed architecture of the TBRTF model, a model that supports individualised realtime feedback in the learning and teaching environment of programming students can be developed. The validation used an artificial neural network as the prediction component and a k-means clustering algorithm as the clustering component. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
Quantifying variability of emissions of greenhouse gas (CO2& CH4) across selected soils and agricultural practices
- Authors: Sebake, Tebogo Matsimela
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54107 , vital:46302
- Description: Increasing concentrations of greenhouse gases (GHG’s)in the atmosphere are warming the planet, and agriculture is responsible for about 30% of these emissions. Soils act as a host for greenhouse gases, since both their storage and emission capacities are large, accounting for two-times the amount of carbon in the atmosphere and in plant and animal life. It sequesters large amounts of carbon, and because agricultural practices depend on soil for production, the practices influence the soil’s ability to store the carbon effectively. Production soils emit greenhouse gas, predominantly carbon dioxide and methane, which are assessed for emissions in this study. Climate change creates unpredictability in precipitation and temperature; farmers need to be flexible and adapt production methods to such environmental changes in order to continue producing sustainably. Global food production needs to grow drastically to meet the projected demands for rising population and diet shifts; studies have shown that feeding a more populated and a more affluent, equal, world will require roughly a doubling of agricultural production by 2050, which means more GHG emissions from the soil. To enable better control on these emissions, their links to agricultural practices need to be better quantified. The study was done in two areas: (1) long-term comparative farming systems research trial with controlled vegetable plots, in the agricultural school of Nelson Mandela University, in George, Western Cape province and (2) long-term wheat research trial of the Free State University, in Bethlehem, Free State province. The objective in study area one is to assess and compare GHG emissions from conventional and organic systems. Temperature and soil moisture were measured during gas samples to establish the influence they have on gas emissions. The objective in study area two is to assess and compare GHG emissions from no-till, plough, and stubble mulch. Stubble mulch refers to crop residue left in place on the land as a surface cover during fallow periods. Two polypropylene canisters are placed in a sampled plot to trap gas emitted from the soil. Analyses of the trapped gases in the headspace gives concentrations of CO2and CH4that was emitted during the duration the canister was closed. The gas is analysed by a G2201-i Picarro gas analyser, presently the only such instrument in South Africa. The analyser’s near-infrared Cavity Ring Down Spectroscopy technology is capable of simultaneous measurements of CO2and CH4down to parts per million. In study area one, conventional plots (R2T6 & R1T6) emitted 65.089ppm CO2and 61.159ppm CO2, and 0.0010ppm CH4and 0.0004ppm CH4, respectively. Organic plots (R1T3 & R2T3) emitted 53.264ppm CO2and 47.885ppm CO2, and 0.0023ppm CH4and 0.0019ppm CH4respectively. Thus, conventional plots emitted 19.98% & 30.98% more CO2than organic plots; but organic plots emitted 81.97% & 155.5% more CH4thanconventional plots. In study area two, ploughed soils emitted 38.727ppm CO2and 0.015ppm CH4, no-tilled soils emitted 31.798ppm CO2 and 0.011ppm CH4andstubble mulched soils emitted 28.373ppm CO2 and 0.009ppm CH4. Thus, ploughed soils emitted 19.65%more CO2than no-tilled soils, no-tilled soils emitted 11.38% more CO2 than stubble mulched soils and ploughed soils emitted 30.36% more CO2 than stubble mulched soils. Ploughed soils emitted 30.77% more CH4 than no-tilled soils, no-tilled soils emitted 20% more CH4 than stubble mulched soils and ploughed soils emitted 50% more CH4than stubble mulched soils. Moist soils result in decreased CO2emissions in conventional plots and increased CH4emissions in organic plots. Increasing temperature patterns are followed by a trend of increasing gas emissions. Reducing GHG emissions from agriculture and developing sustainable tillage practices can help mitigate climate change and increases the chances of stabilizing GHG concentrations and temperature control within a required range. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Sebake, Tebogo Matsimela
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54107 , vital:46302
