published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. September 2014, Johannesburg. / Aims: The adsorptive removal of Cu, Mn, Hg and U by silica and maghemite nanoparticles (NPs) under acid mine drainage (AMD) conditions was investigated with the aim of assessing the applicability of NPs for remediation of AMD-contaminated water. The effect of NPs on metal uptake by algae, an increasingly popular remediation alternative, was also investigated. Methods: NP and algal metal removal were quantified by batch experiments using commercially prepared, bare and amine-functionalised silica-carbon hybrid NPs characterised for size, surface area, porosity, crystallinity, elemental composition and hydrodynamic size. Metal uptake by algae was quantified in the presence and absence of NPs. Results: Silica and maghemite NPs can be used for the adsorptive removal of Cu, Mn, Hg and U from AMD-contaminated surface and ground water. NP metal uptake was rapid and equilibria were attained within 5 minutes with silica and maghemite NPs, and within 45 minutes with amine-functionalised hybrid NPs. Adsorption efficiencies for Cu, Mn, Hg and U at pH 3 were 52, 56, 56 and 49%, respectively with silica and 56, 52, 75 and 50%, respectively, with maghemite NPs. Metal removal was enhanced by >10% in solutions containing ferric, manganese or sulphate ions, although Cu removal was inhibited in solutions with a >1 Mn:Cu ratio. Despite the presence of high affinity amine groups in hybrid NPs, Cu removal was only 52% due to the low surface area of the adsorbent. The comparative study with Hg, however, showed that surface area was not the only determinant of adsorption efficiency: maghemite NPs with a specific surface area ~15 times less than silica adsorbed 21% more Hg. Metal removal by Scenedesmus sp. was enhanced by 12-27% in solutions containing NPs due to the greater sorption surface areas. NPs also modified metal partitioning in algal cells: intracellular concentrations were lower and extracellular concentrations higher in solutions containing NPs relative to controls (no NPs). Conclusion: Silica and maghemite NPs can be applied for the adsorptive removal of Cu, Mn, Hg and U from AMD-contaminated water and to improve the efficiency of phycoremediation by Scenedesmus sp. These findings also point to the possibility of retardation of metals by NPs during their transportation from tailings and contaminated sites. Their partitioning to NPs and the strength of the interactions thereof can determine the prevalence of the metals in solution or in the solid phase.

Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, School of Animal, Plant and Environmental Sciences, 2017. / Acidification of freshwater systems by Acid Mine Drainage (AMD) is a persistent risk to aquatic ecosystems in South Africa, particularly in Gauteng and Mpumalanga. From several studies that have been conducted, it is clear that AMD has profound effects on aquatic life and functionality of the ecosystem. One of the ecosystem processes affected by AMD is the decomposition process. It has been established that AMD-affected streams inhibit the decompositon process. [Abbreviated Abstract. Open document to view full version] / LG2018

Most Appalachian coal refuse materials contain significant amounts of pyritic sulfur and are likely to produce acid mine drainage (AMD). A column technique was designed and implemented to evaluate the effects of various AMD mitigation treatments including fly ash, topsoil, lime, and rock-P. Two types of fly ash were tested, one at four blending rates, the other at two rates. Conventional lime plus topsoil, lime without topsoil, topsoil only, topsoil with fly ash, rock-P plus topsoil, and rock-P plus fly ash were also evaluated and compared with pure refuse controls. The columns were dosed weekly with 2.5 cm of simulated acid rain, an amount equivalent to 152 cm (60 in.) rainfall per year and remained unsaturated at all times. The experiment was conducted for 40 weeks. The drainage from the unamended columns rapidly dropped to less than pH 2 with very high levels of Fe, Mn, B, S, and Al. Alkaline fly ash dramatically reduced drainage Fe concentrations as well as Mn, Al, Cu and S when compared to the untreated refuse. As expected, lime treatments also reduced the drainage Fe, Mn, Al, Cu and S concentrations. The rock-P treatments initially reduced Fe, Mn, Al and S, but eventually decreased in mitigation capability over time. Leachate B concentrations were initially high for some of the ash columns but eventually followed the same B elution trend as the untreated refuse. The combined treatments of phosphate/ash, ash/topsoil, and pure refuse with topsoil were intermediate between the pure ash treatments and unamended refuse in drainage quality. The data were analyzed to determine treatment effectiveness in reducing AMD, and to evaluate the overall replicability of the column design. All treatments varied greatly for the first 5 weeks as the initial flush of salts from the materials occurred, but most treatments stabilized by week 6 with relatively low within treatment variability. The high ash blending rates remained alkaline for extended periods of time and stabilized pyrite while neutralizing any acidity. The rock-P treatment appears to have bound free Fe and other elements released from pyrite oxidation but did not prevent acidification. Long term analysis may prove fly ash to be a viable alternative to conventional topsoiling/lime treatments to ameliorate AMD if adequate alkalinity is present in the ash/refuse mixture. If fly ash alkalinity is inadequate to balance potential acidity, accelerated leaching of ash bound metals may occur. / M.S.

