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排序方式: 共有85条查询结果,搜索用时 62 毫秒
41.
中国城市空气污染呈区域化和恶化趋势,亟需突破当前空气质量管理模式的制约.从管理体制和管理内容两方面对美国空气质量政府管理模式的先进经验进行了分析,并与北京市空气质量管理模式进行了初步比较,得出中国空气质量政府管理模式缺乏外部性的考虑;政府部门内部机构按照行政管理过程划分,导致管理成本偏高;决策机制与执行机制未分离,影响行政效率;对污染源的管理不专业;缺乏信息公开和公众参与等问题.建议成立空气质量管理分局,对固定源实行排污许可证管理,对移动源实行统一综合管理,细化面源的管理,建立空气质量管理信息公开平台. 相似文献
42.
Danielle Tessaro 《国际发展与全球生态学杂志》2013,20(5):471-479
In South Africa, extreme rural poverty often geographically overlaps with areas of high and important biodiversity. Attempts to bring about land-based poverty reduction projects in such areas tends to trigger tensions among stakeholders purporting to be concerned about local people’s welfare, as well as the environment. Using discursive document analysis and semi-structured interviews, the paper discusses a case study of the Wild Coast, an area celebrated for its high biodiversity and ‘beauty’, which reveals that a tension among environmental non-government organisations, government agencies and the private sector, on the best development option, exacerbates the threats to local livelihood options and biodiversity conservation. 相似文献
43.
With the implementation of reform and opening-up, the overall economy of China has made brilliant achievements; meanwhile, however, the economic disparity has been enlarging among some regions, and between the city and the countryside. The existence and evolution of this kind of economic disparity is concerned with social stability, sustainable development and the construction of harmonious society, which has gradually become the hotspot in social economic development. The West Coast of the Strait (WCS) located in southeast littoral areas is adjacent to the Pearl and Yangtze River Delta in the south and north and faces Taiwan Province in the east. The stability and development of this region has vital political and economic meaning in the social economic development of our country. It has important theoretical meaning and practical value to research the form, characteristics and evolution of regional economic disparity in the WCS. Based on insightful analysis on existing study results on the WCS, the paper defines the connotation and extension. By a series of absolute and comparative relative evaluation indexes and taking the WCS since 1992 as the study object, the paper makes analysis on different scales including three regions, four regions, 20 cities and 152 counties, quantitatively evaluates the level, characteristics and evolution of the regional economic disparity and compares the regional economic disparity on different scales. The main conclusions are as follows: the variation trend of the absolute disparity of the whole region is obvious and stable, which has presented an inflating trend; the comparative variation trend on a large scale has waved, The comparative disparity of the three regions increased annually from 1992 to around 2000, which had a decreasing trend from around 2000 to 2005; the comparative variation trend on a small scale was not stable, which showed an annual increase of four regions, 20 cities and 152 counties from 1992 to around 2003 and a decrease from around 2003 to 2005; the 相似文献
44.
Pollution due to persistent pesticides is not a regional but a global problem. Organochlorine pesticides are persistent chemicals, stored and accumulated in the tissues of a wide variety of invertebrates and vertebrates including marine species. In the present study the organochlorine residues HCHs, DDTs and PCBs were measured in different trophic groups of birds (scavengers, inland piscivores, coastal piscivores, insectivores, granivores and omnivores) collected from Tamil Nadu Coast, India. The residue accumulation as a function of sex did not depict distinct variation. However, females had lower residue levels than males in terms of their mean weight and feeding habits. A continuous monitoring programme is recommended to establish the studied organisms as indicator species. 相似文献
45.
本文是在《森林野外火火区上的浮力流动及其与一些环境气象因素关系的数值模拟》的基础上进行的。上文求解了无降雨时的气体流动情况,本文在此基础上加入了降雨模型,形成了能体现降雨与气流相互作用的程序。本文算出了不同大小的雨滴的下落过程,并能估计出多大的雨滴可落入燃烧区。 相似文献
46.