- Description: Increasing concentrations of greenhouse gases (GHG’s)in the atmosphere are warming the planet, and agriculture is responsible for about 30% of these emissions. Soils act as a host for greenhouse gases, since both their storage and emission capacities are large, accounting for two-times the amount of carbon in the atmosphere and in plant and animal life. It sequesters large amounts of carbon, and because agricultural practices depend on soil for production, the practices influence the soil’s ability to store the carbon effectively. Production soils emit greenhouse gas, predominantly carbon dioxide and methane, which are assessed for emissions in this study. Climate change creates unpredictability in precipitation and temperature; farmers need to be flexible and adapt production methods to such environmental changes in order to continue producing sustainably. Global food production needs to grow drastically to meet the projected demands for rising population and diet shifts; studies have shown that feeding a more populated and a more affluent, equal, world will require roughly a doubling of agricultural production by 2050, which means more GHG emissions from the soil. To enable better control on these emissions, their links to agricultural practices need to be better quantified. The study was done in two areas: (1) long-term comparative farming systems research trial with controlled vegetable plots, in the agricultural school of Nelson Mandela University, in George, Western Cape province and (2) long-term wheat research trial of the Free State University, in Bethlehem, Free State province. The objective in study area one is to assess and compare GHG emissions from conventional and organic systems. Temperature and soil moisture were measured during gas samples to establish the influence they have on gas emissions. The objective in study area two is to assess and compare GHG emissions from no-till, plough, and stubble mulch. Stubble mulch refers to crop residue left in place on the land as a surface cover during fallow periods. Two polypropylene canisters are placed in a sampled plot to trap gas emitted from the soil. Analyses of the trapped gases in the headspace gives concentrations of CO2and CH4that was emitted during the duration the canister was closed. The gas is analysed by a G2201-i Picarro gas analyser, presently the only such instrument in South Africa. The analyser’s near-infrared Cavity Ring Down Spectroscopy technology is capable of simultaneous measurements of CO2and CH4down to parts per million. In study area one, conventional plots (R2T6 & R1T6) emitted 65.089ppm CO2and 61.159ppm CO2, and 0.0010ppm CH4and 0.0004ppm CH4, respectively. Organic plots (R1T3 & R2T3) emitted 53.264ppm CO2and 47.885ppm CO2, and 0.0023ppm CH4and 0.0019ppm CH4respectively. Thus, conventional plots emitted 19.98% & 30.98% more CO2than organic plots; but organic plots emitted 81.97% & 155.5% more CH4thanconventional plots. In study area two, ploughed soils emitted 38.727ppm CO2and 0.015ppm CH4, no-tilled soils emitted 31.798ppm CO2 and 0.011ppm CH4andstubble mulched soils emitted 28.373ppm CO2 and 0.009ppm CH4. Thus, ploughed soils emitted 19.65%more CO2than no-tilled soils, no-tilled soils emitted 11.38% more CO2 than stubble mulched soils and ploughed soils emitted 30.36% more CO2 than stubble mulched soils. Ploughed soils emitted 30.77% more CH4 than no-tilled soils, no-tilled soils emitted 20% more CH4 than stubble mulched soils and ploughed soils emitted 50% more CH4than stubble mulched soils. Moist soils result in decreased CO2emissions in conventional plots and increased CH4emissions in organic plots. Increasing temperature patterns are followed by a trend of increasing gas emissions. Reducing GHG emissions from agriculture and developing sustainable tillage practices can help mitigate climate change and increases the chances of stabilizing GHG concentrations and temperature control within a required range. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-12
Potential suppressive effects of alien Acacia melanoxylon on Afrotemperate Forest tree recruitment
- Miles, Bayleigh, Baard, Johan
- Authors: Miles, Bayleigh , Baard, Johan
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55391 , vital:51989
- Description: Acacia melanoxylon R.Br. is a prominent alien and invasive species in many parts of the world and evidence exists of its adverse effects on indigenous forest community composition through allelopathy and alteration of light regimes. The species also occurs extensively in Southern Cape Afrotemperate Forest (South Africa) and is thought to suppress indigenous Afrotemperate Forest tree seedlings through various mechanisms such as the alteration of natural light regimes or allelopathy, although this has not been rigorously verified. This study aimed to investigate whether Acacia melanoxylon has a suppressive effect on Afrotemperate Forest tree recruitment. Firstly, we assessed the potential allelopathic effect of Acacia melanoxylon and an indigenous Afrotemperate Forest species Olea capensis macrocarpa (C.H.Wright) I.Verd. on the germination of Acacia melanoxylon and three prominent indigenous tree species’ seedlings in a nursery trial. Germination of the indigenous species failed; however, we were able to compare the germination of Acacia melanoxylon among the three treatments, namely Acacia melanoxylon leachate, Olea capensis leachate, and no leachate. The average germination of Acacia melanoxylon was 67% and germination was marginally higher under Acacia melanoxylon leachate and Olea capensis leachate, respectively, than under the control. This suggested that germination of the species is improved, or at the least, unaffected, by leachates of itself or that of a common indigenous canopy species. We then critically evaluated the germination requirements of the indigenous test species to determine probable reasons why their germination failed in our trial. The most plausible explanation for the germination failure could