Enactment of hands-on practical activities through using easily accessible resources in a Grade 10 Physical Science classroom
- Authors: Ndevahoma, Martha Kashike
- Date: 2020
- Subjects: Physical science -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/110229 , vital:33251
- Description: The Namibian National Subject Policy Guide for Physical Science Grade 8-12 (MoE, 2010) indicates that science teachers should be creative and innovative in producing their own teaching and learning support materials that are linked to practice. Practical activities play a major role in the learning of science. Due to the lack of science laboratory equipment, however, minimal practical activities are done in some schools especially under-resourced disadvantaged schools. It is against this background that this case study investigated the possibilities and challenges associated with the use of easily accessible resources to carry out hands-on practical activities. Underpinned by an interpretive paradigm, this study used a mixed-method approach by generating both quantitative and qualitative data. It was carried out in the Otjozondjupa region in Namibia at Wato Secondary School (pseudonym). It was conducted with a Grade 10 Physical Science class consisting of 30 learners. To generate data, questionnaires, focus group interviews, lesson observations, stimulated recall interviews, as well as learners’ journal reflections were used. Conceptions, dispositions, interest and sense-making were used as conceptual lenses while Vygotsky’s social constructivism was the theoretical framework that informed this study. Quantitative data were analysed using the conceptual lenses and were subsequently presented in tables and graphs. That is, a deductive approach to analysis was used. On the other hand, a thematic approach was used to analyse the qualitative data. That is, qualitative data were inductively analysed to come up with sub-themes and themes. The findings from this study revealed significant shifts in learners’ conceptions, dispositions and interest towards science after the use of easily accessible resources to do hands-on practical activities. Similarly, learners’ sense-making of science concepts improved. This study thus recommends that science teachers should, where possible, make use of easily accessible resources to carry out hands-on practical activities during their science lessons. During such hands-on practicals, however, emphasis should be on the development of scientific concepts.
- Full Text:
- Date Issued: 2020
- Authors: Ndevahoma, Martha Kashike
- Date: 2020
- Subjects: Physical science -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/110229 , vital:33251
- Description: The Namibian National Subject Policy Guide for Physical Science Grade 8-12 (MoE, 2010) indicates that science teachers should be creative and innovative in producing their own teaching and learning support materials that are linked to practice. Practical activities play a major role in the learning of science. Due to the lack of science laboratory equipment, however, minimal practical activities are done in some schools especially under-resourced disadvantaged schools. It is against this background that this case study investigated the possibilities and challenges associated with the use of easily accessible resources to carry out hands-on practical activities. Underpinned by an interpretive paradigm, this study used a mixed-method approach by generating both quantitative and qualitative data. It was carried out in the Otjozondjupa region in Namibia at Wato Secondary School (pseudonym). It was conducted with a Grade 10 Physical Science class consisting of 30 learners. To generate data, questionnaires, focus group interviews, lesson observations, stimulated recall interviews, as well as learners’ journal reflections were used. Conceptions, dispositions, interest and sense-making were used as conceptual lenses while Vygotsky’s social constructivism was the theoretical framework that informed this study. Quantitative data were analysed using the conceptual lenses and were subsequently presented in tables and graphs. That is, a deductive approach to analysis was used. On the other hand, a thematic approach was used to analyse the qualitative data. That is, qualitative data were inductively analysed to come up with sub-themes and themes. The findings from this study revealed significant shifts in learners’ conceptions, dispositions and interest towards science after the use of easily accessible resources to do hands-on practical activities. Similarly, learners’ sense-making of science concepts improved. This study thus recommends that science teachers should, where possible, make use of easily accessible resources to carry out hands-on practical activities during their science lessons. During such hands-on practicals, however, emphasis should be on the development of scientific concepts.
- Full Text:
- Date Issued: 2020
Investigating conceptual teaching of word problems through visualisation processes: a case of selected Grad 9 mathematics teachers
- Authors: John, Ssennyomo Bernard
- Date: 2020
- Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa , Pythagorean theorem -- Study and teaching (Secondary) , Mathematics teachers -- South Africa , Visualization
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/167497 , vital:41486
- Description: This study investigated how selected grade 9 mathematics teachers used visualisation strategies to conceptually teach Pythagoras' theorem word problems as a result of an intervention program. This research project is an integral component of the ViProMaths project whose goal is to research the effective use of visualisation strategies in the mathematics classroom in the Southern African region. This case study of mathematics teachers in the John Taolo Gaetsewe (JTG) District in the Northern Cape Province, used a social constructivist theory. The study is grounded within an interpretive paradigm and used an explanatory sequential mixed methods design. It surveyed eighty-seven mathematics teachers from all the secondary schools in the JTG District, focusing on their experiences when using visualisation approaches to teach Pythagoras’ theorem word problems. After the survey, three teachers purposively selected from three different schools in the district took part in the intervention programme. I used a survey questionnaire, classroom observations and interviews to collect the data from the study participants. The data were analysed quantitatively and qualitatively. The findings from survey data revealed that while teachers in the JTG District acknowledge the importance and value of visualisation strategies in the teaching of Pythagoras’ theorem word problems, many of them are either using visuals minimally or not using them at all. Challenges such as lack of resources in schools, time constrains, a lack of support from subject advisers, among others were noted. This thus necessitated a need for an intervention with some teachers in the district, specifically focusing on the use of visualisation tools and skills to teach Pythagoras’ theorem word problems for conceptual understanding. Lessons observations showed that all observed teachers used visual models to generate images and used the models to develop mathematical ideas. The teachers used the images to create platforms for classroom discussions. The discussions were driven by questions which teachers asked both for ascertaining learners’ prior knowledge and for finding out if they understood what the teachers were teaching. Interviews revealed that teachers’ perceptions had changed because they now know how to make and use different models to build on learners’ prior knowledge, extend what they are teaching to real life and make sense of Pythagoras’ proposition in multiple ways and to establish connections among a rich set of mathematics concepts when teaching Pythagoras’ theorem word problems. This study concludes that the use of visual strategies has the potential of enhancing conceptual teaching of Pythagoras’ theorem word problems. The implications for teachers are that learners need to be taught how to create visual representations (both internally and externally) of the relations between objects in a word problem as this will help them in maximising understanding. Furthermore, it is hoped that the results of this study could be used by various stake holders who include inter alia, mathematics subject advisers and teacher training institutions to improve the teaching of Pythagoras’ theorem word problems.
