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排序方式: 共有239条查询结果,搜索用时 15 毫秒
1.
Sven Erik J rgensen 《生态毒理学报》2001,23(1):32-34,35
为了管理和保护城市水资源,需要有各种各样的方法 .污水处理是昂贵的,而且发展中国家经常使用的 2- 4步处理也阻碍了他们的污水处理 .化学沉淀法和废水稳定池+构造湿地组合法常常可以明显地减少对水资源的冲击 .建议发展中国家最好考虑采用这些方法 . 相似文献
2.
Globally, conflicts between marine nature conservation and fishery interests are common and increasing, and there is often a glaring lack of dialogue between stakeholders representing these two interests. There is a need for a stronger and enforced coordination between fishing and conservation authorities when establishing marine protected areas for conservation purposes. We propose that an appropriate instrument for such coordination is a broad ecosystem-based marine spatial planning procedure, representing neither nature conservation nor fishery. Strategic environmental assessment for plans and programmes and environmental impact assessment for projects are commonly used tools for assessing the environmental impacts of different human activities, but are seldom used for evaluating the environmental effects of capture fisheries. The diversity of fisheries and the drastic effects of some fisheries on the environment are strong arguments for introducing these procedures as valuable supplements to existing fisheries assessment and management tools and able to provide relevant environmental information for an overall marine spatial planning process. Marine protected areas for nature conservation and for protection of fisheries have different objectives. Therefore, the legal procedure when establishing marine protected areas should depend on whether they are established for nature conservation purposes or as a fisheries resource management tool. Fishing in a marine protected area for conservation purpose should be regulated according to conservation law. Also, we argue that marine protected areas for conservation purposes, in the highest protection category, should primarily be established as fully protected marine national parks and marine reserves. 相似文献
3.
The neonatal incidence rate of Down syndrome (DS) is well-known to accelerate strongly with maternal age. This non-linearity
renders mere accumulation of defects at recombination during prolonged first meiotic prophase implausible as an explanation
for DS rate increase with maternal age, but might be anticipated from chromosomal drive (CD) for trisomy 21. Alternatively,
as there is selection against genetically disadvantaged embryos, the screening system that eliminates embryos with trisomy
21 might decay with maternal age. In this paper, we provide the first evidence for relaxed filtering stringency (RFS) to represent
an adaptive maternal response that could explain accelerating DS rates with maternal age. Using historical data, we show that
the proportion of aberrant live births decrease with increased family size in older mothers, that inter-birth intervals are
longer before affected neonates than before normal ones, and that primiparae exhibit elevated levels of DS incidence at higher
age. These findings are predicted by adaptive RFS but cannot be explained by the currently available alternative non-adaptive
hypotheses, including CD. The identification of the relaxation control mechanism and therapeutic restoration of a stringent
screen may have considerable medical implications. 相似文献
4.
During 19–20 October 2009, the Royal Swedish Academy of Sciences arranged the international symposium Energy 2050 in Stockholm. The symposium was held in association with the Swedish EU presidency in autumn 2009. Internationally renowned scientists assessed the energy issue in a broad perspective, with particular emphasis on the possibilities of a fossil-free future. The symposium focused on key topics emanating from the in-depth energy studies carried through by the Academy´s Energy Committee since 2005. The world community is facing a challenge of historic proportions to define a new energy paradigm based on fossil-energy substitutes. This article gives an overview of the current global energy situation (2007) and of the technologies which have the major potential for supplying energy up to year 2050 without jeopardizing the CO2 emission targets. 相似文献
5.
Sebastian Petrick Kathrin Riemann-Campe Sven Hoog Christian Growitsch Hannah Schwind Rüdiger Gerdes Katrin Rehdanz 《Ambio》2017,46(3):410-422
A significant share of the world’s undiscovered oil and natural gas resources are assumed to lie under the seabed of the Arctic Ocean. Up until now, the exploitation of the resources especially under the European Arctic has largely been prevented by the challenges posed by sea ice coverage, harsh weather conditions, darkness, remoteness of the fields, and lack of infrastructure. Gradual warming has, however, improved the accessibility of the Arctic Ocean. We show for the most resource-abundant European Arctic Seas whether and how a climate induced reduction in sea ice might impact future accessibility of offshore natural gas and crude oil resources. Based on this analysis we show for a number of illustrative but representative locations which technology options exist based on a cost-minimization assessment. We find that under current hydrocarbon prices, oil and gas from the European offshore Arctic is not competitive on world markets. 相似文献
6.
