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Welcome to the University of Venda Institutional Repository, an open digital archive of the research output of the University of Venda. Univen IR contains theses and dissertations, research papers as well as conference papers. For further information and assistance please contact Mr Keith Malabi at +27 15 9628564 or +27 15 962 8314 during office hours

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Bioaccumulation and the human health risk of p,p'-DDT, p,p'-DDD, p,p'-DDE in freshwater fish species from the north-eastern Limpopo River valley, Vhembe District, Limpopo Province, South Africa

(2024-09-06) Mphephu, Sherron; Barnhoorn, I. E. J.; Bornmann, M. S.

Dichloro-diphenyl-trichloroethane (DDT) has been used globally as an agricultural pesticide since the early 1940s, and both the United States and Canada banned its use in 1972. DDT is still used in the malaria-endemic region of South Africa for vector control through indoor residual spraying (IRS). Studies have reported a link between DDT exposure and prostate cancer risk and/or aggressive disease presentation in Italy, Canada, and the United States. Epidemiological analysis of men with prostate cancer (PCa) in South Africa showed an increased PCa risk in Vhavenda people, the predominant population of Vhembe. The Vhembe District municipality falls in the malaria-endemic region, where DDT is used for vector control. The region of interest is fed by three major tributaries of the Limpopo River, which provide communities with agriculture, washing/bathing and portable water as well food (fish). Therefore, environmental levels of p,p-DDT, p,p-dichlorodiphenyldichloroethane (DDD) and p,p- dichlorodiphenyldichloroethylene (DDE) were measured before and after of the 2022 malaria high-transmission period (HTP), through sampling fish, from the Mutale and Mutshindudi rivers, and Thathe Vondo Dam. Fishes were bought from fishermen at the Thathe Vondo Dam and along the Mutale and Mutshindudi rivers. The fish's edible part (muscle), one piece raw and one piece cooked was tested for DDTs. Fish from the Mutshundudi River had higher DDT residuals than all other sites before the IRS. None of the DDTs were present after the yearly IRS. Daily exposure of DDTs for consumers was estimated by comparing estimated daily intake (EDI) with different criteria. The results revealed that the EDIs in our study were all lower than those criteria. Target hazard quotient (THQ) and risk ratio (R) were used to evaluate non-carcinogenic (toxic) and carcinogenic risks. There was no carcinogenic or toxic risk for humans consuming fish from the Mutale and Mutshindudi rivers and Thathe Vondo Dam. This indicates that DDT, DDD, and DDE in fish are not affecting the PCa burden in the Vhavenda men living in remote communities.

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Assessing the potential of biochar to restore degraded lands

(2024-09-06) Shirinda, Hazel; Stam, E. M.; Mugwedi, L.

Land degradation and climate change are interlinked processes that negatively impact sustainable development. Globally, they pose a risk to human livelihoods, but their effects are even more prominent in developing nations, especially in sub-Saharan Africa. Even with land degradation and climate change currently happening, communities, especially in developing countries, still need to adapt to the changes. This may be due to the high adaptation costs and the need for more knowledge. Biochar is the product of the thermochemical conversion of biomass through pyrolysis. Using biochar as a soil ameliorant has been increasingly advocated because of its effects on soil properties, crop productivity, and carbon sequestration. Biochar has been reported to improve soil quality, crop yield, and soil carbon sequestration potential. Despite this, little is known about the effects of biochar on soil physical properties, making it difficult to recommend biochar to improve soil quality in agriculture. Thus, this study aims to assess the potential of biochar to restore severely degraded land by improving soil properties and crop productivity and mitigating climate change through carbon sequestration at the Lapalala Wilderness Reserve, Waterberg District, Limpopo Province, South Africa. For this purpose, four treatments (biochar, biochar with fertilizer, biochar without fertilizer, and control) were applied to four plots, each replicated five times. A 14-species grass mixture was sown in each of the 20 plots. Soil physical and chemical properties, plant biomass, carbon stock, species richness, and species composition were then measured. None of the four treatments had a significant effect on soil bulk density while only biochar had a significant effect on soil chemical properties of soil Total C, Na and soil pH. No treatment had a significant effect on plant biomass. The analysis of similarity showed no significant difference in species composition for all treatments at month three and month six. The species composition for both treatments and sites for months three and six was mostly similar. The effects of biochar were not significant on soil chemical and physical properties as well as plant growth and biomass. Longer-term studies with higher rates of biochar application are required to confirm the effects of biochar on soil properties, plant growth, and species composition. The biochar feedstock (e.g., agricultural residues, forestry residues, and grassland cutting), biochar properties (such as porosity, bulk density, carbon content) and soil types need to be taken into consideration before application of biochar into the soil to enhance soil properties and plant growth.

