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排序方式: 共有215条查询结果,搜索用时 15 毫秒
61.
周万村 《长江流域资源与环境》2002,(1)
坡度和高程是土地资源固有的二个重要环境因子 ,对土地利用和土地生产力有直接作用。在山区 ,坡度和高程基本上决定了土地利用方向和利用方式 ,从而影响到经济效益和发展潜力。三峡库区面积 6 2 6 4 0km2 ,为丘陵、低中山区 ,山高坡陡。按坡度和高程对农业生产的影响程度进行分级 :0~ 7°、7~ 15°、15~ 2 5°、>2 5° ;80 0m以下 ,80 0m以上。在编制的 1:10万土地自然坡度和高程分级图及土地利用图的基础上获取各坡度、高程级及其土地利用类型和数据。 4个坡度级土地面积随坡度的增加而加大 ,随海拔的增高而减小。耕地大部分集中在 80 0m以下 7~ 15°和 15~ 2 5°的坡度上 ,优质耕地少 ,中、低产地多 ,并存在大量的陡坡耕地。森林大多分布在 80 0m以上 >2 5°陡坡上。根据对 1980~ 1996年库区主要县、市农业年产值与自然坡度和高程的定量分析比较 ,可以看出它们之间存在着明显的反比例关系。综合提高库区土地生产力 ,必须遵循“有所为 ,有所不为”原则 ,进行农业结构调整 ,不片面强调增加粮食产量而盲目扩大耕地面积 ,大力改造 15~ 2 5°的中、低产地 ,有计划、按步骤并在尊重农民意愿的基础上进行退陡坡旱地还林 (草 ) ,改善生态环境。 相似文献
62.
A case study of a successful reuse program in a batch blending production environment is presented. This program involves not only addressing the company's own potential waste, but also working with distributors and customers to take back and reuse product, thus eliminating the customers' burden of disposal. Implications of the program for downstream supply chain partners are identified and a structured approach for implementation is presented. Modification for use in similar production environments is possible, enhancing sustainability, while providing environmental as well as economic benefits. 相似文献
63.
中国1990~2004年生态足迹动态变化效应的分解分析 总被引:8,自引:3,他引:5
通过构建生态足迹分解模型,论文将中国1990~2004年生态足迹的动态变化分解为经济规模、产业结构和足迹强度这3种因素的变化效应,并对各分解效应进行了测度与分析。结果表明:生态足迹年度间变化均值为1.065 5×108hm2。其中,由经济规模、产业结构和足迹强度所引起的足迹变化分别为2.108 2×108hm2,-0.439 8×108hm2和-0.602 9×108hm2。总的看,经济规模的变化助长了总足迹的增长,而足迹强度和产业结构的变化对总足迹的扩张起到了一定的遏制作用。生态足迹变化是由各因素共同作用的结果,而在不同时期各因素对足迹变化所发挥的效应不同。该研究结果对于理解我国生态足迹变化与经济发展之间的关系,以及产业发展政策调整及可持续发展研究具有一定参考价值。 相似文献
64.
本文提出了农业生产潜力指数评价的基本理论和方法,并利用这一评价方法对内江市主要家业作物的生产潜力的进行了评价分析。 相似文献
65.
Levels and Influencing Factors of Noise Pollution from Small-Scale Industries (SSIs) in a Developing Country 总被引:1,自引:0,他引:1
Mbuligwe SE 《Environmental management》2004,33(6):830-839
A study was carried out to determine levels and factors that influence noise pollution from small-scale industries (SSIs) in Dar es Salaam City Tanzania. Two sites for wood- and metalworks industries were investigated. Both sites exhibited equivalent noise levels higher than 90.0 dBA, the permissible exposure level limit for occupational noise. At a woodworks SSI, noise levels were found to correlate well with machine-use age, wood-feed speed, and wood-cut depth. Additionally, noise emanating from both types of SSIs was found to influence the level of environmental noise in the neighborhood of the SSIs. One woodworks SSI was found to have a circle of influence of about 140 m. The study concluded that SSIs present a serious source of environmental noise pollution in their neighborhoods. Noise pollution from SSIs is greatly influenced by the type of SSIs and the activities they carry out, the type and age of machines they use, their location relative to residential areas in their vicinity, and in-house noise control measures. 相似文献
66.
