4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item Hydroponic farming for saffron cultivation in South Africa(University of the Witwatersrand, Johannesburg, 2024) Smit, JohanIn South Africa, saffron has exclusively been cultivated using traditional farming methods. Although farmers face an increasing range of challenges and uncertainties, hydroponic farming offers an opportunity to alleviate many of these challenges, while simultaneously increasing output and reducing input expenses. The primary objective of the planned business venture was to investigate the possibility for hydroponic saffron farming in South Africa. The study focused on the development of a hydroponic system to cultivate saffron, aiming to mitigate the daily difficulties and risks faced by conventional farmers. The study adopted a qualitative exploratory research approach. The study gathered substantial information through interviews with farmers in both the traditional saffron and non-saffron hydroponic industries. Interviewing farmers provided insights into the perspectives of persons involved in both the traditional saffron industry and the non-saffron hydroponic growing sector. Three hydroponic cultivators and one saffron farmer were interviewed face-face. Another Saffron farmer was interviewed telephonically. The study examined the necessary requirements for hydroponic saffron cultivation in South Africa, covering technical factors for saffron cultivation, operational prerequisites, financials, market analysis, and challenges. The research findings highlighted the significance of hydroponic systems within an overall context. The main driving force for the transition from traditional farming to hydroponics was climate change among the participants. An essential challenge in hydroponic saffron growing is its relatively lower profitability compared to other crops like herbs, lettuce, and tomatoes. Including the concept of opportunity cost into the breakeven analysis will lead to a reduced repayment period, hence justifying the concept of saffron cultivation with a hydroponic system. In conclusion, cultivating saffron with hydroponics is a sustainable solution when considering opportunity costs due to the value of the spice, and the increasing uncertainty of climate change affecting output.Item Responsiveness of South African semi-commercial farmers to climate change(University of the Witwatersrand, Johannesburg, 2024) Maliba, Bheki; Saruchera, FannyAgriculture is crucial for sustaining rural livelihoods and promoting economic growth. However, climate change threatens agriculture as it is directly linked to climate factors. This study assesses how semi-commercial farmers are responding to climate change. The objectives were to (1) examine the perceptions of South Africa’s semi-commercial farmers on climate change; (2) assess the responsiveness of semi-commercial farmers to climate change; and (3) assess the influence of adaptation strategies on the performance of semi-commercial farmers. The data was collected through a self-administered questionnaire from 90 respondents and analysed. The demographic characteristics of the semi-commercial farmers were analysed using frequencies and descriptive statistics. In addition, a correlation analysis was conducted to determine relationships between different constructs, and multiple linear regression was used to model the relationship between variables. Most of the 90 respondents were 35 to 54 years old and had a high level of tertiary education (83.33%). The analysis of years in farming reveals a moderate experience level among participants, with 56.67% engaged in farming for 10-24 years. Rainfed agricultural practices dominated, with 57.78% relying solely on natural rainfall. Regarding access to credit, the mean score of 2.21 (standard deviation = 1.06) shows that, on average, respondents disagreed with the statements in the questionnaire about access to adequate credit, affordable lending rates, easy access to finance and alternative funding sources. Crop productivity indicated a positive correlation with soil and water conservation, and there was a positive correlation between changes in temperature and soil and water conservation. This suggests that their perception of temperature changes influences semi-commercial farmers' adaption strategies and that adopting climate strategies improves crop productivity. The study proved that soil and water conservation and crop diversification significantly predict crop productivity (performance). Recognising the positive correlation between soil and water conservation and crop diversification techniques and the perceived increased crop productivity, policymakers and agricultural extension services should prioritise and advocate for these strategies. Given the significant variations in respondents' access to credit, interventions should be tailored to the different financial needs of semi- commercial farmers. It is recommended that future research incorporate more comprehensive analyses of the development prospects of semi-commercial farmers, considering regional differences and assessing the long-term impact of adaptation strategies on actual agricultural productionItem A documentation of the morphology of the lungs of the