be that the trial period did not encompass an entire winter season and may not have provided adequate cold stratification. We concluded that the lack of sensitivity of Acacia melanoxylon to leachates of itself or a common indigenous overstorey species likely contribute to its success as an invasive species in Southern Cape Afrotemperate Forest. Secondly, we investigated, through field surveys, whether Acacia melanoxylon affects indigenous Afrotemperate Forest tree sapling composition and light regimes underneath its canopy. Using a paired plot design, we compared light intensity, tree sapling species richness, diversity, and density underneath 30 overstorey Acacia melanoxylon trees and 30 indigenous counterparts. We recorded 2506 indigenous tree saplings from 29 species in the 60 plots and found that there were no significant differences in richness, diversity, or v density of saplings underneath Acacia melanoxylon compared to that under indigenous counterparts. Light intensity did not differ significantly underneath Acacia melanoxylon and indigenous canopies, however light intensity varied significantly more underneath the canopies of Acacia melanoxylon. Canonical correspondence analysis of the abundance of sapling species confirmed that sapling composition was not largely determined by the overstorey species. We concluded that Acacia melanoxylon does not significantly alter indigenous tree species composition underneath its canopy at the typical densities (<3 trees per hectare) at which it occurred in the forests of the Garden Route National Park that we surveyed. Nevertheless, populations of Acacia melanoxylon in the forest interior still act as a source of propagules for invasion in forest margins, riparian areas, and neighbouring fynbos shrubland. These invasive attributes need to be considered in the management of the species in the region at large. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Miles, Bayleigh , Baard, Johan
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55391 , vital:51989
- Description: Acacia melanoxylon R.Br. is a prominent alien and invasive species in many parts of the world and evidence exists of its adverse effects on indigenous forest community composition through allelopathy and alteration of light regimes. The species also occurs extensively in Southern Cape Afrotemperate Forest (South Africa) and is thought to suppress indigenous Afrotemperate Forest tree seedlings through various mechanisms such as the alteration of natural light regimes or allelopathy, although this has not been rigorously verified. This study aimed to investigate whether Acacia melanoxylon has a suppressive effect on Afrotemperate Forest tree recruitment. Firstly, we assessed the potential allelopathic effect of Acacia melanoxylon and an indigenous Afrotemperate Forest species Olea capensis macrocarpa (C.H.Wright) I.Verd. on the germination of Acacia melanoxylon and three prominent indigenous tree species’ seedlings in a nursery trial. Germination of the indigenous species failed; however, we were able to compare the germination of Acacia melanoxylon among the three treatments, namely Acacia melanoxylon leachate, Olea capensis leachate, and no leachate. The average germination of Acacia melanoxylon was 67% and germination was marginally higher under Acacia melanoxylon leachate and Olea capensis leachate, respectively, than under the control. This suggested that germination of the species is improved, or at the least, unaffected, by leachates of itself or that of a common indigenous canopy species. We then critically evaluated the germination requirements of the indigenous test species to determine probable reasons why their germination failed in our trial. The most plausible explanation for the germination failure could be that the trial period did not encompass an entire winter season and may not have provided adequate cold stratification. We concluded that the lack of sensitivity of Acacia melanoxylon to leachates of itself or a common indigenous overstorey species likely contribute to its success as an invasive species in Southern Cape Afrotemperate Forest. Secondly, we investigated, through field surveys, whether Acacia melanoxylon affects indigenous Afrotemperate Forest tree sapling composition and light regimes underneath its canopy. Using a paired plot design, we compared light intensity, tree sapling species richness, diversity, and density underneath 30 overstorey Acacia melanoxylon trees and 30 indigenous counterparts. We recorded 2506 indigenous tree saplings from 29 species in the 60 plots and found that there were no significant differences in richness, diversity, or v density of saplings underneath Acacia melanoxylon compared to that under indigenous counterparts. Light intensity did not differ significantly underneath Acacia melanoxylon and indigenous canopies, however light intensity varied significantly more underneath the canopies of Acacia melanoxylon. Canonical correspondence analysis of the abundance of sapling species confirmed that sapling composition was not largely determined by the overstorey species. We concluded that Acacia melanoxylon does not significantly alter indigenous tree species composition underneath its canopy at the typical densities (<3 trees per hectare) at which it occurred in the forests of the Garden Route National Park that we surveyed. Nevertheless, populations of Acacia melanoxylon in the forest interior still act as a source of propagules for invasion in forest margins, riparian areas, and neighbouring fynbos shrubland. These invasive attributes need to be considered in the management of the species in the region at large. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2022
