Estudo in situ e em laboratório da mobilidade de metais pesados em solo

• Autor(a) principal: Jesus, Simone Cristina de
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/838
• topic: Metais pesados; Estudo in situ; Poços de monitoramento; Heavy metals; In situ study; Monitoring wells; CNPQ::ENGENHARIAS::ENGENHARIA CIVIL

The soil is capable of purifying and immobilizing part of the substances disposed, however, if its retention capacity is exceeded these substances may migrate to groundwater. The filtering properties of the soil are related to its physic-chemical and mineralogical characteristics, to the variation of the hydraulic conductivity and to the mechanisms of transport and retention that occur due to the passage of solutes, such as heavy metals, for example. These metals, toxic in certain concentrations, are major contaminants. Most of them present fairly limited mobility in soil and groundwater, but, however, some may have increasing mobility when they are in competition with other metals preferentially adsorbed by the soil. The determination through laboratory tests of heavy metals mobility does not take into consideration aspects that occur in situ. In the field, the mobility can be distinct from that obtained in the laboratory, primarily due to the different soils in the profile and their macro and micropores, the different values of hydraulic conductivity, the water flow in soil related to rainfall, the stress states that influence the voids distribution, the effects of sampling (soil disturbance), among others. Considering these aspects, this work aimed to evaluate the contamination of soils to which it was injected a solution from nitrates of six heavy metals, at concentrations normally found in landfills. The evaluation of contamination was accomplished by monitoring groundwater samples collected from wells constructed specially for that purpose; and by the determination of adsorption profiles of metals by means of sequential extraction in soil samples collected in situ close to the point of injection. Given the ability of soils to adsorb solutes, in this work it was intended to obtain an estimate of the migration of contaminants through soil profile and the potential for contamination of groundwater. Based on the results, the general conclusion is that there was no contamination of groundwater. The chemical analysis of the water samples did not detect any value of metal concentration above the reference. It appears that the injected metals have been adsorbed and/or precipitated in soil layers between the injection well and the holes from which undisturbed soil samples were extracted.