DSpace Repository

Welcome to the NWU Repository, the open access Institutional Repository of the North-West University (NWU-IR). This is a digital archive that collects, preserves and distributes research material created by members of NWU. The aim of the NWU-IR is to increase the visibility, availability and impact of the research output of the North-West University through Open Access, search engine indexing and harvesting by several initiatives.

Now showing 1 - 17 of 17

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Microplastic pollution in the Vaal River system
(North-West University, 2024) Verster, Carina; Bouwman, H
This thesis aimed to address the escalating issue of plastic pollution in South Africa's freshwater systems across several key objectives. Findings from the study highlighted the extensive presence of microplastics (MPs) throughout the Vaal River system, particularly in sediment samples, with concentrations in some areas comparable to highly polluted rivers in other regions. Notably, the heavily polluted Klip River exhibited the highest MP concentrations, including an unprecedented high presence of microbeads, indicating the severity of pollution in urbanized and densely populated areas where waste mismanagement is prevalent. Identification of plastic pollution sources revealed a strong correlation between macroplastic presence and MP concentrations in water and sediment, emphasizing local environmental plastic pollution as a significant predictor for riverine MP loads. Urbanized catchments, characterized by dense populations and inadequate waste management, were found to host the highest MP concentrations. Furthermore, the temporal dynamics of MPs in South African freshwater systems demonstrated contrasting trends between heavily polluted and less impacted rivers during the rainy season, emphasizing the influence of runoff on MP concentrations. Insights into the sinks of microplastics underscored sediments as temporary repositories for MPs, particularly during low-flow periods, with rapid settling observed, especially for microbeads. Additionally, wetlands were identified as effective filters, trapping MPs in sediment during low flow periods, raising concerns regarding the accumulating MP concentrations in these sensitive ecosystems. Addressing mitigating actions, recommendations emphasized the urgent need to improve waste management infrastructure, enhance functionality at wastewater treatment plants to minimize MP release into rivers, restrict microbead production, raise public awareness, conduct regular river cleanups, and remove macroplastics from the environment to prevent further generation of MPs. These findings collectively underscore the critical importance of strategic interventions and holistic measures to curtail and remediate plastic pollution in South Africa's freshwater systems.
Analysing Integrated Waste Management Plan quality: the case of the Western Cape District Municipalities
(2024) Venter, Francois; Alberts, R.C
Countries worldwide experience increases in waste generation rates. If not managed effectively, waste poses an immediate threat to human well-being and environmental health. Waste management is not a new concept, as history reflects that centuries ago, measures to mitigate and manage waste were implemented. Common challenges experienced globally pertaining to waste management include increased waste generation rates, increased population growth, industrialization, lack of institutional capacity, lack of financial resources, lack of infrastructure and lastly, the lack of knowledge. Integrated Waste Management Planning, as a concept, has been present in the South African legislative framework since 1999. The goal of Integrated Waste Management Planning in the South African context is to provide municipalities with the opportunity to plan and manage waste-related activities within their jurisdictional area. South Africa has made the right steps towards Integrated Waste Management Planning, but flaws in the system persist. The aim of this research is to analyse the quality of Integrated Waste Management Plans of the district municipalities of the Western Cape. Three research objectives were set to achieve the research aim; to provide an overview of waste management and the context of waste management planning in South Africa; to adapt and design a unique Integrated Waste Management Plan review package for South African District Municipalities and to analyse five case study IWMPs with an adapted and unique review package. This study focuses on the quality of Integrated Waste Management Plans of district municipalities of the Western Cape Province of South Africa. A qualitative research approach was applied through means of an adapted Lee and Colley review package, used to analyse the quality of the IWMPs. The findings on the overall quality of the reviewed IWMPs were unsatisfactory as major omissions were noted in the IWMP content. Institutional capacity constraints, insufficient stakeholder communication, lack of awareness campaigns, unclear provision of roles and responsibilities, insufficient coordination between local and district municipalities and budgetary constraints are the main factors influencing the quality of the analysed Integrated Waste Management Plans. Strengthening of communication, coordination and institutional capacity within municipalities has the potential to improve the quality of the Integrated Waste Management Plans. Focusing to strengthen all the identified weaknesses in the IWMPs will lead to better report quality.
