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    A critical analysis of the environmental and social impacts of human settlement development projects in Gauteng, South Africa, A study of City of Ekurhuleni
    (University of the Witwatersrand, Johannesburg, 2025) Marilele, Mkateko Hlongo; Kubanza, Nzalalemba Serge
    With the proliferation of emerging urban human settlement development projects, there is an increasing urban socio-environmental impact that is considered a global challenge facing cities in developing countries. The most affected are the vulnerable urban dwellers whose livelihood is negatively affected by environmental and social challenges. Using the City of Ekurhuleni (CoE), Gauteng, South Africa, as a point of departure, this study critically analysed the environmental and social impacts of human settlement development projects emanating from communities established by the government. The study used a mixed method research strategy to collect and analyse the data. Phase One focused on interviewing community members residing around the five (5) selected human settlement development projects that were constructed between 2020 to 2023. Phase Two focused on interviewing government officials (CoE and Gauteng Department of Agriculture and Rural Development (GDARD) as well as non-government officials (environmental consulting firms). Phase Three consisted of a Focus Group Discussion (FGD) held with a group of environmental specialists from government and non-governmental organisations. The last phase of data collection focused on a review of Environmental Impact Assessment (EIA) reports of the five selected human settlement development projects that were purposively sampled to provide information about the effectiveness of EIA and Social Impact Assessment (SIA) in mitigating environmental and social impacts. The review package designed by Lee and Colley (1999) was utilised in grading performance symbols on the quality of projects’ EIA reports in terms of impact identification and mitigation measures. The collected data was analysed to produce the study results. Qualitative data was subjected to a thematic analysis to arrange data into themes. In contrast, quantitative data was analysed using the Statistical Package for the Social Sciences (SPSS) version 22 and Microsoft Excel simple descriptive analysis to generate percentages and frequencies. The study revealed that the population increase in Gauteng, South Africa, has contributed to a high demand for housing development projects, which further contributed to the continued expansion of residential areas in the CoE. The study revealed that SA government through the ministry of Environmental Affairs, has developed good policies and regulations for EIA processes where SIA is also included as one of the specialist studies to be conducted in the EIA process. A major challenge is the lack of standardised and detailed legislated procedures on EIA regulations that guide how social issues must be assessed in the context of the EIA process. The results further revealed that the current existing environmental policies are insufficient to tackle environmental and social impacts encountered during the operational phase of the housing developments. Of particular concern is the absence of project monitoring once the construction of houses is completed and residents have taken occupation. A major challenge is the lack of standardised and detailed legislated procedures on EIA regulations that guide how social issues must be assessed in the context of the EIA process. The results also emphasised that without the proper implementation of housing developmental programmes, poor vulnerable people will utilise open spaces to establish slums closer to working areas even though they are situated in a sensitive environment. The findings highlighted the urgent need to understand the complex interplay between the sustainability of human settlements and spatial equality. Finally, the study results recommended the need to raise awareness among stakeholders to mitigate the environmental and social impacts of human settlement development projects in the CoE.
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    Profiling Pharmaceutical Residues in South African Aquatic Ecosystems: A Dual Approach Using Grab Sampling and Passive Sampling Techniques
    (University of the Witwatersrand, Johannesburg, 2025-05) Mapetla, Sabetha Makoma; Chimuka, Luke; Richards, Heidi L.
    Pharmaceutical pollution in aquatic ecosystems is a growing environmental concern due to its persistence as a result of the continuous output of pharmaceuticals, their potential to bioaccumulate, and the ecotoxicological risks they pose. This study employed a dual sampling approach, that is grab sampling and passive sampling to assess the occurrence, transport, and distribution of pharmaceutical contaminants in South African freshwater and estuarine systems. Ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-Q-Orbitrap MS) was used to analyse pharmaceutical residues across three case studies focusing on urban rivers and estuarine waters. Chapters 1 and 2 provide a comprehensive review of the existing literature related to pharmaceutical residues in aquatic environments, with a particular focus on the South African context. Chapter 1 provides an overview of pharmaceutical pollution in aquatic ecosystems, highlighting its emergence as a critical environmental issue in South Africa. It discusses the sources, persistence, and ecological impacts of pharmaceutical contaminants, emphasizing their ability to remain biologically active at trace and ultra-trace concentrations. The chapter highlights the importance of effective sampling strategies in monitoring these pollutants, comparing traditional grab sampling with passive sampling techniques. It reviews the limitations of current approaches and identifies knowledge gaps, particularly in South African estuarine systems. The chapter concludes by advocating for an integrated sampling methodology to improve the accuracy and reliability of pharmaceutical pollution assessments, thereby informing better environmental management and policy development. Chapter 2 begins by exploring the global and local occurrence of pharmaceutical contaminants, outlining their sources, pathways, and environmental persistence. The chapter then examines various sampling techniques employed for monitoring these contaminants, specifically highlighting the use of grab sampling and passive sampling methods such as the Chemcatcher device. The strengths, limitations, and comparative efficiencies of these techniques are discussed. Analytical techniques for detecting pharmaceutical residues, especially high-resolution methods UHPLC-MS, are also reviewed. Finally, the chapter addresses the regulatory landscape, potential ecological and identifies existing knowledge gaps that justify the need for further research. This review lays the groundwork for the study’s objectives by contextualizing the environmental threat posed by pharmaceutical pollutants and the methodologies suitable for their detection and monitoring. Chapter 4 explored pharmaceutical pollution in the Hennops River and Hartbeespoort Dam, a heavily polluted system influenced by wastewater treatment plant (WWTP) effluents, agricultural run-off and untreated sewage discharges. In the study, a UHPLC-Q-Orbitrap MS method was developed and optimized for the analysis of carbamazepine, dexamethasone, etilefrine, methocarbamol, nevirapine and venlafaxine. Method optimization yielded SPE recoveries ranging from 55.18 – 80.52 % and 55.73 – 83.92 % for ultrapure and river water, respectively. Method LODs and LOQs ranged from 0.15 – 2.03 ng L-1 and 0.49 – 6.75 ng L-1, respectively. A Chemcatcher passive sampler was calibrated for the uptake of the target pharmaceutical compounds. Five of the six pharmaceutical compounds showed good linearity (R2 > 0.97) for the duration of the calibration experiment. Etilefrine, however, was only linear until day eight. As such, the sampling rate for etilefrine could not be determined. For the five compounds that showed good linearity over the 16-day calibration experiment, sampling rates ranging from 0.360 (dexamethasone) to 0.447 (carbamazepine) L day-1 were obtained. Applying the sampling rates, time-weighted average (TWA) concentrations in the ranges 0.50 (methocarbamol) – 17.87 (dexamethasone) µg L-1 were obtained. These were compared to SPE extract concentrations, which ranged from <LOD (venlafaxine) – 84.71 (dexamethasone) µg L-1. Although the SPE maximum extract concentrations were generally higher than Chemcatcher maximum TWA concentrations, Chemcatcher demonstrated enhanced sensitivity, and in some cases captured TWA concentrations that were up to five times higher than SPE. In suspect screening, 25 pesticides and 61 pharmaceutical compounds were detected with the detection frequency higher for Chemcatcher compared to SPE extracts. Chapter 5 investigated the occurrence of pharmaceutical compounds in the Durban Marina estuary using both sampling approaches. The study was expanded to nine pharmaceutical compounds with the addition of lopinavir, metformin and trimethoprim, however, these compounds were not included in the laboratory calibration of the Chemcatcher sampler in seawater. In the Chemcatcher calibration experiment, five compounds showed good linearity (R2 > 0.981). The exception was etilefrine, which was linear only until day eight. The seawater laboratory calibration experiment yielded sampling rates from 0.34 (dexamethasone) – 0.42 (carbamazepine & venlafaxine) L day-1. The analytical method was optimized and SPE recoveries were in the ranges 74.82–99.45% in seawater, and 72.24–103.42% in ultrapure water. Method LODs and LOQs were found to range from 0.15 to 2.18, and 0.50 to 7.27 ng L-1, for venlafaxine and methocarbamol, respectively. Chemcatcher consistently shows a higher detection frequency (88.89%) across all sampling sites, whereas SPE detection frequencies varied more across sites (55.56 – 77.78%). Extract concentration sums per site were found to be higher in Chemcatcher (up to 2574.52 ng L-1 at S2) than SPE (up to 43.81 ngL-1 at S1). Applying the experimental sampling rates, TWA concentrations up to 290.18 ng L-1 (dexamethasone) at S5 were determined. These were compared to the grab water sample concentrations in the sampling medium, which reached a maximum of 0.1594 ng L-1 (nevirapine) at S2. Passive samplers revealed the persistent presence of these contaminants, while grab sampling showed fluctuating concentrations. The study also highlighted the influence of tidal dynamics on pharmaceutical distribution, emphasising the limitations of grab sampling in estuarine environments. Chapter 6 expanded on Chapter 4 by examining the transport and distribution of the nine target pharmaceutical compounds in the Crocodile River system after it exits Hartbeespoort Dam, using the dual sampling approach. The Crocodile River system is a critical water source, which serves mostly agricultural, domestic and industrial activities. The study identified significant pharmaceutical loads, with Chemcatcher consistently demonstrating a higher detection frequency, reaching 100% at S2 and S3, while SPE exhibited greater variability, with