Landfills have served as the major sites for waste disposal in both developed and developing countries. Upon closure of a landfill site, the surface could be converted to a golf course, recreation park, playground, animal refuge, tennis court and industrial site. Even when closed, landfills still have the potential to contaminate the surrounding environment as a result of the migration of leachate from decomposing waste contained in the site. This study focused on assessing the impacts of a closed landfill on soils and plants at Lumberstewart closed landfill site in Bulawayo, Zimbabwe. Soil samples were collected at three different depths (0-30 cm, 30 - 60 cm and 60-90 cm) at the landfill and a control site. The soil samples were analysed for their texture, pH, electrical conductivity, organic matter content, cation exchange capacity and concentrations of Cd, Cu, Cr, Fe, Ni and Zn. Samples of jimson weed and pigweed growing at the closed landfill and the control site were collected from the same sites where soil samples were collected, and the concentrations of the same set of heavy metals in these weeds determined. Soil samples were digested using EPA method 3050B: Acid Digestion of Sediments, Sludge and soils whereas nitric acid and hydrogen peroxide was used for digestion of plant samples. Both plant and soil digests were analyzed for heavy metals concentrations using Flame Atomic Absorption Spectrometry (AAS). Soils from the landfill as well as the control site had a high content of sand with soil pH values which were alkaline. The electrical conductivity values of the soil samples were relatively low ranging from 0.39 to 1.67 dS/m, indicating low levels of salts in soils at the landfill. The concentrations of heavy metals at the closed landfill site were higher than the control site. Heavy metals concentrations in soils at the closed landfill followed the order Fe>Zn>Cu>Cr>Ni>Cd. Results indicated that Fe was exceptionally higher than the other metals with concentration values averaging 45690±17255 mg/kg. Cadmium on the other hand had the least concentration with values of 0.01±0.00 mg/kg. Values of Enrichment Factors of heavy metals around the soil at different depths indicated that the enrichment of heavy metals increased with depth at the landfill up to 30-60 cm after which a decrease was observed. Values for heavy metal Contamination Factor of soils around the landfill ranged from low concentration (CF<1) to very high concentration (CF>6). The Pollution Load Index (PLI) values for the soil at the Lumberstewart landfill indicated that all sites were polluted (PLI>1). Site 6 had significantly higher mean concentration of heavy metals in soils at the landfill whereas site 11 had the least. The concentrations of Cd and Ni in soils at the landfill were below permissible limits of South African National Norms and Standards (NNS) as prescribed by NEMA (2008) in South Africa whereas Cr, Cu and Zn in soils were above the NNS permissible limits. Heavy metal concentrations in soils at the landfill were above World Health (WHO) permissible limits except for Cd which was equal (0.01 mg/kg) to the permissible values of Cd in the soils at sites 5, 8, 9, 10, 11 and 12. Mean concentrations of heavy metals in jimson weed and pigweed were in the order Fe>Zn>Cu>Cr>Ni>Cd. The concentrations of Cd, Cr, Cu, Fe and Zn in both plants from all sites at the landfill were significantly higher than the control site. Heavy metal transfer coefficient for both plants indicated that heavy metal uptake was more species dependent than soil heavy metal concentration dependent. The results from this research indicate that though the Lumberstewart Landfill has been closed, it is still affecting the soils in the vicinity of the landfill. Plants and water around the Lumberstewart closed landfill could be at risk from heavy metal contamination. High concentrations of heavy metals observed in the soil could present a health risk to communities should they decide to use the landfill site for arable purposes. / Environmental Sciences / M. Sc. (Environmental Science)

Thesis (MScAgric (Zoology))--University of Stellenbosch, 1996. / A number of studies on the general physico-chemical character of the Eerste River, Western Cape, had previously been done, but the problem of heavy metal pollution had, by 1993, not been addressed. A study was therefore undertaken from 1993-1995 in order to investigate these aspects. Since several researchers have shown that freshwater crabs accumulate certain heavy metals in their bodies and may therefore be used as monitors of environmental heavy metal pollution, the present study concentrated mainly on metal concentrations (Mn, Zn, Cu, Pb and Cd) in the local freshwater crab species, Potamonautes perlatus, and its possible use as biomonitor in the Eerste River. Two localities in the Eerste River were chosen,. in order to make comparisons, namely a relatively uncontaminated site in the Assegaaibosch Nature Reserve, Jonkershoek, and a visibly polluted