首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   21篇
  免费   2篇
安全科学   1篇
环保管理   5篇
综合类   6篇
基础理论   6篇
污染及防治   3篇
评价与监测   1篇
社会与环境   1篇
  2022年   1篇
  2017年   1篇
  2016年   2篇
  2014年   3篇
  2011年   1篇
  2010年   4篇
  2008年   1篇
  2007年   1篇
  2006年   1篇
  2002年   2篇
  1998年   1篇
  1983年   1篇
  1980年   1篇
  1973年   2篇
  1972年   1篇
排序方式: 共有23条查询结果,搜索用时 31 毫秒
11.
ABSTRACT As urban expansion outstrips water supplies, the usual solution is to build pipelines to bring in water from sources farther afield. Such water supplies may act as either a leader of urban development or as a follower. In either case, this engineering approach to the provision of water has fostered less than optimal utilization of regional water and land resources for urban growth. More efficient utilization of these resources is achieved when water supply development and urban growth planning are conjoint activities. Water supply planners and land use planners, working together, are able to generate and evaluate the full range of urban development options, including water demand management through conservation. Preferred regional growth plans are achieved using the best mix of water supply and urban growth. The result is a reduced rate of water supply development and a reduction of urban expansion on prime lands. This partnership approach is demonstrated for the Calgary Region under two levels of water conservation.  相似文献   
12.
Shellfish are an important cause of foodborne viral illness. Consumer-friendly cooking recommendations for shellfish could improve food safety and decrease the risk for infection from contaminated products. Thermal inactivation parameters were established for hepatitis A virus (HAV) in mussels and validated with cooking experiments. Steaming for only 2–5 min was not sufficient to inactivate HAV in mussels in all layers of a steamer. Steaming mussels for 6 min was sufficient to inactivate HAV in all layers. These cooking guidelines produce shellfish with a reduced risk for foodborne virus transmission.  相似文献   
13.
In an ongoing effort to propose biologically protective nutrient criteria, we examined how total nitrogen (TN) and its forms were associated with macroinvertebrate communities in wadeable streams of Maryland. Taxonomic and functional metrics of an index of biological integrity (IBI) were significantly associated with multiple nutrient measures; however, the highest correlations with nutrients were for ammonia-N and nitrite-N and among macroinvertebrate measures were for Beck’s Biotic Index and its metrics. Since IBI metrics showed comparatively less association, we evaluated how macroinvertebrate taxa related to proposed nutrient criteria previously derived for those same streams instead of developing nutrient–biology thresholds. We identified one tolerant and three intolerant taxa whose occurrence appeared related to a TN benchmark. Individually, these taxa poorly indicated whether streams exceeded the benchmark, but combining taxa notably improved classification rates. We then extracted major physiochemical gradients using principal components analysis to develop models that assessed their influence on nutrient indicator taxa. The response of intolerant taxa was predominantly influenced by a nutrient-forest cover gradient. In contrast, habitat quality had a greater effect on tolerant taxa. When taxa were aggregated into a nutrient sensitive index, the response was primarily influenced by the nutrient-forest gradient. Multiple lines of evidence highlight the effects of excessive nutrients in streams on macroinvertebrate communities and taxa in Maryland, whose loss may not be reflected in metrics that form the basis of biological criteria. Refinement of indicator taxa and a nutrient-sensitive index is warranted before thresholds in aquatic life to water quality are quantified.  相似文献   
14.
Knowledge co‐production and boundary work offer planners a new frame for critically designing a social process that fosters collaborative implementation of resulting plans. Knowledge co‐production involves stakeholders from diverse knowledge systems working iteratively toward common vision and action. Boundary work is a means of creating permeable knowledge boundaries that satisfy the needs of multiple social groups while guarding the functional integrity of contributing knowledge systems. Resulting products are boundary objects of mutual interest that maintain coherence across all knowledge boundaries. We examined how knowledge co‐production and boundary work can bridge the gap between planning and implementation and promote cross‐sectoral cooperation. We applied these concepts to well‐established stages in regional conservation planning within a national scale conservation planning project aimed at identifying areas for conserving rivers and wetlands of South Africa and developing an institutional environment for promoting their conservation. Knowledge co‐production occurred iteratively over 4 years in interactive stake‐holder workshops that included co‐development of national freshwater conservation goals and spatial data on freshwater biodiversity and local conservation feasibility; translation of goals into quantitative inputs that were used in Marxan to select draft priority conservation areas; review of draft priority areas; and packaging of resulting map products into an atlas and implementation manual to promote application of the priority area maps in 37 different decision‐making contexts. Knowledge co‐production stimulated dialogue and negotiation and built capacity for multi‐scale implementation beyond the project. The resulting maps and information integrated diverse knowledge types of over 450 stakeholders and represented >1000 years of collective experience. The maps provided a consistent national source of information on priority conservation areas for rivers and wetlands and have been applied in 25 of the 37 use contexts since their launch just over 3 years ago. When framed as a knowledge co‐production process supported by boundary work, regional conservation plans can be developed into valuable boundary objects that offer a tangible tool for multi‐agency cooperation around conservation. Our work provides practical guidance for promoting uptake of conservation science and contributes to an evidence base on how conservation efforts can be improved.  相似文献   
15.
避免非洲的水资源冲突   总被引:1,自引:0,他引:1  
非洲大约85%的水资源都是由几个国家共用的大型河流盆地的构成.人口的高速增长,伴随着水需求量的不断增加,已使一些国家超越了水资源供应的短缺严重限制其经济进一步发展的警戒点.  相似文献   
16.