The processes that control the reductive dissolution of Mn0₂ by Fe(II) under conditions simulating the effects of acid mine drainage on subsurface environments and the subsequent precipitation of Fe(III) has been investigated. Results from real-time, in situ X-ray absorption spectroscopy (XAS) flow-through reaction cell studies indicate that a mixed Fe/Mn solid phase with the local structure of the spinel mineral jacobsite (MnFe₂O₄) is formed after the Mn0₂ surfaces are coated with ferric precipitates. In the absence of previously precipitated Fe(III), no reduced manganese solid is formed. The ferric precipitates do not incorporate significant quantities of Mn(II) down gradient from the reactive Fe(II) front. The maximum amount of the original Mn0₂ incorporated into this jacobsite-like solid is 5%. Results from batch experiments showed similar results compared to the flow-through experiments, with an initially fast rate of Mn(II) release, followed by a much slower release after 5-10 min had elapsed. The reaction products, Fe(III)(aq) and Fe(III)(s) were found to decrease the initial reaction rate. A simple model was developed to describe the temporal concentrations of Mn(II)(aq), Fe(II)(aq), and Fe(III)(aq) that include a Langmurian blocking function to describe the effects of the ferric reaction products on the reaction rate. The model also allowed for a second order process to occur at long time that was dependent solely on the aqueous concentrations of Fe(II) and Mn02. The formation of the ferric reaction products were found to transform from aqueous sulfate complexes to (presumable) ternary surface complexes with sulfate. Within 10 h, these precipitates may have formed chains of edge-sharing octahedra on the order of 60 Å. The precipitates have large amount of sulfate associated with them, which may preclude the formation of ferrihydrite, and may indicate the formation of schwertmannite. The average Fe:SO₄ ratio was 4.4 ± 1.0, a value similar to that reported for schwertmannite. The presence of goethite was identified by X-ray diffraction as early as 50 d, indicating that sulfate is being excluded from the precipitates. The release of Mn(II), FeT, and sulfate was controlled by diffusion, which may also be the process that controls the rate of transformation.

