1000 resultados para Environmental Studies


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Energy intensity of the total primary energy supply (TPES), total final energy consumption (TFC) and LOSSES in the conversion from TPES to TFC were analyzed for the World, OECD and Rest of the World (ROW) countries. LOSSES increased significantly for all groups of countries due to the increase of electricity production from coal in the period studied (1971-2008). Electricity share final consumption almost doubled, increasing from 8.8% to 17.2% in the period studied. However the energy intensity of LOSSES remained practically constant, which reflects the fact that the efficiency of electricity generation from coal (the main source of electricity) remained practically constant in that period. Despite the attractiveness of end-use devices running on electricity such as computers, which is typical of modern societies, the CO(2) emissions are bound to increase unless coal is replaced by less carbon emitting sources such as natural gas, renewables and nuclear energy. (C) 2011 Elsevier Ltd. All rights reserved.

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Decarbonizing the world`s energy matrix is the strategy being implemented by most countries to reduce CO(2) emissions and thus contribute to achieve the ultimate objectives of the Climate Convention. The evolution of the carbon intensity (I(c)=CO(2)/GDP) in the period 1990-2007 was encouraging but not sufficient to reduce the growth of carbon emission. As a result of COP-15 in Copenhagen these countries (and regions) made pledges that could lead to more reduction: for the United States a 17% reduction in CO(2) emissions by 2020 below the level of 2005: for the European Union a 20% reduction in CO(2) emissions by 2020 below the 1990 level: for China a 40-45% reduction in the carbon intensity and for India a 20-25% reduction in carbon intensity by 2020. We analyzed the consequences of such pledges and concluded that the expected yearly rate of decrease of the carbon intensity follows basically the ""business as usual"" trend in the period 1990-2007 and will, in all likelihood, be insufficient to reduce carbon emissions up to 2020. (C) 2010 Elsevier Ltd. All rights reserved.

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This work models the carbon neutralization capacity of Brazil`s ethanol program since 1975. In addition to biofuel, we also assessed the mitigation potential of other energy products, such as, bioelectricity, and CO(2) emissions captured during fermentation of sugar cane`s juice. Finally, we projected the neutralization capacity of sugar cane`s bio-energy system over the next 32 years. The balance between several carbon stocks and flows was considered in the model, including the effects of land-use change. Our results show that the neutralization of the carbon released due to land-use change was attained only in 1992, and the maximum mitigation potential of the sugar cane sector was 128 tonnes Of CO(2) per ha in 2006. An ideal reconstitution of the deployment of the sugar cane sector, including the full exploitation of bio-electricity`s potential, plus the capture Of CO(2) released during fermentation, shows that the neutralization of land-use change emissions would have been achieved in 1988, and its mitigation potential would have been 390 tCO(2)/ha. Finally, forecasts of the sector up to 2039 shows that the mitigation potential in 2039 corresponds to 836 tCO(2)/ha, which corresponds to 5.51 kg Of CO(2) per liter of ethanol produced, or 55% above the negative emission level. (C) 2009 Elsevier Ltd. All rights reserved.

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Recently a number of objections have been raised against the use of ethanol produced from agricultural products such as maize, sugarcane, wheat or sugar beets as a replacement for gasoline, despite some of their advantages such as being cleaner and to some extent renewable. We address these objections in this paper. Topics discussed include the ""corn connection"" (which was theorized to be a cause of deforestation in the Amazonia), the rise of food prices due to ethanol production and the real possibilities of ethanol in reducing greenhouse gas emissions. It has been shown that such concerns are grossly exaggerated and that ethanol from sugarcane, as produced in Brazil, is the preferred option for the production of fuel not only in terms of cost but also as a favourable energy balance. Finally, the possibility of expanding ethanol production to other sugar-producing countries is also discussed. (C) 2008 Elsevier Ltd. All rights reserved.

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Biochemical responses in bivalve mollusks are commonly employed in environmental studies as biomarkers of aquatic contamination. The present study evaluated the possible influence of salinity (35, 25,15 and 9 ppt) in the biomarker responses of Crassostrea gigas oysters exposed to diesel at different nominal concentrations (0.01, 0.1 and 1 mLL(-1)) using a semi-static exposure system. Salinity alone did not resulted in major changes in the gill`s catalase activity (CAT), glutathione S-transferase activity (GST) and lipid peroxidation levels (measured as malondialdehyde. MDA), but influenced diesel related responses. At 25 ppt salinity, but not at the other salinity levels, oysters exposed to diesel showed a strikingly positive concentration-dependent GST response. At 25 ppt and 1 mLL(-1) diesel, the GST activity in the gills remained elevated, even after one week of depuration in clean water. The increased MDA levels in the oysters exposed to diesel comparing to control groups at 9, 15 and 35 ppt salinities suggest the occurrence of lipid peroxidation in those salinities, but not at 25 ppt salinity. The MDA quickly returned to basal levels after 24 h of depuration. CAT activity was unaltered by the treatments employed. High toxicity for 1 mLL(-1) diesel was observed only at 35 ppt salinity, but not in the other salinities. Results from this study strongly suggest that salinity influences the diesel related biomarker responses and toxicity in C. gigas, and that some of those responses remain altered even after depuration. (C) 2011 Elsevier B.V. All rights reserved.

