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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Biogenic silica and diatom centricpennate ratios as indicators of historical coastal pollution

Spasojević, Zorana January 2002 (has links)
Historical environmental changes in two shallow, unstratified, estuaries in Buzzards Bay, Massachusetts are compared, using three diatom paleo-production indicators: sedimentary biogenic silica (BSi), BSi flux and ratio of Centric to Penate diatoms. Both estuaries were exposed to pollution. New Bedford Harbor (NBH) has a history of intensive nutrient loading and industrial pollution, while the control site, Apponagansett Bay, has lower levels of nutrient loading. Consideration of local precipitation history and diatom parameters suggests that salinity-driven changes in diatom production are negligible. Over the past ∼350 yrs, BSi concentrations and fluxes are higher in NBH. Thus, overall diatom production is sensitive to nutrient enrichment and less responsive to industrial pollutants. The relationship between the C/P ratio and environmental conditions is not as clear, possibly due to its dependence on eelgrass abundance. The uniqueness of this study lies in its use of the parameters combined, as well as its geographic setting.
102

Investigating non-regulatory barriers and incentives to stakeholder participation in reducing water pollution in Pietermaritzburg's Baynespruit.

Neysmith, Jocelyn. January 2008 (has links)
The Baynespruit, a stream running through the city of Pietermaritzburg in KwaZulu-Natal, is blighted by chronic, severe solid and liquid waste pollution in the form of sewage, industrial effluent and household garbage. It drains a large residential area, then flows through the city's main industrial area before reaching a low-income neighbourhood whose residents are unable to use the water for recreation and small-scale agricultural irrigation due to its polluted state. Both the Department of Water Affairs and Forestry (DWAF) and the local Msunduzi Municipality have been largely unsuccessful in their attempts to use regulatory means to address the situation over the past two decades. Bodies such as the Msunduzi Catchment Management Forum (MCMF) have little representation from industry and have been equally unable to initiate effective action. One possible way to work toward reducing pollution problems is to involve all stakeholders in a co-operative participatory process; a key element is therefore the use of incentives and the removal of barriers to participation. The aim of this research was to analyse past initiatives that have tried to address pollution in the Baynespruit, gain an understanding of stakeholders’ views of the problems and their relative importance, and identify economic, situational, developmental and socio-cultural barriers and incentives to participation in a multi-stakeholder process. To accomplish this, the research methodology included a number of different qualitative techniques as part of a case study approach. The main research tool used was a semi-structured interview conducted with individual stakeholders from government agencies and parastatals, industry, local residents and members of NGOs; the use of historical print media coverage and both participant and direct observation complemented the interview data. Though the details of past initiatives were difficult to trace due to the loss of institutional memory at both the agency and NGO level, they appear to have suffered from a lack of communication, accountability and inclusiveness among key stakeholders. Most of the stakeholders interviewed have an understanding of the various pollution problems affecting the Baynespruit and the consequent threat to human health, and there was general agreement that a mix of education, monitoring and enforcement was necessary to solve these problems. There was also broad support for a multi-stakeholder process, with all subjects stressing the need for action, not just discussion, as well as real engagement on the part of their fellow stakeholders. For local residents, building a network of contacts and partnerships could address many of the economic, developmental and socio-cultural barriers they face, and strengthen their effectiveness in fostering participation among other stakeholders. While barriers to industry participation in pollution reduction included problems such as a lack of consequences for polluting, and the feeling that it was ‘not their problem’, powerful economic and situational incentives, such as pressure from corporate customers and the public, remain largely unexploited. A lack of resources in the form of time, staff and equipment, as well as unsuccessful past experiences which have created a reluctance to prosecute or release information, were the major impediments preventing staff at regulatory agencies and parastatals from motivating other stakeholders to participate, though they were aware of the potential for increase effectiveness offered by participatory processes. It is hoped that by recommending ways to maximise incentives and reduce barriers, this research will assist the recently-established Baynespruit Conservancy, which is involving all interested parties in an effort to address the serious pollution problems in the stream. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
103

Predicting emissions using an on-road vehicle performance simulator.

