Excessive release of metals and metalloids into the environment is a major global environmental concern and there is need for environmentally friendly and cost effective methods for their removal. The present study investigated the adsorptive removal of zinc, lead, copper and nickel ions from synthetic aqueous solutions and various metals from three acid mine drainage (AMD) sites using chicken eggshells. Process parameters including the initial metal concentration were evaluated and the optimum conditions obtained were pH 7, adsorbent dose of 7 g and contact time of 360 minutes (for the removal of 100ppm metal ions). Under these conditions the percentage adsorptions were; 97% for lead, 95% for copper, 94% for nickel and 80% for zinc. Aluminium, iron, potassium, nickel and zinc ions all had percentage adsorptions above 75% in AMD Sample 1. Potassium had a 98.78% adsorption while magnesium, strontium and zinc had 72.33; 68.75 and 53.07% adsorption respectively in Sample 2. Arsenic, chromium, copper, iron, antimony and tellurium ions were above 75% for Sample 3. The study demonstrated the efficacy of chicken eggshells and presents it as a viable low-cost adsorbent for bioremediation. / Environmental Science / M. Sc. (Environmental Science)

The present study was carried out to determine the levels of heavy metals, Arsenic (As), Chromium (Cr), Cadmium (Cd) and Lead (Pb) in samples of water, sediments, and specimens from sheep known to graze and drink from Wonderfontein stream around the Khutsong area in the North West Province of South Africa. Determination of heavy metal levels was carried out using Atomic Absorption Spectrophotometer. Abundance of metals in water samples followed the trend As>Pb>Cd>Cr, while that in sediments followed the trend: Pb>As>Cr>Cd. Faecal levels were highest for Cr, followed by Cd, As then Pb, while serum levels were highest for As, Cd Cr and then Pb. The metal concentration in liver, kidney and muscle showed the following trends respectively: As>Cd>Cr>Pb ; As>Pb>Cd>Pb and As>Cd >Cr> Pb. The liver, kidney and muscle samples had higher concentration of As compared to other heavy metals. Generally, most samples showed a higher concentration in As. The mean concentrations of heavy metals in ppm were compared with European Commission Regulation, World Health Organisation, Korean Soil Environmental Conservation Act and the Australian New Zealand Food Standards maximum acceptable levels. The metal levels generally tended to be higher than the permissible levels and thus, public health risks. A survey conducted also revealed that the community in Khutsong does not have the knowledge on environmental contamination due to mining effluents and the effects thereof. The varying levels of water and sheep specimen contamination with As, Cd, Cr and Pb revealed in this study imply public health risks. Further biomonitoring, public and animal health studies are therefore indicated in this area. / Thesis (Msc in Agric Animal Health) North-West University, Mafikeng Campus, 2012

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Thesis (M. Tech.: Biotechnology)-Dept. of Biotechnology and Food Technology, Durban University of Technology, 2008. xiv, 103 leaves : ill. / Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. Amaranthus dubius (marog or wild spinach) is a popular nutritious leafy vegetable crop which is widespread especially in the continents of Africa, Asia and South America. Their rapid growth and great biomass makes them some of the highest yielding leafy crops which may be beneficial for phytoremediation. This study was undertaken to evaluate the potential of A. dubius for the phytoremediation of Chromium (Cr), Mercury (Hg), Arsenic (As), Lead (Pb), Copper (Cu) and Nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a sewage site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS). Further experiments were conducted with plants from locally collected seeds of A. dubius, in a tunnel house under controlled conditions. The mode of phytoremediation, the effect of the metals on the plants, the ability of the plant to extract metals from soil (Bioconcentration Factor - BCF), and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor - TF) were evaluated for the different metals. Finally, A. dubius was micro-propagated in a tissue culture system with and without exposure to the metal, and the effect was studied by electron microscopy.

