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211.
Twenty-one samples were collected during the dry season (26 January–28 February 2004) at 12 sites in and around Addis Ababa, Ethiopia and analyzed for particulate matter with aerodynamic diameter <10 μm (PM10) mass and composition. Teflon-membrane filters were analyzed for PM10 mass and concentrations of 40 elements. Quartz-fiber filters were analyzed for chloride, sulfate, nitrate, and ammonium ions as well as elemental carbon (EC) and organic carbon (OC) content. Measured 24-h PM10 mass concentrations were <100 and 40 μg m−3 at urban and suburban sites, respectively. PM10 lead concentrations were <0.1 μg m−3 for all samples collected, an important finding because the government of Ethiopia had stopped the distribution of leaded gasoline a few months prior to this study. Mass concentrations reconstructed from chemical composition indicated that 34–66% of the PM10 mass was due to geologically derived material, probably owing to the widespread presence of unpaved roads and road shoulders. At urban sites, EC and OC compounds contributed between 31% and 60% of the measured PM10 while at suburban sites carbon compounds contributed between 24% and 26%. Secondary sulfate aerosols were responsible for <10% of the reconstructed mass in urban areas but as much as 15% in suburban sites, where PM10 mass concentrations were lower. Non-volatile particulate nitrate, a lower limit for atmospheric nitrate, constituted <5% and 7% of PM10 at the urban and suburban sites, respectively. At seven of the 12 sites, real-time PM10 mass, real-time carbon monoxide (CO), and instantaneous ozone (O3) concentrations were measured with portable nephelometers, electrochemical analyzers, and indicator test sticks, respectively. Both PM10 and CO concentrations exhibited daily maxima around 7:00 and secondary peaks in the late afternoon and evening, suggesting that those pollutants were emitted during periods associated with motor-vehicle traffic, food preparation, and heating of homes. The morning concentration maxima were likely accentuated by stable atmospheric conditions associated with overnight surface temperature inversions. Ozone concentrations were measured near mid-day on filter sample collection days and were in all cases <45 parts per billion.  相似文献   
212.
Among the many larvicides tested for the control of s.l. larvae, the vector of human onchocerciasis in West Africa, pyraclofos proved to be 100% effective at 100 μg × L−1 for 10 min in river, with a carry of 20 km at 100 m3 × sec−1. Tests were then performed both in laboratory and field conditions to evaluate its toxicity on the non-target aquatic fauna. In experimental short-term gutter tests, the detachment of the total benthic insects was 35% at 100 μg × L−1 for 10 min against 17% for temephos at the same dose and 59% for chlorphoxim at 50μg × L−1 for 10 min. , and were the most affected organisms. The treatment of a river resulted in a considerable detachment of the same taxonomic groups, plus Orthocladiinae. On the other hand, investigations conducted in tanks showed that the 24-hr LC50 for is 150 μg × L−1 and that for 170 μg × L−1, values which are not very different from the operational dose of the larvicide (100 μg × L−1 for 10 min.). Nevertheless, in a river, no fish mortality was recorded. Based on fish LC50 and drift of benthic insects, pyraclofos at 100 μg × L−1 was judged to be less toxic to aquatic fauna in the short term than permethrin and carbosulfan.  相似文献   
213.
After almost two decades of decline, Ghana's mineral sector has rebounded significantly and is currently the main foreign exchange earner. Gold mining is the principal activity within the sector and accounted for 41 percent of total export earnings in 1996. This paper presents an overview of Ghana's mineral industry and covers mineral resources, production and reserves; mining investments; the role of mining in the economy; and the structure of the industry. An overview of the national mineral policy is also presented to depict the current regulatory and fiscal environment in which the industry operates. The spectacular reversal in mineral sector performance can be attributed to the adoption of World Bank recommendations in a new national mineral policy, the 1986 Minerals and Mining Law, aimed at revitalizing the sector.  相似文献   
214.