Genetic characterization of ticks and tick borne prokaryotic pathogens of urban stray dogs in Potchefstroom, South Africa
(North-West University, 2024) Van Wyk, Clara-lee; Thekisoe, M.M.O; Mtshali, P.S
Ticks are well documented for their ability to transmit pathogenic organisms of medical, veterinary and economical importance mostly to a variety of animal hosts and humans. Ticks harbour various members of bacteria, archaea, and eubacteria and several eukaryotic organisms, including fungi, nematodes, and protozoa, collectively referred to as the microbiome. Associations between the ticks and the microbiota affect several aspects of the ticks such as their vectorial competence, survival, and reproductive fitness. The bacterial composition of ticks varies due to a lot of factors, including but not limited to the tick’s life cycle, host ecology, and the absence or presence of bacterial pathogens. Therefore, this study aimed at conducting a systematic review focusing on the global prevalence of R. sanguineus and H. elliptica, as well as the tick-borne pathogens they harbour. This study also sought to identify the tick species and tick-borne pathogens infesting dogs collected from the Potchefstroom Animal Welfare Society (PAWS). Lastly this study aimed to identify the bacterial communities of dog blood and ticks from the PAWS in comparison to colony ticks from gnotobiotic hosts. For the systematic review, the Scopus, ScienceDirect, PubMed, and Web of Science databases were searched for English journal articles which were assessed by following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. This systematic review was registered on PROSPERO under the following ID: CRD42022327372. Of the studies included in the systematic review, 247 and 19 articles collected and identified R. sanguineus and H. elliptica respectively, whereas 15 articles managed to collect and identify both tick species. In total 121 articles were included in the systematic review that reported the presence of haemoparasite infections within R. sanguineus or H. elliptica ticks. Respectively, 119 and 2 of the aforementioned articles reported the presence of tick-borne pathogens within R. sanguineus and H. elliptica ticks respectively. In addition, only 1 article reported the presence of tick-borne pathogens within both R. sanguineus and H. elliptica ticks. The prevalence of the haemopathogens was similar to the prevalence of their tick hosts, thus indicating the potential of tick-borne pathogens to spread and inhabit new niches. Articles included in the systematic review reported the presence of R. sanguineus and H. elliptica ticks collected from companion animals, vegetation, livestock, humans, as well as several wildlife species. The tick species identification method in the included articles of the systematic review was done employing morphological identification (n=222), as well as a combination of morphological identification and conventional PCR (n=29). Articles that detected tick-borne pathogens within R. sanguineus used molecular techniques (n=139) as well as morphological techniques (n=5). Articles that detected tick-borne pathogens within H. elliptica used molecular techniques (n=2). There were 64 countries that reported the presence of R. sanguineus, whereas H. elliptica was only reported in 6 countries. It is considered that R. sanguineus has a global prevalence, mainly in regions that are tropical or subtropical. H. elliptica was reported in South Africa and countries with close proximity to South Africa. The close proximity between ticks and travelling hosts or migratory hosts (such as birds), is one of the main contributors to the global prevalence of R. sanguineus and the prevalence of H. elliptica in the neighbouring countries of South Africa. In this study tick specimens (n=300) and blood (n=50) were collected from naturally infected dog hosts (n=50) residing at the PAWS located in Potchefstroom of the North West Province, South Africa. In addition, eggs were also collected (n=6 egg batches) from ticks that laid eggs after collection. Tick specimens were morphologically identified and genetically using PCR CO1 and 18S rRNA assays, whilst genus or species specific PCR assays were performed for detection of various bacterial pathogens of veterinary importance from tick pools (n=81), egg batches (n=6), and dog blood (n=50). The PCR amplicons were Sanger sequenced and aligned using the nucleotide Basic Local Alignment Search Tool (BLASTn) for confirmation of detected pathogen identity. In this study, two tick species were identified namely R. sanguineus with an overall abundance of 70.7% (212/300) and H. elliptica with an overall abundance of 29.3% (88/300) based on morphological key features and DNA analysis. For the CO1 gene all of the tick specimens morphologically identified as H. elliptica were 96.89 to 97.74% similar to H. elliptica gene sequences on the NCBI database. On the other hand, the tick species morphologically identified as R. sanguineus were 97.20 to 99.84% similar to R. sanguineus gene sequences on the NCBI database. For the 18S rRNA gene all of the tick specimens morphologically identified as H. elliptica were 99.26 to 99.63% similar to H. elliptica gene sequences on the NCBI database. On the other hand, the tick species morphologically identified as R. sanguineus were 98.53 to 99.90% similar to R. sanguineus gene sequences on the NCBI database. None of E. canis or A. phagocytophylum were detected by PCR from DNA of ticks, egg batches, or dog blood samples from this study. The overall occurrence of C. burnetii within pooled tick DNAs was 9.88% (8/81). The C. burnetii were harboured by 8.82% (3/34) of H. elliptica ticks and 10.64% (5/47) of R. sanguineus ticks. The overall occurrence of C. burnetii within egg batches was 16.67% (1/6). The C. burnetii was present in 25% (1/4) H. elliptica egg batches. One of the