detection frequencies ranging from 44.44% (S5) to 88.89% (S2 & S3). As with detection frequency, pharmaceutical concentration sums per site in the extracts were found to be higher with Chemcatcher (up to 1191.05 ng L-1 at S2), confirming passive sampling advantages in long term monitoring. The major contributors to Chemcatcher concentrations were found to be methocarbamol and etilefrine. S3 and S5 exhibited the lowest concentration sums (447.05 ng L⁻¹ and 388.60 ng L⁻¹, respectively), despite S3 having the highest detection frequency. Time weighted average (TWA) concentrations confirmed methocarbamol as the most persistent compound (68.34 ng L⁻¹ at S1), followed by trimethoprim (29.52 ng L⁻¹ at S3) and lopinavir (30.13 ng L⁻¹ at S1). Contaminant transport was influenced by anthropogenic inputs, dilution, and tributary contributions, particularly from the Gwatlhe, Hex and Elands Rivers, which increased contaminant loads at S7 (518.10 ng L⁻¹). The transport and distribution of pharmaceutical contaminants in the Crocodile River system exhibited spatial variability influenced by multiple factors, including anthropogenic inputs, hydrological processes, and the complexity of tributary networks. Overall, this research highlights the widespread occurrence of pharmaceuticals in South African aquatic environments and emphasises the importance of incorporating passive sampling to capturing low-concentration contamination trends. The study advocates for integrating passive sampling into routine monitoring programs to enhance the detection, management, and mitigation of pharmaceutical pollution.
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    Serum free light chains in a racially diverse population including African Americans and populations from South Africa
    Luca Bertamini; Jean-Baptiste Alberge; David J. Lee; Habib El-Khoury; Lindokuhle Goqwana; Vinitha Philip-Cherian; Natalie Smyth; Wenlong Chen; Maureen Joffe; E et al
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    Structural Analysis of the Lower Witwatersrand Supergroup in the Vredefort Dome, South Africa
    (University of the Witwatersrand, Johannesburg, 2025) Manzi, Shalene; Gibson, Roger L.; Tshibubudze, A.
    Hypervelocity impact craters are sites of exceptionally large, focused, energy release that results in extreme stresses, finite strains and strain rates in target crust. In particular, large impact structures are characterised by complex internal morphologies involving second- and third-order structures. The formation of second-order features, such as central uplifts are successfully reproduced by numerical models such as iSALE, which assume gross hydrodynamic behaviour of the crust, even if the reason for such behaviour is not fully understood. However, within central uplifts, field and petrographic studies show that strain is highly heterogeneous at all scales. This study examines brittle and ductile features in the 2.02 Ga Vredefort Dome, the largest and most deeply eroded central uplift on Earth. It focuses particularly on three areas close to the contact between the massive crystalline core and the basal parts of layered supracrustal sequence located between 20 km and 22 km from the centre of the Dome, where the lithologically-heterogenous lower West Rand Group of the Witwatersrand Supergroup is well exposed. Geometric analysis of shatter cones, branching (horsetail) fractures and a near-orthogonal pair of cm-spaced, so-called shatter cleavages shows some preferred centrosymmetry linking them to the shock wave within the first few seconds of impact. A 3D analysis of two large faults with individual slips of 400 - 500 m provides the first evidence of a conjugate pair of originally tangentially-striking normal faults attributed to collapse of the transient crater wall approximately 1 minute after impact. Structural analysis of large pseudotachylyte dykes and vein networks establishes that they formed by frictional melting related to these faults. Brittle-ductile folding with steep tangentially-striking axial planes and shallow-plunging hinges and wavelength of ~ 800 m and amplitude of ~ 100 m is linked to central uplift collapse between 3 and 4 minutes after impact, and is distinct from previously recognised radially-oriented constrictional folds that formed ~70-90 s after impact. This was followed by late-stage concentric and radial-conjugate normal faults with centre down slip attributed to central uplift collapse, which also contain significant pseudotachylyte volumes. The final stage involves the intrusion of the granophyre impact melt intrusion into tensional fractures. The evidence of multiple stages of faulting emphasises the need for more careful analysis of the fault patterns in the collar of the Dome. Although no bilateral symmetry was detected in fault and bedding strike patterns shown in published maps, future work establishing the 3D geometry and relative chronology of the faults is recommended before testing this aspect again. The cumulative field evidence indicates that second-order structures in the collar of the Vredefort Dome preserve a complex, multistage record of evolving strain that can be resolved into initial transient crater wall collapse, intermediate convergent and upward flow (constriction) related to central uplift rise and later divergent and downward flow (flattening) linked to its collapse, and that can be matched to the general stress-strain predictions of iSALE numerical modelling. This suggests that applying conventional structural mapping techniques to central uplifts in multi-ring impact structures can assist in understanding their highly dynamic evolution.