A community-based Clean Development Mechanism (CDM) project – asolar water heating project in a low-income community in South Africa –is analysed to illustrate the methodological and policy challenges that faceimplementation of the Kyoto Protocol to the United Nations FrameworkConvention on Climate Change. We evaluate four baseline options, andthree potential CDM interventions. The emissions reductions range from –670 to +5 929 Mg CO2 per year, with all option but oneshowing positive emission reductions. Using metered solar water heatingwith liquefied petroleum gas back-up as the CDM intervention, and electricstorage geysers as the baseline, the annual emissions reductions are 5686 Mg CO2. The cost-effectiveness from the national perspective,which is the incremental life cycle costs divided by the lifetime emissionsreductions, is –$18 per Mg CO2 From the perspective of theCDM investor, however, the cost-effectiveness is $5.2 per mgCO2, assuming that the investor receives all of the carbon credits forproviding the incremental capital investment. From our analysis, weconclude that using the current technology (kerosene stoves) as a baselineis probably not appropriate because it does not reflect likely future trendsand also penalises the community for their poverty and current lack ofinfrastructure. We also highlight the importance of credit sharing, and howit affects the cost-effectiveness of the project from the CDM investor'sperspective. The lessons from this analysis are important for the currentinternational policy debate on how to preferentially treat small-scale CDMprojects.  相似文献   
215.
Determining adequate baselinesis a major methodological problem whenquantifying emissions reductions achievedwith the project-based flexibilitymechanisms. Possible methodologies forbaseline setting may be classified intomulti-project and project-specificapproaches. While multi-project approachesprovide baselines for a series of typicalprojects within a certain geographicregion, a sector, or a load range,project-specific (orproject-by-project/single-project)approaches only cover one specific project.Project-by-project baseline approaches havebeen tested extensively within theActivities Implemented Jointly (AIJ) pilotphase; multi-project methodologies, on theother hand, have only rarely been applieddue to the (perceived) political andeconomic complexity of the issue, whichmakes the process of introducingstandardised baselines a very sensitivetask. In particular, there is a lack ofmulti-project baseline approaches takingadvantage of optimising computer modelswithin the electricity sector, even thoughother fields of research have made use ofsuch models quite successfully in the past.Experiences made in the PROBASE projectwith the calculation of standardised,aggregated multi-project baselines forJI/CDM projects using optimising energysystem models are illustrated in this paperfor South Africa, Russia, and Indonesia.Increased transparency and credibility ofstandardised approaches along withpotentially lower transaction costs areidentified as the main arguments for theiruse and further development. In addition,the text gives recommendations wheremodel-based baseline standardisation canpreferentially be applied.  相似文献   
216.
Abstract:  The ability to predict which areas of conservation importance are most vulnerable to transformation and to rank the relative damage that transforming land uses could cause to biodiversity are important components of an effective and realistic conservation planning process. We used the South African grassland biome as a case study to illustrate the assessment of vulnerability to land-use transformation through the construction of a "threat map." We identified the dominant transforming land uses and created suitability models based on area appropriateness for each. Land uses were scored according to their expected relative impacts on biodiversity, with a framework that included compositional, structural, and functional components. This information, once combined, resulted in a map that highlighted the areas most vulnerable to transformation in terms of the likelihood of their transformation and the impact on their biodiversity. We propose that such an analysis of the threat of transformation, in combination with species-representation approaches, will aid the integration of conservation planning theory and decision making. This approach can be applied at any scale and in any region with a robustness and accuracy dependent on data quality, resultant suitability models, and comprehension of how land uses affect an area's biodiversity.  相似文献   
217.
The Limpopo River Basin is underlain by an alluvial aquifer along the main river stem and fractured water-bearing units in tributary catchments. Notwithstanding that development priorities in parts of the basin in South Africa have historically preferred surface water sources for irrigation and domestic supply, water resources auditing suggests that groundwater presents the only viable alternative source of cost-effective supply to meet future requirements. However, while aquifer yields are favourable in places, averaging 16.7 l/s for main-stem alluvium, groundwater is already extensively used. Between 1995 and 2002, total groundwater use in the area rose by almost 40%, increasing from 98 to 136 million m3 per year. In all catchments, groundwater use grew by varying proportions, reaching a rather high 200% in the Mogalakwena catchment. In the particular case of commercial irrigation, over-exploitation of groundwater has been recorded in a number of places, especially in the northwest where drawdowns of more than 50 m have resulted from decades of intense agricultural water use. Although groundwater use for mining is still low at 4% of total usage in the study area, the region is currently witnessing a surge in mining operations, and a significant growth in water requirements is envisaged for mining development. Further, domestic water supply to the predominantly rural dwellers in the area is relatively low, even in terms of meeting the basic need of 25 l/day per person, underscoring the fact that groundwater will remain a critical source of community drinking water in the foreseeable future. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
218.