PCR products was successfully sequenced and BLASTn search results revealed that the aforementioned gene sequence was 96.89 to 100% similar to C. burnetii sequences on the NCBI database. The overall occurrence of Rickettsia spp. within tick pools was 6.17% (5/81). Rickettsia spp. were harboured by 11.76% (4/34) of H. elliptica ticks and 2.13% (1/47) of R. sanguineus ticks. The overall occurrence of Rickettsia spp. within egg batches was 16.67% (1/6). Rickettsia spp. were present in 25% (1/4) H. elliptica egg batches. The BLASTn results revealed that two of the Rickettsia spp. were 98.75 to 100% similar to R. conorii gene sequences on the NCBI database. Another two Rickettsia spp. sequences. BLASTn search results revealed that they were 97.18 to 99.70% similar to R. massiliae gene sequences on the NCBI database. In addition, one R. sanguineus tick pool was co-infected with both C. burnetii and Rickettsia spp. Lastly, this study used Illumina next-generation sequencing targeting the V3 and V4 regions of the 16S rRNA gene to determine bacterial microbiota from R. sanguineus (n=1) and H. elliptica (n=1), dog blood samples from which ticks were collected. The microbiota of these ticks and dog blood was compared with that of colony reared ticks. Dominant bacterial phyla were identified as Proteobacteria (54.02%), Bacteroidetes (18.03%), and Actinobacteria (11.76%). The dominant bacterial classes were identified as Gammaproteobacteria (41.61%), Bacteroidia (17.93%), Alphaproteobacteria (11.20%), and Actinobacteria (11.11%). Dominant orders were identified as Betaproteobacteriales (14.78%) and Coxiellales (14.40%). Dominant bacterial families were identified as Coxiellaceae (14.40%) and Burkholderiaceae (12.12%). The dominating bacterial genera were identified as Coxiella (14.40%). Additionally, at class and genus levels the relative abundance between the R. sanguineus and H. elliptica of the colony ticks from gnotobiotic hosts were similar, whereas the relative abundances of the R. sanguineus and H. elliptica ticks and their natural dog hosts were similar indicating similarities between the species richness, whereas the relative abundance between the colony ticks from gnotobiotic hosts and the ticks collected from naturally infected dog hosts was different indicating differentiation between the species richness. The results of the study indicate the presence of several bacterial communities harboured by and shared between R. sanguineus and H. elliptica ticks from naturally infected dog hosts, dog blood, and R. sanguineus and H. elliptica ticks from gnotobiotic hosts. The aforementioned bacterial communities are taxonomically similar among all the sample types but the relative abundances of the bacterial communities of both the dog blood and ticks from natural dog hosts differ compared to the ticks from gnotobiotic hosts, specifically among the Rickettsia spp. and Coxiella spp. that were very high in the tick specimens collected from gnotobiotic hosts. Additionally, several bacterial genera detected in the sample types were of medical, veterinary, and ecological importance. The systematic review has provided consolidated insight on the prevalence of R. sanguineus, H. elliptica, and their tick-borne pathogens, as well as other associated subjects, such as the expansion of ticks and their tick-borne pathogens to non-endemic areas, the effects of coinfections, and tick identification and parasite detection methods. The results of this study indicate that dogs admitted to PAWS are infected by R. sanguineus and H. elliptica ticks which are harbouring tick-borne pathogens responsible for causing zoonotic diseases.
Molecular dynamics studies of the transfer of ions in multi-walled carbon nanotube poly(2,5-benzimidazole) composites
(North-West University, 2024) van Niekerk, Salomon; Square, L.C
When energetic protons bombard satellites in the context of Low Earth Orbit (LEO), they are shielded by materials such as aluminium and polyethylene [1]. At a certain depth, depending on the energy of the proton and the radiation shielding material, the movement mechanism is no longer energy dominated. Three of the main mechanisms used to describe proton transport in polymers are Grotthuss, diffusion, and direct transport via polymer chain segmental motions[2]. Poly(2,5-benzimidazole) (ABPBI) and two multi-walled carbon nanotube (MWCNT) composites (1wt% and 5wt%) were simulated, using Molecular Dynamics, at typical satellite operating temperatures to investigate the ion movement mechanism and influence of MWCNT loading and temperature. The ions considered in this dissertation are hydrogen ions, i.e. protons. The simulated X-ray diffraction (XRD) patterns give insight into the crystallinity of a structure. The XRD for ABPBI was indicative of a semi-crystalline nature for which direct transport via segmental motions of the polymer chains, according to Gao and Lian [2], is not possible. The simulated temperatures showed little to no effect on the mean square displacement (MSD) of the proton and their affinity to be within hydrogen bonding range of the nitrogens of ABPBI and accompanying composites. The MSD results also ruled out the diffusion mechanism, leaving the Grotthuss mechanism as the most likely vehicle for proton transport in ABPBI and associated composites. This is supported (and corroborated by other studies [3, 4]) by the radial distribution function (RDF) results indicating strong interactions, across all composites and temperatures, between the proton and ABPBI nitrogens possibly leading to hydrogen bonding which is central to the Grotthuss mechanism. ABPBI is not yet a recognised shielding material for space application. The work from this dissertation will, hopefully, aid in the understanding of how ABPBI reacts to proton radiation and add to the merits for using it, and its composites, for space application in future.
