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471.
以灰霾、水质污染等为主要特征的环境问题日益突出,人民群众对蓝天、清水、净土的期盼日益强烈.规划环评作为规划实施前期环境战略安排,能较好地解决长期性、区域性的环境问题.选取江苏省太湖流域一个综合性开发区,以区域环境质量改善作为规划方案合理与否的一个重要准则.通过规划环评引导开发区在维持快速发展的同时进一步减少污染物排放,集约利用资源能源,并基于生态敏感性、适宜性确定合理的开发格局,为开发强度高、现状环境问题较突出的同类开发区规划环评提供借鉴. 相似文献
472.
473.
California’s population increased 25% between 1980 and 1990, resulting in rapid and extensive urbanization. Of a total 123,000
ha urbanized in 42 of the state’s 58 counties between 1984 and 1990, an estimated 13% occurred on irrigated prime farmland,
and 48% on wildlands or fallow marginal farmlands. Sixty-six percent of all new irrigated farmland put into production between
1984 and 1990 was of lesser quality than the prime farmland taken out of production by urbanization. Factors dictating the
agricultural development of marginal farmlands include the availability and price of water and land, agricultural commodity
prices, and technical innovations such as drip irrigation systems that impact the feasibility and costs of production. The
increasing amount of marginal farmland being put into production could have significant water quality consequences because
marginal lands are generally steeper, have more erodible soils, poorer drainage, and require more fertilizer than prime farmlands.
Although no data exist to test our hypothesis, and numerous variables preclude definitive predictions, the evidence suggests
that new irrigated marginal lands can increase nonpoint source (NPS) pollution for a given size area by an order of magnitude
in some cases. 相似文献
474.
In this article a model is proposed that could be used as a basis for ecological planning of natural resources. The role of
people as part of the ecosystem is emphasized, and the various factors that should be considered in such planning are discussed.
An understanding of ecological planning is dependent on the study of human activities in, and the nature of, natural ecosystems.
It also depends on the fact that people are a part of nature, and as a result nature is of value to humans. Realizing the
importance of this principle is a prerequisite to studying nature and also for an understanding of the various steps in the
ecological planning approach.
Realization of these values is often through a series of activities that may result in a negative environmental impact. Nature
is described as an interacting group of natural features and processes. In this study both the features and processes are
described as natural resources. The use of these natural resources obviously affects them, and if this use is to continue
over a long period, both the activity and the resource must be understood if they are to be maintained in a productive state.
In order to limit impact and maintain value, a planning aid called zoning is used to assist in the understanding of the processes
involved. 相似文献
475.
Peder Hjorth 《Natural resources forum》2001,25(4):313-320
The World Commission on Dams (WCD) has now presented its final report on the problems with large dams. Many dam projects were found to be underperforming, especially those built for irrigation purposes. WCD also reports that many projects fail to meet current standards of social equity. A reallocation of costs and benefits is needed, but entrenched interests make this a difficult task. This article identifies shortcomings in large Asian irrigation projects: why the problems emerged, and what could be done to improve the performance of existing projects. The article argues that Asian irrigation agencies take mainly an engineering perspective, focusing on the dam itself. In a large number of cases, it takes over 10 years for the infrastructure to be installed and for the water to be delivered to the fields of the command area. Agencies need to improve their competence in dealing with social and environmental issues. This article argues that social and economic infrastructure is often inadequate; there is a need for an integrated view of the role of agriculture in development. Furthermore, adaptive management practices and water user participation can often be critical elements. To be successful, participation needs to be gender sensitive, and stakeholders at all income levels need to be consulted. To bridge the gulf between rhetoric and action, there is also a need for independent evaluation of dam projects. 相似文献
476.
Ecosystem health: I. Measuring ecosystem health 总被引:12,自引:0,他引:12
Ecosystem analysis has been advanced by an improved understanding of how ecosystems are structured and how they function. Ecology has advanced from an emphasis on natural history to consideration of energetics, the relationships and connections between species, hierarchies, and systems theory. Still, we consider ecosystems as entities with a distinctive character and individual characteristics. Ecosystem maintenance and preservation form the objective of impact analysis, hazard evaluation, and other management or regulation activities. In this article we explore an approach to ecosystem analysis which identifies and quantifies factors which define the condition or state of an ecosystem in terms of health criteria. We relate ecosystem health to human/nonhuman animal health and explore the difficulties of defining ecosystem health and suggest criteria which provide a functional definition of state and condition. We suggest that, as has been found in human/nonhuman animal health studies, disease states can be recognized before disease is of clinical magnitude. Example disease states for ecosystems are functionally defined and discussed, together with test systems for their early detection.This article is contribution VI in D.J. Schaeffer's Environmental Audit series. 相似文献
477.
土壤吸附铬的特性及影响因素研究进展 总被引:4,自引:0,他引:4
铬污染问题越来越突出,尤其是铬渣的堆存造成严重的土壤铬污染。介绍了铬进入土壤后的存在形态及化学行为,论述了土壤对Cr(Ⅲ)和Cr(Ⅵ)的吸附特征,着重讨论了土壤吸附铬的影响因素。铬在土壤中的吸附是一个复杂的过程,受多方面因素的影响,土壤对铬的吸附依赖于土壤的类型、土壤物理化学性质,如土壤的矿物特性、有机组成pH、Eh、等,也与外加阴阳离子、有机质等有关。研究土壤吸附铬的影响因素为土壤铬污染治理提供科学依据,今后的研究可结合周围环境对铬污染的影响展开。 相似文献
478.
太子河流域辽阳段河流水质污染状况分析 总被引:4,自引:0,他引:4
对太子河流域辽阳段河流水质状况进行分析,得出辽阳地区的河流污染主要代表项目为COD和总磷,平均超标率分别为50%和62.5%。朝光断面和孟柳断面的水质污染较为严重。北沙河和汤河的水质状况比较好。蓡窝水库由于接纳本溪市工业废水和生活污水,导致库中的以挥发酚为代表的有机污染严重。 相似文献
479.
中国海岸侵蚀特点及侵蚀加剧原因分析 总被引:40,自引:2,他引:40
中国海岸侵蚀具有普遍性、多样性和加剧发展等三个特点,侵蚀岸线长度占全国大陆岸线的1/3以上,尤以渤海和黄海沿岸较重。但因沿海泥沙来源丰富、堆积条件较好,使总体侵蚀强度通常稍轻于国外许多海岸。中国海岸的侵蚀因素有海平面上升、风暴潮加剧、入海泥沙减少和多种不合理的人为开发活动等9种,其中7种与全球变化有直接或间接关系。它们主要通过增强海洋动力作用、减少沿岸泥沙和降低海岸稳定性三个原因,加剧海岸侵蚀。 相似文献