Coal combustion for power generation is relied on heavily in South Africa. The main residue from the combustion process is fly ash, with about 22 million tons being produced in 1994, of which only about 1 million tons is utilised, the remainder requiring disposal as waste. Various environmental impacts are associated with the disposal of fly ash in surface impoundments, including loss of usable land, contamination of groundwater, and production of wind-blown particulates, effects on vegetation and aesthetic impacts. Ultimately the disposal of fly ash in the mined-out underground workings is highly sought after, as it may limit many of the impacts which fly ash induces on the environment. The main purpose of this study was to assess the degree of hardening of four South African fly ashes from power stations at Kriel, Lethabo, Matla and Sasol in terms of their chemical, physical and mineralogical properties. Samples were taken of fresh and unweathered ashes from each power station. Unweathered ash samples analysed by XRFS were found to have high contents of Si0 2 (49.9-56.3%), Al 2 0 3 (27.2-31.5%), CaO (4.2-8.6%Y and Fez03 (3.1-3.9%) with varying contributions from loss on ignition (L.O.I.) (0.4-4.4%) and MgO (1.1- 2.2%). The major mineral phases detected in unweathered ash by XRD include quartz, mullite and glass, with smaller contributions from hematite and lime. Laser particle size analysis and liquid limit determination (Atterberg tests) were also conducted. The exceptionally high L.O.I of Sasol ash (4.4%) was attributed to the presence of partially burned coal, based on DTA and TGA investigation. Modulus of rupture experiments were conducted on briquettes (dimensions 7.0 x 3.5 x 1.0 em) of unweathered ash from Kriel, Matla, Lethabo and Sasol, which were wetted to their liquid limit and cured for 24 h under ambient conditions. The tests indicated that there is a strong linear relationship between total Ca content and the modulus of rupture for 3 of the 4 unweathered ashes. The fly ash from Kriel deviates from this relationship, providing evidence that other chemical (e.g. form of Ca) and physical factors (e.g. particle size) may also play a role in hardening.

Bibliography: pages 80-90. / This study constitutes a baseline epidemiological investigation into the nutrient status of soils in the Mseleni district of Kwazulu Natal, where nutrient deficiencies have been implicated in the etiology of an endemic disease. Mseleni Joint Disease (MJD) is a crippling, osteo-arthritic condition which afflicts an unusually high proportion of the inhabitants of this district. Home-grown produce and indigenous plants, which form the basis of the local diet, may be nutritionally inadequate due to soil-related nutrient deficiencies. In spite of this, and the fact that epidemiological studies have been successfully utilized to elucidate the etiology of similar diseases elsewhere, studies to date have not included soil chemical investigations. The main purpose of this study was to assess the nutrient status of soils in the area by means of both chemical analyses and plant growth trials. Water samples were also examined, especially in relation to fluoride levels.

The Manganese Metal Company (MMC) situated in Nelspruit, Eastern Transvaal, South Africa produces a manganiferous saline effluent from a manganese ore leaching process. The high NH₄ content of the waste has been identified as a possible nitrogen fertilizer source. Irrigation of the MMC waste over nearby kikuyu ( Pennisetum clandestinum) pastures could thus potentially solve a waste disposal problem as well as provide fertilization of the pastures, although the high manganese content of the waste poses a risk of manganese toxicity or pollution. The kikuyu pastures are presently used as a land disposal system for a saline waste from a pulp bleaching process. Due to process changes, the dominant salt type in the waste is anticipated to change from KaCl to Na₂SO₄. Pot experiments with kikuyu were undertaken to investigate NaCl versus Na₂SO₄ salinity effects, Mn toxicity threshold levels and MMC waste versus a standard nitrogen fertilizer (NH₄NO₃) yield response. The results demonstrated that kikuyu grass is both salinity and Mn tolerant. Kikuyu salinity tolerance, using electrical conductivity as a salinity index, was significantly greater in NaCl than Na₂SO₄ salinity. This difference was attributed to the formation of SO₄ neutral ion pairs in Na₂SO₄ treatments which decreased cation uptake, increased osmotic stress relative to electrical conductivity and led to a possible SO₄-induced Ca deficiency. Cl adsorption in manganous sulphate and Na₂SO₄ treated soils was speculatively attributed to the formation of an undocumented ettringite-like mineral. Kikuyu exhibited both a fertilization effect and a Mn toxicity effect with manganous sulphate applications. An increase in yield occurred between Mn applications of 800 and 1600 mg/kg soil. This effect was attributed to increased nutrient availability as a result of nitrogen mineralisation and soil desorption processes. Mn applications of 3200 and 8000 mg/kg resulted in severe Mn toxicity symptoms and reductions in yield. Fertilization of kikuyu with NH₄NO₃ and MMC waste produced similar yield responses. Manganese toxicity did not manifest itself in MMC waste treated kikuyu, even at nitrogen loadings of 800 kgN/ha. Manganese attenuation in the soil by MnCO₃ precipitation, oxidation of Mn²⁺ and Mn adsorption are expected to prevent excess Mn²⁺ accumulation which would pose a Mn toxicity and water pollution risk. The disposal of untreated MMC waste as a nitrogen fertilizer substitute for kikuyu pastures is thus in principle a feasible operation in terms of maintaining pasture sustainability and preventing pollution of water resources.

