1000 resultados para análises químicas


Relevância:

60.00% 60.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Horticultura) - FCA

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The main purpose of this work is to evaluate the chemical composition of the groundwaters from Guarani Aquifer System and Serra Geral Aquifer System in the Rio Pardo basin, located at the southwestern of São Paulo state. To the hydrochemical characterization, physicalchemical analyses from 32 sampled wells were used. These results were plotted in Piper diagrams allowing the classification of groundwater as calcium or calcium-magnesium bicarbonate type and sodium bicarbonate type for both aquifer systems. Distribution of hydrochemical facies over the study area was obtained using Stiff diagrams. The groundwater can be classified, representing in this sequence its hydrochemical evolution. The recognized mechanisms responsible for groundwater evolution are dissolution of minerals magnesium, such as olivine, present in the basalt, dissolution of feldspars and removal of the carbonate cement of the sandstones mineral framework. Ionic exchange may represent an important processes in the groundwater evolution, responsible for the increase in the sodium concentration and decrease of calcium

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Contamination of rivers and lakes, waste disposed by infiltration into the soil as fertilizer, for example, has been highlighted around the world, since such compounds can contain toxic elements, causing changes in aquatic and/or terrestrial ecosystem. Due to the possible presence of these elements in these wastes, it is possible assess damage to organisms exposed through breaks in genetic material and mutations. In this sense, this work aimed at exploring the cytotoxic, mutagenic and genotoxic vinasse pontential, residue used as fertilizer, from the processing of sugar cane into alcohol, using fish (Oreochromis niloticus - Cichlidae) as a test organism. The individuals were exposed to different dilutions of vinasse in the water and later carried out analysis of their erythrocytes using the micronucleus test and nuclear abnormalities associated and the comet assay. In the first bioassay, tilapia exhibited 5% and 10% vinasse concentrations died after 48h. The number of micronucleated erythrocytes was statistically significant for the 1% vinasse concentration and also for nuclear abnormalities such as broken-egg and nuclear bud, when compared with negative and positive controls; were also significant lobed type erythrocytes, when compared to the negative control. The test results of the comet assay were not significant for 1% vinasse when compared to the negative control, due to the high rate of comets with damage control, which is unusual. The same was observed for changes as notched and blebbed type. In the second chemical analyzes conducted, the detection of heavy metals in the vinasse sample, charged only the presence of copper and chromium, the latter with a concentration 89 times higher than in the first test. Differentially the first bioassay, fish exposed to dilution of 5% did not die... (Complete abstract click electronic access below)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The purpose of this work was the inlay’s characterization from the water supply networks of Rio Claro-SP city; as well analyze the influence of network’s aging in the actual system. To do this, some samples of inlays were collected and made chemistry analysis and X-Ray Diffraction Spectrometry. The history of the source water quality was also analyzed, to make possible to known the origins of the inlays. To evaluate the performance of the network, some different scenarios have been simulated, varying the resistance coefficient of the water supply networks of Rio Claro-SP. The characterization results showed that there are basically oxide and hydroxide of iron (magnetite and goethite) and quartz in the inlays, which are materials of high hardness. The hydraulic simulations indicated that the simulated scenarios had a variation of ~2000% in terms of loss of energy

Relevância:

60.00% 60.00%

Publicador:

Resumo:

In the Serra de Jacobina, localized in the North Central portion of the state of Bahia, occours the Jacobina Group. It’s a sedimentary basin and the gold deposit is stocked on the basal portion, which consist on quartzites intercalated with oligomítico metaconglomerates of Serra do Córrego Formation. There are controversies about the origin of the gold mineralization, but the currently most accepted hypothesis corresponds to a paleoplacer deposit with subsequent ore remobilization and concentration by hydrothermal process. The sulphidation is one of the main results of hydrothermal process, which was more detail characterized, besides identifying if there was more than one sulfides phase generation and its relationship with gold mineralization. The analyzes were performed from the main reef's (metaconglomerates mineralized levels) of Mine Canavieiras: Maneira, Holandez, Liberino, Piritoso, MU and LU. Chemical analyzes semi-quantitative were developed with EDS in MEV and also petrographics analyses. The main sulfide is pyrite, followed by chalcopyrite. Six groups of pyrite were classified according with chemical composition, however they show similarities in their habit and occurrence. Were identified four types of chlorite, labeled A, B, C, D. Gold occurs in free form, associate to pyrites, to Fe-Ti-Muscovite, to chlorite type B and to microfractures with iron hydroxide. Gold presents three different compositions: pure, with Ag or associated with U-Zr. The results of chemical analysis showed that the hydrothermal process have as their main source, ultramafic rocks present in the Jacobina Basin

