167 resultados para análises químicas
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Heavy metals are found naturally in soils at low concentrations, but their content may be increased by human activity, making them one of the barriers in management of tropical soils. These chemical elements can be found in the composition of organic and inorganic fertilizers, insecticides, fungicides, mine tailings, and urban waste, and may cause serious damage to the environment and human health. Thus, adsorption studies are essential in assessing the behavior of heavy metals in the soil. The objective of this study was to evaluate the influence of soil chemical, particle size, and mineralogical properties on adsorption of cadmium (Cd), evaluated by Langmuir and Freundlich models, in Latossolos (Oxisols) with or without human activity. Soil samples were collected from the surface layer, 0.00-0.20 m, and chemical, particle size, and mineralogical analyzes were performed. In the adsorption study, concentrations of 0, 5, 25, 50, 100, 200, 300, and 400 mu g L-1 of Cd were used in the form of Cd(NO3)(2). The empirical mathematical models of Langmuir and Freundlich were used for construction of adsorption isotherms. Data were analyzed by means of multivariate statistical techniques, Cluster Analysis and Principal Component Analysis. The data from the adsorption experiment showed a good fit to the Langmuir and Freundlich models. Soils with a lower goethite/hematite ratio and greater cation exchange capacity and pH, showed higher maximum adsorption capacity of Cd.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The contamination of the physical environment occurs as a result of the lack of planning and inadequate management of hazardous products. Due to the difficulty of the characterization and study of soil and groundwater, the contamination has been long neglected. The characterization of these areas by research techniques through direct methods such as physical and chemical analysis, are widely used in the diagnosis and monitoring. However, despite presenting quantitative results, this method is not representative in spatial terms. The purpose of this work is to bring geophysical complementation with the diagnosis, bringing the spatial element for the detection of the contamination plume. In the study area, there was a railway accident in 1999 in which three wagons fell and spilled 240,000 L of diesel onto the soil. The main objective is to assess the presence of contaminants in the residual phase and dissolved in the subsurface, using the technique of Electrical Tomography (ETR), understand the effects of natural attenuation process in the degradation of hydrocarbons and changes in electrical properties in soil and groundwater. The results allowed the definition of three distinct patterns of resistivity region with presence of dissolved phase, set in a historical chemical analyzes: low values (> 60Ω.m) associated with the presence of hydrocarbons in an advanced stage of degradation, intermediate values (260Ω.me 511Ω .m) indicative of coexistence of residual hydrocarbons and dissolved phase, and high values (> 1000Ω.m), which reveal the prevalence of residual phase with incipient degradation, possibly in high toxicity concentrations for effective action of biodegradation processes. The diagnostic of areas with potential accumulation of residual phase can subsidize the planning of remediation techniques and promote the complete decontamination of the area
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Pós-graduação em Engenharia Mecânica - FEG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Engenharia Civil e Ambiental - FEB
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Pós-graduação em Química - IQ
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This study aimed at determining the levels of macronutrients (N, P, K, Ca, Mg and S) in grafted plants by contact methods such as bevel, cleft grafting by full rift and approach, as compared to non grafted plants. Analyses were performed in different parts of the plants under fertigation in a greenhouse. The hybrid and rootstock were AF 7125 and AF 8253, respectively. The nutrients were supplied via fertigation during the 150-day cycle. The experiment was carried out at the Teaching, Research and Production Farm in São Manuel city, SP which belongs to FCA-UNESP Campus in Botucatu city/SP. A total of 4 treatments and 5 replications were used. Each plot consisted of 12 plants. Chemical analyses were performed in one plant per plot at 35, 85, 112 and 143 days after transplantation to determine nutrient concentrations. The results showed that the macronutrient concentrations in a decreasing sequence in the vegetative parts (leaf + stem) were as follows: K > N > Ca > Mg > S > P; and in the fruits: K > N > P > S > Mg > Ca. Macronutrient concentrations were similar among grafted plants as compared to ungrafted plants, and the rootstock may have influenced absorption and translocation of minerals in grafted plants.
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The land use conservation planning requires knowledge of the soil characteristics, natural susceptibility to erosion and the soil loss limit. In this context, the objectives of this study were to perform a detailed soil survey of Ribeirão das Perobas watershed, located in Santa Cruz do Rio Pardo, São Paulo State and to determine and map the erodibility and soil loss tolerance of the soil classes found in the survey. The following techniques were used to perform the detailed soil survey: photopedology, field sampling, physical analysis, chemical analysis, and morphological description of the soil samples and profiles. The erodibility was determined by the methods described by Denardin (1990) and Mannigel et al. (2002), and the determination of soil loss tolerance followed the methodology of Mannigel et al. (2002). The results of erodibility determined by the methodology of Denardin (1990) were not discrepant and they did not distinguish soils that are known to have different susceptibility to erosion., w\Whereas, using the methodology of Mannigel et al. (2002), very high or very low erodibility values were observed in soils with extreme contents of sand silt or clay. The most influent variable to the soil loss tolerance results was the correction factor for the textural gradient of clay between soil horizons.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)