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   32篇
  免费   2篇
环保管理   8篇
综合类   1篇
基础理论   15篇
污染及防治   4篇
社会与环境   5篇
灾害及防治   1篇
  2019年   1篇
  2018年   3篇
  2017年   5篇
  2016年   2篇
  2015年   3篇
  2013年   3篇
  2012年   1篇
  2011年   5篇
  2009年   3篇
  2008年   3篇
  2007年   3篇
  2006年   1篇
  2002年   1篇
排序方式: 共有34条查询结果,搜索用时 12 毫秒
21.
The species composition of macrofauna associated with floating seaweed rafts is highly variable and influenced by many factors like spatial and temporal variation, period since detachment and probably also the seaweed species. The presence of seaweed preferences was assessed by a combination of in situ seaweed samplings and multiple-choice aquarium experiments in a controlled environment, using the seaweed-associated grazing organisms Idotea baltica and Gammarus crinicornis. Results from the sampling data confirm that the seaweed composition influences macrofaunal species composition and abundance: samples dominated by Sargassum muticum displayed higher densities but lower diversities compared to samples dominated by Ascophyllum nodosum and Fucus vesiculosus. Seaweed preference was also apparent from the multiple-choice experiments, but did not exactly match the results of the community analysis: (1) I. baltica had high densities in seaweed samples (SWS) dominated by F. vesiculosus and A. nodosum, while in the experiments, this isopod was most frequently associated with Enteromorpha sp. and F. vesiculosus, and fed mostly on S. muticum, A. nodosum and Enteromorpha sp.; (2) G. crinicornis had high densities in SWS dominated by F. vesiculosus, while in the experiments, this amphipod was most frequently associated with S. muticum, but fed most on A. nodosum and F. vesiculosus. It is clear from the laboratory experiments that preference for habitat (shelter) and food can differ among seaweed species. However, food and habitat preferences are hard to assess because grazer preference may change if choices are increased or decreased, if different sizes of grazers are used, or if predators or other grazers are added to the experiments. The effects of seaweed composition may also be blurred due to the obligate opportunistic nature of a lot of the associated macrofaunal species.  相似文献   
22.
The impact of commodity price risk management on the profits of a company   总被引:1,自引:0,他引:1  
It is well recognized that for the producing companies hedging the commodity price using financial products like forwards or futures has become an important part of the company's production process. But apart from the direct impacts of hedging on the production and hedging costs the use of financial products affects the financing of the company: hedging the volatile commodity prices leads to a reduction of the risk premium the company has to pay for its debt capital, since hedging contributes to more confidence of the investors in the redemption of the debt. In this paper we therefore analyze this dependency of hedging and financing and derive optimal hedging extents for companies in different market situations based on a long-term model. By hedging the commodity price, companies can realize a surplus in profits. Thereby, the optimal hedging extent for a monopolist is often up to 100%, whereas for companies in a polypolistic market the optimum is always less than 100%. These results are illustrated by examples for a producing company.  相似文献   
23.
We have investigated the relevance of the notion of “peripheralism” in the Beles basin. In this lowland border area of Ethiopia, important investments require an evaluation of their socio-economic and ecological impacts in the light of Ethiopia’s Climate-Resilient Green Economy (CRGE) strategy. We contrasted literature of different periods with field observations. In the middle and lower parts of the basin, the Gumuz people traditionally practised shifting cultivation. Resettlement of highlanders is particularly linked to water and land resources. A large irrigation project was initiated in the 1980s, but vegetables and fruits face post-harvest losses. Large water transfers from Lake Tana since 2010 affect the movement of people, the hydrogeomorphology, and ecology of the river. In several parts of the basin, the settlers’ economy now dominates. Many Gumuz became sedentary but maintained their agricultural system, particularly in the south of the lower basin. Land titling allowed allocation of “vacant” areas to transnational or domestic investors. As a result, the semi-natural vegetation is frequently replaced by open cropland, leading to decreased carbon storage and increased soil erosion. This and water abstraction for irrigation jeopardise hydropower production, in contradiction with the CRGE objectives. Despite the recent developments, the contrasts in economic activity make the core-periphery dichotomy to remain actual in the Beles basin. The resettlements and permanent cropping tend to make the upper basin part of the core. However, the installation of a transit road and commercial farms in the lower basin do not allow to consider that a non-peripheral integration has taken place.  相似文献   
24.
