Detalhes bibliográficos
| Ano de defesa: |
2015 |
| Autor(a) principal: |
Gomes, Luciana Godinho Nery
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| Orientador(a): |
Ribeiro, Adauto de Souza
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| Banca de defesa: |
Não Informado pela instituição |
| Tipo de documento: |
Tese
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| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de Sergipe
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| Programa de Pós-Graduação: |
Pós-Graduação em Desenvolvimento e Meio Ambiente
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| Departamento: |
Não Informado pela instituição
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| País: |
BR
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| Palavras-chave em Português: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
https://ri.ufs.br/handle/riufs/4064
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Resumo: |
The bacterium Escherichia coli is internationally recognized for being the only exact environmental indicator for fecal contamination. In the decades of 2000 and 2010, research found this bacterium does not live only in intestines habitat, losing its exactitude as a fecal indicator. Some important questions were not answered, for instance, soil types and under what physic, chemical and geological conditions, E. coli grows in the environment; how its concentrations in river bank interferes in the water column concentration; why the concentration is so high in soil and sediments in relation to water column; what is its validity as a fecal indicator. This research aimed to answer these questions, more specifically, (1) to verify the occurrence and growth of this bacterium in river bank soil in tropical rivers in Brazil; (2) to evaluate if it is a natural soil specie; (3) to establish some of its ecological relations; (4) to identify techniques to potentialize its use as a fecal indicator. Mathematical models were utilized for E. coli dispersion simulation in river considering the sediments ressuspension and the bank erosion. The E. coli concentration was measured with membrane filtration method using the culture medium Endo at 37° C. The results show a natural E. coli occurrence in soil with concentrations such as 104 CFU/g dry soil, identified as an E. coli source. This work also concluded that the population persistence and growth depend on the clay properties to maintain the temperature and humidity and to adsorb the bacterium, decreasing its lateral flux in the water column. The E. coli adhesion is an evolution adaptation to fix it into its habitat. River bank E. coli goes to water column through erosion and ressuspension, being associated to suspended sediment concentration. The relation between soil and water concentration was 26.762 times more in soil at low velocities of the river, and 266 times in high velocities, showing a direct relation with bank erosion rate and sediment ressuspension. |