- Full Text:
- Date Issued: 2020
- Authors: John, Ssennyomo Bernard
- Date: 2020
- Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa , Pythagorean theorem -- Study and teaching (Secondary) , Mathematics teachers -- South Africa , Visualization
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/167497 , vital:41486
- Description: This study investigated how selected grade 9 mathematics teachers used visualisation strategies to conceptually teach Pythagoras' theorem word problems as a result of an intervention program. This research project is an integral component of the ViProMaths project whose goal is to research the effective use of visualisation strategies in the mathematics classroom in the Southern African region. This case study of mathematics teachers in the John Taolo Gaetsewe (JTG) District in the Northern Cape Province, used a social constructivist theory. The study is grounded within an interpretive paradigm and used an explanatory sequential mixed methods design. It surveyed eighty-seven mathematics teachers from all the secondary schools in the JTG District, focusing on their experiences when using visualisation approaches to teach Pythagoras’ theorem word problems. After the survey, three teachers purposively selected from three different schools in the district took part in the intervention programme. I used a survey questionnaire, classroom observations and interviews to collect the data from the study participants. The data were analysed quantitatively and qualitatively. The findings from survey data revealed that while teachers in the JTG District acknowledge the importance and value of visualisation strategies in the teaching of Pythagoras’ theorem word problems, many of them are either using visuals minimally or not using them at all. Challenges such as lack of resources in schools, time constrains, a lack of support from subject advisers, among others were noted. This thus necessitated a need for an intervention with some teachers in the district, specifically focusing on the use of visualisation tools and skills to teach Pythagoras’ theorem word problems for conceptual understanding. Lessons observations showed that all observed teachers used visual models to generate images and used the models to develop mathematical ideas. The teachers used the images to create platforms for classroom discussions. The discussions were driven by questions which teachers asked both for ascertaining learners’ prior knowledge and for finding out if they understood what the teachers were teaching. Interviews revealed that teachers’ perceptions had changed because they now know how to make and use different models to build on learners’ prior knowledge, extend what they are teaching to real life and make sense of Pythagoras’ proposition in multiple ways and to establish connections among a rich set of mathematics concepts when teaching Pythagoras’ theorem word problems. This study concludes that the use of visual strategies has the potential of enhancing conceptual teaching of Pythagoras’ theorem word problems. The implications for teachers are that learners need to be taught how to create visual representations (both internally and externally) of the relations between objects in a word problem as this will help them in maximising understanding. Furthermore, it is hoped that the results of this study could be used by various stake holders who include inter alia, mathematics subject advisers and teacher training institutions to improve the teaching of Pythagoras’ theorem word problems.
- Full Text:
- Date Issued: 2020
Water footprint and economic water productivity of citrus production: a comparison across three river valleys in the Eastern Cape Milands
- Authors: Danckwerts, Lindsay
- Date: 2020
- Subjects: Water in agriculture -- South Africa -- Eastern Cape , Water consumption -- South Africa -- Economic aspects , Water supply, Agricultural -- South Africa -- Eastern Cape , Citrus fruit industry -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/141064 , vital:37941
- Description: South Africa is a semi-arid, water scarce country. The nation has suffered a spate of severe droughts in several regions in recent years, which have significantly impacted the country’s economy. Global warming, population growth, and rising demand for water intensive products are only expected to intensify water supply problems in the future. The agricultural industry is the largest consumer of water in South Africa, accounting for the majority of total surface water withdrawals. As such, the agricultural sector is faced with complex and difficult management decisions in the face of a potential water supply crisis. The water footprint (WF) and economic water productivity (EWP) of citrus production across three river catchments located in the Eastern Cape Midlands (situated in the vicinity of the settlements of Adelaide, Cookhouse and Fort Beaufort respectively) were calculated and compared. In the long-term average (LTA), blue WF weighted across all three regions accounted for the greatest proportion of total WF (53%), followed in turn by green and grey WF (30% and 17% respectively). LTA blue and grey WF was lowest in the Adelaide region, while green WF was smallest in the Fort Beaufort region. Blue, green and grey WF were found to be greatest in the Cookhouse region. LTA EWP was greatest in the Fort Beaufort region and smallest in the Adelaide region. Of all variety groups assessed, lemons were found to have the lowest LTA crop water use and blue, green and grey WF when considering citrus production averaged across all three study regions. Satsumas has the second smallest LTA blue, green and grey WF, followed by navels, mid-season mandarins, and finally, late mandarins. Lemons had the greatest LTA EWP of all varieties, followed in turn by satsumas, late mandarins, mid-season mandarins and navels. Blue crop water use was consistently lowest in the designated wet year and highest in the dry year. However, this same trend was not necessarily true for WF findings. WF and EWP are useful indicators of water use which can be used to help guide complex water management decisions. However, these indicators are single-factor productivity measures applied in a multi-factor environment. It is therefore important that factors outside of water use are considered when making water management decisions. Moreover, it is important to examine the impact that the various components making up WF and EWP have on the resultant figures, rather than merely considering the superficial results themselves. Factors such as CWU, orchard maturity, crop choice, potential yield, climate, irrigation system, economic return, water allocation and water availability should all be taken into account.