D.Phil. / Over a century gold exploration and extraction on the central Witwatersrand has left a legacy of mine residue deposits. Although there have been numerous complaints and claims of health effects associated with dust from these residue deposits, mostly these have been dismissed as mere nuisance. This study hypothesized that gold mine tailings on the Witwatersrand pose significant health risks to the nearby communities due to respirable airborne tailings material. Preliminary review of information on the tailings led to the insight that tailings source material and atmospheric properties at receptor sites are poorly characterized from the point of view of particle size-mass distributions. For years, routine monitoring of emissions from tailings storage facilities has been limited to sampling of dust fallout (settlable particles ≥ 30 μm). A suite of fifty four source samples (thirty-six slime, six newer slime and twelve sand) were collected from tailings storage facilities along the mining corridor covering deposits in the Carltonville area through to Springs. Size class characterization of source material was performed in the diameter range 0.05 μm to 900 μm using a Malvern® MS-14 Particle Analyser with 64 channels, from which the respirable (dp< 5 μm) and thoracic (dp < 10 μm) components were measured. Secondly, source materials were sieved (using a sieving cloth) in dp < 5 and < 10 μm fractions and the data derived was used in validating the size class results from the Malvern® MS-14 Particle Analyser before subjecting the samples to chemical analyses (elemental, mineralogical and radioactivity). Two years of continuous dust fall samples were collected in two different residential areas close to selected tailings storage facilities and subjected to similar size class characterization with the Malvern® MS-14 Particle Analyser. Further, continuous size-mass characterization of airborne aerosols was conducted in two different locations in the vicinity of tailings storage facilities with the Grimm® aerosol particle counter, in the diameter range 0.25 μm to 32 μm. The Grimm® aerosol particle counter was collocated with the MicroVol® PM10 filter sampler ambient monitor. The risk zones around selected tailings storage facilities were established by conducting dispersion modeling with American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD). The spatial evolution of tailings storage facilities and built-up areas is assessed using multiple aerial photographic images, covering four periods from 1952 to 2008. Overall, detailed spatial analysis was conducted and human inhabitants are now at greater risk than before. We have quantified the number of inhabitants living within the high-risk zone surrounding selected tailings storage facilities. The combined areas occupied by tailings storage facilities have increased from ~4 km2 (1952) to 10 km2 (2002); and residential areas ~4 km2 (1952) to 27 km2 (2002) within a buffer of 2 km. Population grew between 1952 and 2002 by a factor x29 at Crown Gold Recoveries; x43 at Durban Roodepoort Deep (from 1976); and x25 at East Rand Proprietary Mines.

Thesis (MPhil)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Ecosystems, and the very services and resources that they provide, are fundamental to our existence. Regardless, mankind shows scant regard for the biotic and abiotic components of the environment that serve as both sources and sinks for anthropocentric demands, practices and behaviours. Of these vital resources, perhaps the one that is most under threat is water which while crucial for growth and development around the globe, is rapidly becoming a scarce commodity. In South Africa - already a water-scarce country - this situation is further compounded by mining practices that are not only unsustainable, but also largely unregulated from an environmental perspective. Mining activities have resulted in the mass exposure of iron pyrite and heavy metals, both underground and on the surface. Upon exposure to weathering, the iron pyrite gives rise to sulphuric acid, which, in turn results in the mobilisation and concentration of toxic metals. Although this is a geological phenomenon, the increasing concentrations of toxic metals as a result of mining have exposed the Gauteng province to enormous environmental, social and economic risks. Concerning the risks, the research highlighted the following: - Although comprehensive research has been found relating to the physical attributes of acid mine drainage (AMD), very little is known of the health aspects associated with AMD. Of immediate concern is, the subsequent environmental and health implications stemming from the association between living organisms and heavy metals. - In the absence of such information, the credibility of current solutions is thus questionable. Of the solutions