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Many environmental studies require accurate simulation of water and solute fluxes in the unsaturated zone. This paper evaluates one- and multi-dimensional approaches for soil water flow as well as different spreading mechanisms to model solute behavior at different scales. For quantification of soil water fluxes,Richards equation has become the standard. Although current numerical codes show perfect water balances, the calculated soil water fluxes in case of head boundary conditions may depend largely on the method used for spatial averaging of the hydraulic conductivity. Atmospheric boundary conditions, especially in the case of phreatic groundwater levels fluctuating above and below a soil surface, require sophisticated solutions to ensure convergence. Concepts for flow in soils with macro pores and unstable wetting fronts are still in development. One-dimensional flow models are formulated to work with lumped parameters in order to account for the soil heterogeneity and preferential flow. They can be used at temporal and spatial scales that are of interest to water managers and policymakers. Multi-dimensional flow models are hampered by data and computation requirements.Their main strength is detailed analysis of typical multi-dimensional flow problems, including soil heterogeneity and preferential flow. Three physically based solute-transport concepts have been proposed to describe solute spreading during unsaturated flow: The stochastic-convective model (SCM), the convection-dispersion equation (CDE), and the fraction aladvection-dispersion equation (FADE). A less physical concept is the continuous-time random-walk process (CTRW). Of these, the SCM and the CDE are well established, and their strengths and weaknesses are identified. The FADE and the CTRW are more recent,and only a tentative strength weakness opportunity threat (SWOT)analysis can be presented at this time. We discuss the effect of the number of dimensions in a numerical model and the spacing between model nodes on solute spreading and the values of the solute-spreading parameters. In order to meet the increasing complexity of environmental problems, two approaches of model combination are used: Model integration and model coupling. Amain drawback of model integration is the complexity of there sulting code. Model coupling requires a systematic physical domain and model communication analysis. The setup and maintenance of a hydrologic framework for model coupling requires substantial resources, but on the other hand, contributions can be made by many research groups.

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Negative impacts of invasive plants or weeds on biodiversity have been well established yet their role in providing key habitats and resources for wildlife has been little understood. Weed removal thus has the potential to adversely affect wildlife but whether this is considered during weed management is poorly known. To determine the extent of this knowledge, we examined the perceptions of weed managers regarding wildlife and weed management in Victoria, Australia. We surveyed 81 weed managers of varying levels of experience from different types of organisations, including state and local government, community groups and private companies. We found 90% of managers had observed wildlife-weed interactions and that most (70%) adjusted management programmes to accommodate wildlife. Despite this, few (19%) had adopted the recommended practice of combining gradual weed removal with re-vegetation. While management programmes included monitoring of native vegetation, consideration of wildlife monitoring in weed management was rare. This highlights the need for management to better understand and respond to wildlife-weed relationships. If the improvement of wildlife habitat is included in the objectives of weed programmes, as it should be, then wildlife should also be incorporated in project monitoring. This would lead to a greater understanding of the role weeds and their management have in each situation and, ultimately, more informed decision making. Copyright: © Carlos et al. 2014.

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 Since 1958 the hukou (household registration) system has assigned Chinese citizens either a rural or urban status. Some studies argue that the rural-to-urban migrants in China who do not have urban hukou are not entitled to urban social insurance schemes, due to institutional discrimination, which applies differing treatment to urban and rural hukou (chengxiang fenge). Although rural-urban migrants participate less in the social insurance system than their counterparts with urban hukou, a closer examination of recent policy developments shows that migrants actually do have the legal right to access the system. This implies that discrimination between rural and urban workers has been declining, and distinctions based on household registration status are less able to explain China's current urban transition. This paper provides a new way of examining Chinese migrants' social insurance participation, by adopting a framework that includes both rural-to-urban migrants and urban-to-urban migrants, which are an important, but less studied, migrant group. Among our key findings are that urban migrants are more likely to sign a labour contract than rural migrants; urban migrants have higher participation rates in social insurance than rural migrants; having a labour contract has a greater impact than hukou status in determining whether Beijing's floating population accesses social insurance; and urban migrants who have signed a labour contract have higher participation rates in social insurance than either rural migrants or urban migrants without a labour contract. © 2013 Elsevier Ltd.