Sprague Dawley rat after chronic heat exposure(University of the Witwatersrand, Johannesburg, 2023) Peya, Yolanda; Reddy, DeranClimate change is a natural phenomenon that is exacerbated by mul4ple human ac4vi4es in the environment. These ac4vi4es lead to a rise in global temperatures. This increases the occurrence of heatwaves which pose a major threat to ecosystems, biodiversity, and the conserva4on of species on Earth. This study, aimed to document the effects of chronic heat exposure on the lungs of the Sprague Dawley rat using histological and immunofluorescence techniques. Twenty-four (24) rats were assigned to three groups; each exposed to different temperatures; (i) group A (n = 8) exposed to 25 °C (ii) group B (n = 8) exposed to 33 °C and (iii) group C (n = 8) exposed to 34 °C. This was done for a period of 4 weeks and the rats were euthanised therea`er. Methods employed included Intratracheal instillation, and histological and immunofluorescence techniques. This study found that rats in group A (25 °C) displayed no structural adapta4ons in comparison to groups B and C. Enlarged blood vessels with thick smooth muscle and prominent elas4c fibres, bronchus-associated lymphoid 4ssue (BALT), and increased collagen deposi4on were observed in group B (33 °C). These indicate the ac4va4on of immune responses and adapta4on to new environmental temperatures. In group C (34 °C), the lung morphology was severely damaged. There was an increased loss of epithelial integrity, oedema, pulmonary alveolar proteinosis (PAP), and a severe decrease in the lung- to-surface area ra4o. The significant changes caused by the 1 °C temperature difference between groups B (33 °C) and C (34 °C) illustrate the detrimental effects of chronic heat stress. It is evident that increasing environmental temperatures due to climate change is harmful to life and immediate interven4ons are necessary to combat rising temperaturesItem Symmetry reductions and approximate solutions for heat transfer in slabs and extended surfaces(University of the Witwatersrand, Johannesburg, 2023-06) Nkwanazana, Daniel Mpho; Moitsheki, Raseelo JoelIn this study we analyse heat transfer models prescribed by reaction-diffusion equations. The focus and interest throughout the work is on models for heat transfer in solid slabs (hot bodies) and extended surface. Different phenomena of interest are heat transfer in slabs and through fins of different shapes and profiles. Furthermore, thermal conductivity and heat transfer coefficients are temperature dependent. As a result, the energy balance equations that are produced are nonlinear. Using the theory of Lie symmetry analysis of differential equations, we endeavor to construct exact solutions for these nonlinear models. We will employ a number of symmetry techniques such as the classical Lie point symmetry methods, the nonclassical symmetry, nonlocal and nonclassical potential symmetry approach to construct the group-invariant solutions. In order to identify the forms of the heat source term that appear in the considered equation for which the principal Lie algebra (PLA) is extended by one element, we first perform preliminary group classification of the transient state problem. Also, we consider the direct group classification method. Invariant solutions are constructed after some reductions have been performed. One-dimensional Differential Transform Method (1D DTM) will be used when it is impossible to determine an exact solution. The 1D DTM has been benchmarked using some exact solutions. To solve the transient/unsteady problem, we use the two-dimensional Differential Transform Method (2D DTM). Effects of parameters appearing in the equations on the temperature distribution will be studied.Item The application of machine learning methods to satellite data for the management of invasive water hyacinth(University of the Witwatersrand, Johannesburg, 2023-06) Singh, Geethe; Reynolds, Chevonne; Byrne, Marcus; Rosman, BenjaminBiological invasions are responsible for some of the most devastating impacts on the world’s ecosystems, with freshwater ecosystems among the worst affected. Invasions threaten not only freshwater biodiversity, but also the provision of ecosystem services. Tackling the impact of invasive aquatic alien plant (IAAP) species in freshwater systems is an ongoing challenge. In the case of water hyacinth (Pontederia crassipes, previously Eichhorniae crassipes), the worst IAAP presents a long-standing management challenge that requires detailed and frequently updated information on its distribution, the context that influences its occurrence, and a systematic way to identify effective biocontrol release events. This is particularly urgent in South Africa, where freshwater resources are scarce and under increasing pressure. This research employs recent advances in machine learning (ML), remote sensing, and cloud computing to improve the chances of successful water hyacinth management. This is achieved by (i) mapping the occurrence of water hyacinth across a large extent, (ii) identifying the factors that are likely driving the occurrence of the weed at multiple scales, from a waterbody level to a national extent, and (iii) finally identifying periods for effective biocontrol