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Matching biological and chemical data were compiled from numerous modeling, laboratory, and field studies performed in marine and estuarine sediments. Using these data, two guideline values (an effects range-low and an effects range-median) were determined for nine trace metals, total PCBs, two pesticides, 13 polynuclear aromatic hydrocarbons (PAHs), and three classes of PAHs. The two values defined concentration ranges that were: (1) rarely, (2) occasionally, or (3) frequently associated with adverse effects. The values generally agreed within a factor of 3 or less with those developed with the same methods applied to other data and to those developed with other effects-based methods. The incidence of adverse effects was quantified within each of the three concentration ranges as the number of cases in which effects were observed divided by the total number of observations. The incidence of effects increased markedly with increasing concentrations of all of the individual PAHs, the three classes of PAHs, and most of the trace metals. Relatively poor relationships were observed between the incidence of effects and the concentrations of mercury, nickel, total PCB, total DDT and p,p′-DDE. Based upon this evaluation, the approach provided reliable guidelines for use in sediment quality assessments. This method is being used as a basis for developing National sediment quality guidelines for Canada and informal, sediment quality guidelines for Florida. The methods and guidelines presented in this report do not necessarily represent the policy of the National Oceanic and Atmospheric Administration, Environment Canada, or Florida Department of Environmental Protection.  相似文献
我国农作物秸秆资源的利用现状与前景   总被引:71,自引:0,他引:71  
我国农作物秸秆资源丰富,年产量达6亿t。传统上,秸秆被作为农户生产燃料或用于牲畜的粗饲料,少量用于造纸。近年来,由于农户生活用燃料锐减,腐熟还田量少,而田间直接焚烧量大,导致大气严重污染。作者在分析秸秆资源综合利用前景的基础上,提出应用先进的就地还田和快速腐熟技术促进农业的持续发展。  相似文献
发展循环经济是21世纪的大趋势   总被引:69,自引:0,他引:69  
本文阐述了循环经济是一种生态经济,主要有减量化、再利用、资源化三大原则,介绍了发达国家发展循环经济的情况,并提出了中国可借鉴国际上发展循环经济的基本经验.  相似文献
Modeling the spatial dynamics of regional land use: the CLUE-S model   总被引:59,自引:3,他引:56  
Land-use change models are important tools for integrated environmental management. Through scenario analysis they can help to identify near-future critical locations in the face of environmental change. A dynamic, spatially explicit, land-use change model is presented for the regional scale: CLUE-S. The model is specifically developed for the analysis of land use in small regions (e.g., a watershed or province) at a fine spatial resolution. The model structure is based on systems theory to allow the integrated analysis of land-use change in relation to socio-economic and biophysical driving factors. The model explicitly addresses the hierarchical organization of land use systems, spatial connectivity between locations and stability. Stability is incorporated by a set of variables that define the relative elasticity of the actual land-use type to conversion. The user can specify these settings based on expert knowledge or survey data. Two applications of the model in the Philippines and Malaysia are used to illustrate the functioning of the model and its validation.  相似文献
城市旅游竞争力的实证研究--以广东省为例   总被引:52,自引:0,他引:52  
城市旅游竞争力研究是目前国内外城市旅游研究的热点.作为我国城市旅游发展较早的地区,广东省旅游业发展的整体水平较高,但各个城市之间的发展水平极度不平衡.在统计资料的基础上,建立了城市旅游竞争力指标体系,并用主成分分析法和系统聚类法对广东省21个地级市的旅游竞争力进行了综合对比分析,认为旅游规模与组织能力是影响广东旅游业发展的重要因素;同时,把广东省21个地级市按照旅游竞争力的大小分为综合型、客源地型、目的地型和待开发型4大类型,提出了广东省要提高城市旅游竞争力、实现城市旅游可持续发展必须制订合理的发展目标、加大旅游投入力度、完善旅游交通网络、加强旅游行业管理.  相似文献
论多自然型河流治理法对河流生态环境的影响   总被引:49,自引:0,他引:49  
杨芸 《四川环境》1999,18(1):19-24
本文首先介绍了成都府河望江公园段多自然型护岸工程的由来,然后通过简述国外多自然型河川治理常用方法论述了对河流生态环境的改善作用,最后在对府河多自然型护岸设计介绍的基础上提出了试验工程的深远意义及其对今后工作的启迪  相似文献
论社会主义生态文明   总被引:49,自引:0,他引:49  
潘岳 《绿叶》2006,(10)
社会主义思想最早出现于15世纪,是早期无产者同资产者矛盾逐步激化的产物,我们称之为空想社会主义。早期空想社会主义有两种,一个是主张通过暴力革命建立政权的闵采尔式;一个是主张和平改造社会的莫尔式。 一、社会主义(一)社会主义的产生什么是社会主义?对这个词解释了200年  相似文献
关于循环经济理论与政策的几点思考   总被引:48,自引:0,他引:48  
作者结合学习贯彻十六大精神,详细论述了发展循环经济的重大意义、模式和前景,提出了我国发展循环经济的理论和政策建议。  相似文献
Modeling the relationship between land use and surface water quality   总被引:47,自引:0,他引:47  
It is widely known that watershed hydrology is dependent on many factors, including land use, climate, and soil conditions. But the relative impacts of different types of land use on the surface water are yet to be ascertained and quantified. This research attempted to use a comprehensive approach to examine the hydrologic effects of land use at both a regional and a local scale. Statistical and spatial analyses were employed to examine the statistical and spatial relationships of land use and the flow and water quality in receiving waters on a regional scale in the State of Ohio. Besides, a widely accepted watershed-based water quality assessment tool, the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS), was adopted to model the plausible effects of land use on water quality in a local watershed in the East Fork Little Miami River Basin. The results from the statistical analyses revealed that there was a significant relationship between land use and in-stream water quality, especially for nitrogen, phosphorus and Fecal coliform. The geographic information systems (GIS) spatial analyses identified the watersheds that have high levels of contaminants and percentages of agricultural and urban lands. Furthermore, the hydrologic and water quality modeling showed that agricultural and impervious urban lands produced a much higher level of nitrogen and phosphorus than other land surfaces. From this research, it seems that the approach adopted in this study is comprehensive, covering both the regional and local scales. It also reveals that BASINS is a very useful and reliable tool, capable of characterizing the flow and water quality conditions for the study area under different watershed scales. With little modification, these models should be able to adapt to other watersheds or to simulate other contaminants. They also can be used to study the plausible impacts of global environmental change. In addition, the information on the hydrologic effects of land use is very useful. It can provide guidelines not only for resource managers in restoring our aquatic ecosystems, but also for local planners in devising viable and ecologically-sound watershed development plans, as well as for policy makers in evaluating alternate land management decisions.  相似文献
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