Isolation of High Purity Phase II Biotransformation Conjugates from Urine using HPLC fractionation: A Proof of Concept
(North-West University, 2024) Van Huyssteen, Ruhan; Erasmus, E; Venter, G
Biotransformation plays an essential role in converting xenobiotics into more excretable forms. Phase II biotransformation, also known as the conjugation phase, is often overlooked. Complications in phase II biotransformation activity can lead to severe adverse health consequences and even death. One of the methods for assessing biotransformation activity is by administering probe drugs and measuring the concentrations of the drug biotransformation conjugates excreted in urine after 12 hours using HPLC-UV/Vis or HPLC-MS. To produce sensitive and selective HPLC results, analytical standards are required during method development and for quality control. Analytical standards for some phase II biotransformation conjugates are very expensive and, in some cases, unavailable for purchase, as these compounds can be difficult to synthesise. An alternative approach to synthesising analytical standards would be to isolate them from a matrix containing high concentrations of these conjugates. The urine samples at the biotransformation and oxidative stress status (BOSS) laboratory serve as a good starting material since these urine samples already contain high concentrations of biotransformation conjugates. The aim of this study was to develop a method that can be used for the isolation of high-purity phase II biotransformation conjugates. Salicyluric acid and paracetamol glucuronide were selected as the metabolites of interest, as these metabolites are the phase II biotransformation end-products of aspirin and paracetamol metabolism. Hippuric acid as selected as an additional phase II biotransformation conjugate based on the polarity of the molecule and its role in benzoic acid metabolism. Based on the literature reviewed HPLC is the gold standard method for isolating small polar compounds, such as phase II biotransformation conjugates. HPLC has the added benefit of being able to be combined with an inline fraction collector, allowing for highly efficient fraction collection. During the first part of the study, a liquid chromatography fractionation method was developed for the isolation of high-purity phase II conjugates from a standard mixture. The method was divided into 1) sample pre-treatment, 2) chromatography optimisation and fraction collection, and 3) MS optimisation. In the second phase of the study, the effectiveness of the optimised extraction, LC-UV and fraction collection methods was tested. This was achieved by employing these methods on a urine sample to isolate hippuric acid, salicyluric acid and paracetamol glucuronide. Ethyl acetate liquid-liquid extraction proved to be most efficient and scalable for the isolation of hippuric acid, salicyluric acid and paracetamol glucuronide, with recoveries of 23.74 %, 32.17 % and 45.44 % respectively. Chromatographic separation on the Agilent XBD C18 (150 × 4.6 mm 5 μm) produced excellent chromatographic resolution that aided with easier fraction collection. Time-based fraction collection proved most effective for fraction collection, as abundance-based detection missed compounds below a specific threshold. MS source conditions and transition states were well optimised and could reliably detect hippuric acid, salicyluric acid and paracetamol glucuronide. The most abundant MRM transitions were as follows: 328.1 → 152 m/z for paracetamol glucuronide, 180.1 →105 m/z for hippuric acid, and 196.1 → 121 m/z for salicyluric acid. The optimised source conditions for these compounds were as follows: a drying gas temperature of 350°C, a drying gas flow rate of 3 L/min, a nebuliser pressure of 45 psi, and a capillary voltage of 6000 volts. Purity assessment of the primary fractions captured from urine using isocratic HPLC produced single peaks at the expected retention time for hippuric acid and salicyluric acid. The paracetamol glucuronide fraction captured was not pure after primary fractionation and required secondary fractionation. The secondary fractionation produced was a single pure peak indicating that HPLC fractionation can be employed for the isolation of high-purity phase II biotransformation conjugates.