PhD (Environmental Sciences) / Department of Ecology and Resource Management / The presence of arsenic in groundwater has drawn worldwide attention from researchers and public health officials due to its effects on human health such as, cancer, skin thickening, neurological disorders, muscular weakness, loss of appetite and nausea. World Health Organisation (WHO) has set the limit of 10 μg/L for arsenic in drinking water in trying to reduce the effects of arsenic. This was further adopted by South African National Standard (SANS). The present study aims at evaluating arsenic concentration in selected groundwater sources around Greater Giyani Municipality in Limpopo Province and further synthesize clay based adsorbents for arsenic removal using Fe3+ and Mn2+ oxides and hexadecylammonium bromide (HDTMA-Br) cationic surfactant as modifying agents. The first section of the work presented the hydrogeochemical characteristics of groundwater in the Greater Giyani Municipality. The results showed that the pH of the samples ranges from neutral to weakly alkaline. The dominance of major anionic and cationic species was found to be in the order: HCO3 ->Cl->SO4 2->NO3 - and Na+>Mg2+>Ca2+>K+>Si4+, respectively. Hydrogeochemical facies identified in the study area include CaHCO3 (90%) and mixed CaNaHCO3 (10%) which shows the dominance of water-rock interaction. About 60% of the tested samples contains arsenic concentration above 10 μg/L as recommended by SANS and WHO. Concentration of arsenic was found to be ranging between 0.1 to 172.53 μg/L with the average of 32.21 μg/L. In the second part of this work, arsenic removal efficiency of locally available smectite rich and kaolin clay was evaluated. Results showed that the percentage As(V) removal by kaolin clay was optimum at pH 2 while the percentage As(III) removal was greater than 60% at pH 2 to 12. For smectite rich clay soils, the percentage of As(III) and As(V) removal was found to be optimum at pH between 6 and 8. The adsorption isotherm data for As(III) and As(V) removal by both clays fitted better to Freundlich isotherm. Adsorption of both species of arsenic onto the clay mineral occurred via electrostatic attraction and ion exchange mechanisms. Both clay soils could be regenerated twice using Na2CO3 as a regenerant. Kaolin clay showed a better performance and was selected for further modification. In the third section of this work, Fe-Mn bimetal oxide modified kaolin clay was successfully synthesized by precipitating Fe3+ and Mn2+ metal oxides to the interlayer surface of kaolin clay. Modification of kaolin clay increased the surface area from 19.2 m2/g to 29.8 m2/g and further v decreased the pore diameter from 9.54 to 8.5 nm. The adsorption data fitted to the pseudo second order of reaction kinetics indicating that adsorption of As(III) and As(V) occurred via chemisorption. The adsorption isotherm data was described by Langmuir isotherm models showing a maximum As(III) and As(V) adsorption capacities of 2.16 and 1.56 mg/g, respectively at a temperature of 289 K. Synthesized adsorbent was successfully reused for 6 adsorptiondesorption cycles using K2SO4 as a regenerant. Column experiments showed that maximum breakthrough volume of ≈2 L could be treated after 6 hours using 5 g adsorbent dosage. Furthermore, the concentration of Fe and Mn were within the WHO permissible limit. In the fourth part of the work kaolin clay was functionalized with hexadecyltrimethylamonium bromide (HDTMA-Br) cationic surfactant and its application in arsenic removal from groundwater was investigated. The results revealed that adsorption of As(III) and As(V) is optimum at pH range 4-8. The maximum As(III) and As(V) adsorption capacities were found 2.33 and 2.88 mg/g, respectively after 60 min contact time. Pseudo first order model of reaction kinetics described the adsorption data for As(V) better while pseudo second order model described As(III) adsorption data. The adsorption isotherm data for As(III) and As(V) fitted well to Langmuir model indicating that adsorption of both species occurred on a mono-layered surface. Adsorption thermodynamics model revealed that adsorption of As(III) and As(V) was spontaneous and exothermic. The As(III)/As(V) adsorption mechanism was ascribed to electrostatic attraction and ion exchange. The regeneration study showed that synthesized adsorbent can be used for up to 5 times. In the firth part of the work inorgano-organo modified kaolin clay was successfully synthesized through intercalation of Fe3+ and Mn2+ metal oxides and HDTMA-Br surfactant onto the interlayers of the clay mineral. The batch experiments showed that As(III) removal was optimum at pH range of 4-6, while the As(V) removal was optimum at pH range 4-8. The adsorption data for both species of arsenic showed a better fit to pseudo second order of reaction kinetics which suggest that the dominant mechanism of adsorption was chemisorption. The isotherm studies showed better fit to Langmuir isotherm model as compared to Freundlich model. The maximum adsorption capacity As(III) and As(V) at room temperature as determined by Langmuir model were found to be 7.99 mg/g and 7.32 mg/g, respectively. The thermodynamic studies for sorption of As(III) and As(V) showed negative value of ΔGᴼ and ΔHᴼ indicating that adsorption process occurred spontaneously and is exothermic in nature. The regeneration study showed that the vi inorgano-organo modified kaolin clay can be