Govindasamy, Prabeshan. January 2002 (has links)
South Africa is coming under increasing pressure to conform to the rest of the world in terms of emissions regulations. The pressure is caused by a number of factors: international organisations requiring local companies to adhere to environmental conservation policies, evidence from within South Africa that efforts are being made to reduce environmental pollution in line with other countries and keeping abreast of the latest technologies that have been incorporated into vehicles to reduce emissions. In light of these problems associated with emiSSions, a study was initiated by the Department of Transport and the School of Bioresources Engineering and Environmental Hydrology at the University of Natal to investigate and develop a method of predicting emissions from a diesel engine. The main objective of this research was to incorporate this model into SimTrans in order to estimate emissions generated from a vehicle while it is travelling along specific routes in South Africa. SimTrans is a mechanistically based model, developed at the School, that simulates a vehicle travelling along a route, requiring input for the road profile and vehicle and engine specifications. After a preliminary investigation it was decided to use a neural network to predict emissions, as it provides accurate results and is more suitable for a quantitative analysis which is what was required for this study. The emissions that were predicted were NOx (Nitric oxide-NO and Nitric dioxide-N02), CO (carbon monoxide), HC (unbumt hydrocarbons) and particulates. The neural netWork was trained on emissions data obtained from an ADE 447Ti engine. These neural networks were then integrated into the existing SimTrans. Apart from the neural network, an algorithm to consider the effect of ambient conditions on the output of the engine was also included in the model. A sensitivity analysis was carried out using the model to prioritise the factors affecting emissions. Finally using the data for the ADE 447Ti engine, a trip with a Mercedes Benz 2644S-24 was simulated using different scenarios over the routes from Durban to Johannesburg and Cape Town to Johannesburg in South Africa to quantify the emissions that were generated. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.
104

Factors preventing the successful implementation of the polluter pays principle : a case study of the Bayne's Spruit.

Pole, Adrian Leonard. January 2002 (has links)
Despite the pollution control provisions provided in national and local legislation that explicitly or implicitly give effect to the polluter pays principle (PPP), certain rivers continue to suffer from persistent industrial pollution. This research focuses on one such river, the Bayne's Spruit, as a case study. The Bayne's Spruit is a small river that is located within an urban catchment, and which has been subjected to wet industrial pollution for over a decade. Much of this pollution is associated with the Pietermaritzburg edible oil industry. This pollution impacts negatively on a downstream community that uses the river for irrigation of subsistence crops, for recreation and for subsistence fish harvesting. The pollution has also severely degraded the riverine ecosystem. This research commenced with a literature review of the PPP in its international, national and local context. It was noted that the current legislative framework for implementation of the PPP with regard to pollution of rivers in South Africa comprises primarily of the National Water Act 36 of 1998 (NWA), the National Environmental Management Act 107 of 1998, and the Pietermaritzburg-Msunduzi industrial effluent bylaws of November 1998. The case study was approached using a largely qualitative methodology, although quantitative data was also relied upon where feasible. The historical context of the case study was provided by conducting a review of newspaper reports, a review of. government inspection records, and a review of water quality data (including biomonitoring and chemical data). The current status of the Bayne's Spruit was then explored by conducting in-depth historical interviews with community members, and by conducting direct observation of the environmental status of the Bayne's Spruit. This data was supplemented by an analysis of the test results of sampled industrial effluent, and by information obtained from representatives of two edible oil companies. In-depth, purposively selected interviews were conducted with various role players. (local government, regional government and industry) to identify what factors are preventing the successful implementation of the PPP in the case study area. Factors identified include a lack of environmental ethic within the edible oil industry, with some of these companies free riding on the Bayne's Spruit to maximize their profits. At a local level, factors preventing implementation of the PPP include deficiencies in the local industrial effluent bylaws, failures to administer and implement provisions contained in the bylaws, capacity restrictions and institutional paralysis. National legislation is not being successfully implemented because the government agency empowered under the NWA is deferring primary responsibility for dealing with pollution to the local authority. Factors also include difficulties associated with monitoring of rivers, including lack of capacity to engage in monitoring, and confusion over the functions of the various spheres of government. Finally, enforcement complexities are a major factor preventing successful implementation of the PPP. These problems relate to inadequate penalties, enforcement arrangements, capacity problems, separation of authority to operate the municipal sewer works and to enforce the industrial effluent bylaws, difficulties in identifying the offending polluter (causation), problems with access to company premises, the open access character of the storm water drainage system, previous failed prosecutions and reliance on the criminal justice system. / Thesis (M.Sc.)-University of Natal, 2002.
105

Humic acid pretreatment for enhancing microbial removal of metals from a synthetic 'wastewater'.