- Full Text:
- Date Issued: 2020
- Authors: Danckwerts, Lindsay
- Date: 2020
- Subjects: Water in agriculture -- South Africa -- Eastern Cape , Water consumption -- South Africa -- Economic aspects , Water supply, Agricultural -- South Africa -- Eastern Cape , Citrus fruit industry -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/141064 , vital:37941
- Description: South Africa is a semi-arid, water scarce country. The nation has suffered a spate of severe droughts in several regions in recent years, which have significantly impacted the country’s economy. Global warming, population growth, and rising demand for water intensive products are only expected to intensify water supply problems in the future. The agricultural industry is the largest consumer of water in South Africa, accounting for the majority of total surface water withdrawals. As such, the agricultural sector is faced with complex and difficult management decisions in the face of a potential water supply crisis. The water footprint (WF) and economic water productivity (EWP) of citrus production across three river catchments located in the Eastern Cape Midlands (situated in the vicinity of the settlements of Adelaide, Cookhouse and Fort Beaufort respectively) were calculated and compared. In the long-term average (LTA), blue WF weighted across all three regions accounted for the greatest proportion of total WF (53%), followed in turn by green and grey WF (30% and 17% respectively). LTA blue and grey WF was lowest in the Adelaide region, while green WF was smallest in the Fort Beaufort region. Blue, green and grey WF were found to be greatest in the Cookhouse region. LTA EWP was greatest in the Fort Beaufort region and smallest in the Adelaide region. Of all variety groups assessed, lemons were found to have the lowest LTA crop water use and blue, green and grey WF when considering citrus production averaged across all three study regions. Satsumas has the second smallest LTA blue, green and grey WF, followed by navels, mid-season mandarins, and finally, late mandarins. Lemons had the greatest LTA EWP of all varieties, followed in turn by satsumas, late mandarins, mid-season mandarins and navels. Blue crop water use was consistently lowest in the designated wet year and highest in the dry year. However, this same trend was not necessarily true for WF findings. WF and EWP are useful indicators of water use which can be used to help guide complex water management decisions. However, these indicators are single-factor productivity measures applied in a multi-factor environment. It is therefore important that factors outside of water use are considered when making water management decisions. Moreover, it is important to examine the impact that the various components making up WF and EWP have on the resultant figures, rather than merely considering the superficial results themselves. Factors such as CWU, orchard maturity, crop choice, potential yield, climate, irrigation system, economic return, water allocation and water availability should all be taken into account.
- Full Text:
- Date Issued: 2020
A comparative study of CERBER, MAKTUB and LOCKY Ransomware using a Hybridised-Malware analysis
- Authors: Schmitt, Veronica
- Date: 2019
- Subjects: Microsoft Windows (Computer file) , Data protection , Computer crimes -- Prevention , Computer security , Computer networks -- Security measures , Computers -- Access control , Malware (Computer software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92313 , vital:30702
- Description: There has been a significant increase in the prevalence of Ransomware attacks in the preceding four years to date. This indicates that the battle has not yet been won defending against this class of malware. This research proposes that by identifying the similarities within the operational framework of Ransomware strains, a better overall understanding of their operation and function can be achieved. This, in turn, will aid in a quicker response to future attacks. With the average Ransomware attack taking two hours to be identified, it shows that there is not yet a clear understanding as to why these attacks are so successful. Research into Ransomware is limited by what is currently known on the topic. Due to the limitations of the research the decision was taken to only examined three samples of Ransomware from different families. This was decided due to the complexities and comprehensive nature of the research. The in depth nature of the research and the time constraints associated with it did not allow for proof of concept of this framework to be tested on more than three families, but the exploratory work was promising and should be further explored in future research. The aim of the research is to follow the Hybrid-Malware analysis framework which consists of both static and the dynamic analysis phases, in addition to the digital forensic examination of the infected system. This allows for signature-based findings, along with behavioural and forensic findings all in one. This information allows for a better understanding of how this malware is designed and how it infects and remains persistent on a system. The operating system which has been chosen is the Microsoft Window 7 operating system which is still utilised by a significant proportion of Windows users especially in the corporate environment. The experiment process was designed to enable the researcher the ability to collect information regarding the Ransomware and every aspect of its behaviour and communication on a target system. The results can be compared across the three strains to identify the commonalities. The initial hypothesis was that Ransomware variants are all much like an instant cake box consists of specific building blocks which remain the same with the flavouring of the cake mix being the unique feature.
- Full Text:
- Date Issued: 2019
- Authors: Schmitt, Veronica
- Date: 2019
- Subjects: Microsoft Windows (Computer file) , Data protection , Computer crimes -- Prevention , Computer security , Computer networks -- Security measures , Computers -- Access control , Malware (Computer software)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92313 , vital:30702
- Description: There has been a significant increase in the prevalence of Ransomware attacks in the preceding four years to date. This indicates that the battle has not yet been won defending against this class of malware. This research proposes that by identifying the similarities within the operational framework of Ransomware strains, a better overall understanding of their operation and function can be achieved. This, in turn, will aid in a quicker response to future attacks. With the average Ransomware attack taking two hours to be identified, it shows that there is not yet a clear understanding as to why these attacks are so successful. Research into Ransomware is limited by what is currently known on the topic. Due to the limitations of the research the decision was taken to only examined three samples of Ransomware from different families. This was decided due to the complexities and comprehensive nature of the research. The in depth nature of the research and the time constraints associated with it did not allow for proof of concept of this framework to be tested on more than three families, but the exploratory work was promising and should be further explored in future research. The aim of the research is to follow the Hybrid-Malware analysis framework which consists of both static and the dynamic analysis phases, in addition to the digital forensic examination of the infected system. This allows for signature-based findings, along with behavioural and forensic findings all in one. This information allows for a better understanding of how this malware is designed and how it infects and remains persistent on a system. The operating system which has been chosen is the Microsoft Window 7 operating system which is still utilised by a significant proportion of Windows users especially in the corporate environment. The experiment process was designed to enable the researcher the ability to collect information regarding the Ransomware and every aspect of its behaviour and communication on a target system. The results can be compared across the three strains to identify the commonalities. The initial hypothesis was that Ransomware variants are all much like an instant cake box consists of specific building blocks which remain the same with the flavouring of the cake mix being the unique feature.