site downstream from Stellenbosch, behind Stellenbosch Farmers' Winery (SFW). Crabs, water and sediment samples were collected seasonally at both localities, and metal concentrations thereof determined by atomic absorption spectrophotometry. The results showed that the Eerste River down to the SFW locality is still relatively unpolluted in terms of heavy metals. It was, however, clear that runoff from the Stellenbosch municipal, industrial and agricultural areas do have an influence on other physico-chemical features of the river. The concentrations of heavy metals in whole crabs, tissues and carapace showed that Zn concentration was well regulated in P. perlatus from both localities, Mn and Cu were accumulated in individuals from SFW, and Pb and Cd accumulated in both populations. Compartmentalization of heavy metals was shown to occur in P. perlatus: the carapace was found to be the most important storage site for Mn, Zn and Pb, the carapace and gonads equally important for Cd storage, and the digestive gland the most important site for Cu storage. Whereas gender was shown, generally, to be of little importance in heavy metal uptake in P. perlatus, crab body size and seasonality were both shown to influence heavy metal uptake to some extent. However, only summer peaks in whole crab, carapace and tissue manganese concentrations were shown to correlate with peaks in environmental Mn concentrations. It was concluded that P. perlatus would possibly only be a Suitable monitor of environmental Mn, Pb and Cd pollution, although there is no guarantee that the crab body would accurately reflect environmental concentrations. It was also ascertained that, since a study of the sperm ultrastructure of P. perlatus showed a significantly larger number of abnormal spermatozoa in male crabs from ,SFW, and since these observed differences could possibly be related to heavy metal exposure, the sperm of this species might be a more reliable indicator of heavy metal pollution. It was finally concluded that more intensive research need to be undertaken on various aspects, especially the use of the spermatozoon as indicator of environmental heavy metal pollution, and that the results of the present study could serve as a basis for future studies.

University of Macau / Institute of Chinese Medical Sciences

Pavement markings are vital for safely navigating roadways. The nighttime visibility of pavement markings is enhanced by addition of retroreflective glass beads, most of which are made from recycled glass. Concern has been raised over the presence of heavy metals in glass beads used in pavement markings and their effect on human and environmental health. Based upon the potential risk associated with the presence of arsenic and lead in the glass beads, two Bills are currently being considered before the 112th Congress of the United States of America seeking to set a maximum permissible limit for the amount of arsenic and lead in glass beads used within pavement marking systems on domestic roadways. This study was designed to support legislative decision making by providing data necessary for risk assessment. The experiments carried out provide: an analysis of glass bead metal content and extractability; an evaluation of the relationship between arsenic content of the glass beads and their retroreflective performance; an evaluation of analytical methods used to measure the total bead metal content; and an analysis of samples of glass bead and soil mixture from a glass bead storage site used to determine site-specific metal concentrations in the soil media. Mean arsenic content, measured using the Pacific Northwest National Laboratory's KOH fusion digestion, in all the glass beads examined ranged from 11 ppm to 82 ppm, while mean lead content, measured using KOH fusion digestion, ranged from below quantification limit to 199 ppm. Total metal content measurements indicated a high amount of variability in the glass bead samples; most likely associated with the use of recycled glass feed during manufacturing. The relationship between the retroreflective performance and the arsenic content of the glass beads was analyzed and a weak but positive correlation was observed between the two factors. However, a more detailed study is required to evaluate the relationship between arsenic content and retroreflectivity. Different methods to evaluate the total metal content in glass beads were compared; it is recommended that any analytical method may be used, as long as the standard reference material is reproduced within the range of concentration expected in the glass beads. In the analysis of the field site samples of soil containing glass beads obtained from a glass bead storage and transfer facility, the mass content of beads in the soil varied from a mean of 19% to 78% depending on the location within the facility. However, a detailed analysis with larger number of samples must be performed to evaluate the effect of glass beads on the total arsenic content of the soil.