that have been proposed, most have been reductionist in approach and have only focused on dealing with the surface decant of contaminated water from predominately non-functioning mines. The health risks associated with radioactive and highly toxic waste have been down played or simply ignored (Albrecht, 2011). - The absence of a comprehensive solution also raises questions as to the assessment and decision-making process utilised to date by the Department of Water Affairs (DWA). - Both government and the private sector have allowed the AMD threat to amplify over the years. Their inaction has been facilitated by the poor enforcement of legislation and, clever manoeuvring by mining companies, in what can only be described as a mutually beneficial relationship between government and the mining industry. In stark contrast to the inaction of government and the private sector, environmental activists have been very vocal in calling for a solution to a number of the risks associated with AMD. This, together with the recent decant of AMD in the Western Basin, has culminated in a public outcry and prompted calls for a solution to the AMD threat. Government's response to this was a narrow and incomprehensive solution, which only served to further frustrate the different stakeholder groups. Where stakeholders have different themes as to the implications and thus solutions to the AMD threat on the Witwatersrand (as driven by the profiles of the different stakeholder groups), an appropriate solution will only be realised by adopting the following recommendations: - Government must show the necessary political will, to fully engage the threat of AMD and address their poor track record as regulator - their credibility has been skewed through their vested interests in the mining industry. - Having taken ownership of the AMD threat on the Witwatersrand, government must move to avert any immediate risks to human well-being. - Under governments' leadership, the capacity of all stakeholders must be addressed to facilitate a participatory trans-disciplinary review of the assessment mechanisms and facts, in order to reach a mutually acceptable solution(s) to the social and environmental impacts associated with mining activities - a solution that will ensure future environmental integrity, social development and economic growth. / AFRIKAANSE OPSOMMING: Ekosisteme, en die dienste en hulpbronne wat dit voorsien, is grondliggend aan die mensdom se bestaan. Tog toon die mensdom weinig respek vir die biotiese en abiotiese komponente van die omgewing, hoewel ons met ons behoeftes, praktyke en gedrag daarop staatmaak én daaraan afbreuk doen. Van hierdie lewensnoodsaaklike hulpbronne is die mees bedreigde waarskynlik water, wat – hoewel dit vir groei en ontwikkeling wêreldwyd van deurslaggewende belang is – spoedig besig is om ʼn skaars kommoditeit te word. In Suid-Afrika, wat in elk geval ʼn waterarm land is, word hierdie toedrag van sake vererger deur mynboupraktyke wat nie net onvolhoubaar is nie maar ook ongereguleerd. Mynboubedrywighede het gelei tot die massablootstelling van ysterpiriet en swaarmetale, sowel ondergronds as op die oppervlak. Wanneer ysterpiriet chemies verweer, vorm dit swawelsuurwater, wat op sy beurt toksiese metale mobiliseer en konsentreer. Hoewel dít ʼn geologiese verskynsel is, het hierdie verhoogde konsentrasies as gevolg van mynbou die Gautengprovinsie aan enorme omgewings-, maatskaplike en ekonomiese risiko’s blootgestel. Wat die risiko’s betref, beklemtoon hierdie studie die volgende: - Hoewel omvattende navorsing oor die fisiese kenmerke van suur mynwater (“acid mine drainage” – AMD) onderneem is, is weinig bekend oor die gesondheidsaspekte wat daarmee gepaardgaan. Wat tot dusver van onmiddelliker belang was, was die omgewings- en gesondheidsimplikasies wat daaruit voortvloei wanneer lewende organismes aan swaarmetale blootgestel word. - In die afwesigheid van sodanige inligting is die geloofwaardigheid van huidige oplossings dus twyfelagtig. Die meeste van die oplossings wat voorgestel is, is reduksionisties van aard en beklemtoon slegs die hantering van besoedelde water wat op die oppervlak uit hoofsaaklik onaktiewe myne sypel. Die gesondheidsgevare wat met radio-aktiewe en hoogs toksiese afval gepaardgaan, word geheel en al onderspeel of bloot misgekyk (Albrecht, 2011). - Die gebrek aan ʼn omvattende oplossing laat ontstaan ook vrae oor die beoordelings- en besluitnemingsprosesse wat die Departement van Waterwese oor die jare sowel as meer onlangs gevolg het. - Sowel die regering as die privaat sektor het toegekyk hoe die bedreiging deur suur mynwater oor die jare vererger. Dié gebrek aan optrede is aangehelp deur swak wetstoepassing sowel as slimmer bewimpeling deur mynboumaatskappye in wat eenvoudig as ʼn wedersyds voordelige verhouding tussen die regering en die mynboubedryf