reused for up 7 adsorption-regeneration cycles using 0.01 M HCl as a regenerant. Thomas kinetic model and Yoon-Nelson model showed that the rate of adsorption increases with increasing flow rate and initial concentration and decreases with increasing of the bed mass. In conclusions, adsorbents synthesized from this work showed a better performance as compared to other adsorbents available in the literature. Among the synthesized adsorbents, inorgano-organo modified clay showed highest adsorption capacity as compared to surfactant functionalized and Fe-Mn bimetal oxides modified kaolin clay. However, all adsorbents were recommended for use in arsenic remediation from groundwater. The following recommendations were made following the findings from this study: 1) routine monitoring of arsenic in groundwater of Greater Giyani Municipality, 2) evaluating the possible link between arsenic exposure and arsenic related diseases within Giyani in order to find the extent of the problem in order to establish the population at risk, 3) The toxicity assessment for HDTMA-Br modified kaolin clay should be carried out, 4) Materials developed in the present study should be modeled and tested at the point of use for arsenic removal, and lastly, 5) this study further encourage the development of other arsenic removal materials that can be used at household level. / NRF

MSc (Chemistry / Department of Chemistry / In this study, three sampling sites (Tshipise thermal spring, Mphephu thermal spring and Siloam borehole) in Limpopo Province South Africa were considered for an investigation into the mineral composition of their water and soil samples. Tshipise and Mphephu thermal springs are well developed and located within tourist resorts. On the other hand, Siloam is a borehole on the grounds of a private household. The water is used for various domestic purposes such as laundry, general cleaning of the household and bathing. Water and soil samples from the three sites were collected once per week every week in February 2018. The sampling bottles were spiked with 1M HNO3 before sampling to keep any metal ions present in the water samples in solution. The soil and water samples were analysed for their chemical composition using X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) respectively. XRF analysis of the soil samples found many major oxides of which SiO2 made up 63.67%, 85.37% and 46.28% by mass of Tshipise, Mphephu and Siloam soil samples respectively. XRF analysis also showed the presence of dangerous levels of heavy metals such as As, Tl, Pb and V. The analysis of the water samples by ICP-MS found that Tshipise, Mphephu and Siloam mineral water were soft, soft-moderately hard and soft-hard respectively with regards to the water hardness scale according to the United States Geological Survey (USGS) and the Water Quality Association (WQA). Analysis of water samples also found the presence of As, Cd, Cr and V. Arsenic was found to occur at concentrations above the Maximum Allowable Concentration (MAC) set by the World Health Organisation (WHO) (10 μg L-1) for Tshipise, Mphephu and Siloam mineral water (13.63 μg L-1, 15.83 μg L-1 and 20.97 μg L-1 respectively). Water temperatures for the three sites ranged from 38°C (Siloam borehole) to 64°C (Tshipise thermal spring). The pH values were 7.25 (Siloam borehole), 7.40 (Mphephu thermal spring) and 8.67 (Tshipise thermal spring). Due to the presence of As, Tl, Pb, V, Cd and Cr, the mineral water from all three thermal springs is unsafe to consume as it would lead to serious negative health effects some of which are outlined in this study. / NRF

PhDENV / Department of Hydrology and Water Resources / Geothermal springs are natural geological phenomena that occur throughout the world. South Africa is endowed with several springs of this nature. Thirty-one percent of all geothermal springs in the country are found in Limpopo province. The springs are classified according to the residing mountain: Soutpansberg, Waterberg and Drakensberg. This study focused on the geothermal springs within the Soutpansberg region; that is, Mphephu, Siloam, Sagole and Tshipise. The study was aimed at elucidating on the isotopic signatures and trace metals concentrations from the geothermal springs to their environmental media in Soutpansberg region. This study also assessed the interconnectivity of the isotopic signatures within the ecosystem and evaluated the potential human health risks associated with trace metals from geothermal springs and surrounding soils in the study areas. Geothermal springs and boreholes were sampled for a period of twelve months (May 2016 – May, 2017) to accommodate two major seasons in the study areas. The surrounding soils were sampled vertically from a depth of 10 cm to 50 cm for trace metals and isotopic compositions. Three different plants were sampled at each of the study sites, namely, Amarula tree, Guava tree and Mango tree at Siloam; Acacia tree, Fig tree and Amarula tree at Mphephu; Amarula tree, Lowveld mangosteen and Leadwood tree at Sagole; Sausage tree, Amarula tree and Acacia tree at Tshipise. To achieve the objectives, the physicochemical, geochemical and isotopic compositions of the geothermal springs, boreholes, soils and vegetation were analysed using ion chromatography (IC) (Dionex Model DX 500), inductively coupled plasma-mass spectrometer (ICP-MS), HTP-Elemental analyzer, Liquid water isotope analyzer (LWIA-45-EP) and