Plants are able to take up and accumulate certain environmental contaminants such as heavy metals. When the plants are ingested by man, these contaminants are transferred along the food chain. Due to the poorly regulated medicinal plant trade in South Africa, many opportunities exist for heavy metal contamination of medicinal plants namely contaminated harvest sites as well as poor drying, processing, storage, transport and manufacturing conditions. The concentrations of five heavy metals (As, Cd, Co, Ni, Pb) and six microelements (B, Cu, Fe, Mn, Mo, Zn) were determined in some commonly used South African medicinal plants obtained from street markets. Elemental content was determined using inductively coupled plasma optical emission spectrophotometry (ICP-OES). Some of the medicinal plant samples investigated contained As and Cd at levels exceeding the World Health Organization limits of 1 and 0.3 mg kg-1 respectively. Lead and Ni were detected in all the samples. Elevated Fe and Mn levels were recorded in certain plant species. The results revealed multiple metal contamination in some medicinal plant parts sold in local markets and is thus grounds for concern. The effects of Cd application on growth parameters of some medicinal plant species belonging to the Hyacinthaceae (Albuca setosa, Eucomis autumnalis, Eucomis humilis, Merwilla plumbea) gave insight into heavy metal accumulation and distribution in these species. Application of Cd at 5 mg l-1 over a 12 week period reduced growth in A. setosa. The medicinally used A. setosa bulbs accumulated 37 mg kg-1 Cd after 12 weeks. Cadmium application at 2 mg l-1 over a six week period had no effect on growth parameters of E. autumnalis or E. humilis. However, a substantial difference in total Cd accumulation was detected in the plants (40.2 and 15.3 mg kg-1 respectively). Cadmium application at 2 mg l-1 significantly reduced the fresh weight of leaves, bulbs and roots of M. plumbea. Although most of the Cd was stored in the roots, the medicinally used bulbs accumulated up to 11.6 mg kg-1 when applied at 10 mg l-1. The antagonistic effect between Cd and Zn treatments and their effect on micronutrient distribution in M. plumbea were investigated. Five treatments were evaluated: (1) Hoagland’s nutrient solution (HS) (control) (2) HS + Cd 2 mg l-1 (single) (3) HS + Cd 2 mg l-1 + Zn 50 mg l-1 (combination) (4) HS + Cd 2 mg l-1 + Zn 100 mg l-1 (combination) (5) HS + Cd 2 mg l-1 + Zn 150 mg l-1 (combination). Cadmium readily accumulated in leaves, bulbs and roots of M. plumbea when supplied at 2 mg l-1. Zinc at 50 mg l-1 led to increased Cd accumulation. However, further increases in Zn concentration showed an antagonistic effect of Zn on Cd uptake and accumulation. Thus, increasing Zn levels in soils may be favourable for reducing toxic Cd accumulation in M. plumbea plants. Boron was not significantly affected by the addition of Cd to the media. However, with an increase in Zn, leaf B content increased while the B content in the bulbs and roots decreased. Copper and Mo levels were not significantly affected by treatments with Cd or Cd/Zn combinations. Compared to the control, Cd and Cd/Zn applications caused an increase in Mn content in leaves, bulbs and roots. Iron levels of M. plumbea were not significantly affected by Cd in the media. However, with an increase of Zn in the Cd-containing media, Fe content in the leaves, bulbs and roots increased. Tulbaghia violacea is one of the few medicinal plants that is also frequently used as a leafy vegetable. Application of Cd at 2 and 5 mg l-1 to T. violacea of varying sizes (small 8 - 10 g, medium 16 - 20 g, large 80 – 95 g) elicited a difference in growth response, Cd accumulation and micronutrient distribution. Leaf length and fresh weight of leaves of the medium-size plants decreased with application of Cd at 2 mg l-1 whilst 5 mg l-1 Cd significantly decreased the number of leaves in small-sized plants. Small plants accumulated more Cd in the leaves than medium- or large-sized plants. Application of Cd at 2 mg l-1 and 5 mg l-1 lowered the leaf Cu, Fe, Mo and Zn contents in small- and medium-size plants. This study indicated that T. violacea has the ability to accumulate Cd. In addition, plant size plays an important role with regards to Cd accumulation and elemental distribution. The effect of various nutrient applications (10%, 50% and 100% Hoagland’s nutrient solutions (HS); and HS deficient in N, P or K) on growth parameters and micronutrient distribution in Dioscorea dregeana were investigated. Irrigating