No description available.

Thesis (Ph.D.) -- McMaster University, 2000 / Includes bibliographical references (leaves 139-150). Also available via World Wide Web.

No description available.

O principal objetivo do presente trabalho foi o de propor estratégias para a remediação de uma das áreas fontes de contaminação por metais na Bacia do Rio Ribeira de Iguape. Assim, inicialmente foi efetuado um diagnóstico da contaminação na área de estudos que possibilitou a elaboracão de uma análise espaço-temporal da contaminação por metais na bacia e a identificação das atuais fontes desses elementos para os ecossistemas naturais. A partir da escolha de uma destas fontes, qual seja a área de disposição de rejeitos de mineração de chumbo-prata (Pb-Ag) da Mina do Rocha, foram feitas caracterizações químicas, mineralógicas e toxicológicas (bioensaios) dos resíduos e conduzidos experimentos em microcosmos que buscaram simular tanto a permanência destes rejeitos em pilhas quanto a sua inundação, já que existe uma proposta de implantação de uma represa no local para geração de energia (Usina Hidrelétrica do Tijuco Alto). O trabalho conclui que a forma de disposição atual das pilhas é totalmente inadequada e que a submersão dos rejeitos também é desaconselhada, pois propiciaria a liberação de metais para a água e colocaria em risco a sobrevivência de organismos planctônicos de água doce que constituem a base da cadeia alimentar deste ecossistema. A alternativa proposta pelo presente trabalho sugere a retirada dos rejeitos do local e sua disposição de maneira que permaneçam insaturados e protegidos da ação de processos erosivos. Uma possível alternativa seria a colocação do material no interior das galerias subterrâneas da Mina do Rocha. No entanto, a implantação desta medida exigiria um estudo detalhado a respeito da influência do lençol freático ou de outros dutos d\'água no local. Outras alternativas consideradas adequadas envolvem a utilização de técnicas de estabilização/solidificação e disposição em aterros de resíduos perigosos de acordo com as normas e exigências legislativas existentes. / The aim of the present work was to propose strategies for the remediation of one of the contamination sources by metals in the Rio Ribeira de Iguape Basin. Initially a diagnosis of the contamination was made in the study area, which allowed for a space-temporal analysis of the contamination by metals in the basin and the identification of the present sources of such elements for natural ecosystems. The lead-silver waste disposal site of Rocha Mine was chosen as a test area for the suggestion of remediation strategies, where chemical, mineralogical, and toxicological (bio-essays) characterization ofthe wastes were carried out. Experiments were conducted in order to simulate the stability of the wastes in piles and their immersion, since there is project of the construction of a dam for energy generation in this place (Usina Hidréletrica de Tijuco Alto). The study concluded that the present localization of the waste piles is inadequate and their submersion is also inadvisable, propitiating the liberation of metals to the water and threatening the survival of plankton organisms in the water. The alternative proposed in the present work suggests the removal of the waste from the area and their proper disposal so that they remained unsaturated and protected from erosive processes. A possible alternative is to locate them within the subterranean galleries of the Rocha Mine. Other alternatives proposed involve stabilization/solidification techniques and disposal of dangerous wastes in landfills according to the norms and requirements of related legislation.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A bacia hidrográfica do rio São Domingos constitui uma das sub-bacias do rio Muriaé pertencente ao sistema Paraíba do Sul e, tem seus limites coincidentes com os limites do município de São José de Ubá, sendo este o segundo maior produtor de tomate do estado do Rio de Janeiro, com sua principal fonte econômica baseada na agropecuária. Este tipo de atividade resulta em utilização de produtos químicos nas lavouras e juntamente a ocupação inadequada resulta em modificação das paisagens e da mata nativa, resultando em diversos tipos de impactos no ambiente. Neste estudo foram abordados os impactos relacionados a concentração de metais e sua proveniência através das assinaturas isotópicas Pb/Pb, utilizando para tal o procedimento analítico de lixiviação dos sedimentos de corrente e abertura total de rochas para a obtenção de razões isotópicas e concentrações de metais por ICP-MS. Os resultados mostraram que as contribuições nos sedimentos de corrente se dão a partir de cinco fontes compreendidos no intervalo de assinatura isotópica 206Pb/207Pb 1,1229 e 1,1949, representadas em intervalos bem definidos. Por correlação com as respectivas concentrações se observa que, preferencialmente, existe maior influência das rochas do embasamento, seguido de atividade antrópicas como a urbanização e disposição de lixo doméstico. As maiores concentrações estão associadas ao cobre, chumbo, estrôncio, níquel e zinco. Contudo todas as concentrações de metais obtidas se encontram abaixo da legislação vigente. Desta forma a contaminação antrópica é limitada a regiões de maior densidade populacional e as influências naturais predominam na área da bacia. / The São Domingos river basin is a sub-basin of the river Muriaé belonging to the Paraíba do Sul system, than his boundary are coincide with the limits of São Jose de Ubá County the second largest tomato producer in the Rio de Janeiro state, with its main financial activity based on the agricultural economy. This kind of activity results in a use of chemicals on crops and modification of the landscape and native vegetation, resulting in various types of environmental impacts. In this paper was study the impacts related to concentration of metals and their provenance by Pb/Pb isotopic signatures, using to analyze procedure the rocks sample digest and leaching of stream sediments to obtained metal concentration and isotope ratios by ICP-MS. The results showed that concentrations on stream sediments have five different sources identifiable from five intervals isotopic signature 206Pb/207Pb 1.1229 to 1.1949 clearly defined. By this correlation with owner respective concentration it is observed than, preferentially, the basement rocks are the main influence in the basin stream and in second place come the mixtures of products of activities anthropogenic, mainly urbanization and sewage disposal. The biggest metals concentrations are cupper, lead, strontium, nickel and zinc. However all of metals concentrations are below actual legislation. That way the anthropic contamination it is located in areas with more intensity occupation and the natural sources predomination on the basin.

