Estudo da mobilidade de metais pesados em um solo residual compactado

• Ano de defesa: 2006
• Autor(a) principal: Nascentes, Rejane
• Orientador(a): Azevedo, Izabel Christina D' Almeida Duarte de
• Banca de defesa: Fontes, Maurício Paulo Ferreira , Matos, Antonio Teixeira de , Barbosa, Maria Claudia , Boscov, Maria Eugenia Gimenez
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Engenharia Civil
• Departamento: Geotecnia
• País: BR
• Palavras-chave em Português: Solos; Contaminação; Metais pesados; Transporte de contaminantes
• Palavras-chave em Inglês: Soils; Contamination; Heavy metals; Contaminant transport
• Área do conhecimento CNPq: CNPQ::ENGENHARIAS::ENGENHARIA CIVIL::GEOTECNICA
• Link de acesso: http://locus.ufv.br/handle/123456789/811

Several factors have created conditions to a great world population growth that implicates in a larger generation of residues and, as a consequence, in an increase of water, air and soil contamination. Heavy metals, toxic in specified concentrations, are important contaminant. The contamination of a soil by heavy metals are, mainly, due to municipal and industrial waste disposition, atmospheric deposition due to automotive vehicles and industries, as well as, agriculture practices with the progressively higher use of fertilizes, pesticides and correctives. Compacted tropical soils, associated or not with geotextiles, have been used in liners in areas of disposition of urban and industrial waste. This practice, however, creates some uncertainties due to little knowledge about the utilization of this material for this purpose. In this sense, more studies have to be developed about interactions that occur between tropical soils and contaminant solutions, because these interactions can modify some of the soil properties as, the hydraulic conductivity, the diffusion coefficient, the retarding factor and the coefficient of hydrodynamic dispersion, important in the contaminant transport in soils. Having in mind the shortage of information available in the literature concerning these parameters for Brazilian tropical soils, it is studied, in this work the mobility of six heavy metals in a residual gneissic compacted soil. Three groups of tests were performed with the same compacted soil, however, each group with compaction degrees and water contents slightly different. For Group I samples, the testing program consisted of column tests to evaluate the influence of the soil structure in the hydraulic conductivity and the mobility parameters of a synthetic contaminant solution made of made of nitrates of six heavy metals, Mn, Zn, Cd, Cu, Pb and Cr. Batch tests were also realized as well as, chemical, physical and micro morphological analyses that served to support discussions about the previous test results.With the samples of Groups II and III, only column tests were performed. The Group II tests were performed percolating the same contaminant solution used in Group I. Group II tests aimed at to confirm the tests performed by Nascentes (2003) and Azevedo et al. (2003), since the results obtained in the Group I tests were, unexpectedly, different from the ones verified in that work. In the tests of Group III, samples were percolated, one only with distilled water and, two others, only with rain water. The objective of these tests was to establish differences since tests in Group I and II used only distilled water and, in real cases, percolation is obviously made with rain water. Among the several conclusions that may be withdrawn from this work, it is emphasized that the percolation with distilled water in the initial phase of the column tests to saturate, without back pressure, the soil, influences the results, since the soil structure is altered, especially when a large porous volume is percolated. With relation to the mobility of the six heavy metals studied, it was observed that there was no relationship between the manganese adsorption and the hydraulic conductivity of the soil. This means that the mobility of this metal is independent of flow velocity. This conclusion is important because, even if the liner material has low hydraulic conductivity, a great mobility of Mn may occur, leading to the contamination of lower soil layers and the ground water.