beskryf kan word. In skrille kontras met die regering en privaat sektor se traagheid het omgewingsaktiviste nog nooit geskroom om hul stem te verhef en op oplossings vir baie van hierdie risiko’s aan te dring nie. Dít, tesame met die onlangse uitvloei van suur mynwater in die Westelike Kom, het op openbare protes uitgeloop en aanleiding gegee tot oproepe om ʼn oplossing vir die bedreiging van suur mynwater. Die regering se antwoord hierop was ʼn eng, beperkte oplossing wat die verskillende belangegroepe slegs verder frustreer het. Aangesien belangegroepe (in ooreenstemming met hul uiteenlopende profiele) verskillende aspekte van die implikasies van – en dus ook die oplossings vir – die bedreiging van suur mynwater aan die Witwatersrand beklemtoon, sal ʼn toepaslike oplossing gevind word slegs deur die volgende aanbevelings te aanvaar: - Die regering moet die nodige politieke wil toon om die bedreiging van suur mynwater ten volle die hoof te bied, en moet daadwerklik verbeter op sy swak prestasiegeskiedenis as reguleerder, waarin hy heelwat geloofwaardigheid ingeboet het vanweë regeringsbelang by die mynboubedryf. - Nadat die regering sy verantwoordelikheid rakende die bedreiging van suur mynwater aan die Witwatersrand aanvaar het, moet hy dringend optree om enige onmiddellike gevare vir menslike welstand te voorkom. - Onder leiding van die regering moet die vermoëns van alle belanghebbendes betrek word ten einde ʼn deelnemende, kruisdissiplinêre beoordeling van die meganismes en feite te onderneem, om sodoende (ʼn) wedersyds aanvaarbare oplossing(s) vir die maatskaplike en omgewingsimpak van mynboubedrywighede te bedink – ʼn oplossing wat die integriteit van die omgewing, maatskaplike ontwikkeling en ekonomiese groei sal verseker.

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)

Msc. / This study focuses on the functional evaluation of a gold Tailings Storage Facility (TSF), the Fleurhof TSF (designated slimes dam 2L3), which is representative of gold slimes (tailings) dams in the Witwatersrand. The aim is to evaluate the rehabilitation status (in terms of species composition and landscape function) of TSF surfaces that were planted ~20 to ~40 years ago using the most common rehabilitation practice, namely pasture grassing. Pasture grassing aims to obtain rapid dust control. Mine closure was not considered at the time, and the vegetation was hence not designed with ecological processes or long-term objectives in mind. However, over time, grassing practices became routine in the TSF vegetation industry, and the contribution that they have made towards surface rehabilitation needs to be assessed against the current site closure objectives. On the selected site, evaluations of vegetation cover, species composition, and substrate physical and chemical properties were conducted in 1975 (Thatcher, 1979). The aim of the current mid-summer study in 2009 was addressed by assessing the same parameters of vegetation cover, species composition, and soil physical and chemical properties, and comparing these to the results of the previous assessment in 1975. Landscape Function Analysis (LFA – an index-based method of evaluating the retention of resources by surfaces and soil condition), was applied to determine the landscape function (stability, infiltration and nutrient cycling that are derived from the eleven soil surface assessment indicators), and compared with the landscape function of natural analogues in the same locality. Landscape organisation (also an indicator of LFA) was used to investigate the contribution of vegetation overall, and of discrete plant functional groups to landscape functionality. A total of 35 plant species were observed in the quadrats (56 species on the TSF overall), with 51% of species overall being alien. Perennial vegetation and cryptogam covers contributed the most to stabilising the TSF slopes and flat (top) surfaces. The percentage of vegetation basal cover on the TSF (30% – 70%) was lower than for analogue grassland sites on a nearby hill (80% – 100%). Lower basal vegetation cover on the TSF than on the analogue site, were associated with lower LFA indices of stability on all TSF slope aspects (P = 8.19 x 10-13 for all aspects), iii lower nutrient cycling for the northern and southern TSF slopes (south aspect P = 4.20 x 10-6; top aspect P = 0.03), and lower infiltration on the southern slope of the TSF (P = 2.68 x 10-6). However, a higher infiltration on the northern TSF aspect (P = 0.02) than on the analogue site, was attained. Perennial tussock grass patch types (which included perennial forbs) made the largest contribution to the soil surface assessment (SSA) indicators on the TSF and analogue sites, and therefore to the LFA indices that were derived from these SSA indicators. The contribution of woody patches to function was not evaluated.

