972 resultados para Fossil Fuels


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This article discusses the policy implications of agricultural modernization implemented by the military - after 1964. This policy, which became known as the Green Revolution, on the one hand contributed to the development of big business, but another caused serious social and environmental impacts. Currently, not only in Brazil but all over the world, have been in a great debate about the need to find alternatives to contain the problems caused to the environment resulting from the use of high technology in the field. One alternative proposed by several researchers is to replace fossil fuels by biofuels. As we believe that the error is in the current model of agricultural production based on mass production, which serves the major markets, the attention in this article, the need to develop an agricultural model designed for small property, with the use of family work and agroecology.

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Thirty-seven rainwater samples were collected at Jaú River watershed, Dois Córregos city (SP), between August 2009 and July 2010, where were analyzed the following variables: pH, Na+ , K+ , Ca2+, Mg2+, NO3- , Cl- , SO4 2- , PO4 3- and SiO2. The results indicate that Ca2+ (6.65%) and NO3- (35%) are the most abundant ions that followed the trend: Ca2+ > Mg2+ > K+ > Na+ for cations and NO3 - > SO4 2- > Cland PO4 3- for anions. The phosphate fertilizers use, agricultural soils dust, lithology, biomass burning and fossil fuels can be the major contributing factors to explain the chemical composition of rainwater at Jaú River watershed, Dois Córregos city (SP).

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Pós-graduação em Engenharia Civil e Ambiental - FEB

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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If burning a gallon of ethanol emits less greenhouse gas or GHGs (CO2, primarily), than the gasoline it replaces then it has a smaller carbon footprint than gasoline. Actually, it is the amount of fossil CO2 emitted that matters, because CO2 from fossil fuels represents "new" carbon in the atmosphere, whereas the CO2 released by corn ethanol is recycled atmospheric carbon.

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Over the next decade or two, the energy sector on which the world economy is based will undergo significant transformations. The fossil fuels on which the industrial revolution was built are on their way out. Nebraskans will face higher energy prices, but they will also produce more energy.

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The rapid expansion of ethanol production from sugarcane in Brazil has raised a number of questions regarding its negative consequences and sustainability. Positive impacts are the elimination of lead compounds from gasoline and the reduction of noxious emissions. There is also the reduction of CO2 emissions, since sugarcane ethanol requires only a small amount of fossil fuels for its production, being thus a renewable fuel. These positive impacts are particularly noticeable in the air quality improvement of metropolitan areas but also in rural areas where mechanized harvesting of green cane is being introduced, eliminating the burning of sugarcane. Negative impacts such as future large-scale ethanol production from sugarcane might lead to the destruction or damage of high-biodiversity areas, deforestation, degradation or damaging of soils through the use of chemicals and soil decarbonization, water resources contamination or depletion, competition between food and fuel production decreasing food security and a worsening of labor conditions on the fields. These questions are discussed here, with the purpose of clarifying the sustainability aspects of ethanol production from sugarcane mainly in Sao Paulo State, where more than 60% of Brazil`s sugarcane plantations are located and are responsible for 62% of ethanol production. (c) 2008 Elsevier Ltd. All rights reserved.

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This paper describes the first results of polycyclic aromatic hydrocarbons (PAHs) and spheroidal carbonaceous particles (SCPs) in sediment cores of Admiralty Bay, Antarctica. These markers were used to assess the local input of anthropogenic materials (particulate and organic compounds) as a result of the influence of human occupation in a sub-Antarctic region and a possible long-range atmospheric transport of combustion products from sources in South America. The highest SCPs and PAHs concentrations were observed during the last 30 years, when three research stations were built in the area and industrial activities in South America increased. The concentrations of SCPs and PAHs were much lower than those of other regions in the northern hemisphere and other reported data for the southern hemisphere. The PAH isomer ratios showed that the major sources of PAHs are fossil fuels/petroleum, biomass combustion and sewage contribution generally close to the Brazilian scientific station. (C) 2009 Elsevier Ltd. All rights reserved.