release. Consequently, the capacity of these tools demonstrates their potential to facilitate wide-scale, consistent, automated, pre-emptive, data-driven, and evidence-based decision making for managing water hyacinth. The first chapter is a general introduction to the research problem and research questions. In the second chapter, the research combines a novel image thresholding method for water detection with an unsupervised method for aquatic vegetation detection and a supervised random forest model in a hierarchical way to localise and discriminate water hyacinth from other IAAP’s at a national extent. The value of this work is marked by the comparison of the user (87%) and producer accuracy (93%) of the introduced method with previous small-scale studies. As part of this chapter, the results also show the sensor-agnostic and temporally consistent capability of the introduced hierarchical approach to monitor water and aquatic vegetation using Sentinel-2 and Landsat-8 for long periods (from 2013 - present). Lastly, this work demonstrates encouraging results when using a Deep Neural Network (DNN) to directly detect aquatic vegetation and circumvents the need for accurate water extent data. The two chapters that follow (Chapter 3 and 4 described below) introduce an application each that build off the South African water hyacinth distribution and aquatic vegetation time series (derived in Chapter 2). The third chapter uses a species distribution model (SDM) that links climatic, socio-economic, ecological, and hydrological conditions to the presence/absence of water hyacinth throughout South Africa at a waterbody level. Thereafter, explainable AI (xAI) methods (specifically SHapley Additive exPlanations or SHAP) are applied to better understand the factors that are likely driving the occurrence of water hyacinth. The analyses of 82 variables (of 140 considered) show that the most common group of drivers primarily associated with the occurrence of water hyacinth in South Africa are climatically related (41.4%). This is followed by natural land cover categories (32.9%) and socio-economic variables (10.7%), which include artificial land-cover. The two least influential groups are hydrological variables (10.4%) including water seasonality, runoff, and flood risk, and ecological variables (4.7%) including riparian soil conditions and interspecies competition. These results suggest the importance of considering landscape context when prioritising the type (mechanical, biological, chemical, or integrated) of weed management to use. To enable the prioritisation of suitable biocontrol release dates, the fourth chapter forecasts 70-day open water proportion post-release as a reward for effective biocontrol. This enabled the simulation of the effect of synthetic biocontrol release events under a multiarmed bandit framework for the identification of two effective biocontrol release periods (late spring/early summer (mid-November) and late summer (late February to mid-March)). The latter release period was estimated to result in an 8-27% higher average open-water cover post-release compared to actual biocontrol release events during the study period (May 2018 - July 2020). Hartbeespoort Dam, South Africa, is considered as a case study for improving the pre-existing management strategy used during the biocontrol of water hyacinth. The novel frameworks introduced in this work go a long way in advancing IAAP species management in the age of both ongoing drives towards the adoption of artificial intelligence and sustainability for a better future. It goes beyond (i) traditional small-scale and infrequent mapping, (ii) standard SDMs, to now include the benefits of spatially explicit model explainability, and (iii) introduces a semi-automated and widely applicable method to explore potential biocontrol release events. The direct benefit of this work, or indirect benefits from derivative work outweighs both the low production costs or equivalent field and lab work. To improve the adoption of modern ML and Earth Observation (EO) tools for invasive species management, some of the developed tools are publicly accessible. In addition, a human-AI symbiosis that combines strengths and compensates for weaknesses is strongly recommended. For each application, directions are provided for future research based on the drawbacks and limitations of the introduced systems. These future efforts will likely increase the adoption of EO-derived products by water managers and improve the reliability of these products.Item Assessing aquifer vulnerability to landfill pollution using drastic method in Gauteng, South Africa(University of the Witwatersrand, Johannesburg, 2023) Mphaphuli, Idah; Abiye, TamiruThis study integrated the DRASTIC method and field investigations into mapping the degree of vulnerability of aquifers to landfill pollution in the Gauteng Province, which is one of the most populated provinces in South Africa. In order to investigate the aquifer vulnerability of Gauteng's heterogeneous and complex geology, the DRASTIC method was used to generate intrinsic and specific vulnerability maps. Three vulnerability classes were generated from the DRASTIC index, namely, low vulnerability, moderate vulnerability and high