- Full Text:
- Date Issued: 2019
Researching the development of a programme that merges mathematics and music in Grade R
- Authors: Stevenson-Milln, Carolyn
- Date: 2018
- Subjects: Mathematics Study and teaching (Elementary) Activity programs , Music and children , Music, Influence of , Music Africa , Action research in education
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61928 , vital:28084
- Description: This small-scale case study explores the potential for synergy between music and mathematics learning in early childhood education whereby music can be used to help enhance children’s mathematical proficiency. Informal observations of the young learners participating in an Early Number Fun programme initiated by the South African Numeracy Chair Project suggested that many children struggled to exercise executive functioning and self-regulated skills, and struggled also with fluency in basic numeracy concepts such as understanding pattern. This case study was set up to investigate the effect of the development and implementation of a programme in which African music and mathematics learning, (particularly in relation to pattern and sequencing) were blended. The study’s core aim was to contribute to strengthening learners’ executive function and self-regulated learning competencies, both of which are important to learners’ developing agency over their own learning. An Action-Research-embedded-in-Design-Research approach was employed. This allowed an iterative process in developing a new mode of learning through blending music and mathematics. The theory of enactivism provided a theoretical framework to the study. The basic assumptions of an enactive perspective are shared understanding and joint action through engagement (as exemplified through group interaction between learner and teacher, and learning through action). The programme was developed and implemented with ongoing refinements in two Grade R classrooms. Data collected through observation, interviewing, document analysis and the keeping of a reflective research journal, are qualitative in nature. Analysis of the data indicate that the use of African block notation, as a rhythmic medium was well within reach of the participating children, such that at the end of each 16 session intervention programme, learners at both research sites demonstrated their capacity to: • Focus their attention on one activity while a different activity was taking place alongside them. • Watch, listen and only then act. • Practise their numbers through play: to count out and to write up to 16 and beyond. • Notate, read and interpret rhythmic patterns through block notation and instrumentation. The findings suggest the intervention programme could be continued over a longer period for maximum benefit, possibly through following Grade R learners through to Grade 1. The findings further suggest that fun with rhythmic, number-based patterning can assist learners’ development of executive function and self-regulated learning skills.
- Full Text:
- Date Issued: 2018
- Authors: Stevenson-Milln, Carolyn
- Date: 2018
- Subjects: Mathematics Study and teaching (Elementary) Activity programs , Music and children , Music, Influence of , Music Africa , Action research in education
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61928 , vital:28084
- Description: This small-scale case study explores the potential for synergy between music and mathematics learning in early childhood education whereby music can be used to help enhance children’s mathematical proficiency. Informal observations of the young learners participating in an Early Number Fun programme initiated by the South African Numeracy Chair Project suggested that many children struggled to exercise executive functioning and self-regulated skills, and struggled also with fluency in basic numeracy concepts such as understanding pattern. This case study was set up to investigate the effect of the development and implementation of a programme in which African music and mathematics learning, (particularly in relation to pattern and sequencing) were blended. The study’s core aim was to contribute to strengthening learners’ executive function and self-regulated learning competencies, both of which are important to learners’ developing agency over their own learning. An Action-Research-embedded-in-Design-Research approach was employed. This allowed an iterative process in developing a new mode of learning through blending music and mathematics. The theory of enactivism provided a theoretical framework to the study. The basic assumptions of an enactive perspective are shared understanding and joint action through engagement (as exemplified through group interaction between learner and teacher, and learning through action). The programme was developed and implemented with ongoing refinements in two Grade R classrooms. Data collected through observation, interviewing, document analysis and the keeping of a reflective research journal, are qualitative in nature. Analysis of the data indicate that the use of African block notation, as a rhythmic medium was well within reach of the participating children, such that at the end of each 16 session intervention programme, learners at both research sites demonstrated their capacity to: • Focus their attention on one activity while a different activity was taking place alongside them. • Watch, listen and only then act. • Practise their numbers through play: to count out and to write up to 16 and beyond. • Notate, read and interpret rhythmic patterns through block notation and instrumentation. The findings suggest the intervention programme could be continued over a longer period for maximum benefit, possibly through following Grade R learners through to Grade 1. The findings further suggest that fun with rhythmic, number-based patterning can assist learners’ development of executive function and self-regulated learning skills.