Abstract: Networks of sites of high importance for conservation of biological diversity are a cornerstone of current conservation strategies but are fixed in space and time. As climate change progresses, substantial shifts in species’ ranges may transform the ecological community that can be supported at a given site. Thus, some species in an existing network may not be protected in the future or may be protected only if they can move to sites that in future provide suitable conditions. We developed an approach to determine appropriate climate‐change adaptation strategies for individual sites within a network that was based on projections of future changes in the relative proportions of emigrants (species for which a site becomes climatically unsuitable), colonists (species for which a site becomes climatically suitable), and persistent species (species able to remain within a site despite the climatic change). Our approach also identifies key regions where additions to a network could enhance its future effectiveness. Using the sub‐Saharan African Important Bird Area (IBA) network as a case study, we found that appropriate conservation strategies for individual sites varied widely across sub‐Saharan Africa, and key regions where new sites could help increase network robustness varied in space and time. Although these results highlight the potential difficulties within any planning framework that seeks to address climate‐change adaptation needs, they demonstrate that such planning frameworks are necessary, if current conservation strategies are to be adapted effectively, and feasible, if applied judiciously.  相似文献   
219.
Abstract: We combined ethnographic investigations with repeated ecological transect surveys in the Dzanga‐Sangha Dense Forest Reserve (RDS), Central African Republic, to elucidate consequences of intensifying mixed use of forests. We devised a framework for transvaluation of wildlife species, which means the valuing of species on the basis of their ecological, economic, and symbolic roles in human lives. We measured responses to hunting, tourism, and conservation of two transvalued species in RDS: elephants (Loxodonta cyclotis) and gorillas (Gorilla gorilla). Our methods included collecting data on encounter rates and habitat use on line transects. We recorded cross‐cultural variation in ideas about and interactions with these species during participant observation of hunting and tourism encounters and ethnographic interviews with hunters, conservation staff, researchers, and tourists. Ecologically, gorillas used human‐modified landscapes successfully, and elephants were more vulnerable than gorillas to hunting. Economically, tourism and encounters with elephants and gorillas generated revenues and other benefits for local participants. Symbolically, transvaluation of species seemed to undergird competing institutions of forest management that could prove unsustainable. Nevertheless, transvaluation may also offer alternatives to existing social hierarchies, thereby integrating local and transnational support for conservation measures. The study of transvaluation requires attention to transnational flows of ideas and resources because they influence transspecies interactions. Cross‐disciplinary in nature, transvalution of species addresses the political and economic challenges to conservation because it recognizes the varied human communities that shape the survival of wildlife in a given site. Transvaluation of species could foster more socially inclusive management and monitoring approaches attuned to competing economic demands, specific species behaviors, and human practices at local scales.  相似文献   
220.
Abstract:  Biodiversity conservation outcomes are closely related to the rules and institutions governing resource use. Creating local incentives for conservation through more secure resource tenure is central to conservation outcomes on private and communal lands, where the preponderance of biodiversity occurs. Conservation efforts in sub-Saharan Africa are therefore centrally concerned with governance dynamics and institutional reform processes, such as the decentralization of property rights, and how best to achieve such reforms. Traditional mechanisms for financing conservation efforts in Africa rely heavily on funds channeled through multilateral and bilateral aid agencies. The history of development aid highlights a range of constraints these aid agencies face in terms of working toward more effective resource governance arrangements and promoting reforms. Government aid agencies possess incentives for promoting large-scale and short-term projects that maximize expenditure volumes and tend to define issues in technical rather than political terms. The history of development aid suggests that these and other characteristics of aid agencies impedes their ability to influence governance reform processes and that aid funding may discourage the adoption of reforms. Greater emphasis in African conservation financing needs to be placed on flexible, small-scale investments aligned to local interests and constituencies that prioritize innovation, learning, and experimentation. Additionally, more research is required that explores the linkages between conservation funding, donor decision-making processes, and governance reforms.  相似文献   
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