vulnerability, which covered 46%, 37% and 17% of the study area, respectively. The highly-vulnerable areas were associated with the karst aquifer of Malmani dolomite, permeable vadose zone, high hydraulic conductivity and loamy sand/sandy loam soil type, whilst moderately-vulnerable areas were associated with fractured/weathered aquifers, high recharge and low topography. The intrinsic vulnerability was validated using average NO3+NO2-N (nitrate + nitrite as nitrogen) and the results of water samples from field investigations conducted in Marie Louise and Robinson landfill sites. Elevated NO3+NO2-N concentration (9.85-16.03 mg/l) was observed in the highly-vulnerable areas. Water samples were collected, in order to analyse the water chemistry, stable isotopes and radioactive isotopes (tritium). Gibbs and Piper diagrams were used to evaluate the main mechanism controlling the groundwater chemistry and the dominant major ions that influence it. Pollution by leachate was detected in the Marie Louise landfill site, where the groundwater showed high tritium and ammonia concentration. The main hydrochemical facies detected in Marie Louise were Mg SO4, Ca-SO4, Na-SO4 and Na-Cl. The hydrochemical facies detected in Robinson were Na-SO4, Ca-HCO3, Na-Cl and Ca-Cl. The DRASTIC method was shown to be effective in assessing groundwater vulnerability on a regional scale, provided that there is adequate input data.Item Late Triassic to Early Jurassic ecology: An insight into diet and trophic levels using non-traditional Ca isotopes(University of the Witwatersrand, Johannesburg, 2023-07) Davechand, Priyanka; Bybee, Grant; Choiniere, JonahThe diet and trophic structuring of organisms in deep time is poorly understood, making comparison of ancient and modern ecosystems challenging. Proxy data (e.g., dental morphology, jaw muscle reconstruction) remain the most common mode of palaeodietary inference, but the correlative strength of these proxies remains untested due to a lack of direct evidence and an incomplete sampling of palaeobiodiversity. These major challenges in palaeodietary reconstruction can be overcome using novel geochemical markers in fossilised tooth enamel, which provide direct evidence of palaeodiet and trophic relationships. Traditional stable isotopes of carbon, oxygen, and nitrogen have been used in the past to infer palaeodiets, but these elements are susceptible to diagenetic alteration during fossil preservation and require large sample amounts for assays. In contrast, non-traditional calcium (δ44/42Ca) isotopes are less susceptible to diagenesis and require significantly smaller sample amounts. This, together with the fractionation that Ca isotopes undergo as a bio-essential element, allows δ44/42Ca to be utilised on a broad range of palaeontological questions including assessing dietary range and trophic level. The diverse ecosystems of the Elliot Formation (Karoo Supergroup) in South Africa are represented by abundant fossils of a variety of reptilian and mammalian stem lineages that coexisted during the latest Triassic–earliest Jurassic interval (218–190 Ma). The broad range of body sizes, inferred dietary preferences, and phylogenetic positions make the Elliot palaeoecosystems an ideal natural laboratory in which to apply palaeodietary isotopic tools. This dissertation aims to assess the palaeotrophic divisions of the Elliot Formation vertebrates using non-traditional δ 44/42Ca isotopes. This research uses ion-exchange chromatography on vertebrate tooth enamel to assess the palaeodietary preferences of Elliot Formation reptilian and mammalian lineages. To obtain these data, existing techniques for sample preparation of non-traditional δ 44/42Ca isotopes were modified and optimised at the Wits Isotope Geoscience Laboratory (WIGL) at the University of the Witwatersrand. δ 44/42Ca analysis was conducted on a variety of specimens across a broad range of amniote lineages, ranging from: dinosaurs such as presumed herbivorous sauropodomorphs Massospondylus and Aardonyx, the presumed omnivorous ornithischian (Lesothosaurus and Heterodontosaurus), and the presumed carnivorous theropod Megapnosaurus; to cynodont therapsids (Tritylodon, Pachygenelus and Scalenodontoides); to pseudosuchians such as the crocodylomorphs Protosuchus and Orthosuchus and earlier branching taxa (‘rauisuchians’ and poposauroids). A leaching procedure was also tested to ensure that the results produced were not influenced by diagenetic biases. Once consistent and reproducible methods were finalised, column chemistry and Multicollector-Inductively Coupled Plasma Mass Spectrometery (MC-ICPMS) analysis was conducted on the different Karoo-aged specimens. There are various outcomes from this dissertation. One important outcome was the optimisation of time for Ca separation using ion-exchange chromatography. This allowed for a shorter chemical preparation time and increased the number of analyses completed per session. Another improvement of the method was that the leaching procedure can be used to control for any diagenetic biases by removing secondary calcite in samples as old as those from the Triassic–Jurassic period. Elliot taxa were then analysed, and significant differences were found between δ 44/42Ca values of