- Full Text:
- Date Issued: 2022-04
Plastic particle characterization and concentrations found in the river and marine water environment of Algoa Bay, South Africa
- Authors: Moss, Kerry-Leigh
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53874 , vital:46025
- Description: Only 12% of the world's published plastic research includes references to Africa despite it being a significant contributor to the global plastic waste and mismanagement problem (~88.5% of Africa's plastic waste is mismanaged). Ocean plastics are transported from land by rivers to the sea. However, source contextualization is complex. Many African rivers predominantly run alongside human settlements that host informal waste dumpsites. In this study a simple cost effective, easily deployed, consistent and replicable survey methodology was employed. The study quantified macro plastic in three rivers discharging into Algoa Bay, South Africa. The results indicated that industrial Swartkops and metropolitan Baakens Rivers both illustrate moderate plastic pollution (>3000 plastic particles/day), with the relatively natural Sundays River to showing minimal evidence of river macroplastic (<100 plastic particles/day). The types of plastic were noted using the RIMMEL app (premier African implementation), enabling proportional comparison of different plastic litter types to be completed. , Thesis (MSc) -- Faculty of Science, Oceanography Department,2021
- Full Text:
- Date Issued: 2021-12
- Authors: Moss, Kerry-Leigh
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53874 , vital:46025
- Description: Only 12% of the world's published plastic research includes references to Africa despite it being a significant contributor to the global plastic waste and mismanagement problem (~88.5% of Africa's plastic waste is mismanaged). Ocean plastics are transported from land by rivers to the sea. However, source contextualization is complex. Many African rivers predominantly run alongside human settlements that host informal waste dumpsites. In this study a simple cost effective, easily deployed, consistent and replicable survey methodology was employed. The study quantified macro plastic in three rivers discharging into Algoa Bay, South Africa. The results indicated that industrial Swartkops and metropolitan Baakens Rivers both illustrate moderate plastic pollution (>3000 plastic particles/day), with the relatively natural Sundays River to showing minimal evidence of river macroplastic (<100 plastic particles/day). The types of plastic were noted using the RIMMEL app (premier African implementation), enabling proportional comparison of different plastic litter types to be completed. , Thesis (MSc) -- Faculty of Science, Oceanography Department,2021
- Full Text:
- Date Issued: 2021-12
Plastic particle characterization and concentrations found in the river and marine water environment of Algoa Bay, South Africa
- Authors: Moss, Kerry-Leigh
- Date: 2021-12
- Subjects: Marine pollution , Plastic marine debris --Environmental aspects , Algoa Bay -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55645 , vital:53403
- Description: With just 4% of published plastic pollution research, the African region remains one of the most poorly 221 understood areas, leaving a large knowledge gap in our understanding of this global pollution problem 222 (Hurley, Woodward, & Rothwell, 2018). It is estimated that 64 to 90% of the ocean’s plastics originate 223 from fluxes in the terrestrial environment, however determining the exact source is not a simple task 224 (Andrady, 2011; Hurley et al., 2018). Plastic items, including the biodegradable plastic items, 225 breakdown in the marine environment through mechanical action resulting in non-degradable 226 microscopic fragments of synthetic polymers (Thompson et al., 2004). However, the consequences of 227 these microplastic fragments.This research intends to address two aims; first, to provide an estimation of the quantity of plastic 235 transportation via African rivers to the greater body of knowledge of global plastic emissions. This aim 236 will specifically focus on determining plastic output via Port Elizabeth rivers into the Algoa Bay marine 237 environment. The second aim of this research is to quantify and characterize the amount of microplastic 238 in the marine environment of Algoa Bay. The second aim will focus on identifying microplastic (MP) 239 throughout the water column. 240 This research consists of six objectives; first, to identify, design and field test a cost-effective system for 241 monitoring macroplastic quantity output from riverine to marine environments. Second, to contribute to 242 the body of knowledge of African river plastic pollution through quantification and characterisation of 243 macroplastics in the Port Elizabeth rivers. Third, to compare three very different rivers with different 244 levels of urbanisation (industrial, urban, and remote) to ascertain the impact of population and 245 government pollution management protocols on plastic emissions. Fourth, to measure microplastic 246 quantities at three depths from eight locations across the marine environment of Algoa Bay. Fifth, quantitatively characterize the microplastics in Algoa Bay to highlight any patterns of distribution. Sixth, 248 to compare the Algoa Bay concentrations with published international marine microplastic findings. , Thesis (MSc) -- Faculty of Science, Ocean Science, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Moss, Kerry-Leigh