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Economic optimization of assurance in stochastic yield analysis of water resource systems

(2024-09-06) Nyadawa, Chris Nduba; Makungo, R.; Mwaka, B.; Ndiritu, J.

Allocation of water from South Africa’s already straining water resources systems is a complex task given the ever-increasing water demand. The situation is made worse because of diminishing suitable sites for water resources infrastructure development, limited financial resources, and effects of climate change. To mitigate failure of water supply and ensure progressive water allocation, South Africa adopted a risk-based water allocation system in which it allocates water at different assurances of supply. Since assurance of supply is inversely proportional to yield, some water authorities tend to allocate water at relatively excessive high assurances of supply to mitigate total failure of water resources. This practice of allocating water at excessively high assurances of supply in turn reduces the amount of allocable water from the water resource. Consequently, the practice in turn results in either emerging users being denied access to water and/or lowly prioritised users being curtailed more early/frequently to satisfy the highly prioritised users. This study, therefore, examined prospects of optimizing existing water resources by specifically investigating the prospects of increasing the economic benefits from a water resource through reduction of its assurance of supply. The study therefore conducted a comparative analysis on the Western Cape Water Supply System (WCWSS) to assess if the yield of the system could be increased for more economic benefits by either reducing the assurance of supply only or by adopting an infrastructural development. To achieve this objective, the study compared the net benefits derived from the Berg River Voelvlei Augmentation Scheme (BRVAS) infrastructural development project that would increase the yield of the WCWSS by 23 x106 m3/a, and the net benefits that could be derived from an increase in yield due to reduction of assurance of supply by a margin that would result in a yield similar to that of the intended BRVAS infrastructural project. The second section determined incremental yields from Tzaneen Dam and their corresponding net economic benefits due to reduction of assurance of supply. The third section tested if the optimum assurance of supply of Tzaneen Dam was sensitive to other water resources systems characterized by different hydrological regimes. To conduct this sensitivity analysis, incremental yields and corresponding net benefits due reduction of assurance of supply from, Midmar, Goedertrouw, Mokolo and Boegeberg dams were determined. The comparative analysis demonstrated that the yield of the WCWSS could also be increased by reducing the assurance of supply from the existing 1 in 50 years (1:50) to 1 in 30 years (1:30). It also demonstrated that adoption of reduction of assurance of supply as a method of increasing assurance of supply more economic benefits when compared to yield augmentation through infrastructural interventions as reduction of assurance of supply had a net benefit of R 96.2 x106 while the BRVAS infrastructural intervention had a net benefit of R 15.5 x106. Results established that Tzaneen Dam could be optimised at 1:18 assurance of supply. It was therefore concluded that not all reductions of the assurance of supply result in an incremental increase of the net benefits. Results from the sensitivity analysis revealed that each water resources system is unique as different water resources used in the sensitivity analysis, Midmar, Goedertrouw, Mokolo and Boegeberg Dams had their optimum assurances of supply at 1:12, 1:12, 1:8 and 1:10 levels, respectively. Both the comparative analysis and the sensitivity analyses acknowledge the role played by water availability in socio-economic development, however, for ease of analysis due to challenges of quantifying contribution due to sufficient or insufficient water, the socio-economic aspect was not included in the analysis. Overall, the study highlighted that the economic benefits of a water resource may be optimized by reducing the assurance of supply up to a certain level. The study therefore recommended that this practice should also be considered as an alternative method of increasing water availability from a system.