Shailendra Bajpai J.P. Gupta 《Journal of Loss Prevention in the Process Industries》2005,18(4-6):301-309
Chemical process industries such as oil refineries, fertiliser plants, petrochemical plants, etc., which handle hazardous chemicals, are potential targets for deliberate actions by terrorists, criminals and disgruntled employees. Security risks arising out of these threats are real and must be assessed to determine whether the security measures employed within the facility are adequate or need enhancement. The essential steps involved are threat analysis, vulnerability analysis, security countermeasures, and emergency response. Threat analysis involves the study of identifying sources, types of threats, and their likelihood. Vulnerability analysis identifies the weaknesses in a system that adversaries can exploit. Depending on the threat likelihood and vulnerabilities, various security countermeasures are suggested to improve the plant security. Appropriate emergency response measures that could mitigate the consequences of a successful attack and concepts of inherently safer processes in the light of process security are also discussed in the paper. It is recognised that serious terrorist threats exist to the transport system of hazardous chemicals (by road, rail cars, ships, pipelines, etc.). However, that is not a part of this study, which concentrates on process plants and hazardous materials within immovable boundaries. A case study of a fertiliser plant is used to show the application of ideas presented. 相似文献
67.
森林对非点源污染的调控研究 总被引:13,自引:0,他引:13
借助大量观测资料分析研究了不同森林类型、不同土地利用状况以及不同尺度下 ,森林对非点源污染的调控能力较强 ,坡面森林可使固体污染物减少 60 %以上 ,林地的营养元素损失减少 30~ 50 %。对于不同尺度下的流域 ,森林覆盖率高的流域水质参数指标大多低于森林覆盖率低的流域 ,尤其是 NH+ 4 ,从坡面小流域到大流域急剧下降。被采伐过的流域的水温上升 0 .2~ 0 .4℃ ,N损失量从 4kg/hm2· a上升到 1 42 kg/hm2· a。 相似文献
68.
用筑后模型估算我国植物气候生产力 总被引:50,自引:5,他引:50
本文根据日本农业气象学家内(山島)善兵卫先生采用的植物气候生产力的“筑后数学模型”NPP=0.29[exp(-0.216RDI2)]Rn,计算了我国气候生产力分布、并与迈阿密和桑斯威特数学模型计算结果做了比较分析。 相似文献
69.
Assessment of the Status of Urban Air pollution And Its Impact on Human Health in the City of Kolkata 总被引:1,自引:0,他引:1
Air pollution has significant effects on exacerbation of asthma, allergy and other respiratory diseases. Like many other magacities in the world the ambient air quality of Kolkata is also being deteriorated day by day. Automobile exhausts and certain industrial pollutants produce O3 by photochemical reactions. The particulate matter, particularly less than 10 μ in size, can pass through the natural protective mechanism of human respiratory system and plays an important role in genesis and augmentation of allergic disorders. Sources of air pollution in the area and the unique problem arising out of the emission from the vehicles, industries, etc. have been described. Ambient air quality was monitored along with micrometeorological data and the results are discussed. The status of air pollution in the area has been evaluated and a questionnaire survey was conducted to estimate the allergic symptoms and exposure to assess the respiratory disorders. The data are analysed to evaluate the critical situation arising out of the emission of air pollutants and the impact on human health due to respirable diseases (RDs) to middle class sub-population (activity-wise) in the area are assessed. A strategic air quality management plan has been proposed. For the mitigation of air pollution problems in the city, the different measures to be adopted to maintain the balance between sustainable development and environmental management have been discussed. 相似文献
70.