Current atmospheric warming due to increase of greenhouse gases will have severe consequences for the structure and functioning of arctic ecosystems with changes that, in turn, may feed back on the global-scale composition of the atmosphere. During more than two decades, environmental controls on biological and biogeochemical processes and possible atmospheric feedbacks have been intensely investigated at Abisko, Sweden, by long-term ecosystem manipulations. The research has addressed questions like environmental regulation of plant and microbial community structure and biomass, carbon and nutrient pools and element cycling, including exchange of greenhouse gases and volatile organic compounds, with focus on fundamental processes in the interface between plants, soil and root-associated and free-living soil microorganisms. The ultimate goal has been to infer from these multi-decadal experiments how subarctic and arctic ecosystems will respond to likely environmental changes in the future. Here we give an overview of some of the experiments and main results. 相似文献
7.
Cecilia Sundberg Dan Yu Ingrid Franke-Whittle Sari Kauppi Sven Smårs Heribert Insam Martin Romantschuk Håkan Jönsson 《Waste management (New York, N.Y.)》2013,33(1):204-211
A major problem for composting plants is odour emission. Slow decomposition during prolonged low-pH conditions is a frequent process problem in food waste composting. The aim was to investigate correlations between low pH, odour and microbial composition during food waste composting. Samples from laboratory composting experiments and two large scale composting plants were analysed for odour by olfactometry, as well as physico-chemical and microbial composition. There was large variation in odour, and samples clustered in two groups, one with low odour and high pH (above 6.5), the other with high odour and low pH (below 6.0). The low-odour samples were significantly drier, had lower nitrate and TVOC concentrations and no detectable organic acids. Samples of both groups were dominated by Bacillales or Actinobacteria, organisms which are often indicative of well-functioning composting processes, but the high-odour group DNA sequences were similar to those of anaerobic or facultatively anaerobic species, not to typical thermophilic composting species. High-odour samples also contained Lactobacteria and Clostridia, known to produce odorous substances. A proposed odour reduction strategy is to rapidly overcome the low pH phase, through high initial aeration rates and the use of additives such as recycled compost. 相似文献
8.
Model fitting for individual-based effects in forests has some problems. Because samples measuring the separate influence of each individual are rarely available, the measured value in the sample represents the influence of all surrounding individual trees. Therefore, it is helpful to build inverse models that use the spatial pattern of the variable as well as that of the source trees. For example, since seed dispersal is influenced by wind effects, a model is discussed describing anisotropic effects to ensure an unbiased estimate of the total fruit number. Further, we present a model describing the absorption of radiation by trees. In this case a multiplicative combination of individual effects yields the total effect. Our approach uses logarithmic transformations of the original data to model multiplicative combinations as sum of transformed single effects. For fitting model parameters we propose an approach based on Bayesian statistics, to ensure ecologically interpretable parameters. 相似文献
9.
10.
Sven Rannow Nicholas A. Macgregor Juliane Albrecht Humphrey Q. P. Crick Michael Förster Stefan Heiland Georg Janauer Mike D. Morecroft Marco Neubert Anca Sarbu Jadwiga Sienkiewicz 《Environmental management》2014,54(4):732-743
The implementation of adaptation actions in local conservation management is a new and complex task with multiple facets, influenced by factors differing from site to site. A transdisciplinary perspective is therefore required to identify and implement effective solutions. To address this, the International Conference on Managing Protected Areas under Climate Change brought together international scientists, conservation managers, and decision-makers to discuss current experiences with local adaptation of conservation management. This paper summarizes the main issues for implementing adaptation that emerged from the conference. These include a series of conclusions and recommendations on monitoring, sensitivity assessment, current and future management practices, and legal and policy aspects. A range of spatial and temporal scales must be considered in the implementation of climate-adapted management. The adaptation process must be area-specific and consider the ecosystem and the social and economic conditions within and beyond protected area boundaries. However, a strategic overview is also needed: management at each site should be informed by conservation priorities and likely impacts of climate change at regional or even wider scales. Acting across these levels will be a long and continuous process, requiring coordination with actors outside the “traditional” conservation sector. To achieve this, a range of research, communication, and policy/legal actions is required. We identify a series of important actions that need to be taken at different scales to enable managers of protected sites to adapt successfully to a changing climate. 相似文献