M.Sc. (Zoology) / Pans are endorheic wetlands, and are abundant in South Africa in a band from the western Free State into Mpumalanga. The pan environment experiences daily and seasonal fluctuations in physico-chemical conditions. The physico-chemical variables are influenced by the local climatological and hydrological conditions, and are all inter-related. An imbalance of one variable can have countless effects on the others. The physico-chemical composition of the water ultimately determines the existence of the biota in such wetlands. Branchiopod crustaceans are a unique group of fauna which have various morphological, physiological and behavioural adaptations which enable them to survive in these variable environments. One such adaptation is the production of dormant egg banks. These eggs reside within the sediment through the dry phase and hatch during a following wet phase when conditions are favourable. Due to the endorheic nature of pans they are more vulnerable to anthropogenic stress. Anthropogenic activities are having profound effects on the integrity of these ecosystems. Agricultural and mining activities have some of the largest influences. The impacts that the following activities have include: the over utilisation of water, decreased periods of inundation, erosion and sedimentation, effluent discharge and direct habitat destruction. Many wetlands as a result are experiencing a rapid loss in biodiversity. Mining activities are on the increase especially in the Highveld region of southern Africa. Many of these wetlands are already (and will be in the future) affected by mining activities, making the effect of acid mine drainage (AMD) on the biota a priority concern. In conjunction with the uniqueness and vulnerability of pan ecosystems it is necessary to find new ways of monitoring such environmental impacts in the shortest time possible with minimal efforts, for the benefit of both the environment and researchers involved. This study therefore aimed to assess the diversity of branchiopod crustaceans hatching from egg banks of selected pans and obtain a reference community structure. It also aimed to assess the impacts AMD could have on the hatching success of branchiopods from these egg banks with the objective to determine whether these egg banks are still viable after exposure. To achieve the stated aims and objectives, sediment samples were collected from selected pans in mining regions of the country. Regions selected included Chrissiesmeer in the Mpumalanga province, Wesselsbron in the Free State province and Delareyville in the North West province. The sediment was used for hatching experiments in the laboratory. Pan sediment was exposed to three different treatments which included two salt solutions (1000 mg/l and 1500 mg/l respectively) and AMD. The salt solutions served as controls while the AMD served as an exposure. The number of nauplii hatching was counted in the controls and compared to the number of nauplii hatching in the AMD. The diversity of nauplii was also assessed and compared between controls and the AMD. The recovery potential of eggs exposed to AMD was also assessed by exposing the sediment treated with AMD to distilled water after its removal to get a better understanding on the effects of AMD at the community level. Results from the control treatments indicated that most pans have a range of taxa hatching that follow patterns of pan succession. Between the 1000 mg/l and 1500 mg/l controls there was no treatment that proved superior to the other. Representatives of all four orders of branchiopoda hatched from the experiments. The North West and Free State pans were the most diverse and had had the greatest abundances of individuals hatching. Spatially all three provinces differed in the diversity of individuals hatching from pans, as there were distinct differences in the taxonomic compositions. Although taxonomic composition of pans grouped together per province, pans from just a single province were largely dissimilar. Results from the AMD treatments indicated that AMD has a negative effect on the hatching ability of branchiopod crustacean eggs. Eggs that were initially exposed to AMD were unable to hatch in its presence. The recovery experiments indicated that recovery after exposure is limited as recovery only occurred in a few pans. The taxonomic composition of nauplii in the pans where recovery took place was altered and less diverse than the taxonomic composition found in the respective control treatments. Overall it was found that hatching experiments can be used as a monitoring tool in lieu of field sampling. Hatching experiments showed that AMD is detrimental to the branchiopod egg banks, inhibiting the ability of eggs to hatch in its presence. Recovery can take place but the recovery potential is low. Since the recovery potential of the egg banks is low, pans which are affected by AMD could experience extinction of the entire branchiopod community in years to come. As branchiopod communities are unique among pans, and serve as an important food source for many aquatic bird species, their extinction will bring about further losses in biodiversity.