- Full Text:
- Date Issued: 2018
The ecological risk of acid mine drainage in a salinising landscape
- Authors: Vellemu, Emmanuel Captain
- Date: 2018
- Subjects: Acid mine drainage Environmental aspects South Africa Mpumalanga , Salinization South Africa Mpumalanga , Water salinization South Africa Mpumalanga , Water quality South Africa Mpumalanga , Aquatic animals Effect of water quality on South Africa Mpumalanga , Freshwater ecology South Africa Mpumalanga
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60563 , vital:27797
- Description: Acid mine drainage (AMD) and increasing salinity of freshwater ecosystems pose serious threats to water quality in water-stressed South Africa. These threats are exacerbated by mining activities, mainly gold and coal from both active and abandoned mines that continue to release acidic water that is rich in toxic metals and high sulphate concentrations. Therefore, the overarching hypothesis for this study was that “the combination of AMD and sulphate salts confers high ecological risk to the aquatic biota”. The study employed both laboratory and field investigations to test this hypothesis and provide appropriate tools to protect freshwater ecosystems from increasing anthropogenic impacts. Firstly, a laboratory investigation was carried out to develop risk-based water quality guidelines (WQGs) for sulphates and treated AMD (TAMD) using the species sensitivity distributions (SSDs) technique. Five South African freshwater species belonging to five different taxonomic groupings, including Adenophlebia auriculata (insect), Burnupia stenochorias (mollusc), Caridina nilotica (crustacea), Pseudokirchneriella subcapitata (algae) and Oreochromis mossambicus (fish) were exposed to varying concentrations of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4) and calcium sulphate (CaSO4), as well as TAMD in separate ecotoxicological experiments, applying short-term (96 h) non-renewal and long-term (240 h) renewal exposure test methods. Secondly, a novel trait-based approach (TBA) was also used to predict the vulnerability of taxa to treated acid mine drainage (TAMD). The TBA used a combination of carefully selected traits of organisms that are mechanistically linked to TAMD for their potential vulnerability predictions. Leptoceridae (caddisflies) and Leptophlebiidae (mayflies) were selected taxa for evaluation of the trait-based vulnerability predictions to TAMD for laboratory toxicity exposures. This was followed by a field investigation to assess macroinvertebrates assemblage responses, abundance and richness to a TAMD-impacted stream using the South African Scoring System version 5 (SASS5) protocol. Outcomes form the above three sources were combined in a multi-criteria analysis (MCA) to develop an appropriate water quality management strategy in a form of a trait-based decision-making support tool. Results of the risk-based WQGs revealed that Na2SO4 was the most toxic of the tested salts. A concentration of 0.020 g/L Na2SO4, 0.055 g/L CaSO4, and 0.108 g/L MgSO4 or a combined sulphate salts limit of 0.067 g/L were derived as long-term WQGs to protect over 95% of the population species in a natural environment considered as relatively pristine. This means that the generic 0.25 g/L sulphate compliance limit for South African freshwater systems is under-protective. Burnupia stenochorias was the most sensitive to AMD after long-term exposures, and it was adjudged as a good indicator of AMD along with P. subcapitata. Long-term scenario-specific WQG for AMD for the protection of over 95% of the population species was derived as 0.014%. Results of the TBA revealed that the relative abundance and diversity of taxa at a site that received direct impact from TAMD generally corresponded to trait-based predictions. The site that received direct TAMD was largely dominated by members of the Corixidae and Naucoridae families. However, Leptoceridae was more vulnerable to TAMD than Leptophlebidae contrary to predictions. Its assemblage did not match the predictions although Leptophlebiidae corresponded to predictions in terms of its assemblage and diversity. As water quality improved further downstream of the TAMD source, macroinvertebrates assemblage and diversity also improved as predicted. However, it is important to note that other equally important traits that were not studied might influence the response of organisms during toxicity test exposures. The MCA findings suggest that the trait-based decision-making support tool is a useful management strategy for the predicting vulnerability of taxa aquatic stressors including AMD and increasing salinity. Overall, the outcome of this study suggests that AMD poses an ecological risk to aquatic biota, but this becomes riskier in the presence of excess sulphate salts. Albeit, the WQGs for sulphate salts and AMD as well as the developed trait-based decision support tool all contribute novel sound scientific knowledge basis for managing the AMD and increasing salinity in freshwater ecosystems. The study recommends incorporating different life stages of indigenous species tested to determine if their sensitivity to AMD and sulphate would correspond to current findings because early life stages could be more sensitive to aquatic stressors than juveniles or adults. This is important for the derivation of strong and relevant WQGs. The TBA requires further refinement for its incorporation in ecotoxicology on a wide scale.
- Full Text:
- Date Issued: 2018
- Authors: Vellemu, Emmanuel Captain
- Date: 2018
- Subjects: Acid mine drainage Environmental aspects South Africa Mpumalanga , Salinization South Africa Mpumalanga , Water salinization South Africa Mpumalanga , Water quality South Africa Mpumalanga , Aquatic animals Effect of water quality on South Africa Mpumalanga , Freshwater ecology South Africa Mpumalanga
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60563 , vital:27797
- Description: Acid mine drainage (AMD) and increasing salinity of freshwater ecosystems pose serious threats to water quality in water-stressed South Africa. These threats are exacerbated by mining activities, mainly gold and coal from both active and abandoned mines that continue to release acidic water that is rich in toxic metals and high sulphate concentrations. Therefore, the overarching hypothesis for this study was that “the combination of AMD and sulphate salts confers high ecological risk to the aquatic biota”. The study employed both laboratory and field investigations to test this hypothesis and provide appropriate tools to protect freshwater ecosystems from increasing anthropogenic impacts. Firstly, a laboratory investigation was carried out to develop risk-based water quality guidelines (WQGs) for sulphates and treated AMD (TAMD) using the species sensitivity distributions (SSDs) technique. Five South African freshwater species belonging to five different taxonomic groupings, including Adenophlebia auriculata (insect), Burnupia stenochorias (mollusc), Caridina nilotica (crustacea), Pseudokirchneriella subcapitata (algae) and Oreochromis mossambicus (fish) were exposed to varying concentrations of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4) and calcium sulphate (CaSO4), as well as TAMD