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961.
We draw attention to a number of key factors in the evaluation of major projects, such as smelters, which are highly capital- and energy-intensive as well as export-orientated. The practice of justifying such projects by upvaluing foreign exchange is considered, as is the cost of distortion. Export efficiency is introduced as the key criterion: the efficiency of some recent smelter proposals in Oceania was between 36 and 50 cents in the dollar. A correct power price is essential: hydropower (in contrast with hydroenergy) should be priced as a depletable resource.  相似文献   
962.
This paper uses a model of the optimum buffer stock as a ‘filter rule’ together with a financial model that can be used to assess the efficiency of international commodity markets. The approach is simpler to apply than many other methods which have hitherto been used and yields an economy in theoretical and computational effort. The arguments are applied as a case study to the international copper market. The main conclusion is that private storage is not under-provided for and that a public buffer stock agency would be unlikely to be self-financing.  相似文献   
963.
Between 1999 and 2003, the Oak Ridge National Laboratory (ORNL) made a preliminary effort to integrate an analysis of mitigation and adaptation to climate change impact vulnerabilities in two ways: top-down and bottom-up. This paper briefly describes these early experiments and summarizes their findings, both about climate change vulnerability reduction and about the challenges of integrated analysis, expanding upon results previously reported [Wilbanks et al. (Environment 45/5:28–38, 2003); ORNL (Integrated analysis of mitigation and adaptation as responses to concerns about impacts of global climate change, ORNL Working paper 2003); ORNL and CUSAT 2003; Wilbanks 2005]. The U.S Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged  相似文献   
964.
Radium-226 present in rock phosphate is carried to CaCO3, the main process waste sludge of the fertilizer industry. Disposal of the sludge in the environment enhances the radiation background in the area. Two states of adherence of radium in the sludge have been identified, one loosely bound and the other chemically exchanged. The loosely bound fraction accounts for nearly 40% of the total activity, as demonstrated by leaching studies. Laboratory experiments show that activity leach-out by infiltration of water through the sludge is low. Lateral seepage is found to cause extensive areal contamination due to dispersal of suspended solids in the vicinity of the disposal area. The rate of emanation of radon from the sludge is found to be high, a factor of 10 over the normal background emanation rate. The radiation field in the waste disposal area also shows enhancement, with levels 4–6 times higher than natural background.  相似文献   
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968.
The nutritional status of a phytoplankton community was investigated in a coastal jet-front located in the Gulf of St. Lawrence, Canada, in 1987. During the sampling period, the frontal community was mainly composed of the diatomsChaetoceros debilis, Skeletonema costatum, Thalassiosira gravida andC. pelagicus. As previously reported for the St. Lawrence, some frontal stations were depleted both in nitrate and silicate. At stations impoverished in nitrate, internal nitrate pool concentrations were low or undetectable, suggesting that cells had not, recently, been exposed to a nitrate flux which exceeded the nitrate assimilation rate. At these impoverished stations, however, ambient and intracellular concentrations of ammonium and urea were high, suggesting that the community was not nitrogen-deficient. The comparison between the ambient silicate concentrations and the silicate requirement (K s ) of the dominant diatoms suggests thatC. debilis andS. costatum were Si-deficient. This is further supported by the low silicate uptake rates and intracellular concentrations measured at the silicate impoverished stations. The silicate deficiency also resulted in a decrease in the seston and phytoplankton N:C ratios.Please address all correspondence and requests for reprints to Dr Levasseur at his new address: Maurice Lamontagne Institute, 850 Route de la Mer, Mont-Joli, Québec G5H 3Z4, Canada  相似文献   
969.
The scope of mitigation options in tropical agriculture is discussed for three different activities (a) agroforestry, (b) rice-based production systems and (c) pasture/animal husbandry. The prevention of deforestation - and the re-forestation of degraded land - could become a key elements to national climate protection programs of some developing countries. Agroforestry may offer economically viable windows of opportunity for sustainable use of tropical forests whereas additional funds (e.g. through “Clean Development Mechanism”) will be required to make re-forestation programs profitable. Alternative management practices in rice-based systems may offer win-win options to reduce emissions and - at the same time - to obtain another improvement in the production system, namely through optimized timing of nitrogen fertilizer, temporary drainage in irrigated rice fields and integrated residue management. Introducing pasture in degraded land can sequester substantial amounts of carbon (similar to re-forestation). Future research has to include participation of stakeholders from all conceivable levels, i.e. farmers' cooperatives, non-governmental organizations, national agricultural research centers and extension services, to devise simple and financially interesting incentives for reducing emissions. The feasibility of environmentally friendly production techniques has to be disseminated to the public through ‘success stories’ (documented in public media) and demonstration farms.  相似文献   
970.
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