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Physicochemical, antioxidant and microstructural properties of malted finger millet (Eleusine coracana) flour(s) and their use in gluten-free biscuits.

(2024-09-06) Murungweni, Kundai Thelma; Ramashia, S. E.; Mashau, M. E.

Finger millet is a gluten-free crop with outstanding malting qualities, and a low glycaemic index. The study aimed to determine the physicochemical, antioxidant, and microstructural properties of malted finger millet flours (light and dark brown) and their use in gluten-free biscuits. The two varieties of finger millet grains were germinated for 0, 24, 48, and 72 hours (h) and kilned for 8 h at 30°C. The lightness (L*) values of malted finger millet flours significantly increased (p ≤ 0.05), with light brown having the highest L* value of 76.62. The moisture, ash, fibre, protein, mineral, total phenolic and total flavonoid contents and DPPH activity of both malted finger millet flours and biscuits significantly increased (p ≤ 0.05). Both malted finger millet flours' solubility index, water and oil absorption capacity increased significantly, while the packed and loose bulk density decreased. A significant decrease in the viscosity of the cooked paste in both finger millet flours was observed. Malting resulted in an increase in the onset, peak, and conclusion temperatures. FTIR showed that malting slightly changed the peaks of both finger millet flours. Scanning electron microscopy showed that malting altered the microstructural characteristics of finger millet flours. The yellowness and whiteness index of FM biscuits significantly increased, ranging from 41.47 to 42.12 and 42.21 to 45.47 (light brown) and from 67.78 to 70.97 and 71.92 to 75.41 for dark brown, respectively. The weight, diameter, thickness, and spread ratio significantly decreased with an increase in malting in both FM biscuits. The hardness of the biscuits significantly increased from 762.53 to 1720.28 g (light brown) and 747.50 to 1918.71 g (dark brown). The LB biscuits had more desirable sensory attributes as compared to the DB biscuits. It was concluded that malted FM flour can be used to prepare nutritious and healthier gluten-free bakery products.

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Mapping activities of stakeholders along selected value chains in Vhembe District Municipality, South Africa

(2024-09-06) Mulaudzi, Rotondwa; Zuwarimwe, J.; Mathaulula, M. A.

Farmer’s, transporters and retailers are major key players along the vegetable value chains in South Africa and globally. Their roles and activities along the vegetable value chain are affected by lack of capital, resources, transportation, storage, packaging materials, education and high transactional costs. This is evidenced by high levels of dissatisfactions along the vegetable value chain and is contributing to high loss of jobs in the vegetable industry, shortage and high cost of vegetables and increasing number of vacant farms. Thus, this study was carried out to Map activities of stakeholders along selected vegetable value chain in Vhembe District Municipality, South Africa. The quantitative research approach was adopted. Stratified simple random sampling technique was used to select 185 respondents. Self-administered structured questionnaire consisting of closed-ended questions was used to collect primary (raw data). A 5-point Likert-type scale ranging from 5 (strongly agree) to 1 (strongly disagree) was also used in the process. The study used descriptive analysis, (mean, median, and mode), range variance, standard deviation and some inferential statistics for the analysis. The data was analysed using IBM Statistical Package for the Social Science version 28.0.1.1. Atlas t.i version 8 was also used to create diagrams for analysis. Cronbach’s alpha was used to ensure reliability and high internal consistency of Likert-type scale. The study shows that players need various sources of assistants as to ensure sustainable vegetable value chain. The study further reflects that though they are faced with various challenges players are striving to ensure food security, sustainable vegetable value chains, good nutrition and to achieve goal 2 (ending hunger, achieving food security and promoting sustainable agriculture) of the SDG’S.