- Date: 2021-12
- Subjects: Marine pollution , Plastic marine debris --Environmental aspects , Algoa Bay -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55645 , vital:53403
- Description: With just 4% of published plastic pollution research, the African region remains one of the most poorly 221 understood areas, leaving a large knowledge gap in our understanding of this global pollution problem 222 (Hurley, Woodward, & Rothwell, 2018). It is estimated that 64 to 90% of the ocean’s plastics originate 223 from fluxes in the terrestrial environment, however determining the exact source is not a simple task 224 (Andrady, 2011; Hurley et al., 2018). Plastic items, including the biodegradable plastic items, 225 breakdown in the marine environment through mechanical action resulting in non-degradable 226 microscopic fragments of synthetic polymers (Thompson et al., 2004). However, the consequences of 227 these microplastic fragments.This research intends to address two aims; first, to provide an estimation of the quantity of plastic 235 transportation via African rivers to the greater body of knowledge of global plastic emissions. This aim 236 will specifically focus on determining plastic output via Port Elizabeth rivers into the Algoa Bay marine 237 environment. The second aim of this research is to quantify and characterize the amount of microplastic 238 in the marine environment of Algoa Bay. The second aim will focus on identifying microplastic (MP) 239 throughout the water column. 240 This research consists of six objectives; first, to identify, design and field test a cost-effective system for 241 monitoring macroplastic quantity output from riverine to marine environments. Second, to contribute to 242 the body of knowledge of African river plastic pollution through quantification and characterisation of 243 macroplastics in the Port Elizabeth rivers. Third, to compare three very different rivers with different 244 levels of urbanisation (industrial, urban, and remote) to ascertain the impact of population and 245 government pollution management protocols on plastic emissions. Fourth, to measure microplastic 246 quantities at three depths from eight locations across the marine environment of Algoa Bay. Fifth, quantitatively characterize the microplastics in Algoa Bay to highlight any patterns of distribution. Sixth, 248 to compare the Algoa Bay concentrations with published international marine microplastic findings. , Thesis (MSc) -- Faculty of Science, Ocean Science, 2021
- Full Text:
- Date Issued: 2021-12
Perceptions of small-scale vegetable farmers on drought mitigation strategies in the Amathole District Municipality of the Eastern Cape Province
- Authors: Dingiswayo, Xolisile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53676 , vital:45686
- Description: The present study aimed to investigate perceptions of small-scale vegetable farmers on drought mitigation strategies in the Amathole District Municipality of the Eastern Cape Province. The research objective was to investigate what small-scale vegetable farmers’ perceptions and readiness are in terms of strategies to cope with drought conditions. The study was conducted within the Mbashe, Mnquma, Amahlathi and Great Kei local municipalities of the Eastern Cape. Primary data collection was conducted among 44 small-scale vegetable farmers of the Amathole municipal district. These are farmers who receive social support from the government, are registered with the Department of Rural Development and Agrarian Reform and contribute to the fight against food insecurity in the Amathole district. The primary data was also collected from 13 agricultural extension officers with high experience in advising small-scale farmers residing in the Amathole district. Data collection took place in various local municipalities under Amathole District Municipality, namely: Mbashe, Mnquma, Amahlathi and Great Kei. A multi-method approach was adopted in this study as an appropriate technique to create an improved quality of research which eliminates the deep-rooted bias to either qualitative or quantitative methods alone. A self-administered questionnaires with both closed and open-ended questions – one for the small-scale farmer survey and the second for the extension officer survey – was employed as data collection instrument. The demographic characteristics of small-scale vegetable farmers in the survey area indicated that the present majority of farmers are married male Xhosa farmers between the ages of 56 and 65 years old, with a secondary level of education. The majority of the farmers are typically resource-poor − which implies that the added menace of drought poses the risk that small-scale vegetable farming could decline to mere subsistence level or worse. Drought was found to be a major problem in Mbashe, Mnquma, Amahlathi and Great