Desta, Tsegazeab Goje. January 2004 (has links)
The presence of heavy metal ions in waste streams is one of the most pervasive environmental issues of present times. A rotating biological contactor (RBC) was used to investigate the potential capacity of microbial biofilms in remediation of the metal ion species from a mixed metal contaminated effluent solution containing Cr+3 , Pb+2 and Cu+2 , each at a concentration of 200 mg r1 • In the first part of this study the effectiveness of various support materials for the development of microbial biofilms capable of removing heavy metals from a synthetic effluent was investigated. EDX analysis showed that none of the support matrices investigated, viz. gravel, polyester batting and sand, adsorbed metal ions on their surfaces; hence, metal adsorption was due purely to microbial activities. The biofilms attached more firmly and uniformly to polyester batting than to gravel and sand. The characteristics of polyester batting which made it a superior support matrix were its surface roughness and porous hydrophilic nature, which provided a larger surface area for the adhesion of microorganisms and attraction of nutrients during the biofilm development process. The selective accumulation of metal ion specIes by various microbial populations grown as biofilm using polyester batting as support matrix in separate compartments of a single-stage RBC bioreactor was examined. Lead ions were readily accumulated by almost all the microbial biofilms tested. Fungus-dominated biofilms selectively accumulated chromium ions whereas biofilms comprising mainly bacteria more readily accumulated copper ions from the mixed metal contaminated effluent solution. However, where interactions between the bacterial and fungal components were encouraged the mechanical stability of the biofilms was enhanced so that large amounts of all three metal ion species were removed by this biofilm. The combined effect of a series of bench-scale columns containing liquid humic acid and a three stage RBC bioreactor on the removal of metal ion species from a mixed metal contaminated effluent was investigated. After seven days of treatment the combined system had removed approximately 99% of the Cr+3, 98% of the Pb+2 and 90% of the Cu+2 ions from the mixed metal contaminated synthetic effluent. Complexation of the metal ions with humic acid was the predominant factor accounting for approximately 68-86% Cr+3 , 70-86% Pb+2 and 53-73% Cu+2 removal levels within the columns. A large proportion of the remaining Cr+3 and Pb+2, but not of the Cu+2, was removed in compartment 1 of the RBC. This suggested that the presence of the former two metals in solution might have reduced the removal of the Cu+2 ions from the system. The removal of substantially large amounts of the competing ions chromium and lead during the initial stages of the treatment process meant that copper was successfully taken up in the second and third RBC compartments. Hence, the economy of the treatment process was improved as larger quantities of the metal ions were removed in a shorter period of time than was possible when using the individual treatments (humic acid-metal complexation and biofilm adsorption) separately. More than 75%,92% and 86% of the adsorbed Cr+3 , Pb+2 and Cu+2 ions, respectively, were recovered from the three RBC bioreactor compartments following repeated washing of the biofilms with 0.1 M HCI. This relatively easy desorption suggested that the metal ions were simply adsorbed onto the surfaces of the biofilm cells rather than being taken into the cytoplasm of the cells. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.
106

A survey of inorganic chemical pollution in the Bottelary River, Cape Town.

Feng, Xiao Yi January 2005 (has links)
Chemical pollution of freshwater is a worldwide environmental problem / eutrophication, heavy metals and salinity are amongst the most widely used indicators of pollution. The aim of this study was to assess the status of nutrients, heavy metals and salinity, and the seasonal variation int he Bottelary River.
107

An investigation into the representations of environmental issues relating to Lake Victoria, Uganda, and their negotiation by the lakeside communities / An exploration of how CBS radio represents and constructs environmental issues relating to Lake Victoria, Uganda, and the negotiation of the radio programmes by lakeside communities

