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排序方式: 共有62条查询结果,搜索用时 15 毫秒
41.
Terence R Lee 《Natural resources forum》1995,19(4):275-283
Financing investments in water supply and sanitation has been a perennial problem in all countries of Latin America and the Caribbean. The contribution to capital funding derived from the income of operating companies has been very small, a direct consequence of unrealistically low tariffs. The situation has worsened with the increasing need to provide sewage treatment to reduce the gross pollution of most water bodies in the vicinity of large cities. This paper, on the basis of recent studies conducted in EC LAC, explores the practicability of the self-financing of water supply and sanitation services, including sewage treatment, through the income derived from tariffs. If this is to be achieved then it is important that the entire population pays for services, an issue of some importance given the unequal distribution of income in most cities of the region. The conclusion reached is that on the basis of the available information on costs, together with the experience of some countries, financing through tariffs is feasible, particularly if subsidies are provided to the poorest households. Tariff based financing is probably the only means of achieving universal coverage by the year 2000 as well as sewage treatment, the rehabilitation of existing systems, maintenance and the necessary institutional development . 相似文献
42.
The fungicide diclobutrazol (2RS,3RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol was irradiated by ultra-violet light in methanol solution using (1) borosilicate glass apparatus and (2) quartz apparatus. The major differences observed were that photodegradation occurred more rapidly in (2) than (1) and more breakdown products were found in the former. Using g.c.-m.s. ten compounds were detected in (1) of which five were identified. In (2) twelve of the eighteen compounds observed were identified and the major component was 1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-one. The compounds reported were formed by oxidation, loss of chlorine or by cyclisation. This previously unreported cyclisation gave the s-triazolo-(5,1a)isoquinoline ring system. 相似文献
43.
The spatial dispersion of individuals across multiple spatial scales can significantly influence biodiversity patterns. Here we characterize the dispersion of corals in reef assemblages distributed across a 10000-km longitudinal biodiversity gradient from Indonesia to the Society Islands, using a multiscale sampling design. Our results indicate that most coral species were aggregated among 10-m transect samples across this vast distance. Using observed and randomized species sampling curves, we show that aggregation reduced the number of species per transect, site, and island sample on average by 13-27%. Across site, island, and regional scales, aggregation also reduced the area under species sampling curves by an average of 2.7-6.5%. The level of aggregation was relatively constant across spatial scales within regions and did not vary among habitats. However, there was significant variation among regions using transect samples across individual sites. Specifically, aggregation reduced the species richness per transect and the area under species sampling curves nearly twice as much in the Indonesian biodiversity hotspot than in the Society Islands. As a significant component of the spatial structure of coral assemblages, aggregation should be integrated into our understanding of coral community dynamics and the development of conservation strategies designed to protect these communities. 相似文献
44.
Adaptive management of the Great Barrier Reef and the Grand Canyon world heritage areas 总被引:2,自引:0,他引:2
Hughes TP Gunderson LH Folke C Baird AH Bellwood D Berkes F Crona B Helfgott A Leslie H Norberg J Nyström M Olsson P Osterblom H Scheffer M Schuttenberg H Steneck RS Tengö M Troell M Walker B Wilson J Worm B 《Ambio》2007,36(7):586-592
Conventional perceptions of the interactions between people and their environment are rapidly transforming. Old paradigms that view humans as separate from nature, natural resources as inexhaustible or endlessly substitutable, and the world as stable, predictable, and in balance are no longer tenable. New conceptual frameworks are rapidly emerging based on an adaptive approach that focuses on learning and flexible management in a dynamic social-ecological landscape. Using two iconic World Heritage Areas as case studies (the Great Barrier Reef and the Grand Canyon) we outline how an improved integration of the scientific and social aspects of natural resource management can guide the evolution of multiscale systems of governance that confront and cope with uncertainty, risk, and change in an increasingly human-dominated world. 相似文献
45.
Effects of Experimental Otter Trawling on Surficial Sediment Properties of a Sandy-Bottom Ecosystem on the Grand Banks of Newfoundland 总被引:3,自引:0,他引:3
46.
Terence Price 《Safety Science》2010,48(10):1498-1515
PurposeThe purpose of this research is to assess whether the practice of retro-fitting passive magnetic shielding to Magnetic Resonance Imaging (MRI) suites is effective in retaining the 0.5 mT footprint of the static magnetic field to within its designed position.MethodologyThe research methodology involved identification of an MRI installation where passive magnetic shielding was to be fitted to an installation already in operational use. Site based physical measurements of the magnetic flux density of the static field were then taken both ante and post installation of the shielding, so as to be able to determine its effectiveness.FindingsThe results identified areas in the retrofitted magnetic shielding where, as a result of its design, hot spots in excess of 0.5 mT occurred.Practical implicationsThis research highlights design, construction and safety issues that the designer could, if he had this prior knowledge, have eliminated at source.ValueAt the planning stage of a new MRI suite, designers could use the information contained in this research as part of their design risk management process. This research serves to demonstrate the importance of eliminating any possible future need to install retrofitted passive magnetic shielding to an original MRI suite design. It also shows the need for designers to identify the location of any hot spots in the shielding installation where the magnetic flux density may exceed 0.5 mT and become a potential hazard to those individuals fitted with heart pacemakers or other electronic body implants. 相似文献
47.