ABSTRACT The tremendous growth of participation in recreational boating has focused attention on the ability of surface waters to support different types of water-based recreation under intensive use. An important factor in determining the capacity of recreational waters for boating is the satisfaction boaters derive from an area and its use. The recreational experiences of two groups of users as they were affected by levels of use were examined on three intensively used lakes in southeastern Michigan during the summer of 1969. The reactions toward levels of use were obtained from personal interviews with users at the access sites following participation and by self-administered questionnaires distributed to shoreline property owner users. The level of use was recorded by aerial photography at hour intervals. The dispersion of boats and area consumed by boats on the water surface areas over time were quantified and investigated individually and in combination for possible relationships describing the level of use. The satisfaction of users was defined in terms of an index calculated by dividing the number of unfavorable boater responses by the total number of responses for a given time and place. Definite mathematical relationships between levels of use and user satisfaction were established. Based on these relationships, a range of levels of satisfaction for various numbers and groupings of boaters was used to develop boating carrying capacity limits.  相似文献   
17.
ABSTRACT The paper presents a systems approach for planning and evaluating alternative plans for resource use incorporating the concepts of multiobjective planning and evaluation (MOPE). The need for multidisciplinary input and strong interagency cooperation in planning for resource use is related to the logical and orderly completion of the planning steps. The paper briefly describes MOPE, emphasizing two important concepts: (1) the relationship of the study problems and objectives to national social objectives, and (2) the display of alternative solutions showing tradeoffs. Several important characteristics of a plan of study which implements MOPE are presented and discussed. A proposed MOPE analytical system is discussed in detail. The MOPE analytical system is divided into eight interdependent subsystems that describe data collection, use, analysis, and results. A linear program (L.P.) model is proposed to analyze the present and future demand relationships for natural resources. The model will also evaluate the interaction of agriculture, forestry, and recreation with the resource base of the basin, considering National Economic Development, Environmental Quality, and Regional Development.  相似文献   
18.
Ashton IW  Miller AE  Bowman WD  Suding KN 《Ecology》2010,91(11):3252-3260
Niche complementarity, in which coexisting species use different forms of a resource, has been widely invoked to explain some of the most debated patterns in ecology, including maintenance of diversity and relationships between diversity and ecosystem function. However, classical models assume resource specialization in the form of distinct niches, which does not obviously apply to the broadly overlapping resource use in plant communities. Here we utilize an experimental framework based on competition theory to test whether plants partition resources via classical niche differentiation or via plasticity in resource use. We explore two alternatives: niche preemption, in which individuals respond to a superior competitor by switching to an alternative, less-used resource, and dominant plasticity, in which superior competitors exhibit high resource use plasticity and shift resource use depending on the competitive environment. We determined competitive ability by measuring growth responses with and without neighbors over a growing season and then used 15N tracer techniques to measure uptake of different nitrogen (N) forms in a field setting. We show that four alpine plant species of differing competitive abilities have statistically indistinguishable uptake patterns (nitrate > ammonium > glycine) in their fundamental niche (without competitors) but differ in whether they shift these uptake patterns in their realized niche (with competitors). Competitively superior species increased their uptake of the most available N form, ammonium, when in competition with the rarer, competitively inferior species. In contrast, the competitively inferior species did not alter its N uptake pattern in competition. The existence of plasticity in resource use among the dominant species provides a mechanism that helps to explain the manner by which plant species with broadly overlapping resource use might coexist.  相似文献   
19.
Reducing emissions from deforestation and forest degradation (REDD) can be an effective and efficient means of mitigating climate change. However, the perceived equity in the distribution of financial incentives for REDD could also emerge as a critical issue in international negotiations. The design of reference levels, which provide the benchmark for crediting emissions reductions, affects the economic incentives for national participation in a REDD mechanism and thus the overall willingness to reach an agreement on REDD. This paper compares the equity impacts of five proposed reference level designs using a partial-equilibrium model. Tradeoffs among equity, environmental effectiveness and cost-efficiency indicate the proposals trigger similar aggregate emissions reductions but lead to different outcomes in efficiency and alternative measures of equity. If equity across countries is measured as the financial incentive provided relative to a country's forest carbon stock, then a REDD mechanism compensating a uniform share of at-risk carbon stocks is the most equitable. On the other hand, if equity is evaluated as the financial incentive relative to the opportunity costs of participating in REDD, then the most equitable approach would be compensating emissions reductions but withholding a part of the payments to compensate for carbon stocks, which also encourages broader country participation under our model.  相似文献   
20.
An increase in the rate of sea-level rise and potential changes in storminess represent important components of global climate change that will likely affect the extensive coasts of the Northeastern USA. Raising sea level not only increases the likelihood of coastal flooding, but changes the template for waves and tides to sculpt the coast, which can lead to land loss orders of magnitude greater than that from direct inundation alone. There is little question that sea-level rise, and in particular an increased rate of rise, will result in permanent losses of coastal land. However, quantitative predictions of these future coastal change remains difficult due in part to the complexity of coastal systems and the influence of infrequent storm events, and is further confounded by coastal science’s insufficient understanding of the behavior of coastal systems over decadal timescales. Recently, dramatic improvements in technology have greatly improved our capabilities to investigate and characterize processes and sedimentary deposits in the coastal zone, allowing us, for the first time, to address some of the over-arching problems involved in shoreline change. Despite advances in many areas of coastal geology, our fundamental understanding of shoreline change has been limited by a lack of a broad and integrated scientific focus, a lack of resources, and a lack of willingness on the part of policymakers who make crucial decisions about human activity along the coast to support basic research in this area. Although quantitative predictions remain constrained, there remains little doubt that the predicted climates changes will have profound effects upon the Northeastern coast.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号