Lwanga, Margaret Jjuuko Nassuna January 2013 (has links)
The state of the environment is increasingly present as an urgent concern for contemporary political, social, cultural and physical life. Yet the roles of the mass media (radio, television and newspapers) in shaping and influencing crucial public awareness, debates and environmental decision-making remain inadequately understood. Positioned as a critical studies inquiry into media representations and audience reception, this study forms part of a wider project amongst media scholars and culture critics on the relationship between media textual production and consumption. It explores how one radio station in Uganda, Central Broadcasting Service (CBS) radio, represents and constructs the environmental crises faced by Lake Victoria, especially pollution and overfishing. The focus is on the Victoria Voice radio documentaries aired on CBS radio in the year 2005. The study further explores how three lakeside communities negotiate these issues as radio broadcasts. It recognises that while the mass media contribute significantly to creating public awareness about such social concerns, their likelihood of having a direct and predictable impact on social behaviour is slight. The context and the lived experiences at the reception stage where the decisions are made on whether to adopt an innovation are ultimately the factors which impact on how they are negotiated. The thesis is informed by the theoretical and analytical framework of Cultural Studies as well as the Participatory Approach to Communication for Development perspectives. The study is specifically informed by the theories of ‘discourse’ (Foucault, 1980a, 1981) and the ‘circuit of culture’ (du Gay et al., 1997 and Johnson, 1987) and these provided the conceptual framework for investigating the representations, the production and the consumption of media texts. Predominantly qualitative methods have been employed in data collection and analysis. In the first place, a Critical Discourse Analysis (CDA) (Fairclough, 1995a, 1995c) of the radio texts has interrogated the discourses and discursive practices of CBS’ Victoria Voice environmental radio programmes in order to consider its representations of particular issues and consequently the discourses it privileged. Qualitative methods of participant observation, in-depth interviews and focus group discussions were deployed to investigate the negotiation of the texts by the lakeside communities. This research establishes that the Victoria Voice radio texts foreground three contesting types of discourses: the discourse of basic economic survival and livelihoods is articulated largely by the ordinary people, the lakeside communities; the discourse of sustainable development, particularly the protection and sustainability of Lake Victoria, by scientists and environmental experts; and the discourse of modernisation and corporate investment by politicians and/or policy makers and industrialists. The texts, to a large degree, reaffirm the hegemonic relations of power in Ugandan society, and thus contribute to the maintenance of the status quo. The selection of an elite category of informers (scientists, experts, politicians, policy makers) serves to marginalise the less powerful ordinary people (the fisher folk, farmers and other eyewitnesses). The construction of the elite as active and speaking subjects within the various debates introduced in these programmes, for example, works both to obscure and endorse the unequal power relations. At the reception side, while the lakeside communities attest to the relevance of the programmes in providing information on the issues concerning Lake Victoria and other aspects of their livelihood, they also recognise the power relations that underpin the sets of representations. Amongst these sets is government’s complicity with industry, in line with their economic policies and the global capitalist economy, while espousing the rhetoric of nature conservation. The study argues that sustainable solutions for the crises on Lake Victoria should take into account the socio-historical and cultural contexts of the lakeside communities. For the Ugandan media, particularly radio, there is a need to rethink the nature of the coverage, which tends to neglect the contextual factors, such as local socio-economic and cultural factors within which environmental issues and problems occur and which, as this thesis establishes, greatly influences the way people make sense of environmental issues and problems. I posit that the Participatory Approach that seeks to address the communities’ most pressing concerns should be adopted – to include more of the communities’ voices and involve them in the production of radio programmes.
108

Analyses of the impacts of bacteriological seepage emanating from pig farming on the natural environment