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Concerns about the quality of groundwater have been continuously rising, considering its importance for the public water supply in the State of São Paulo, and even more due to the impact that anthropic action has been causing to the original quality of that natural resource. It is extremely relevant to identify the contamination focuses along the aquifers of the State of São Paulo. This report aims to evaluate nitrates and fluorides concentrations along the aquifers present in the state, in order to identify places where change in the quality of groundwater is observed, through the comparison between measured concentrations and reference values, such as: “Intervention Value” (maximum allowed value) and “Alert Value” (attention required value). To perform this research, a full compilation and organization has been done on chemical analysis data from the “Sistema de Informações de Águas Subterrâneas - SIDAS”, made available by the “Divisão de Procedimentos de Outorga – DPO” of the “Departamento de Água e Energia Elétrica – DAEE”. This work has made possible the build-up of a database composed by 6,860 wells, with analytical data ready to be interpreted, containing information about water pH, electrical conductivity, hardness and chloride, iron, fluoride, nitrogen, nitrates and total dissolved solids concentrations. This database shows concentration data for nitrates (6,157 wells) and fluoride (3,316 wells). From this information, maps for nitrates and fluorides concentration distributions have been made, by each aquifer and each “Unidade de Gerenciamento de Recursos Hídricos – UGRHI”, which has enabled the identification of wells where the concentrations of these chemical compounds exceeds the reference values. Concerning nitrates, these analysis indicated the existence of contamination sources from rural and urban zones, mostly present in the west region... (Complete abstract click electronic access below)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

A contaminação do solo por metais potencialmente tóxicos constitui um dos principais problemas ambientais. Por meio da lixiviação e percolação das águas, esses metais podem ser mobilizados e vir a contaminar mananciais superficiais e subterrâneos, comprometendo sua qualidade. A biodisponibilização desses metais para as plantas e, a partir dessas, para o homem é outro desfecho negativo dessa situação. O cádmio é um elemento tóxico. Os teores encontrados nos solos costumam não oferecer riscos. Porém, esses teores são potencializados pela utilização de fertilizantes. O níquel pode ser carcinogênico em doses elevadas. Sua presença em fertilizantes fosfatados proporciona maiores concentrações do metal no solo. É amplo o registro sobre efeitos do excesso desses metais, tanto em plantas, quanto em animais e no ser humano. O manganês é um dos elementos mais abundantes na crosta terrestre e se encontra largamente distribuído em solos, sedimentos, rochas, água e materiais biológicos. Contrariamente aos dois metais anteriores, esse micronutriente é um elemento essencial ao ser humano. Sua carência causa inúmeras enfermidades, por outro lado, seu excesso também. Nesse caso, poucos são os relatos sobre o assunto. Nesse estudo foram utilizados métodos de extração de metais de fertilizantes e se constatou que, quando presentes, os metais cádmio e níquel apresentaram concentrações proibitivas o que é motivo de preocupação e demonstra a falta de controle sobre a indústria de insumos agrícolas. Para o manganês não há parâmetros orientadores com limites de teores, mas com certeza, são necessários trabalhos nesse sentido para se evitar seu consumo indiscriminado.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

This work will address the study of fatigue conditions with constant load in an alloy of aluminum analysis 7475 - T761, so we can better understand the conditions of the aircrafts which contain this alloy in their structures. A literature review, which was discussed the concepts of fracture mechanics, fatigue, aeronautical components, chemical analysis of aluminum alloys, fatigue problems that appears in the aircrafts, metallographic analysis, and testing of optical microscopy tensile, fatigue and microhardness, surface analysis (MEV) study of the chemical composition of the alloy in question, the main causes of crashes, was performed, completing the work, analysis of data from tensile test, hardness and fatigue together with the interpretation of images of optical microscopy and scanning electron was taken. The data indicated the high mechanical strength of the alloy, along with its microstructure indicating elongated grains and high surface contour, which shows such resistance by hindering the movement of dislocations. The grooves are clearly shown in the MEV images as well as the classic with increased fatigue loading and subsequent reduction of the number of cycles to rupture behavior shown in the graphs. Therefore we observed the optimal behavior is supported by the league when subjected to fatigue loadings

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Pós-graduação em Engenharia Mecânica - FEIS

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

60.00% 60.00%

Publicador:

Resumo:

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.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)