This research involved the study of sediment cores from Loch Etive, Loch Long, Loch Goil and Loch Fyne with the aims of investigating the geochemistry of natural, and manmade radionuclides and heavy metals within the sea loch environment. The main aims of the research were to determine accumulation rates and the extent of mixing within these sediments and to assess the fluxes, sources and temporal variations in input of pollutant heavy metals to these environments. In recent years it has been suggested that Pb is mobile in sea loch sediments which questions the validity of applying ²¹⁰Pb dating in this environment. This has important implications with respect to interpreting sediment cores to assess temporal trends of pollutant inputs and investigating the rates of physical and biogeochemical processes that are taking place in the coastal environment. Hence, one of the aims of this research was to determine whether Pb was mobile in these sediments. The ²⁰⁶Pb/²⁰⁷Pb isotope ratio can potentially be used to determine the extent of pollutant Pb input from leaded petrol to the environment and a further objective of the work was to investigate the isotopic signature of pollutant Pb in the sediment. Concentration of ²¹⁰Pb, ²²⁶Ra, ²²⁸Ra, ²²⁸Th, ²³⁸U, ¹³⁷Cs, ¹³⁴Cs and ²⁴¹Am in the sediments were analysed using gamm a spectroscopy and the heavy metals, Pb, Zn and Cu were determined using X-ray Fluorescence. Stable Pb isotope ratios were determined using Inductively coupled plasma Mass spectrometry. The results obtained indicated that Pb is not subject to diagenetic mobility in these sediments and that ²¹⁰Pb profiles can be used to determine sedimentation rates for most of the sediment cores. lt was not possible to determine accumulation rates for the two cores from Loch Fyne by ²¹⁰Pb dating, and in this case the sedimentation rate was assessed by correlating the maximum concentration of ¹³⁷Cs in the sediments with the maximum ¹³⁷Cs discharge from Sellafield, BNFL's reprocessing plant located on the Cumbrian coast. The flux of ²¹⁰Pb to the lochs varied significantly suggesting that there has been sediment focusing of fine and/or organic rich material to the deeper sites, resulting in an enhanced flux of ²¹⁰Pb to these sediments. Sellafield waste radionuclides also provided useful chronologies by relating sediment maximum concentrations to maxima in the discharges. ¹³⁷Cs was observed to be subject to diffusive movement, invalidating the use of its total depth of penetration as a chronological indicator. The temporal trends of pollutant metal input agreed well with known historical trends and the Pb isotope profiles indicated that the onset of deposition from pollutant Pb from petrol occurred in the late 1920's. The maximum input of Pb from petrol peaked in the early 1980's and since then there has been a decrease in this input. The two sea lochs which were closest to the industrial centre of Glasgow exhibited a large anthropogenic pollutant input, confirming that these sediments have been highly perturbed by human activities, either directly as a result of sludge dumping or due to changes in land use (eg. road construction, deforestation, etc.) in the catchment. All the sea lochs reflected a change in the supply of material to the sediments over the last eighty years, indicating that increased anthropogenic activity has had an effect on these environments.

The goal of this work was to establish the suitable and limiting concentrations of Zn, Cu and Mn compounds during syngas fermentation. The results showed that cells encased in polyvinylidene difluoride (PVDF) membranes had a faster accumulation of methane in reactors containing fermentation medium dosed with 5 mg/L of each heavy metal compared to free cells. It was also revealed that total inhibition of biohydrogen production occurred in medium containing 5 mg/L Cu, 30 mg/L Zn and 140 mg/L Mn while the most suitable metal concentration level was 0.1 mg/L Cu, 0.6 mg/L and 2.8 mg/L Mn. In addition, a comparison test showed that for the most suitable metal concentration in the medium, rate of performance at pH 6 and 7 was higher than at pH 5.