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 One consequence of China's marketisation has been the emergence of a 'floating population' - rural Chinese who migrate to China's cities to work. Many urbanites have negative attitudes towards such migrants. To understand how these negative attitudes might be ameliorated, the paper employs Allport's influential contact hypothesis to investigate whether urbanite-migrant friendships affect attitudes. More negative attitudes were observed among males and older urbanites. There was no effect of simply knowing a migrant, supporting Allport's thesis that non-intimate contact is not sufficient to affect attitudes. Friendship alone did not influence attitudes, but interaction effects were detected between having migrant friends and each of age, income and education. Negative attitudes were reduced among urbanites in older, higher-income and higher-education groups if they had a migrant friend. © 2006 The Editors of Urban Studies.

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Urbanization impacts on the composition and distribution of wildlife. The tawny frogmouth (Podargus strigoides) is an endemic, nocturnal bird species widespread throughout Australia with recent research highlighting high densities within urban environments. The aim of this study was to investigate homerange size and land-use in response to a gradient of urbanization by determining (a) the key land-use types influencing home-range size and location in the urban landscape (b) whether urbanization impacts on home-range size; and (c) whether the response to urbanization is gender specific. Twelve birds, seven male and five female were radio-tracked within a study zone located in Melbourne, Australia. We used minimum convex polygons (MCP) 95% and 50% fixed-kernel isopleths to calculate home-range size and areas of core use within each home-range. In both the landscape and core areas of their home-range, birds positioned their home-range in areas with more trees, avoiding impervious surfaces and utilizing grassed areas. Male mean kernel home-range was 17.65 ± 4.35 ha and female 6.55 ± 1.40 ha. Male home-ranges contained higher levels of impervious surfaces than females. Modelling demonstrated that as urbanization intensified the home-range size of males increased whereas female home-ranges remained static in size. This research identifies land-use selection and highlights the possibility that spatial behaviour in the species is sex-biased in response to a gradient of urbanization. © 2014 Elsevier B.V.

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Landfill waste has a negative impact on the environment and small and medium sized enterprises (SMEs) are believed to be significant contributors. There is little government or scholarly research, however, quantifying the collective volume of waste SMEs send to landfill. Where studies do exist they measure total volumes (landfill and recycling combined) and/or do not distinguish between specific waste streams (e.g. wood) and subcategories (e.g. dust). This paper contributes to knowledge by giving insight into the collective volume of waste of 404 SMEs, reconceptualising SME waste into subcategories and by measuring landfill volumes. It presents findings from these 404 Australian SMEs which found that, in descending order, cardboard, paper, plastic wrap, wood dust and particleboard were the subcategories these SMEs sent to landfill in the greatest volumes. It also argues that this reconceptualisation, and associated data collection protocols, have the potential to enable scholars and policy makers to determine the waste subcategories to which SMEs contribute most, formulate targeted interventions and research or evaluate environmental outcomes. © 2014 © 2014 Environment Institute of Australia and New Zealand Inc.

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K’gari-Fraser Island, the world's largest barrier sand island, is at the crossroads of World Heritage status, due to destructive environmental use in concert with climate change. Will K’gari-Fraser Island exemplify innovative, adaptive management or become just another degraded recreational facility? We synthesize the likely impact of human pressures and predicted consequences on the values of this island. World-renown natural beauty and ongoing biological and geological processes in coastal, wetland, heathland and rainforest environments, all contribute to its World Heritage status. The impact of hundreds of thousands of annual visitors is increasing on the island's biodiversity, cultural connections, ecological functions and environmental values. Maintaining World Heritage values will necessitate the re-framing of values to integrate socioeconomic factors in management and reduce extractive forms of tourism. Environmentally sound, systematic conservation planning that achieves social equity is urgently needed to rectify historical mistakes and update current management practices. Characterizing and sustaining biological refugia will be important to retain biodiversity in areas that are less visited. The development of a coherent approach to interpretation concerning history, access and values is required to encourage a more sympathetic use of this World Heritage environment. Alternatively, ongoing attrition of the islands values by increased levels of destructive use is inevitable.

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This paper tests the convergence in per-capita carbon dioxide emissions for a collection of developed and developing countries using data spanning the period 1870-2002. For this purpose, three recently developed panel unit root tests that permit for dependence among the individual countries are employed. The results lend strong support in favor of convergence for the panel as a whole. Estimates of the speed of this convergence is also provided. © 2007 Springer Science+Business Media B.V.

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Insight into tourist travel behaviors is crucial for managers engaged in strategic planning and decision making to create a sustainable tourism industry. However, they continue to face significant challenges in fully capturing and understanding the behavior of international tourists. The challenges are primarily due to the inefficient data collection approaches currently in use. In this paper, we present a new approach to this task by exploiting the socially generated and user-contributed geotagged photos now made publicly available on the Internet. Our case study focuses on Hong Kong inbound tourism using 29,443 photos collected from 2100 tourists. We demonstrate how a dataset constructed from such geotagged photos can help address such challenges as well as provide useful practical implications for destination development, transportation planning, and impact management. This study has the potential to benefit tourism researchers worldwide from better understanding travel behavior and developing sustainable tourism industries.