东南沿海经济发达地区发展趋势与问题 总被引:1,自引:0,他引:1
东南沿海经济发达地区是我国改革开放和现代化建设的先行地区。在持续十几、二十几年的经济快速发展过程中,该地区产业结构进一步优化,经济实力迅速提高,已经基本形成城乡一体化、城市连绵化的格局,为我国综合实力的增强做出了巨大贡献。随着经济全球化、一体化的发展,该地区将继续担负我国国际竞争力提升和国内经济发展示范的重要作用。然而,产业自主创新能力不强、能源缺口较大、耕地流失严重、粮食安全问题、产业发展空间受限、生态环境恶化等已成为该地区可持续发展的瓶颈。在分析该地区发展状况与问题的基础上,从协调经济、环境与社会的角度出发,以科学发展观为指导,对东南沿海地区经济可持续发展提出了建议。 相似文献
47.
The local resource enhancement (LRE) model predicts that in cooperatively breeding species, sex ratios will be biased in favor
of the more helpful sex. In this study, we assess the assumptions underlying the LRE model in a population of cooperatively
breeding wild dogs (Lycaon pictus) in Northern Botswana monitored over a 15-year period. In this population, litter size and pup survival to 1 year are strongly
affected by pack size and the breeding female’s age, but adult males have a stronger and more linear effect on females’ reproductive
performance than do adult females. This asymmetry in the benefits derived from male and female helpers is reflected in male-biased
sex ratios in litters at the time pups emerge from the den. Sex ratio biases are most pronounced in the litters of the youngest
mothers who live in significantly smaller packs than older females. The presence of potential rivals for the dominant female’s
position depresses pup production at the time of emergence, suggesting that competition among females for breeding positions
may also contribute to the selective forces affecting birth sex ratios. 相似文献
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50.
Characterizing Small Subbasins: A Case Study from Coastal Oregon 总被引:1,自引:0,他引:1
A fine-grained statisticaly robust probability sample of stream segments is used to compare two small (20,000 hectare) subbasins of the Tillamook watershed, north coastal Oregon. The two subbasins are matched with respect to several variables [size coastal climates], but vary in terms of geology and consequently land use. A total of 67 wadeable + non-wadeable sizes were identified for sampling in the two subbasins (combined) over two field seasons from a sampling universe consisting of the River Reach File 3 (blue lines on 1:100,000 maps). Target variables include an extensive array of physical habitat endpoints, selected water chemistry endpoints, species composition, and relative abundance of both benthic macroinvertebrates and fish. Field protocols generally followed those of the U.S. EPA's Environmental Monitoring and Assessment Program (EMAP).Eleven fish species were encountered, a typically low number for coastal Oregon streams. Exploratory analysis using nonmetric multidimensional scaling revealed that 92.4% of the variation in the fish assemblages could be explained with two ordination axes. Environmental factors related to stream size and substate were the most correlated to these axes. Further, stream segments for the two subbasins tended to map in different areas of species space. Therefore, we also give unweighted probability distributions for several of the factors that heavily on these two axes by subbasins, as well as probability distributions for chemical endpoints. Results from the subset of sites sampled during the first year (21 wadeable sites) reveal: 1) differences between samples from the two subbasins relates to dream size and substrate composition that are consistent with known differences in geology and land use, 2) unexpectedly minor differences between samples from the two subbasins for stream temperature, canopy cover, and dissolved oxygen, 3) differences between samples from the two subbasins for total P, and total N, possibly related to land use, and 4) unexpected differences in samples from the two subbasins for conductivity, probably related to geological factors. Sample size for each subbasin is low and therefore our samples cannot be taken to necessarily characterize either subbasin. However, our findings are consistent with a comprehensive assessment that had been previously produced for one of the two subbasins.All field work was completed in 8 weeks 3-person field crew. We conclude that rapid assessment protocols, based on probability samples at this level of resolution, can be a cost-effective approach to watershed analysis. This approach should be seen as a complement to, rather than a replacement for, systematic surveys that produced finer scale, reach specific information on factors such as channel complexity and cover relevant to in-stream restoration planning. 相似文献