http://hdl.handle.net/10386/73 2026-04-05T17:46:43Z http://hdl.handle.net/10386/5387 A low flow-high flow investigation into the effect of selected micronutrients on pre-determined innate immune biomarkers in two freshwater fish species from Witbank dam, Mpumalanga Radzuma, Murendeni Unarine Sandra The aquatic environment is constantly in jeopardy since it is the ultimate recipient of waste disposal. Mining, industrial and agricultural developments have led to a significant increase in, amongst others, heavy metal contamination in aquatic systems. The aim of this study was to use seasonal surveys to investigate the impact of Fe, Cu, and Zn levels on immune modulation in Cyprinus carpio and Micropterus salmoides collected from Witbank Dam, Mpumalanga. This study consisted of two surveys that were conducted during low flow periods in June and high flow periods in November. Temperature, pH, dissolved oxygen, conductivity, total dissolved solutes (TDS) and salinity were measured using YSI multiparameter instrument. A litre of water and sediment samples were collected from three different sites, while 26 common carp and 12 largemouth bass were sampled using conventional fishing gear. For each fish, the weight and length were measured. Furthermore, epidermal mucus and blood samples were collected. Serum and mucus samples were divided, half was treated with PBS and the other with protease inhibitor cocktail and stored at -20°C until further analysis. Gills, liver, and muscle tissue were dissected, weighed, rinsed, and frozen at -85°C for later analysis of Fe, Cu, and Zn levels by Waterlab (Pty) Ltd, Pretoria. From the results, it was discovered that Witbank dam is polluted by Cu and Zn. Furthermore, Cu concentrations were only detected in the liver of both common carp and largemouth bass. Iron and zinc were detected in varying concentrations across tissues, with Fe levels being highest in the liver and gills, particularly in largemouth bass, and Zn levels being highest in the gills of common carp. The use of the protease inhibitor cocktail was found to significantly preserve CRP levels, with treated samples showing higher concentrations compared to untreated samples, indicating its effectiveness in preventing protein degradation. The study highlights the need for pre-analytical care in feral studies to ensure accurate biomarker measurements and highlights the seasonal fluctuations in metal exposure, which could influence immune responses in fish. The recommendations of the study include implementing regular monitoring of metal concentrations in aquatic ecosystems and considering the use of protease inhibitors in future studies involving immune biomarkers. The study was limited to a small sample size and one sampling area. Thesis (M.Sc. (Physiology)) -- University of Limpopo, 2025 2025-01-01T00:00:00Z http://hdl.handle.net/10386/5056 Evaluation of climate change influence on non-point source pollution in the Sand River Catchment, Limpopo, South Africa Chuene, Tlhogonolofatso Abram Non-point source (NPS) pollution of freshwater resources is a major environmental concern as untraceable pollutants contribute to the deterioration of water quality which affects human, animal and environmental wellbeing and sustainability. This study evaluated the influence of climate change on NPS pollution in the Sand River Catchment (SRC). Excel statistical (XLSTAT, version 2023) Mann-Kendall and Sen’s slope trend analysis were employed to determine the historical trends in precipitation and minimum, maximum, and average temperature, using monthly timeseries data from October 1992 to September 2022. Soil and Water Assessment Tool plus (SWAT+ rev. 61) was set up, calibrated, validated, and used to simulate the monthly and annual sediment and nutrient constituents, Total Inorganic Nitrogen (TIN), and Total Inorganic phosphorus (TIP) loads in the SRC. The one-way analysis of variance (ANOVA) was used to determine the significance of the relationships between temperature and precipitation and the sediment, TIN, and TIP loads. SWAT+ was further used to implement and evaluate the performance of Best Management Practices (BMPs) (Vegetative Filter Strips (VFS), Grassed Waterways (GWW), and VFS+GWW on the pollution control in the SRC. The trend analysis results showed that there has been an insignificant (P > 0.05) steady increase in average and maximum temperature in the SRC. There was, however, a decrease in minimum temperature. Moreover, the results showed a significant (P < 0.05) decrease in precipitation in the same timeframe. The SWAT+ calibration and validation results showed that the statistical indices (NSE and R2 ≥ 0.72; –17.30 ≤ PBIAS ≤ 14.74) fell within an acceptable range with a good agreement between the observed data and the simulated output. The results of the assessment of the impact of climate change on the nutrient constituents of the basin confirmed the influence of average monthly temperature and precipitation on average monthly sediment, TIN, and TIP loads. The load decreased during low precipitation months and increased during high precipitation months. The average annual precipitation significantly (P < 0.05) decreased with a decrease in average annual sediment (R2 = 0.63), TIN (R2 = 0.73), and TIP (R2 = 0.55) load. However, average annual temperature significantly (P < 0.05) increased with a decrease in sediment (R2 = 0.23), TIN (R2 = 0.19), and an insignificant (P > 0.05) decrease in TIP (R2 = 0.05). The BMP results showed that the VFS was effective in retaining low sediment, TIN, and TIP loads at sub-catchment level and catchment level (27/23%, 23/20%, and 30/25%), respectively, compared to