Mofokeng, Dikonketso Shirley-may 03 1900 (has links)
Modern pig farming production may over burden the environment with organic substances, exposure of bacterial pathogens and introduction of resistance gene. This may be caused by the pig’s droppings, lack of seepage management or accidental spillage of seepage which may impact on the environment and its physicochemical parameters. The objective of this study is to determine and assess the level of bacteriological pollution emanating from the pig farm and their impact on the physicochemical parameters of soil and water as well as to identify the presence of antibiotic resistance gene of these prevailing bacteria. Soil and water samples were collected monthly for a period of six months (March- August 2013). Samples were collected at pig enclosures, soil 20 m and 100 m away from pig enclosures, constructed wetland used for treating pig farm wastewater, soil 20m and 100 m away from constructed wetland. Procedure followed for analysing soil and water samples includes physicochemical analyses, viable cell counts of 10-1 to 10-8 dilutions, identification of bacteria using API 20E test kit, antibiotic susceptibility analyses, and identification of resistance gene using molecular procedures. The media that were used for viable cell counts were, Nutrient agar, MacConkey Agar, Xylose Lysine Deoxycholate agar (XLD agar), and Eosin Methylene Blue (EMB). Physicochemical parameters of water showed unacceptable high levels of analysed parameters for BOD (163 mg/L to 3350 mg/L), TDS (0.77 g/L to 6.48 mg/L), COD (210 mg/L to 9400 mg/L), NO3 (55 mg/L to 1680 mg/L), NO2 (37.5 mg/L to 2730 mg/L), and PO43− (50 mg/L to 1427 mg/L) were higher than the maximum permissible limits set by Department of Water Affairs and Forestry (DWAF). For soil samples TDS (0.01g/L to 0.88 g/L), COD (40 mg/L to 304 mg/L), NO3 (32.5 mg/L to 475 mg/L), and NO2 (7.35 mg/L to 255 mg/L) and PO43- (32.5 mg/L to 475 mg/L ) were observed to be higher than recommended limits set by Federal Ministry for the Environmental (FME). The viable cells in soil samples 30cm depth ranged from 0 cfu/mL to 2.44 x 1010cfu/mL, in soil 5cm depth ranged from 1.00 x 101 cfu/mL to 1.91 x 1010 cfu/mL, and in water samples viable cells ranged from 5.00 x 101 to 5.05 x 109. Pseudomonas luteola (Ps. luteola), Escherichia vulneris (E. vulneris), Salmonella choleraesuis spp arizonae, Escherichia coli 1(E. coli 1), Enterobacter cloacae, Pseudomonas flourescens/putida (Ps. flourescens/putida), Enterobacter aerogenes, Serratia ordoriferal, Pasteurella pneumotropica, Ochrobactrum antropi, Proteus vulgaris group, Proteus vulgaris, Salmonella spp, Aeromonas Hydrophila/caviae/sobria1, Proteus Mirabillis, Vibrio fluvials, Rahnella aquatillis, Pseudomonas aeruginosa (Ps. aeruginosa), Burkholderia Cepacia, Stenotrophomonas maltophilia (St. maltophilia), Shwenella putrefaciens, Klebsiela pneumonia, Cedecea davisa, Serratia liquefaciens, Serratia plymuthica, Enterobacter sakaziki, Citrobacter braakii, Enterobacter amnigenus 2, Yersinia pestis, Serratia ficaria, Enterobacter gergoriae, Enterobacter amnigenus 1, Serratia marcescens, Raoutella terrigena, Hafnia alvei 1, Providencia rettgeri, and Pantoa were isolated from soil and water samples from the pig farm. Isolates were highly resistant to Penicillin G, Sulphamethaxazole, Vancomycin, Tilmocozin, Oxytetracycline, Spectinomycin, Lincomycin, and Trimethoprim. The most resistance genes detected in most isolates were aa (6’)-le-aph (2”)-la, aph (2”)-lb, aph (3”)-llla, Van A, Van B, Otr A and Otr B. Pig farm seepage is causing bacterial pollution which is impacting negatively on the natural environment in the vicinity of pig farm by introducing bacterial pathogens that have an antibiotic resistance gene and is increasing the physicochemical parameters for soil and water in the natural environment at the pig farm. It is therefore recommended that pig farms should consider the need to implement appropriate regulatory agencies that may include the regular monitoring of the qualities of final effluents from waste water treatment facilities. In addition there is a need to limit soil pollution in order to safe guard the natural environment in the vicinity of pig farm from bacteriological pollution and introduction of antibiotic resistance gene. It is also recommended that more advanced technologies should be introduced that will assist pig farms to manages the seepage properly. / Environmental Sciences / M. Sc. (Environmental Sciences)
109

