Dube, NontembekoGokul, ArunKheswa, Nozipho2025-06-042025-06-042024Thesis (Ph.D.(Zoology))--University of the Free State, 2024http://hdl.handle.net/11660/13091Most municipal solid waste (MSW) landfills in South Africa fail to meet regulatory standards due to resource constraints in municipalities and the increasing volume of waste generated by households and local industries. Landfills are designed to contain waste and prevent leachate from contaminating the surrounding environment; however, poor management can lead to severe environmental damage and public health risks. Studies in the Free State province indicate that most landfills are non-compliant with regulations, contributing significantly to environmental pollution. The Maluti-a-Phofung municipality, for example, faces substantial waste management challenges, with only 25% of households receiving regular refuse collection services, leading to illegal dumping and unmanaged waste sites near residential areas, heightening environmental and health risks. Leachate from landfills contaminates soil and water, adversely affecting ecosystems and human health, and improper compaction and containment of waste is a major operational shortcoming. Ecotoxicologists assess the heavy metal concentrations to evaluate potential ecological risks in terrestrial environments and assess the impact when these concentrations are concerning. Furthermore, plastic waste, which is more resistant to degradation compared to organic matter, poses significant threats to terrestrial and aquatic life. Despite the urgency of these challenges, the environmental and health hazards of poorly managed landfills remain under-researched in South Africa. This study aimed to evaluate the toxicity of landfills by measuring heavy metal concentrations in soil samples from an active landfill site in Harrismith (H-landfill) and a dormant landfill site in Phuthaditjhaba (P-landfill); assess the toxicity impact of landfill soils on ground-dwelling organisms such as earthworms and collembolans through ecotoxicological tests. Both sites are in close proximity to households and are unregulated. This study also examined how these landfills impact arthropod assemblages during wet and dry seasons, as arthropods are vital bioindicators for assessing the effects of anthropogenic activities. Furthermore, the potential for bioremediation using local fungal isolates was explored. Results showed that heavy metals, including copper (Cu), lead (Pb), cadmium (Cd), manganese (Mn), and chromium (Cr), exceeded permissible limits for soil, irrigation, and agricultural use. The study revealed that lead (Pb), a highly toxic element with no biological function, had concentrations above allowable limits. Ecotoxicological tests revealed that 65% of earthworms exhibited avoidance behaviour at the Harrismith landfill, indicating higher toxicity at this site, while 80% did not avoid the Phuthaditjhaba landfill, likely due to lower heavy metal concentrations. Collembolan reproductive rates did not show significant differences between landfill and control soils, suggesting low sensitivity to sublethal toxicity. These findings underscore the environmental hazards associated with landfill contamination, particularly the presence of toxic heavy metals above permissible limits and highlight the need for restoration efforts following landfill closure to prevent ecological and public health risks. Arthropods were collected using pitfall traps during wet and dry seasons. Eleven arthropod taxa were recorded in landfills compared to nine in control sites, with significant representation from the orders Diptera, Hymenoptera, Coleoptera, and Araneae. A total of 10 547 arthropods was recorded from Harrismith and Phuthaditjhaba landfills. Arthropod abundance and diversity were notably higher in landfill sites, especially during the wet season, with 9354 individuals recorded compared to 3684 in control sites. In contrast, the dry season yielded fewer individuals, with 1193 in landfills versus 788 in control sites. Dipteran families such as Muscidae, Simulidae, and Calliphoridae were more abundant in landfill sites and are known for their medical importance, indicating potential public health risks. These findings demonstrate that landfills attract arthropod families that may affect human health and suggest that waste and pollution in landfills support diverse arthropod communities, particularly detritivores, which were less common in control sites. This study is the first to report arthropod assemblages in the landfill sites in the country. The high insect populations and the prevalence of dipteran families point to poor waste management practices and indicate the dual impact of these species as potential disease vectors and decomposers. Eighteen fungal isolates were identified, nine of which demonstrated the ability to degrade polyethylene (PE) plastic, a common environmental pollutant. The most effective strains, viz., 𝘗𝘦𝘯𝘪𝘤𝘪𝘭𝘭𝘪𝘶𝘮 𝘤𝘩𝘳𝘺𝘴𝘰𝘨𝘦𝘯𝘶𝘮 SP17MK, 𝘈𝘴𝘱𝘦𝘳𝘨𝘪𝘭𝘭𝘶𝘴 𝘤𝘳𝘦𝘣𝘦𝘳 SP6MK, and 𝘌𝘯𝘨𝘺𝘥𝘰𝘯𝘵𝘪𝘶𝘮 𝘢𝘭𝘣𝘶𝘮 SP3MK, caused over 20% weight loss in PE plastic. FTIR analysis revealed significant changes in the plastic's chemical structure, with reductions in absorption peaks at 719 and 1472 cm⁻¹, indicating degradation. Additionally, 𝘋𝘪𝘥𝘺𝘮𝘰𝘴𝘱𝘩𝘢𝘦𝘳𝘪𝘢 𝘷𝘢𝘳𝘪𝘢𝘣𝘪𝘭𝘦 SP11INT and 𝘓𝘦𝘤𝘢𝘯𝘪𝘤𝘪𝘭𝘭𝘪𝘶𝘮 𝘤𝘰𝘱𝘳𝘰𝘱𝘩𝘪𝘭𝘶𝘮 SP7MK were discovered for the first time as potential plastic-degrading fungi. These findings suggest that local fungal species can be utilized in waste management strategies to mitigate plastic pollution in landfill sites. Use of fungal isolates for plastic bioremediation now has a record in South Africa. The identification of fungal isolates with plastic-degrading potential offers a promising avenue for bioremediation and highlights the importance of exploring local microorganisms as part of sustainable solutions to plastic pollution. Further research is needed to optimise these fungal species for large-scale environmental applications and waste management strategies.enWaste pollutionLandfillsDumpsitesPollutantsToxicantsArthropodsEarthwormsCollembolansPlastic pollutionFungal speciesBiodegradationThesisUniversity of the Free State