plants with 50% HS resulted in better growth performance, whereas a deficiency of either N, P or K negatively affected seedling growth. Plants grown in 10% HS contained higher total B, Fe and Mo levels compared to seedlings grown in 50% and 100% HS. Compared to the control, P deficiency resulted in a Fe increase in the leaves, tuber and roots while a lack of P and K significantly increased total Mn content in D. dregeana. The effect of excess Zn (100, 200 and 300 mg l-1) on growth performance, chlorophyll content and microelemental distribution on Dioscorea sylvatica was investigated. Growth parameters showed a significant decrease when supplied with Zn at 100 mg l-1. Zinc phytotoxicity was evident by the reduction in chlorophyll content. Highest Zn concentrations were detected in the roots. Certain micronutrients appear to be redistributed due to Zn toxicity. The effect of microelements (Cu, Zn) and heavy metals (Cd, Pb, Hg) on germination and seedling development of Bowiea volubilis, Eucomis autumnalis and Merwilla plumbea was investigated. Copper and Zn applied at 1 mg l.1 significantly reduced the percentage germination of E. autumnalis. Low concentrations (. 1 mg l.1) of Cu and Zn negatively affected the root growth of all three species. Mercury concentrations of 0.5 and 1 mg l.1 significantly decreased the percentage germination of B. volubilis and E. autumnalis respectively. Cadmium and Hg at 2 mg l.1 showed a negative effect on the root growth of B. volubilis. Concentrations of 0.5 mg l.1 of all heavy metals tested significantly decreased shoot length of M. plumbea. The effect of Cd on biological activity (anti-inflammatory, antibacterial and antifungal) of medicinal plants with previously confirmed activity was evaluated. When supplied with Cd at 2 mg l-1, Eucomis humilis bulbous extracts showed lower anti-inflammatory activity than the control for both COX-1 and COX-2 activity. Eucomis autumnalis bulbous extracts had greater COX-1 activity compared to the control. However, Cd suppressed the activity of COX-2. Compared with non-Cd-treated Merwilla plumbea plants (control), those supplied with Cd at 10 mg l-1 showed increased antibacterial activity against Bacillus subtilis, Klebsiella pneumoniae and Staphylococcus aureus. However, no change in activity against Escherichia coli was observed. Cadmium accumulation in the bulbs had no effect on antifungal activity of Tulbaghia violacea. Thus, optimized agricultural practices are essential for quality control of cultivated medicinal plants. The studies presented in this thesis collectively answer several questions related to heavy metal involvement in South African medicinal plants. The findings substantiate the need to regulate and monitor the South African medicinal plant trade against heavy metal contamination which will in turn provide a product of safety and quality to the consumer. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Cupriavidus metallidurans CH34 is a Gram-negative & / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

A des concentrations supra-optimales, les métaux lourds essentiels (comme le Cu, Zn ou Ni) ou les métaux lourds non essentiels (comme le Cd, Pb ou Hg) peuvent être toxiques. La contamination des sols et de l’eau par des métaux lourds toxiques est un problème mondial qui peut nuire à l’environnement et à la santé humaine. En particulier, le cadmium est l’un des métaux lourds les plus toxiques pour les organismes. L’utilisation de plantes pour extraire ou dégrader les polluants (dans le cas de polluants organiques) constitue une stratégie intéressante, à bas coût et respectueuse de l’environnement pour remédier au problème des sites pollués. Pour une phytoextraction des métaux lourds, les plantes doivent avoir une croissance rapide, développer des biomasses importantes et accumuler des niveaux élevés de métaux lourds dans leurs parties récoltables. En d’autres termes, elles doivent être très tolérantes et accumulatrices. Une alternative consiste à utiliser des plantes tolérantes de façon à contenir la pollution (pour réduire la biodisponibilité et limiter la dispersion dans l’environnement). Des gènes d’une banque d’ADNc synthétisée à partir d’un hyperaccumulateur Cd/Zn Thlaspi caerulescens, dont l’expression augmente la tolérance au Cd dans les cellules, ont été identifiés. Dans cette thèse de Doctorat, notre but est d’une part de contribuer à la caractérisation fonctionnelle de ces gènes et d’autre part de créer de nouveaux outils en vue d’améliorer les techniques de phytoremédiation. Nous avons sélectionné