GWW (47/38%, 35/31%, and 43/31%), respectively. Moreover, the combination of VFS and GWW (VFS+GWW) effectively retained high loads of sediment, TIN, and TIP in sub-catchment level when compared to catchment level (70/58%, 66/56%, and 71/62%), respectively. The study concluded that climate change influences NPS pollution in the SRC, and BMPs can be employed to manage and control the agricultural NPS pollution within the catchment. Furthermore, implementing BMPs at sub-catchment level is the most effective management of NPS pollution in the SRC. Thesis (M. Sc. (Geography)) -- University of Limpopo, 2025 2025-01-01T00:00:00Z http://hdl.handle.net/10386/4955 Evaluation of community perceptions on outdoor air pollution in Marapong and Onverwacht Townships, Lephalale Local Municipality, South Africa Mabeba, Motsoka Refiloe Audrey Outdoor air pollution is a challenge globally, especially in developing countries. It is associated with deleterious effects on the environment and human health. The aim of this study is to evaluate how the communities of Marapong and Onverwacht perceive outdoor air pollution and the risks they are exposed to. It is conducted to identify whether the respondents are relating outdoor air pollution to particular diseases and environmental issues, as well as how they perceive the measures implemented to tackle outdoor air pollution and its related effects. The study area is located in Lephalale Local Municipality. For this study, primary data and secondary data were collected. The primary data was collected using questionnaires distributed to 232 participants from the two townships of Lephalale Local Municipality. Questionnaires were used to collect data to assess how communities perceived outdoor air pollution and its effects. Existing literature from secondary data sources such as the internet, government publications, articles and journals were also used to collect and extract information on outdoor air pollution in global, regional and local countries as well as its associated human health and environmental implications. The study findings revealed that participants from both Marapong and Onverwacht townships are aware of the occurrence of outdoor air pollution in their localities and the impact it has on their health as well as their surrounding environment. However, the participants had limited knowledge of measures implemented by the private and public sectors to address the challenges of outdoor air pollution and its associated environmental and human health implications. The study concludes that residents in the affected areas lack awareness and are not adequately involved in decision-making processes to address outdoor air pollution and implement control measures. Therefore, it recommends raising awareness in the communities both public and private sectors about the sources, consequences, and mitigation measures of outdoor air pollution through various information sources. This includes encouraging individuals to take action to minimize the generation of outdoor air pollution. Understanding how people are impacted, their concerns, priorities, and willingness to accept governmental policies or laws is essential for developing effective measures to address the issue of outdoor air pollution. Thesis (M. Sc. (Geography)) -- University of Limpopo, 2023 2024-01-01T00:00:00Z http://hdl.handle.net/10386/4871 A longitudinal investigation on the effects of sodium and potassium intake have on the development of hypertension and abdominal obesity from childhood to young adulthood amongst Ellisras rural population, South Africa Raphadu, Thato Tshepo Background: Hypertension (HT) and obesity have both been on the rise in children. Each is associated with an increase in cardiovascular disease risk and both track into adulthood. Objectives: Hence, this study aimed to identify the association of sodium intake (Na), potassium (K) intake, and sodium-to-potassium (Na/K) ratio with the development of HT and abdominal obesity amongst the Ellisras rural population over time. Methods: In this longitudinal study, data on dietary intake of Na and K were collected using a 24-h recall questionnaire from a total of 325 participants tracking them from 1999 (5–12 years), 2001 (7–14 years) and 2015 (18–30 years). Blood pressure (BP) and anthropometric measurements [waist circumference (WC) and height] Parametric (independent t-test) and Chi-square/Fishers’ exact tests were conducted to determine the difference between the years for numerical data and categorical variables. A generalized estimating equation (GEE) was conducted to assess the association of Na intake, K intake; and their ratio on BP, WC and WHtR. Results: Our results indicate a significant positive association between K intake and WHtR [β= 0.019, (95% CL: 0.004, 0.034) p-value= 0.012], and even the model was adjusted for age and sex there was still an association with WHtR. Na/K ratio was associated with SBP [β= 4.326, (95% CL: 2.056, 6.595) p-value= < 0.001], DBP [β= 2.028, (95% CL: 0.703, 3.353) p-value= 0.003], WC [β= 4.191, (95% CL: 2.080, 6.302) p-value= < 0.001] and WHtR [β= 0.014, (95% CL: 0.003, 0.026) p-value= 0.015], respectively. Furthermore, Na/K was shown to be associated with an increased risk of developing HT [Exp = 1.603, (95% CL: 1.164, 2.207) p-value= 0.004] and abdominal obesity [Exp = 1.797, (95% CL: 1.207, 2.677) p-value= 0.004]. Conclusion: In our study we observed that an increase in Na/K it’s a predictor of HT and abdominal obesity over time compared to Na and K alone. However, more studies are required to further prove this. Thesis (M.Sc. (Physiology)) -- University of Limpopo, 2023 2023-01-01T00:00:00Z