Sistemas inteligentes aplicados à análise de riscos ambientes

Francisco Sales de Albuquerque Filho 17 October 2012 (has links)
Este trabalho aplica técnicas da área de inteligência artificial (IA) com o intuito de prever e classificar riscos ambientais, com o foco no problema da qualidade do ar. Para prever os riscos, dados foram adquiridos acerca das concentrações gasosas de determinados poluentes. Tais concentrações, denominadas de indicadores da qualidade do ar, são regulamentadas por várias legislações ao redor do mundo, inclusive a do Brasil. Estes dados foram empregados em um modelo que consiste de duas técnicas de IA: redes neurais artificiais e otimização por enxame de partículas. O resultado do modelo é a previsão de um dia adiante das concentrações gasosas dos indicadores da qualidade do ar. As previsões são usadas como entradas para a modelagem de riscos. A modelagem de riscos correlaciona as previsões dos poluentes observados para obter a qualidade do ar e o risco que tal qualidade oferece à saúde humana. O modelo de risco é baseado em lógica nebulosa, uma terceira técnica de IA. Ao término do trabalho, dois resultados foram alcançados. O primeiro foi o modelo de previsões que obteve resultados com um bom nível de acuidade. Em seguida, o modelo de riscos foi capaz de alcançar uma classificação coerente dos riscos ambientais. / In order to forecast and classify environmental risks, artificial intelligence (AI) techniques were applied to the air quality problem. Predetermined gaseous pollutant concentration data were acquired with the intent of predicting the risks. Such concentrations are denominated air quality indicators, and are regulated all around the world, including by brazilian law. The data concerning these indicators were used in a model that consists of two AI techniques: artificial neural networks and particle swarm optimization. The air quality indicators concentration prediction resulted in one day ahead values. The risk modeling utilizes the predictions as inputs values, correlating them in order to obtain the resulting air quality and, the risk that such quality has upon the human health. The risk model is based on a third AI technique, called fuzzy logic. The present work obtained two main results. The first was the accurate forecasts made by the prediction model. The second was the achievement of a coherent classification of the risks.
110

Oxigênio dissolvido e demanda bioquímica de oxigênio no Rio Uberabinha: um estudo da poluição orgânica biodegradável

Shimizu, Wilson Akira 17 October 2000 (has links)
O rio Uberabinha, localizado na região do Triângulo Mineiro, em Minas Gerais, compõe a sub-bacia do rio Araguari, afluente da bacia do rio Paranaíba, na região hidrográfica do rio Paraná. Mede, da sua nascente no município de Uberaba à foz no rio Araguari, aproximadamente 150 km, percorrendo cerca de 135 km no município de Uberlândia. Drena uma bacia de cerca de 2.190 km2, onde se localizam as captações da água que abastece uma população que hoje se aproxima de meio milhão de habitantes. Os esgotos produzidos pela cidade são também todos descarregados no rio. O trabalho consistiu na análises de pH, temperatura, oxigênio dissolvido e demanda bioquímica de oxigênio em amostras coletadas em cinco pontos do rio Uberabinha, a partir de uma seção a montante da cidade, até cerca de 20,5 km a jusante do último ponto de lançamento de esgoto, abrangendo uma extensão de aproximadamente 42 km. Neste trecho, o relevo passa de medianamente dissecado para intensamente dissecado, com presença de inúmeras corredeiras e cachoeiras. As amostras foram coletadas de junho de 1999 a maio de 2000 e a vazão também foi medida nos dois pontos extremos de coleta. Os resultados mostram que os teores de OD sofrem uma redução ao receber a carga de poluição e gradativamente tendem a recuperar sua taxa de saturação. Em contrapartida, a DBO segue uma curva inversa, denotando a atuação do fenômeno da autodepuração, embora dentro do trecho estudado não se verifique ainda a completa remoção da carga orgânica. / The Uberabinha River, located in the region of Triângulo Mineiro, in the state of Minas Gerais, Brazil, is part of the Araguari River sub-basin. From its head in the city of Uberaba to its mouth in the Araguari River, it measures approximately 150 km, spanning about 135 km in the municipality of Uberlândia. The river drains a watershed of about 2.190 km2, from which water is collected to supply a population that approaches half a million inhabitants. Later, the sewage produced by the city is also discharged directly into the river. This research consisted in the analyses of pH, temperature, dissolved oxygen and biochemical oxygen demand of samples collected in five points of the Uberabinha River, from a section starting upstream of the urban area down to 20.5 km downstream the last point of sewage discharge, encompassing approximately 42 km. In this river section, the landforms go from low to medium hills with many rapids and waterfalls. The samples were collected from June 1999 to May 2000 and the water flow was measured on the two extremes of the studied river section. The results show that the dissolved oxygen values are reduced when receiving the sewage and it tends to slowly return to its normal saturation rate. On the other hand, the biochemical oxygen demand follows a reverse path, as a result of the natural phenomenon of self-restoration even though the organic material is not yet completely removed from the studied river section. / Dissertação (Mestrado)

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