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Title: Assessment of the effect of groundwater quality on human health in Ovitoto, Otjozondjupa region, Namibia.
Other Titles: Thesis submitted in fulfilment of the requirements for the award of Master of Health Sciences degree in the Department of Health Sciences, Faculty of Health, Applied Sciences and Natural Resource Sciences.
Authors: Mwatukange, Priskila Shevamwaveke
Keywords: Groundwater
Health Risk
Heavy metals
Issue Date: Apr-2022
Publisher: Namibia University of Science and Technology
Citation: Mwatukange, P. S. (2022). Assessment of the effect of groundwater quality on human health in Ovitoto, Otjozondjupa region, Namibi. Assessment of the effect of groundwater quality on human health in Ovitoto, Otjozondjupa region, Namibia. (Unpublished master's thesis). Namibia University of Science ands Technology, Windhoek.
Abstract: Water is an essential part to the well-being and economic development of mankind. Namibia’s dry climate makes it susceptible to drought; hence, water is a scarce resource. To address water scarcity, boreholes are drilled to access groundwater for agricultural, industrial and domestic use. Many local authorities rely on this resource for supply to residents for domestic and other uses. But, the quality of groundwater is influenced by various factors, including pollution from point and non-point sources. A case study was done which involved the collection of water samples in the boreholes and laboratory analysis and assessment of the quality of sampled water. Non-probability-purposive sampling method was applied in the selection of sampling site. This study assessed the physicochemical (toxic heavy metals such as zinc (Zn), copper (Cu), cadmium (Cd), iron (Fe), manganese (Mn) and lead (Pb) as well as microbiological (Coliforms, E. coli and heterotrophic plate count) water quality of groundwater from boreholes that are supplied to the community of Ovitoto in Otjozondjupa region. This was done to assess the prevalence and possible human health concern as an outcome of consumption of the water. A total of 108 water samples were collected over a period of six months at an average of monthly intervals. Elemental components were extracted from water samples using mineral acid digestion and analysed through the use of Inductively Couple-Plasma Emission Spectroscopy (ICP-OES), while the microbial entities were analysed using the Polymerase Chain Reaction method (PCR). The overall mean concentration of heavy metals in the absorbed water samples through the sampling periods were Zn (0.83 mg/kg), Cd (0.01 mg/kg), Pd (0.02 mg/kg), Fe (17.76 mg/kg) and Mn (7.09 mg/kg). A strong correlation (r=0.99) was obtained between Zn and Cd while Cd and Cu were averagely correlated (r=0.55). Target Hazard Quotient (THQ) values < 1 was recorded for all analysed heavy metals, both in children and adults were below the permissible limits. However, Carcinogenic Risk Index (CRI) values for Mn was > 1 for both adults (4.75) and children (18.10). There is the possibility of carcinogenic health risk by Zn with a value of 0.13. Of great concern, however, is the potential development of carcinogenic health risk with respect to Mn. Other metals do not have physical benefits to human system, and they are toxic at low levels. Therefore, proper monitoring and quality assurance protocol of the level of toxicity of heavy metals in borehole water is recommended.
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