in separate ecotoxicological experiments, applying short-term (96 h) non-renewal and long-term (240 h) renewal exposure test methods. Secondly, a novel trait-based approach (TBA) was also used to predict the vulnerability of taxa to treated acid mine drainage (TAMD). The TBA used a combination of carefully selected traits of organisms that are mechanistically linked to TAMD for their potential vulnerability predictions. Leptoceridae (caddisflies) and Leptophlebiidae (mayflies) were selected taxa for evaluation of the trait-based vulnerability predictions to TAMD for laboratory toxicity exposures. This was followed by a field investigation to assess macroinvertebrates assemblage responses, abundance and richness to a TAMD-impacted stream using the South African Scoring System version 5 (SASS5) protocol. Outcomes form the above three sources were combined in a multi-criteria analysis (MCA) to develop an appropriate water quality management strategy in a form of a trait-based decision-making support tool. Results of the risk-based WQGs revealed that Na2SO4 was the most toxic of the tested salts. A concentration of 0.020 g/L Na2SO4, 0.055 g/L CaSO4, and 0.108 g/L MgSO4 or a combined sulphate salts limit of 0.067 g/L were derived as long-term WQGs to protect over 95% of the population species in a natural environment considered as relatively pristine. This means that the generic 0.25 g/L sulphate compliance limit for South African freshwater systems is under-protective. Burnupia stenochorias was the most sensitive to AMD after long-term exposures, and it was adjudged as a good indicator of AMD along with P. subcapitata. Long-term scenario-specific WQG for AMD for the protection of over 95% of the population species was derived as 0.014%. Results of the TBA revealed that the relative abundance and diversity of taxa at a site that received direct impact from TAMD generally corresponded to trait-based predictions. The site that received direct TAMD was largely dominated by members of the Corixidae and Naucoridae families. However, Leptoceridae was more vulnerable to TAMD than Leptophlebidae contrary to predictions. Its assemblage did not match the predictions although Leptophlebiidae corresponded to predictions in terms of its assemblage and diversity. As water quality improved further downstream of the TAMD source, macroinvertebrates assemblage and diversity also improved as predicted. However, it is important to note that other equally important traits that were not studied might influence the response of organisms during toxicity test exposures. The MCA findings suggest that the trait-based decision-making support tool is a useful management strategy for the predicting vulnerability of taxa aquatic stressors including AMD and increasing salinity. Overall, the outcome of this study suggests that AMD poses an ecological risk to aquatic biota, but this becomes riskier in the presence of excess sulphate salts. Albeit, the WQGs for sulphate salts and AMD as well as the developed trait-based decision support tool all contribute novel sound scientific knowledge basis for managing the AMD and increasing salinity in freshwater ecosystems. The study recommends incorporating different life stages of indigenous species tested to determine if their sensitivity to AMD and sulphate would correspond to current findings because early life stages could be more sensitive to aquatic stressors than juveniles or adults. This is important for the derivation of strong and relevant WQGs. The TBA requires further refinement for its incorporation in ecotoxicology on a wide scale.
- Full Text:
- Date Issued: 2018
Principled, pragmatic revitalisation of catchment management forums in South Africa
- Munnik, Victor, Burt, Jane C, Price, Leigh, Barnes, Garth, Ashe, Bryan, Motloung, Sysman
- Authors: Munnik, Victor , Burt, Jane C , Price, Leigh , Barnes, Garth , Ashe, Bryan , Motloung, Sysman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436743 , vital:73298 , ISBN 978-1-4312-0831-9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20682-17.pdf
- Description: There are many views on Catchment Management Forums (CMFs). They are seen as places for enthusiastic participation, communities of practice in the making, and crucial to the devo-lution of water management to local stakeholders. They are also seen as exhausted, toothless talk shops, unrepresenta-tive, undemocratic, haunts of the privileged, ignored by officials and a waste of time.
- Full Text:
- Date Issued: 2016
- Authors: Munnik, Victor , Burt, Jane C , Price, Leigh , Barnes, Garth , Ashe, Bryan , Motloung, Sysman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/436743 , vital:73298 , ISBN 978-1-4312-0831-9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20682-17.pdf
- Description: There are many views on Catchment Management Forums (CMFs). They are seen as places for enthusiastic participation, communities of practice in the making, and crucial to the devo-lution of water management to local stakeholders. They are also seen as exhausted, toothless talk shops, unrepresenta-tive, undemocratic, haunts of the privileged, ignored by officials and a waste of time.
- Full Text:
- Date Issued: 2016
An investigation into the possible neuroprotective role of melatonin in copper-loading
- Authors: Parmar, Paresh H
- Date: 2001
- Subjects: Melatonin , Copper , Nervous system -- Degeneration -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3783 , http://hdl.handle.net/10962/d1003261
- Description: Copper is an extremely toxic metal in biological systems and thus, its availability to the system, must be effectively and efficiently controlled. Copper is vital for life, as it is essential for critical enzymes in biological systems. It is free copper in the biological systems that is toxic, as free copper induces free radical generation, which disrupts lipid membranes, interacts with DNA causing mutations, and eventually leads to cell death. Wilson’s disease is a inherited copper disease, which results in hepatolenticular disease. Copper is unable to be excreted, and thus accumulates, eventually spilling over into the bloodstream from the liver, and “poisons” the patient. The Wilson’s disease patient leads a short life, due to neurological and hepatological problems. There is no cure for Wilson’s disease, only chelation therapy using potent chelators such as penicillamine and EDTA. Zinc, in high doses, can be used to compete with copper absorption. This has proved to be the only successful therapy at present. This study investigates the possible use of melatonin as a copper binder/chelator. Melatonin has been shown to interact with copper in vitro. By binding/chelating to copper, melatonin may inhibit copper-induced free radical generation, and thus prevent copper from interacting with DNA to cause mutations and act as a cytotoxin. In vivo studies on copper (2mg/kg) administered for 2-weeks and 6-weeks were carried out on Wistar rats. The potential of melatonin (12mg/kg) to prevent copper-induced cellular damage was investigated. The results indicate that melatonin does not protect the lipid membranes from copper-induced lipid peroxidation. In vitro investigations using 1mM, 5mM and 10mM copper and 5mM melatonin, show