Liquid scintillation analyzer. The temperature, electrical conductivity (EC), pH and total dissolved solid (TDS) of the geothermal springs and boreholes samples were measeured in situ and in the laboratory. Trace metals analysed in geothermal springs, boreholes, soil and vegetation include Beryllium (Be), Chromium (Cr), Manganese (Mn), Cobalt (Co), Nickel (Ni), Copper (Cu), Arsenic (As), Selenium (Se), Cadmium (Cd), Antimony (Sb), Barium (Ba), Vanadium (V), Zinc (Zn), and Mercury (Hg). vii | Isotopic signatures and trace metals in geothermal springs and their environmental media within Soutpansberg Results obtained from this study in the studied geothermal springs and boreholes were classified according to their temperature as hot and scalding; except for tepid boreholes. This study has provided comprehensive physicochemical, geochemical and isotopic compositions of the geothermal springs within the Soutpansberg region (Siloam, Mphephu, Sagole and Tshipise). The local meteoric line (δD = 7.56δ18O + 10.64) was generated from rainwater in Vhembe district. This is a crucial component for depicting the source and flow path of the geothermal springs/boreholes; and could be used for future isotopic hydrological studies within the locality. Rain formation processes within Soutpansberg occurred under isotopic equilibrium conditions with minor evaporation effect during rainfall. The δD and δ18O values of the geothermal spring water/boreholes confirm that the waters are of meteoric origin, which implies that rainfall is the fundamental component of these groundwaters because they were derived from the infiltration of rainwater, with significant contribution of another type of water in the deeper part of the aquifer. Na-Cl and Na-HCO3 were established as the water types, which are typical of marine and deep groundwaters which are influenced by the ion - exchange process. The reservoir/aquifer temperature of these springs ranges between 95 – 185°C (Na-K geothermometer), which implies most of the waters are mature water (not native). Hence, geothermal springs water is a mixture of the rainwater and salt water. Radiocarbon values of the geothermal springs ranged from 2700 to 7350 BP, this implies that they are submodern and a mixture of submodern and modern waters. Tritium relative age also corroborates with radiocarbon age, that is the groundwaters were recharged before and after 1952. This gives an indication that the rainfall contributes to the geothermal springs recharge. Various radiocarbon correction models were employed and constrained by tritium relative age. Ingerson and Pearson, Eichinger and Fontes and Garnier correction models have been shown to be the most appropriate models for radiocarbon correction of groundwater in this semi-arid region. Although, geothermal springs water and boreholes are not fit for drinking due to high fluoride content, they could be used for the following: domestic uses (drinking exclusive) due to its softness, direct heating in refrigeration, green-housing, spa, therapeutic uses, aquaculture, sericulture, concrete curing, coal washing and power generation. In contrast with mentioned uses, viii | Isotopic signatures and trace metals in geothermal springs and their environmental media within Soutpansberg the studied geothermal springs are currently used for domestic purposes (drinking inclusive), limited irrigation and spa (swimming and relaxation). This is an eco-hydrological study that shows the interconnectivity of isotopic signatures among water (rainwater, geothermal springs and boreholes), soils and vegetation. The soil-water reflects the rainwater/geothermal springs water in isotopic composition, which is more depleted as a result of isotopic fractionation in soil. δD values of soil-water increase, whereas δ13C values in soil-water decrease with the soil depth at all sites. Two equations connecting δD and δ13C in soil-water were deduced per season for soil-water; δ13C = 0.0812δD - 10.657 in winter; δ13C = -0.0278δD - 21.945 for summer. δ13C in soil-water is induced by Crassulacean Acid Metabolism (CAM) (mixture of C3 and C4 photosynthetic cycles) with a stronger C4 trend, which corroborates with δ13C of the geothermal springs. From literature, Amarula and Acacia trees have been documented for isotopic compositions, while this study has given additional information on other plants including Lowveld, Leadwood, Sausage, Fig, Guava and Mango trees. These plants are categorised as C3, C4 and CAM plants. C3 plants include Amarula, Lowveld and Leadwood trees; C4 plants include Acacia and Sausage trees; and CAM plants include Fig, Guava and Mango trees. This study shows that with CAM soils, there is a possibility of having either C3, C4 or CAM vegetation. This finding has shown that the δD and δ13C isotopes in water, soil and vegetation are interrelated, which has been statistically justified. This study has shown the potential human health risks associated with trace metals concentrations from geothermal springs and their surrounding soils. From the geothermal spring’s water, it was found that As, Cr and Cd were the highest contributors to the cancer risk with children having a higher risk than adults. Whereas in soils, it was found that Cr, As and Co were the highest contributors to the cancer risk in the studied communities. Therefore, the cancer risk is high in the general population; that is 1 in 72-162 individuals in children and 1 in 7-107 individuals