O principal objetivo do presente trabalho foi o de propor estratégias para a remediação de uma das áreas fontes de contaminação por metais na Bacia do Rio Ribeira de Iguape. Assim, inicialmente foi efetuado um diagnóstico da contaminação na área de estudos que possibilitou a elaboracão de uma análise espaço-temporal da contaminação por metais na bacia e a identificação das atuais fontes desses elementos para os ecossistemas naturais. A partir da escolha de uma destas fontes, qual seja a área de disposição de rejeitos de mineração de chumbo-prata (Pb-Ag) da Mina do Rocha, foram feitas caracterizações químicas, mineralógicas e toxicológicas (bioensaios) dos resíduos e conduzidos experimentos em microcosmos que buscaram simular tanto a permanência destes rejeitos em pilhas quanto a sua inundação, já que existe uma proposta de implantação de uma represa no local para geração de energia (Usina Hidrelétrica do Tijuco Alto). O trabalho conclui que a forma de disposição atual das pilhas é totalmente inadequada e que a submersão dos rejeitos também é desaconselhada, pois propiciaria a liberação de metais para a água e colocaria em risco a sobrevivência de organismos planctônicos de água doce que constituem a base da cadeia alimentar deste ecossistema. A alternativa proposta pelo presente trabalho sugere a retirada dos rejeitos do local e sua disposição de maneira que permaneçam insaturados e protegidos da ação de processos erosivos. Uma possível alternativa seria a colocação do material no interior das galerias subterrâneas da Mina do Rocha. No entanto, a implantação desta medida exigiria um estudo detalhado a respeito da influência do lençol freático ou de outros dutos d\'água no local. Outras alternativas consideradas adequadas envolvem a utilização de técnicas de estabilização/solidificação e disposição em aterros de resíduos perigosos de acordo com as normas e exigências legislativas existentes. / The aim of the present work was to propose strategies for the remediation of one of the contamination sources by metals in the Rio Ribeira de Iguape Basin. Initially a diagnosis of the contamination was made in the study area, which allowed for a space-temporal analysis of the contamination by metals in the basin and the identification of the present sources of such elements for natural ecosystems. The lead-silver waste disposal site of Rocha Mine was chosen as a test area for the suggestion of remediation strategies, where chemical, mineralogical, and toxicological (bio-essays) characterization ofthe wastes were carried out. Experiments were conducted in order to simulate the stability of the wastes in piles and their immersion, since there is project of the construction of a dam for energy generation in this place (Usina Hidréletrica de Tijuco Alto). The study concluded that the present localization of the waste piles is inadequate and their submersion is also inadvisable, propitiating the liberation of metals to the water and threatening the survival of plankton organisms in the water. The alternative proposed in the present work suggests the removal of the waste from the area and their proper disposal so that they remained unsaturated and protected from erosive processes. A possible alternative is to locate them within the subterranean galleries of the Rocha Mine. Other alternatives proposed involve stabilization/solidification techniques and disposal of dangerous wastes in landfills according to the norms and requirements of related legislation.

The Penrith Lakes Scheme is a series of inter-connected lakes, produced by the rehabilitation of a sand and gravel quarry, for water quality treatment and recreational uses. Presently, 5 lakes are operational comprising 4 upstream lakes for treatment of storm-water and quarry discharge and a single downstream recreational lake as the Sydney International Regatta Centre used during the Sydney 2000 Olympic Games. This report is the result of a study, during 1998-2003, with an aim to develop dynamic budget models of water, sediments and nutrients for these lakes, providing suitable data for long-term management planning and evaluation of short-term operational management.Findings showed that while progressive reassessment and refinement will be required as management control increases, the approach provides the foundation modelling procedures and frame-work for suitable hydrological and water quality management of the Penrith Lakes Scheme, and may be extended to include further lakes, water sources and management strategies. / Doctor of Philosophy (PhD)