that melatonin prevents copper-induced lipid peroxidation at a copper concentration of 1mM (p<0.001). The 5mM and 10mM copper induces less lipid peroxidation, compared to the 1mM copper. It has been reported that metal ions, antioxidants and chelating agents can influence peroxide decomposition during the assay. Melatonin (5mM) administration does not significantly prevent copper-induced lipid peroxidation at 5mM and 10mM copper. It is possible that due to melatonin’s relatively low concentration, it is unable to inhibit lipid peroxidation induced by the copper. The chemical nature of the interaction between melatonin and copper was also investigated, using NMR, IR and electrochemistry techniques. The NMR and IR techniques show that melatonin coordinates with Cu²⁺ and not Cu¹⁺, at the carbonyl group of melatonin. The electrochemistry experiments using cyclic voltammetry and adsorptive stripping voltammetry, show that melatonin forms a strong bond with Cu¹⁺. Cu²⁺ prefers binding to oxygen, and that is clearly seen in the NMR and IR. Cu¹⁺ prefers binding to nitrogen and then oxygen, and this is seen in the electrochemistry, as Cu¹⁺ is forced to bind through one of the nitrogens on the melatonin. Previously, it has been shown that melatonin binds/chelates with Cu²⁺. Histochemical investigations show that copper administration for 2-weeks and 6-weeks, causes extensive mitochondrial damage in liver and kidney’s proximal convoluted tubule epithelium cells. Melatonin (12mg/kg) co-administration with copper for 2-weeks and 6-weeks did not significantly protect the mitochondria from copper-induced damage. Copper-specific stains (rhodanine, silver sulphide and rubeanic acid) were used to stain liver, brain and kidney tissue samples. Rhodanine and silver sulphide were equally sensitive in staining copper in the 2-week samples, but not at all in the 6-week samples. This could not be explained. Rubeanic acid was ineffective in all samples tested. Thus, it appears that specific copper stains cannot be used in making a definitive diagnosis in cases of copper overload, and that specific copper stains do not always correlate with a high concentration of copper present in tissues. Pineal organ culture was used to determine the effect of copper administration on pineal indole synthesis. Exogenous (³H) tryptophan was administered to the pineal organ cultures, and the level of (³H) pineal indoles synthesised, were measured. Pineals from 2-week and 6-week copper/melatonin treated animals exhibited paradoxical 5- methoxytryptophol (ML) levels, as compared to the 2-week and 6-week copper treated animals. The 2-week copper/melatonin administered animals, showed a decrease in the ML level (p<0.01), and the copper/melatonin administered for 6-weeks, showed an increase in the ML levels (p<0.01). This indicates that melatonin interacts with the HIOMT enzyme. Pineals from 6-week copper/melatonin treated animals, as compared to the 6-week copper treated animals, showed an increase in N-acetylserotonin levels. This indicates that melatonin prevents the inhibition of the NAT enzyme. The final experiment was to determine in vitro, the effect of Cu²⁺ and Cu¹⁺ administration, on mitochondrial electron transport chain. Rat liver homogenate was incubated with and solutions of Cu²⁺ (10mM) and Cu¹⁺ (10mM) and melatonin (10mM). Cu²⁺ administration caused an inhibition of the electron transport at t=0 and t=60, whereas Cu¹⁺ administration at t=0 caused an inhibition of electron transport, but at t=60, Cu¹⁺ administration stimulated electron transport. Melatonin administered with Cu²⁺, resulted in an inhibition of the electron transport chain at t=0 and t=60. The findings of this study indicate that melatonin might have a potentially beneficial effect in copper overloading, by binding/chelating copper.
- Full Text:
- Date Issued: 2001
- Authors: Parmar, Paresh H
- Date: 2001
- Subjects: Melatonin , Copper , Nervous system -- Degeneration -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3783 , http://hdl.handle.net/10962/d1003261
- Description: Copper is an extremely toxic metal in biological systems and thus, its availability to the system, must be effectively and efficiently controlled. Copper is vital for life, as it is essential for critical enzymes in biological systems. It is free copper in the biological systems that is toxic, as free copper induces free radical generation, which disrupts lipid membranes, interacts with DNA causing mutations, and eventually leads to cell death. Wilson’s disease is a inherited copper disease, which results in hepatolenticular disease. Copper is unable to be excreted, and thus accumulates, eventually spilling over into the bloodstream from the liver, and “poisons” the patient. The Wilson’s disease patient leads a short life, due to neurological and hepatological problems. There is no cure for Wilson’s disease, only chelation therapy using potent chelators such as penicillamine and EDTA. Zinc, in high doses, can be used to compete with copper absorption. This has proved to be the only successful therapy at present. This study investigates the possible use of melatonin as a copper binder/chelator. Melatonin has been shown to interact with copper in vitro. By binding/chelating to copper, melatonin may inhibit copper-induced free radical generation, and thus prevent copper from interacting with DNA to cause mutations and act as a cytotoxin. In vivo studies on copper (2mg/kg) administered for 2-weeks and 6-weeks were carried out on Wistar rats. The potential of melatonin (12mg/kg) to prevent copper-induced cellular damage was investigated. The results indicate that melatonin does not protect the lipid membranes from copper-induced lipid peroxidation. In vitro investigations using 1mM, 5mM and 10mM copper and 5mM melatonin, show that melatonin prevents copper-induced lipid peroxidation at a copper concentration of 1mM (p<0.001). The 5mM and 10mM copper induces less lipid peroxidation, compared to the 1mM copper. It has been reported that metal ions, antioxidants and chelating agents can influence peroxide decomposition during the assay. Melatonin (5mM) administration does not significantly prevent copper-induced lipid peroxidation at 5mM and 10mM copper. It is possible that due to melatonin’s relatively low concentration, it is unable to inhibit lipid peroxidation induced by the copper. The chemical nature of the interaction between melatonin and copper was also investigated, using NMR, IR and electrochemistry techniques. The NMR and IR techniques show that melatonin coordinates with Cu²⁺ and not Cu¹⁺, at the carbonyl group of melatonin. The electrochemistry experiments using cyclic voltammetry and adsorptive stripping voltammetry, show that melatonin forms a strong bond with Cu¹⁺. Cu²⁺ prefers binding to oxygen, and that is clearly seen in the NMR and IR. Cu¹⁺ prefers binding to nitrogen and then oxygen, and this is seen in the electrochemistry, as Cu¹⁺ is forced to bind through one of the nitrogens on the melatonin. Previously, it has been shown that melatonin binds/chelates with Cu²⁺. Histochemical investigations show that copper administration for 2-weeks and 6-weeks, causes extensive mitochondrial damage in liver and kidney’s proximal convoluted