deux séquences codant pour des protéines riches en cystéines, capables de lier certains métaux lourds et d’augmenter la tolérance au cadmium :une métallothionéine de type 3 (Tc-MT3) et une métallothionéine potentielle (MRP) provenant d’un organisme contaminant de la banque d’ADNc. Nous avons générer des lignées de tabac exprimant TcMT3 ou MRP, sous le contrôle d’un promoteur fort et constitutif, CaMV35S. Les plantes MT3 et MRP ont présenté un retard de croissance par rapport aux plantes contrôles, en croissance sur milieu non contaminé. Différents tests de croissance ont été réalisés en présence d’excès de Zn, Ni ou Cu et dans des milieux modifié avec du Cd. Nous avons remarqué qu’en présence de plusieurs métaux lourds en particulier le Cu et le Cd, les plantes Tc-MT3 et MRP étaient plus tolérantes que les plantes contrôles. La tolérance au Cd était la plus augmentée dans les plantes MRP. Les plantes Tc-MT3 ou MRP semblaient avoir un besoin en métaux lourds plus grand. L’accumulation des métaux lourds dans les parties aériennes n’était pas augmentée mais la minéralomasse des plantes Tc-MT3 et MRP l’était sur sol contaminé de la Région Bruxelloise. Une analyse biochimique a confirmé un changement dans le statu rédox de ces plantes. Une tendance à un statut plus oxydant a été observée dans les milieux non contaminés. Enfin, l’induction d’une métallochaperonne (CCH) du Cu indique une diminution de la biodisponibilité de cet élément, alors que la concentration totale n’est pas altérée. Il semble donc que pour la première fois, des métallothionéines puissent entrer en compétition avec une métallochaperonne végétale. Cette compétition pour les métaux pourrait être à l’origine de l’altération du statut rédox, du retard de croissance ainsi que de la meilleure tolérance aux métaux lourds. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The contamination of heavy metals in the environment is a looming concern worldwide. Egeria densa (Planch) (Submerged aquatic plant) from two ponds: Site A with co-ordinates (32º 48’22.04”S; 26°48’58.79” E) and Site B with co-ordinates (32°48’33.25”S; 26°48’33.25”S) in Alice (Eastern Cape) was evaluated for its ability to absorb heavy metals, phytochemical constituents, antimicrobial activity and ultra-structure using standard analytic procedures. Cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), and zinc (Zn) were measured in water, sediments and plant. The concentrations of these metal elements were determined with use of Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES). In sediments, the heavy metals (mg/kg) decreased in the order of their average concentration as follows: Fe (40.320) > Zn (1.259) > Pb (0.564) > Mn (0.186) > Cu (0.037) in Pond 1 whereas in Pond 2 Fe (61.527) > Cd (0.999) > Mn (0.648) > Pb (0.586) > Zn (0.156) > Cu (0.045). The highest concentration of Fe was detected in both sites and Cu being the least. The concentrations of the metals in the plants sample (from Pond 1) were found in order of Mn > Pb > Cu > Fe whereas cadmium and zinc were not detected, while the concentration in Pond 2 decreases in order of Zn > Mn > Pb > Cd > Fe > Cu. In the water samples, concentrations of heavy metals (mg/L) decreased in the order of their average concentrations as follows: Pb (35.36) > Fe (3.07) > Mn (0.238) > Cu (0.104), both cadmium and zinc were below the limit of detection in Pond 1, whereas in Pond 2 the concentrations decreased as follows: Pb (13.033) >Fe (1.69) > Cu (0.270) > Mn (0.248) > Cd (0.004) and Zinc was not detected. Phytochemical analyses of the plant extracts revealed the presence of phenols, flavonoids, proanthocyanidin, flavonols, saponins, alkaloid and tannins in all the extracts (water, acetone and n-hexane). Both acetone and water extracts, showed high concentration of proanthocyanidin, while tannin was the lowest in acetone extract. Antimicrobial evaluation using, Gram positive (Staphylococcus aureus, Bacillus pumilus, Bacillus cereus, Streptococcus pyogenes, Enterococcus faecalis) and Gram negative (Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Serratia marcescens) bacteria showed negative results for all the strain, except Streptococcus pyogenes which was inhibited at MIC of 0.1 mg/ml. Scanning electron microscopy (SEM) of ultra-structure of Egeria densa, showed that certain bacteria attached to the leaf, However more work has to be done on E. densa to verify the mechanism by which it accumulates heavy metals. The study shows that E. densa has a potential of accumulating heavy metals especial Manganese in plant.