large carnivorous pseudosuchians (‘rauisuchians’; -0.45 ‰ to -1.17 ‰) and co occurring herbivorous sauropodomorph genera (-0.26 ‰ to -0.69 ‰). These results indicated that non-traditional δ 44/42Ca isotopes can be used to understand trophic structures and palaeodiets in ecosystems at least 210 million years old. We also found that while some taxa had δ44/42Ca isotope values in-line with their presumed diets, other taxa had more diverse diets than initially presumed. δ 44/42Ca-enriched values in this study provide evidence for herbivory in crocodylomorph and the oldest theropod. There is also a possibility of an omnivorous diet for presumed herbivorous Lesothosaurus as the δ 44/42Ca values are relatively depleted to other herbivores. In addition to diet, calcium plays a major role in the formation of reptilian eggs and there are documented changes in δ 44/42Ca values during the reproductive cycle. To assess this in a living system, Crocodylus niloticus, was analysed to understand if δ 44/42Ca could be used to identify the difference in sex based on the δ 44/42Ca values. No isotopic differences were found between the juvenile male and female Crocodylus niloticus samples. Testing these important ecological principles in temporally constrained formations allows us to understand the historical nature of biodiversity changes, especially across periods when environments on Earth were experiencing extreme conditions. The ability to determine factors such as palaeodiet and palaeotrophic range will enable the development and improvement of palaeoecological analysis. This research presents the first ever δ 44/42Ca values on Karoo-aged vertebrate fossils and will have a large impact on how palaeoecological reconstruction is conducted in the future of palaeosciences.Item Peat dynamics in the Angolan Highlands(University of the Witwatersrand, Johannesburg, 2023-03) Lourenco, Mauro Cesar; Woodborne, Stephan; Fitchett, JenniferThe Angolan Highlands is a war stricken, threatened, and under-studied area. The region is hydrologically and ecologically important and supports extensive tropical peatland deposits. Peatland preservation has been acknowledged to address climate change, is sensitive to drought and fire, and is directly influenced by vegetation and hydrological conditions. However, little research has been conducted in the Angolan Highlands. This study addresses gaps in the literature through four key contributions. The first is a critical review of peat definitions: the implications of disparate definitions are detailed, and a new proposed definition for peatlands in the interest of climate science is provided. The second is the first map of peatland extent in the Angolan Highlands, containing details on the age and growth dynamics. The study presents a conservative estimate of peatland extent that is much larger than previously estimated for Angola and is a crucial first step in facilitating the preservation of this deposit. The third contribution is the first historical assessment of drought and vegetation response in the region. This contains a 40-year drought and 20-year vegetation history, demonstrating that drought occurrence is increasing and there is a strong relationship between precipitation and the peatland vegetation region. The fourth contribution is the first assessment of the contemporary (2001-2020) fire regime of these peatlands, and reveals that among all land cover classes, peatlands burn more frequently and at a higher proportion. Investigation into the peat dynamics of the Angolan Highlands indicate that they have critical importance and are naturally resistant to both droughts and fire. Failure to preserve these deposits will have direct implications on the communities, environment, and surrounding areas.Item The tectonic evolution of the Bredasdorp Basin and its implications for oil and gas formation(University of the Witwatersrand, Johannesburg, 2023-10) Tau, Rethabile; Enslin, Stephanie; Manzi, Musa; Saffou, EricThe Bredasdorp Basin is an offshore rift basin located in the southernmost tip of Africa, within the larger Outeniqua Basin. Previous studies have indicated the presence of hydrocarbons, as well as structures or evidence that allude to the presence of hydrocarbons, where the basin has not yet been extensively drilled or explored. In this study, seismic attributes applied to high resolution pre-stack time migrated 3D seismic data are analyzed, in conjunction with well logs, specifically the gamma ray logs. By employing these methods, the study aims to delineate the presence of hydrocarbons and their migration, as well as deduce the evolution of the basin based on the structures observed. Using artificial neural network (ANN) to predict the lithologies and analyzing the patterns in the gamma ray logs, the stratigraphic results show that the basin begins with a marine dominated environment from the Valanginian age to Aptian age. From the Aptian to Albian age, there are consistent changes in sea level and sedimentation, caused by thermal sag and uplift. Past the Albian age to present age, the deposition environment is dominated by sandstones and coarse sediments. This is due to the evolving basin moving from a distal to a proximal environment of deposition. Using