tubule epithelium cells. Melatonin (12mg/kg) co-administration with copper for 2-weeks and 6-weeks did not significantly protect the mitochondria from copper-induced damage. Copper-specific stains (rhodanine, silver sulphide and rubeanic acid) were used to stain liver, brain and kidney tissue samples. Rhodanine and silver sulphide were equally sensitive in staining copper in the 2-week samples, but not at all in the 6-week samples. This could not be explained. Rubeanic acid was ineffective in all samples tested. Thus, it appears that specific copper stains cannot be used in making a definitive diagnosis in cases of copper overload, and that specific copper stains do not always correlate with a high concentration of copper present in tissues. Pineal organ culture was used to determine the effect of copper administration on pineal indole synthesis. Exogenous (³H) tryptophan was administered to the pineal organ cultures, and the level of (³H) pineal indoles synthesised, were measured. Pineals from 2-week and 6-week copper/melatonin treated animals exhibited paradoxical 5- methoxytryptophol (ML) levels, as compared to the 2-week and 6-week copper treated animals. The 2-week copper/melatonin administered animals, showed a decrease in the ML level (p<0.01), and the copper/melatonin administered for 6-weeks, showed an increase in the ML levels (p<0.01). This indicates that melatonin interacts with the HIOMT enzyme. Pineals from 6-week copper/melatonin treated animals, as compared to the 6-week copper treated animals, showed an increase in N-acetylserotonin levels. This indicates that melatonin prevents the inhibition of the NAT enzyme. The final experiment was to determine in vitro, the effect of Cu²⁺ and Cu¹⁺ administration, on mitochondrial electron transport chain. Rat liver homogenate was incubated with and solutions of Cu²⁺ (10mM) and Cu¹⁺ (10mM) and melatonin (10mM). Cu²⁺ administration caused an inhibition of the electron transport at t=0 and t=60, whereas Cu¹⁺ administration at t=0 caused an inhibition of electron transport, but at t=60, Cu¹⁺ administration stimulated electron transport. Melatonin administered with Cu²⁺, resulted in an inhibition of the electron transport chain at t=0 and t=60. The findings of this study indicate that melatonin might have a potentially beneficial effect in copper overloading, by binding/chelating copper.
- Full Text:
- Date Issued: 2001
An investigation of the role of conflict in the stratificationary process of the African in the copper mining industry of Northern Rhodesia between the years, 1943-1961
- Authors: Coetzee, J A G
- Date: 1964
- Subjects: Social conflict -- Zambia , Conflict management -- Zambia , Copper industry and trade -- Zambia
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3382 , http://hdl.handle.net/10962/d1013332
- Description: The aim of this study is to investigate the role of CONFLICT in the stratificationary process of the African in the Copper Mining Industry of Northern Rhodesia between the years 1943 - 1961. The hypothesis and assumptions which it is desired to prove can be classified as falling into four categories: 1. that which accepts human beings as individuals acting in group structures, each group having its appropriate goals and ends forming discernable patterned action systems; 2. that these groups can be reconstructed to show variable patterns of action which might be either accommodative or initially contradictory as conflicts emerge within the system; 3. that items 1 and 2 above can be objectivised by empirical materials and that they change in time, and, in so doing, are modified in structure-functional relations; 4. that conflict is the process which animates the patterns and prescribes new goals and ends within the patterned activity systems. An indefinite number of causality factors are possible in explaining social change, but we confine ourselves to the concept CONFLICT, with special reference to the Copperbelt of Northern Rhodesia. The economic factors operating, together with the political and social factors, producing a typical stratification of the African in the industry, sofar as this reveals changing patterns of progressive and aggressive goal thrusts and redefinition of the social positions of the contesting participants, are dealt with in the appropriate sections of this investigation. The model has been developed in relation to the study of the total social system with special emphasis on their overtly political and economical aspects. Part 1, in its entirety, deals with the theory of conflict. It also contains our own development of the theme. The empirical data are contained in parts 2, 3, with a section on envisaged future social developments. The conclusion, to this investigation, forms the last part , with an exhaustive testing of the TEN-POINT HYPOTHESIS given at the end of Part 1.
- Full Text:
- Date Issued: 1964
- Authors: Coetzee, J A G
- Date: 1964
- Subjects: Social conflict -- Zambia , Conflict management -- Zambia , Copper industry and trade -- Zambia
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3382 , http://hdl.handle.net/10962/d1013332
- Description: The aim of this study is to investigate the role of CONFLICT in the stratificationary process of the African in the Copper Mining Industry of Northern Rhodesia between the years 1943 - 1961. The hypothesis and assumptions which it is desired to prove can be classified as falling into four categories: 1. that which accepts human beings as individuals acting in group structures, each group having its appropriate goals and ends forming discernable patterned action systems; 2. that these groups can be reconstructed to show variable patterns of action which might be either accommodative or initially contradictory as conflicts emerge within the system; 3. that items 1 and 2 above can be objectivised by empirical materials and that they change in time, and, in so doing, are modified in structure-functional relations; 4. that conflict is the process which animates the patterns and prescribes new goals and ends within the patterned activity systems. An indefinite number of causality factors are possible in explaining social change, but we confine ourselves to the concept CONFLICT, with special reference to the Copperbelt of Northern Rhodesia. The economic factors operating, together with the political and social factors, producing a typical stratification of the African in the industry, sofar as this reveals changing patterns of progressive and aggressive goal thrusts and redefinition of the social positions of the contesting participants, are dealt with in the appropriate sections of this investigation. The model has been developed in relation to the study of the total social system with special emphasis on their overtly political and economical aspects. Part 1, in its entirety, deals with the theory of conflict. It also contains our own development of the theme. The empirical data are contained in parts 2, 3, with a section on envisaged future social developments. The conclusion, to this investigation, forms the last part , with an exhaustive testing of the TEN-POINT HYPOTHESIS given at the end of Part 1.
- Full Text:
- Date Issued: 1964
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