MSc (Chemistry) / Department of Chemistry / Increasing health and environmental concern about the effects of most toxic heavy metals emitted from cement plants in developing countries, which are going through rapid development, has led to this study. Cement industry in South Africa has been the primary industry over the years contributing immensely to infrastructure development and economic growth. Cement has been used to build many large cities, industries, homes, bridges and shopping malls around the country and still continue to be used by constructors. At this point, there has been no other substitute for cement and it will continue to be produced for decades to come. Unfortunately, this industry is now known to be amongst the major environmental polluters. Less has been done to address the adverse effects that comes with the production of cement, especially in the developing countries where there is huge demand for cement. This study focusses on dust emanating from production processes especially cement manufacturing from rotary kiln stage during production of cement and cement bricks. The production of cement and cement bricks generate dust, which is distributed over large areas of the environment. In South Africa, there are a number of factories in operation without proper planning of pollution prevention and compliance to environmental legislature. Since the production of cement is associated with the release of dust containing heavy metals, the dust is atmospherically deposited on the land, water surfaces and residential areas. The soil, street pavements, wetlands and water surfaces have become the sinks of heavy metals. Heavy metals that are being deposited include arsenic, cadmium, chromium, manganese, cobalt, copper, barium, antimony, selenium, vanadium, nickel and lead. Such metals pose health threat to the animals, plants and human beings living around the cement factories. These metals can easily be leached out from the soil and washed to the water bodies causing water pollution. Old processing techniques have been found to be inefficient to prevent emission of dust to the atmosphere. Hence, the emission of the toxic heavy metals to the environment was uncontrollable. Since cement is used to produce cement bricks, the whole process is subjected to heavy metals being discharged with dust from the factory to the surrounding environment. Four papers (I, II, III and V) were written to assess the level of heavy metals. In paper I, water and plants samples (Bidens Pilosa, Phragimites Australis and Xanthium Strumarium) were collected in the Mvudi River nearby a cement factory. Sampling was done before, within and after the wetland. Samples were digested with nitric acid for analysis. The concentration of zinc, chromium and lead were determined in the samples using a graphite furnace atomic absorption spectromentry. Results showed that the concentrations of zinc, chromium and lead were above the permissible limits in different parts of the plants analysed and water. The pH of water samples were below the threshold recommended by Department of water affairs and forestry (DWAF) and World health organisation (WHO). In paper II, seven soils at different distance, seven soils below soil surface at seven different layers and a bulk were sampled nearest to the cement brick making factory. Bulk sample was separated into five particle sizes (2 - 3 mm, 1 - 2 mm, 0.5 - 1 mm, 0.5 mm). Five sediments samples were also collected before, within and after the wetland along Mvudi river. Modified three step BCR sequential extraction was applied to the 23 samples in order to obtain the metal distribution in the samples. Heavy metal concentrations of nickel and chromium were determined using graphite atomic absorption spectrometry. Results showed that the levels of nickel and chromium exceeded the permissible limits recommended by WHO. Elevated concentrations Ni and Cr in soil and sediments also showed that the cement brick making factory is the main source of pollution in the area. To assess the contribution of cement dust to heavy metal pollution from the cement plants to the surrounding environment, two studies were carried out in the vicinity of two cement plants one in Thabazimbi and the other in Pretoria. Two papers (III and IV) were written from the studies and were summarised as follows: In paper III, dust samples were collected along the road leading to and passing by the cement plant in Thabazimbi, South Africa. The samples were collected using a brush and pan into sampling bags. After sampling dust samples were sieved into three particle size fractions (PM125, PM75, and PM32). A bulk and five samples were collected beneath the soil at different depth for depth analysis nearest to the cement plant. Water samples were collected along the Crocodile River before and after the cement plant site. The samples were digested using aqua ragia and extracted using Modified BCR sequential extraction. The samples were analysed using inductive coupled plasma optical emission spectrometry (ICP-OES) for concentration of platinum group metals and x-ray fluorescence for