seismic attributes such as envelope attribute, edge detection and variance attribute, structures such as paleo pockmarks and fluid escape structures are identified. These identified paleo pockmarks have diameters ranging from 400m to 900m. In addition to these structures, erosive features were observed which could be classified as submarine channels or slump structures, with the dominating channel having depths of up to 1585 m. Using variance and ant-tracking, the fault structures observed of the study areas revealed two dominating phases of rifting. The first phase has horsts and grabens bounded by normal faults trending E-W, with implications that the rifting propagated N-S in this phase of rifting. This phase of rifting ends during the Aptian age. The next phase of rifting begins during the Santonian age, with the fault bound horsts and grabens trending N-S, which indicate an E-W rifting direction.Item The impact of nickel and chrome mine tailings on the growth of Hibiscus cannabinus and Linum usitatissimum and a preliminary assessment of their applicability as economically beneficial phytoremediation species(University of the Witwatersrand, Johannesburg, 2023-07) Campbell, Tiago Roberto; Furniss, David; Scholes, MaryCurrent and previous mining activities in South Africa have caused various environmental, human health and societal impacts. This has led to the formation and enforcement of legislation regarding the rehabilitation of active, closed and abandoned mines in South Africa. The requirements contained in this legislation include rehabilitation, skills transfer, job creation and development of post mine land use regarding active, closed and abandoned mines. A common impact of mining activities is the contamination of soils with various metals. The process of phytoremediation has demonstrated potential in the remediation of metal contaminated soils. Plant species commonly utilised in this process are hyper accumulators, which can translocate and accumulate high concentrations of various metals from soils into their biomass. However, large areas of previously economically productive land become underutilised when hyper-accumulators are used for phytoremediation. Economically valuable fibrous plant species have demonstrated potential in their use as phytoremediation species. This presents an opportunity in which economically valuable plant species could be utilised in phytoremediation applications on active, closed and abandoned mines in South Africa. Thus, the aim of this research was to assess the ability of Hibiscus cannabinus and Linum usitatissimum to grow in and extract metals from soil contaminated with nickel and chrome mine tailings. Furthermore, the concurrent use of H. cannabinus and L. usitatissimum as phytoremediative and economically beneficial plant species was determined. Normal (non impacted), rehabilitated (previously impacted) and tailings (impacted) soil treatments were collected and used from the Onverwacht tailings storage facility of Nkomati Nickel mine. Hibiscus cannabinus and L. usitatissimum were cultivated in each soil treatment in greenhouse conditions over a six-month period. Multiple plant growth parameters were recorded at monthly intervals. The amount (mg) and concentration (mg/kg) of Mn, Zn, Ni, Cu, Cr and Co contained within plant tissue samples at the end of the six-month period was determined. The area (ha) of land categories available for H. cannabinus and L. usitatissimum cultivation onsite was determined using Sentinel 2B satellite imagery and supervised image classification. The measured and expected total yield (t), yield value (R), profit/loss margin (R) and amount (g/ha) of Mn, Zn, Ni, Cu, Cr and Co extracted through cultivation of H. cannabinus and L. usitatissimum onsite was determined. The growth of H. cannabinus and L. usitatissimum cultivated in rehabilitated soil was severely impacted. While growth of each species exhibited minimal differences between those cultivated in normal and tailings soil. Hibiscus cannabinus consistently exhibited greater growth than L. usitatissimum. Both species demonstrated the ability to accumulate varying amounts and concentrations of each of the tested metals in their total, above and below ground components. Both species consistently accumulated increased amounts and concentrations of Mn and Zn. Those cultivated in tailings soil exhibited increased accumulation of Cr. Linum usitatissimum generally accumulated metals at higher concentrations than H. cannabinus, however, minimal differences in the amount of metal accumulated between species were observed. Based on the measured yield cultivation of each species onsite would result in economic loss and generally low metal extraction. However, based on the expected yield, species cultivation onsite, in normal and tailings soil, would result in economic gain and generally high metal extraction. Hibiscus cannabinus and L. usitatissimum exhibited phytoremediative and economic potential. Aspects of the current state of mine impacted land in South Africa and the requirements of rehabilitation enforced through South African legislation could possibly be addressed through the application of H. cannabinus and L. usitatissimum for mine rehabilitation strategies.