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Located in southeastern Brazil, the Santos Estuary has the most important industrial and urban population area of South America. Since the 1950`s, increased urbanization and industrialization near the estuary margins has caused the degradation of mangroves and has increased the discharge of sewage and industrial effluents. The main objectives of this work were to determine the concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) in sediment cores in order to investigate the input of these substances in the last 50 years. The PAHs analyses indicated multiple sources of these compounds (oil and pyrolitic origin), basically anthropogenic contributions from biomass, coal and fossil fuels combustion. The distribution of PAHs in the cores was associated with the formation and development of Cubatao industrial complex and the Santos harbour, waste disposal, world oil crisis and the pollution control program, which results in the decrease of organic pollutants input in this area. (C) 2011 Elsevier Ltd. All rights reserved.

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Admiralty Bay (Antarctica) hosts three scientific stations (Ferraz, Arctowski and Macchu Picchu), which require the use of fossil fuel as an energy source. Fossil fuels are also considered the main source of pollution in the area, representing important inputs of major pollutants (organic compounds) and trace metals and metalloids of environmental interest. Accordingly, this work presents the results of As, Cd, Cr, Cu, Ni, Pb and Zn in sediment profiles from Admiralty Bay. The sediment results from Ferraz station were slightly higher than the other sampling sites. The highest contents were observed for Cu and Zn (from 44 to 89 mg kg(-1)). Otherwise, by using enrichment factors and geochronology analysis, the most relevant enrichment was observed for As in the samples collected close to the Ferraz station, indicating that increasing As content may be associated with the activities associated with this site. Published by Elsevier Ltd.

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Admiralty Bay on the King George Island hosts the Brazilian, Polish and Peruvian research stations as well as the American and Ecuadorian field stations. Human activities in this region require the use of fossil fuels as an energy source, thereby placing the region at risk of hydrocarbon contamination. Hydrocarbon monitoring was conducted on water and sediment samples from the bay over 15 years. Fluorescence spectroscopy was used for the analysis of total polycyclic aromatic hydrocarbons (PAHs) in seawater samples and gas chromatography with flame ionization and/or mass spectrometric detection was used to analyse individual n-alkanes and PAHs in sediment samples. The results revealed that most sites contaminated by these Compounds are around the Brazilian and Polish research stations due to the intense human activities, mainly during the summer. Moreover, the sediments revealed the presence of hydrocarbons from different sources, suggesting a mixture of the direct input of oil or derivatives and derived from hydrocarbon combustion. A decrease in PAH concentrations occurred following improvement of the sewage treatment facilities at the Brazilian research station, indicating that the contribution from human waste may be significant.

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The sources and concentrations of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs), faecal and biogenic sterols, and trace metals at 10 sampling sites located in Laranjeiras Bay, a large Environmental Protection Area in the southern Atlantic region of Brazil, were determined to assess the sources of organic matter and the contamination status of estuarine sediments. Organic compounds were determined by GC-FID and GC-MS, and ICP-OES was used to evaluate trace metals. The total AHs concentration ranged from 0.28 to 8.19 mu g g(-1), and n-C-29 and n-C-31 alkanes were predominant, indicating significant inputs from higher terrestrial plants. Unresolved complex mixtures (UCM) were not detected at any site, suggesting that the study area was not significantly contaminated by fossil fuels. The total PAH concentration varied from 3.85 to 89.2 ng g(-1). The ratio between selected PAH isomers showed that combustion of biomass, coal, and petroleum is the rnain source of PAHs in the study area. The concentrations of the faecal sterols coprostanol and epicoprostanol were below the detection limits, suggesting that sewage was not a significant contributor to sedimentary organic matter. The concentrations of the trace metals (As, Cr, Cu, Ni, Pb and Zn) were low, except near sites located at the mouths of rivers that discharge into the study area and near urbanised regions (Paranagua city and the adjoining harbour). In general, the concentrations of PAHs were below the threshold effect concentrations (TEL) levels. Although the As, Cr and Ni concentrations were above the TEL levels, the study area can be considered as preserved from human activities.