Local government is attributed a vital role in climate-change adaptation. Previous studies contend that conflicting priorities, insufficient institutional incentives and knowledge of risks, and inadequate resources all impede local climate adaptation. Though the importance of local political support in enabling climate adaptation is widely acknowledged, the views of local politicians have rarely been analysed. Drawing on semi-structured interviews with local politicians in Sweden, we explore what affects their engagement in climate adaptation. The study claims that climate adaptation contrary to mitigation is not viewed as political beyond directing attention and sanctioning guidelines set by officials. A limited number of interviewees claim a more strategic political role in adaptation. The combined effect of institutional incentives (e.g. fragmented national guidelines, unappealing goals, and lack of funding), relative weight in local politics, and ability to exercise political leadership (e.g. campaign value, public and media pressure, and lack of ideology) is perceived as too insignificant to trigger strong political engagement. In less-populous municipalities, adaptive measures were highly valued for demonstrating political action.  相似文献   
25.
Changes in sulphur and nitrogen pollution in Swedish forests have been assessed in relation to European emission reductions, based on measurements in the Swedish Throughfall Monitoring Network. Measurements were analysed over 20 years with a focus on the 12-year period 1996 to 2008. Air concentrations of SO2 and NO2, have decreased. The SO4-deposition has decreased in parallel with the European emission reductions. Soil water SO4-concentrations have decreased at most sites but the pH, ANC and inorganic Al-concentrations indicated acidification recovery only at some of the sites. No changes in the bulk deposition of inorganic nitrogen could be demonstrated. Elevated NO3-concentrations in the soil water occurred at irregular occasions at some southern sites. Despite considerable air pollution emission reductions in Europe, acidification recovery in Swedish forests soils is slow. Nitrogen deposition to Swedish forests continues at elevated levels that may lead to leaching of nitrate to surface waters.  相似文献   
26.
While strengthening public–private interplay is expected to improve the climate profile of urban planning in terms of mitigation and adaptation, less is known about the practice of such new interactive modes of governing. The paper critically examines the role, benefits and limitations of extended public–private interplay in developing a new housing district in Sweden. The developer dialogue between municipal officials and property developers confirms mutual interests, shared understandings and the added value of interacting. However, the closer the dialogue comes to settling agreements, the more difficult it gets for municipal officials to steer the process and its outcomes in favor of climate proofing. Complications with adapting to the new interactive setting means that municipal officials balance between acting as facilitators and/or regulators and property developers between acting as partners, competitors and/or defenders. Refining steering-strategies for sustaining commitments and securing formal agreements are pertinent for using public–private interplay to climate-proof urban planning.  相似文献   
27.
The processes governing distribution of a xenobiotic compound discharged initially into the environment are discussed, and attention is drawn to (a) binding to organic matter in the sediment phase which affects both persistence and toxicity to biota and (b) the role of atmospheric transport for compounds of low water solubility and high vapour pressure. Important limitations in the use of sum parameters such as EOCI are pointed out. The important distinction between biodegradation and biotransformation is pointed out, and significant experimental determinants noted. Pathways for the aerobic metabolism of chlorophenolic compounds are discussed, and attention is drawn to the role of O‐methylation as an environmentally significant alternative to biodegradation. Evidence for the biodegradation of chlorinated aliphatic acids and hydrocarbons under both aerobic and anaerobic conditions is presented. Anaerobic metabolism of chlorophenolic compounds is discussed with respect to (a) de‐O‐methylation of chloroguaiacols, (b) dechlorination of chlorocatechols and (c) reduction of chlorovanillins. It is emphasized that current evidence provides a complex metabolic picture, and that only partial dechlorination may occur. Brief attention is given to the important issue of the persistence of chlorolignin, and attention drawn to technical issues which render this problem difficult of access by traditional procedures. Biohalogenation—particularly by fungi—is noted, though its quantitative contribution cannot be estimated at the moment. A number of important unresolved issues are underscored: (a) the problem of determining rates of microbial reactions which may be translated to environmental situations, (b) the cardinal role not only of the number of chlorine atoms in an aromatic compound but also the substitution pattern and (c) limitations in current understanding of the role of anaerobic bacteria in bringing about biodegradation and biotransformation.  相似文献   
28.
29.
30.
It is increasingly expected that private actors play the role as entrepreneurs and front-runners in implementing climate measures, whereas empirical studies of the position, role and engagement of private actors are scarce. Situated in the context of urban planning, a critical arena for triggering climate transitions, the aim of this paper is to explore how Swedish property developers respond to climate change. Qualitative analyses of corporate policy documents and semi-structured interviews with property developers reveal a vast divergence between the written policies, where leadership ambitions are high, and how the practice of property development is discussed in interviews. In the latter, there is little evidence of property developers pursuing a forward-looking or cutting-edge climate change agenda. Instead, they are critical of increased public regulation for climate-oriented measures. Explanations both confirm previous studies, highlighting lack of perceived customer demand, uncertainty of financial returns and limited innovations, and add new elements of place-dependency suggesting that innovative and front-runner practices can only be realized in the larger urban areas. Municipalities seeking to improve their climate-oriented profile in urban planning by involving private property developers need to develop strategies to maneuver the variance in responses to increase the effectiveness of implementation.  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