for adults. The ingestion route seems to be the major contributor to excess lifetime cancer risk followed by the dermal pathway. Therefore, proper monitoring and control measures to protect human health, particularly in children, should be implemented for safety. The study also explored the use of surrounding trees ix | Isotopic signatures and trace metals in geothermal springs and their environmental media within Soutpansberg for phytoremediation and found their uptake capacity to be high, thus, they could be used as bio-indicators to assess the level of contamination of trace metals in the soil. In conclusion, this study has eludicated on the isotopic signatures and trace metals concentrations from the geothermal springs and their surrounding soils and vegetation within Soutpansberg. This study has contributed towards the advancement and enhancement of the existing knowledge of the geothermal systems, such that water resource management could be applied successfully in the respective areas with similar characteristics for the benefit of the local communities and society at large. Hence, this study recommends that proper monitoring and control measures need to be put in place to protect human health, especially in children. / NRF

MENVSC / Department of Geography and Geo-Information Sciences / Many rural communities of South Africa are living without adequate water supplies mainly due to historical lack of infrastructure and effective water reticulation systems. Day to day challenges of accessing water from distant boreholes and rivers are a reality particularly for women and children in rural Limpopo. This study investigates the nature and extent of water supply problems and how communities are living without adequate water in three rural communities of Greater-Giyani Local Municipality in South Africa. The study area lies in a semi-arid region which regularly experiences climate extremes such as droughts and floods which can reduce the ability of the municipality to supply water. Primary data was collected through questionnaires, key informant interviews and field observations while population, climate and hydrological data are also analyzed. A mixed methods research design was employed using qualitative methods such as content analysis whilst quantitative methods were dominated by time series analysis techniques and online interactive climate platforms such as the Climate Engine. It was found that households, schools and clinics in the study area rely mainly on boreholes for water supply but sometimes rivers supply those living nearby. An incomplete and poor water reticulation system coupled with erratic and shortening summer rainfall seasons are some of the major causes of water shortages in the study area. In order to cope with inadequate water, community members and public institutions in the study area have drilled boreholes and the sustainability of groundwater in the area is not well established. During summer, most households and institutions practise rainwater harvesting while a few resort to purchasing water from vendors. Despite these challenges which are not well documented, it was concluded that most of the rural poor households and institutions in the study area are well adapted to cope with water scarcity in the short term, while being vulnerable in the long term due to population growth and climate change. The study recommends the need for government and municipalities to invest in water reticulation systems in the long term whilst providing water to affected rural communities through water tankers, drilling more boreholes and maintenance of existing ones. Lessons learnt from this study may be useful to other municipalities across South Africa that are grappling with challenges of water access and supply. / NRF

MPH / Department of Public Health / Water quality of drinking water has been linked to good health outcomes across the world. The aim of this study was to assess physico-chemical, bacteriological, community practices regarding collection and storage of water and evaluation of human health risk characteristics of drinking water supplied by the government to Lufule village in Thulamela municipality, Limpopo Province, South Africa A cross-sectional study was conducted using questionnaires and interviews to determine drinking water handling practices and levels of contamination between the source and point-of-use at household. Assessment of water quality was carried out on 114 samples from selected sampling points using scientifically approved protocols. Total coliform was determined in 62.5% and 87.5% of the samples during the dry and wet seasons respectively. Similarly, E. coli was determined in 10.4 % and 13.2% in the dry and wet seasons, respectively. Trace metals levels in the drinking water samples were analysed and were within permissible range of both SANS and WHO. The calculated non-carcinogenic effects using hazard quotient toxicity potential, cumulative hazard index and chronic daily intake of drinking water through ingestion pathways were less than one unity, which showed that consumption of the water could pose little or no significant health risk. The results of this research suggest that lead has the potential of cancer risk to the residents through the cumulative ingestion in the drinking water samples of the studied area. Therefore, precaution needs to be taken to avoid potential risk of people in Lufule area especially, children. / NRF