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991.
Human society consumes resources that it is not able to reproduce. Human activities are still based on “open cycles,” starting from a condition of natural environmental balance and reaching an environmental imbalance. The challenging scope of scientific and technological research towards sustainability appears clear if it is based on this analysis: to find development systems based on “closed cycles” of resources. The challenging objective of realizing closed cycles leads to a definition of sustainability that indicates the path to sustainable development, as well as stating the general principle. It also provides a key to the qualitative measurement of sustainability. This means that the sustainability level of a system can be measured by measuring its capacity to avoid the consumption of resources. Zero consumption is a necessary condition for sustainability, and brings about as a side effect the highly desired “zero-waste” result. Materials entering the proposed endless scheme pass through the process of usefulness without losing their capacity to feed the system again after being used. Thus, the concept of “consumption” itself is replaced by one of “use” when resources are inserted into closed loops capable of feeding human development. The application of the closed cycle sustainability criterion particularly displays its feasibility, and a theoretical guiding role, in the energy sector. Energy vectors such as hydrogen and electricity enable the closure of the energy resources loop by effectively approaching the objective of “zero consumption” (and the side result of “zero waste”) through already demonstrated technological solutions.  相似文献   
992.
993.
The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO2. The tensile stress obtained were 110, 104, and 95 N/mm2, while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities.  相似文献   
994.
Humans’ superiority over all other organisms on earth rests on five main foundations: command of fire requiring fuel; controlled production of food and other biotic substances; utilization of metals and other non-living materials for construction and appliances; technically determined, urban-oriented living standard; economically and culturally regulated societal organization. The young discipline of ecology has revealed that the progress of civilization and technology attained, and being further pursued by humankind, and generally taken for granted and permanent, is leading into ecological traps. This metaphor circumscribes ecological situations where finite resources are being exhausted or rendered non-utilizable without a realistic prospect of restitution. Energy, food and land are the principal, closely interrelated traps; but the absolutely decisive resource in question is land whose increasing scarcity is totally underrated. Land is needed for fulfilling growing food demands, for producing renewable energy in the post-fossil and post-nuclear era, for maintaining other ecosystem services, for urban-industrial uses, transport, material extraction, refuse deposition, but also for leisure, recreation, and nature conservation. All these needs compete for land, food and non-food biomass production moreover for good soils that are scarcer than ever. We are preoccupied with fighting climate change and loss of biodiversity; but these are minor problems we could adapt to, albeit painfully, and their solution will fail if we are caught in the interrelated traps of energy, food, and land scarcity. Land and soils, finite and irreproducible resources, are the key issues we have to devote our work to, based on careful ecological information, planning and design for proper uses and purposes. The article concludes with a short reflection on economy and competition as general driving forces, and on the role and reputation of today’s ecology. Updated version of the keynote lecture presented at the EcoSummit 2007 in Beijing, China, May 24. The article is gratefully dedicated to the memory of my late colleague and friend Frank B. Golley.  相似文献   
995.
This study estimates efficient nitrogen load reductions to the Stockholm archipelago, a Swedish coastal zone in the Baltic Sea, and compares these with politically determined and implemented nitrogen abatement programs. The region is relatively well equipped with necessary data, and a simple programming model is constructed. The results show a large divergence in efficient nitrogen reductions, mainly due to the divergences in benefit estimates from water quality improvements in the archipelago. However, the results need to be interpreted with caution due to all uncertainties related to predicting net values from changes in nitrogen load to a coastal zone. In spite of this, it is still of policy relevance to infer results which show that the politically determined target coincides with an efficient nitrogen reduction at relatively low benefit estimate, but that actual net benefits could be increased from a reallocation of abatement measures towards more low cost measures.  相似文献   
996.
997.
998.
A global analysis shows that considerable forces contribute nowadays to the perpetuation of the so-called “developed” model of consumption, and its extension to growing parts of the world, despite reiterated calls for “modification of production and consumption patterns”. Environmental product regulation can be situated in this general perspective. This paper returns to the framing of policies devoted to ecologically sustainable consumption, taking the example of the Integrated product policy at the European level. How are the objectives of such policies defined? What instruments are privileged? Comparing theoretical approaches with policy design, we focus on the role devoted to consumers in these contexts. Bringing in literature evidence, survey results and findings from an original study, we argue that appropriate knowledge of the diversity of consumers’ attitudes and about the limitations of their possible actions is not properly taken into account in product policies, notably when information and voluntary tools are dominant. From this point of view, environmental product regulations are well justified, but they should, as all policy instruments implicating consumers, take careful notice of their situation.  相似文献   
999.
We compared measures of ecosystem state across six adjacent land-tenure groups in the intact tropical savanna landscapes of northern Australia. Tenure groups include two managed by Aboriginal owners, two national parks, a cluster of pastoral leases, and a military training area. This information is of relevance to the debate about the role of indigenous lands in the Australian conservation estate. The timing and frequency of fire was determined by satellite imagery; the biomass and composition of the herb-layer and the abundance of large feral herbivores by field surveys; and weediness by analysis of a Herbarium database. European tenures varied greatly in fire frequencies but were consistently burnt earlier in the dry season than the two Aboriginal tenures, the latter having intermediate fire frequencies. Weeds were more frequent in the European tenures, whilst feral animals were most abundant in the Aboriginal tenures. This variation strongly implies a signature of current management and/or recent environmental history. We identify indices suitable for monitoring of management outcomes in an extensive and sparsely populated landscape. Aboriginal land offers a unique opportunity for the conservation of biodiversity through the maintenance of traditional fire regimes. However, without financial support, traditional practices may prove unsustainable both economically and because exotic weeds and feral animals will alter fire regimes. An additional return on investment in Aboriginal land management is likely to be improved livelihoods and health outcomes for these disadvantaged communities.  相似文献   
1000.
Investigating local people’s environmental perceptions can produce useful information that could be incorporated into decision making processes that help resolve environmental problems. Although China is undergoing severe desertification, the perceptions of the local people toward their degraded environment and the related issues have so far not been actively solicited. This article, which is a supplement to Lee and Zhang’s (2004, 2005) studies, seeks to further investigate the lay public’s general environmental attitudes, perceptions of desertification, interpretations of land-degrading activities, and particularly their interrelations in severely desertified areas. Minqin County in Gansu Province, northern China, was chosen to be the study area. Data was collected via a questionnaire survey (n = 1138) administered in December 2002. Major findings were: (1) Most respondents had only weak altruistic environmental attitudes, with educational level to be a significant determinant. (2) Respondents’ perceptions of desertification and interpretations of land-degrading activities were contingent on personal attributes, general environmental attitudes, and other conceptions related to desertification. It is recommended that the interrelations between the various aspects of the public’s environmental perceptions should be thoroughly examined to facilitate their participation in environmental management.  相似文献   
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