elementary analysis (XRF). Analysis of samples included characterisation of the dust samples using x-ray diffraction (XRD). The vi concentrations were also compared to that of the control study (blank) area to find out if the metals were discharged from the cement factories of interest. In paper IV, street dust samples were collected randomly on the paved surfaces, on the streets and accessible residential and roadsides on locations close to the cement plant in Pretoria. Some samples were collected along the road leading to the gate of the factory and also on the road near the cement plant. The samples were collected into sampling bags using a brush and pan. After sampling dust samples were sieved into three particle size fractions (PM125, PM75 and PM32). A bulk and five samples were collected beneath the soil at different depth for depth analysis nearest to the cement plant. Water samples were collected along the Apies River before and after the cement plant. All samples were kept in a cooler box with ice bags to keep them in good condition. The samples were digested using aqua ragia and extracted using Modified BCR sequential extraction. Results were used to establish spatial distribution of the heavy metals around the urban streets. The samples were analysed using ICP-OES for concentration of heavy metals and XRF. Analysis of samples included characterisation of the dust samples using XRD. The concentrations were also compared to that of the control study (blank) area to find out if the metals were discharged from the cement factories of interest. In paper V, seven different vegetables (spinach/Spinacia oleracea, Chinese cabbage/Brassica rapa, onion/Allium cepa, beetroot/Beta vulgaris, sweet potatoes/Ipomoea batatas, tomatoes/ Lycopersicon esculentum and cabbage/Brassica pekinensis), fruits (bananas/Musa acuminate) and their soils taken after uprooting them were sampled in farming area close to Thohoyandou town and the cement factory. The concentrations of cadmium, nickel and manganese were measured using the graphite atomic absorption spectrometry (GFAAS). Cadmium, nickel and manganese levels were found above permissible limits proposed by Food agricultural organisation (FAO) and WHO in edible parts of vegetables, fruits and soils and hence, may pose a health risk to consumers. Similarly the results from XRF also showed high concentration of the heavy metals in soil analysed. The aim of this project is to determine the levels of toxic heavy metals carried with dust emanating from cement factories. This assessment is meant to identify and highlight the levels of heavy metals in areas that are close to cement factories. The study will develop a database of heavy metals in affected areas and the pollution impact to the affected environments. / NRF

M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / In the present study, the removal of Ca2+ and Mg2+ from cooling tower water using Amberlite IR120 and Amberjet 1200 was studied by the application of one factor at a time method (OFAT) and response surface modelling (RSM). The effect of operational parameters such as contact time (min), pH, dosage (mL), concentration (mg/L) and temperature (K) were investigated using central composite design. The regeneration of the Amberlite IR120 and Amberjet were also studied. The purpose of the study was to apply OFAT and RSM to investigate and optimize the ion exchange operating parameters. Furthermore, the second-order empirical model that was developed, using the analysis of variance (ANOVA), presented a sufficient correlation to the ion exchange experimental data. The optimal ion exchange operating conditions for Amberlite IR120 and Amberjet 1200 were found to be: contact time was 120 min, dosage of 150mL, initial pH level of 2, concentration of 400mg/L and temperature of 343K. Regeneration of Amberlite IR120 and Amberjet 1200 using 0.5 M NaCl stripping solution initially showed an increase in % Ca2+ and Mg2+ removal, then a decrease in subsequent cycles. The correlation coefficients (R2) of Langmuir, Freudlich and Tempkin isotherms were found to range from 0.92 to 1 and this suggest that experimental data best described the models. However correlation coefficients (R2) for Dubinin–Radushkevich (D-R) model were found to range between 0.5 to 0.8 and this means that experimental data does not fit the model. Thermodynamic functions such as entropy (Δ𝑆𝑜), enthalpy (Δ𝐻𝑜) and change of free energy (Δ𝐺𝑜) were obtained from the gradient and intercepts of straight line graphs. The positive values of ΔG° were found meaning that the adsorption is not spontaneous and positive values of ΔH° were found meaning the endothermic type of adsorption which indicate the chances of physical adsorption.The correlation coefficient (R2) values of pseudo-first-order, pseudo-second-order and intraparticle models were found to range from 0.89 to 1 on both metals as shown in table 4.4. This observation clearly indicates that pseudo-first-order, pseudo-second-order and intraparticle diffusion models best describe the experimental data in the removal Ca2+ and Mg2+ from cooling tower water.