Centner TJ 《Environmental management》2006,37(6):745-752
As point sources of pollution in the United States, concentrated animal feeding operations (CAFOs) are subject to the National
Pollution Discharge Elimination System permitting system requirements. Changes to federal regulations in 2003 and a 2005 court
decision have increased the governmental oversight of CAFOs. Manure application to fields from “large CAFOs” that results
in unpermitted discharges can be regulated under the Clean Water Act. The U.S. Environmental Protection Agency’s interpretation
of agricultural stormwater discharges was approved so that unpermitted discharges may arise if an owner or operator of a CAFO
fails to apply manure correctly. Owners and operators do not, however, have a duty to secure governmental permits in the absence
of a discharge. Turning to the federal provisions regarding nutrient management plans, a court found that they were deficient.
Moreover, the federal government needs to reconsider requirements that would reduce pathogens from entering surface waters.
Although these developments should assist in reducing the impairment of U.S. waters, concern still exists. Greater oversight
of nutrient management plans and enhanced enforcement efforts offer opportunities to provide greater assurance that CAFO owners
and operators will not allow a discharge of pollutants to enter surface waters. 相似文献
48.
Over two years after the original creation of a sand excavation pit 8 km off the Louisiana coast, benthic macrofauna communities
and sedimentary characteristics are still effected. Macrofaunal communities inside the pit had lower abundance, biomass, and
diversity than communities outside the pit. This difference, however, was only significant with some of the stations outside
the pit. Results from multi-dimensional scaling and cluster analysis showed that macrofaunal communities were less than 32%
similar inside the pit to communities outside the pit. The polychaete Mediomastus ambiseta was the most abundant species outside the excavation pit, but the species was only counted once inside the pit. The most
dominant species, which made up over 90% of organisms inside the pit, was the pioneer polychaete Paraprionospio pinnata. Only three species were found at each station inside the pit as opposed to 9–27 species at stations outside the pit. All
species inside the pit were also found outside the pit; thus, change was due to a loss of species rather than replacement
by different species. Sediment inside the pit contained more silt and clay; however, no difference in water quality was detected
compared with outside the pit. Hurricanes Katrina and Rita passed near the dredge pit in 2005 and could have effected sediment
transport in the region. Because the macrofaunal community inside the pit has not recovered within 38 months, it is likely
that it will require more time before it resembles the surrounding conditions. 相似文献
49.
Assessing community vulnerability to floods and hurricanes along the Gulf Coast of the United States
Hurricanes and flooding have affected millions of people and generated massive economic losses over the past several decades. Geographic information system (GIS) methods are employed in this paper to analyse coastal communities' vulnerability to these two hazards along the Gulf Coast of the United States. Specifically, two types of quantitative indicators are developed: (i) exposure to hurricanes and flooding, based on information from multiple sources; and a social vulnerability index, constructed using census data. These indices are combined to depict the spatial patterns of overall community vulnerability to hurricanes and flooding along the US Gulf Coast. The results of this study can potentially inform disaster management agencies, county governments, and municipalities in areas at heightened risk. Furthermore, the demonstration of the geographic distribution of community vulnerability can assist decision-makers in prioritising to-do items and designing policies and plans for the more effective allocation of resources. The paper ends by discussing the study's limitations and its practical implications. 相似文献
50.
Overexploitation is the second biggest driver of global plant extinction. Meanwhile, useful plant species are vital to livelihoods across the world, with global conservation efforts increasingly applying the concept of ‘conservation-through-use.’ However, successfully balancing conservation and biodiversity use remains challenging. We reviewed literature on the sustainability of wild-collected plant use across the countries of Colombia, Ecuador, Peru, and Bolivia—a region of global importance for its biological and cultural richness. After applying defined search terms and a two-stage screening process, 68 articles were reviewed. The numbers which reported sustainable, unsustainable, or context-dependent outcomes were relatively even, but national differences emerged. Through narrative synthesis, we identified five key, reoccurring themes: plant biology; land tenure; knowledge, resource, and capacity; economics and market pressures; and institutional structures, policy, and legislation. Our results show the need for flexible, context-specific approaches and the importance of collaboration, with bottom-up management and conservation methods involving local communities and traditional ecological knowledge often proving most effective. Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01529-7. 相似文献