Kei local municipalities within the Amathole municipal district, with an acute impact on farmers’ production and generation of income. From the data, it emerged that farmers are not sufficiently informed about and do not receive specific training in drought mitigation strategies. Farmers rely on drought alleviation methods but there is a lack of adaptive strategies and timely, long-term ii state intervention. Being resource-poor, these small-scale producers are reliant on natural resources – notably water for irrigating crops. The study established further that there is neither the resources nor sufficient training by and involvement of the extension service. Farmers therefore rely on the use of drought coping mechanisms and drought mitigation techniques and on adapting their production systems. The information-sharing sessions recommended can assist in improving rural livelihoods and the productivity of small-scale vegetable farmers. The absence of engagement of youth in farming means that modern conservation and innovative farming techniques and systems are not implemented towards reducing the impacts of climate change − as well as revitalizing rural areas such Amathole. Access to education about drought, improved drought coping mechanisms and adaptive strategies should be created to facilitate an exchange of traditional and modern agricultural information. The development of infrastructure in rural communities and farming areas is another factor crucial to improving farming systems and operations in the Amathole municipal district. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Dingiswayo, Xolisile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53676 , vital:45686
- Description: The present study aimed to investigate perceptions of small-scale vegetable farmers on drought mitigation strategies in the Amathole District Municipality of the Eastern Cape Province. The research objective was to investigate what small-scale vegetable farmers’ perceptions and readiness are in terms of strategies to cope with drought conditions. The study was conducted within the Mbashe, Mnquma, Amahlathi and Great Kei local municipalities of the Eastern Cape. Primary data collection was conducted among 44 small-scale vegetable farmers of the Amathole municipal district. These are farmers who receive social support from the government, are registered with the Department of Rural Development and Agrarian Reform and contribute to the fight against food insecurity in the Amathole district. The primary data was also collected from 13 agricultural extension officers with high experience in advising small-scale farmers residing in the Amathole district. Data collection took place in various local municipalities under Amathole District Municipality, namely: Mbashe, Mnquma, Amahlathi and Great Kei. A multi-method approach was adopted in this study as an appropriate technique to create an improved quality of research which eliminates the deep-rooted bias to either qualitative or quantitative methods alone. A self-administered questionnaires with both closed and open-ended questions – one for the small-scale farmer survey and the second for the extension officer survey – was employed as data collection instrument. The demographic characteristics of small-scale vegetable farmers in the survey area indicated that the present majority of farmers are married male Xhosa farmers between the ages of 56 and 65 years old, with a secondary level of education. The majority of the farmers are typically resource-poor − which implies that the added menace of drought poses the risk that small-scale vegetable farming could decline to mere subsistence level or worse. Drought was found to be a major problem in Mbashe, Mnquma, Amahlathi and Great Kei local municipalities within the Amathole municipal district, with an acute impact on farmers’ production and generation of income. From the data, it emerged that farmers are not sufficiently informed about and do not receive specific training in drought mitigation strategies. Farmers rely on drought alleviation methods but there is a lack of adaptive strategies and timely, long-term ii state intervention. Being resource-poor, these small-scale producers are reliant on natural resources – notably water for irrigating crops. The study established further that there is neither the resources nor sufficient training by and involvement of the extension service. Farmers therefore rely on the use of drought coping mechanisms and drought mitigation techniques and on adapting their production systems. The information-sharing sessions recommended can assist in improving rural livelihoods and the productivity of small-scale vegetable farmers. The absence of engagement of youth in farming means that modern conservation and innovative farming techniques and systems are not implemented towards reducing the impacts of climate change − as well as revitalizing rural areas such Amathole. Access to education about drought, improved drought coping mechanisms and adaptive strategies should be created to facilitate an exchange of traditional and modern agricultural information. The development of infrastructure in rural communities and farming areas is another factor crucial to improving farming systems and operations in the Amathole municipal district. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-12