published_or_final_version / Chemistry / Master / Master of Philosophy

Urbanisation leads to increases in stormwater runoff, resulting in elevated contaminant (e.g. metal, sediment, and nutrient pollutant) loads, decreased local infiltration and greater peak flow intensities. Heavy metal contaminants of concern, primarily copper (Cu), lead (Pb), and zinc (Zn), originate from a variety of sources including wear-and-tear of vehicle parts, corrosion of alloy roofs, legacy petroleum contamination, and multifarious construction practices. Different technologies have been used to mitigate stormwater runoff, ranging from traditional drainage networks fitted with concrete proprietary devices (e.g. vortex sediment separators and filters) to more environmentally integrated sustainable solutions. Rain gardens, a type of Sustainable Urban Drainage System (SUDS) or Water Sensitive Urban Design (WSUD), are employed to control stormwater peak flows and runoff volumes and simultaneously reduce contaminant loads to neighbouring waterways through biologically-active landscaped design. Despite increases in use of rain gardens as a best management practice (BMP) to treat urban stormwater runoff, there is a dearth of knowledge about their treatment and infiltration performance worldwide. It is believed that incorporating topsoil into rain garden design is likely to improve contaminant removal efficiencies (Davis et al. 2001; ARC 2003; Fletcher et al. 2004; Carpenter and Hallam 2010), but design recommendations are not informed by performance data which is limiting. Performance data is necessary for understanding the long-term responses of bioinfiltrative treatment systems and for modelling efforts aiming to predict their mitigation behaviour (Fletcher et al. 2004). In order to evaluate the influence of substrate composition on stormwater treatment and hydraulic effectiveness in rain gardens, mesocosm-scale (180 L, 0.17 m2) laboratory systems were established. Saturated (constant-head) hydraulic conductivity was determined before and after contaminant (Cu, Zn, Pb and nutrients) removal experiments on three rain garden systems comprising various proportions of organic topsoil. Raw stormwater runoff from a neighbouring Christchurch city catchment was collected, characterised, and applied in the removal efficiency experiments. The system with only topsoil had the lowest saturated hydraulic conductivity (160 mm/hr initial to 164 mm/hr final) and poorest metal (Cu, Zn) removal efficiency (Cu 0.3%, Zn 60.5% and Pb 89.5%) at a ‘standard’ contaminant loading rate (Cu = 5.99 ± 0.73 µg/min, Zn = 57.89 ± 6.06 µg/min, Pb = 13.65 ± 2.80 µg/min). The sand-only system demonstrated good metal removal (Cu 56.4%, Zn 73.5%, and Pb 81.6%) with hydraulic conductivity (up to 805 mm/hr) adequate for practical implementation (i.e. greater than the 13 mm/hr minimum requirement (ARC 2003; MDE 2009; SFPUC 2009)). Overall, total metal amounts in the effluent were <50% of influent loads for all experiments, with the exception of Cu in the topsoil-only system, whose removal was negligible (0.3%). Greater metal removal was observed when effluent pH was elevated (up to pH 7.38). The pH increase (from an initial pH of 6.23 in raw stormwater) was provided by the calcareous sand, whereas the topsoil-only system lacked an alkaline source. Consequently, organic topsoil had poorer contaminant removal due to higher dissolved metal fractions, which are more difficult to immobilise at the lower pH. The relationship between pH and dissolved fraction was highly significant (Pearson’s Correlation, p < 0.0001, df = 74) for Cu, Zn, and Pb. Mesocosm-scale systems were then re-established with a calcareous substrate supplement to quantify the effects of pH augmentation on contaminant removal and hydraulic efficiencies. Mussel shells, a waste product from the shell-fish industry, were employed in two different volumetric proportions. Metal removal efficiency was increased in systems with mussel shells (Cu up to 46.6%, Zn up to 80.2%, Pb up to 88.7%) compared to the topsoil-only system (Cu 27.5%, Zn 55.5%, Pb 81.0%). Larger increases in removal efficiency were seen for Cu and Zn because increases in pH from mussel shell enhanced particulate fractions, which are easier to remove in filtration systems, while Pb is mainly in the particulate form at influent pH (Morrison et al. 1990). Effluent from systems with mussel shells also had higher hardness (hardness up to 101.7 mg/L as CaCO3) compared with 22.4 mg/L as CaCO3 in topsoil-only effluent. Hardness reduces metal ecotoxicity (Hyne et al. 2005). Results of these experiments show that mussel shells are a promising rain garden substrate capable of increasing metal removal efficiency and also decreasing metal ecotoxicity in effluent of bioinfiltration systems. Concurrently, an operational field-scale “rain garden” (42 m3; 60 m2) in Christchurch was monitored for hydraulic throughput and contaminant removal. The field system performed extremely well at mitigating peak flows, detaining water throughout storm events and removing total suspended solids (TSS) (90.6% average removal). However, the system failed to reduce effluent median total metal concentrations (Cu = 15.9 µg/L, Zn = 139.6 µg/L, Pb = 11.7 µg/L) below relevant ANZECC guidelines (Cu = 1.8 µg/L, Zn = 15.0 µg/L, Pb = 5.6 µg/L) highlighting the opportunity to optimise these field designs to improve metal removal.

The aim of this study was to develop a suitable monitoring protocol for mediated amperometric whole-cell biosensors for in situ assessment of heavy metals in soil. E. coli 8277, Pseudomonas 9773, Pseudomonas 9046 and Pseudomonas 8917 were screened as biosensor catalysts to select the sensitive biosensor configurations to heavy metals. A new protocol was developed for monitoring heavy metals in defined solution, soil pore water, and in situ in soil. This study also demonstrated the applications of mediated amperometric bacterial biosensors for in situ assessing the bioavailability and toxicity of heavy metals in freshly spiked soils or historically contaminated soils, and mixture toxicities of heavy metals. It was found that the biosensors incorporating selected bacterial strains were appropriately sensitive to copper, but less sensitive to Zn, Pb, and Hg, compared to Microtox assay. The advantage of the mediated amperometric bacterial biosensor system is its in situ application in soils. The present study demonstrated that soil pore water does not accurately reflect conditions of soil ecosystem, and that in situ bioassays are more reliable for determining the bioavailability and toxicity of heavy metals. This is the first reported use of disposable whole cell biosensors for in situ heavy metal bioavailability and toxicity assessment. The biosensor protocol developed here can be adapted to allow the incorporation of dfferent bacterial biocatalysts for applications in soil quality assessment, screening of sites for contamination ‘hot spots’, and the evaluation of soil degradation or rehabilitation from metal pollution. Mediated amperometric bacterial biosensors are not analyte specific, their response reflecting the metabolic impact of the combined chemical and physical properties of the environment to which they are exposed. In assessing the toxicity of soil samples from fields using these biosensors, it is vital to get appropriate control soil samples. The conditions of soil samples also need to be well defined. The sensitivity of the mediated amperometric whole-cell biosensors to heavy metals need to be further improved. Investigations are also required to determine how the natural conditions affect the application of the biosensor system in the field.