首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Using a bioeconomic model of the cod (Gadus morhua) and capelin (Mallotus villosus) fisheries of the Barents Sea, this study assesses the role of the fishermen’s behavior in reducing or intensifying the effects on the stocks caused by altered population dynamics. The analysis focuses on the economic development of the fisheries employing a coupled stock size–hydrography-based fishing strategy, which attempts to maximize returns from fishing over a given number of fishing periods. Results show that if the fishing strategy is based on a short optimization period of only two fishing periods, changes in population dynamics have a direct influence on the returns from fishing due to the strong pressure on the stocks applied by the fisheries. If the strategy is based on a longer optimization period, fishing activities may be deferred to allow for stock regrowth, which improves the economic performance of the fisheries. However, in that case, the relationship between population dynamics and fishing activities becomes less clear, as even a reduction of the carrying capacities of the two species allows for an increase in the amount of fish landed without causing a stock collapse due to an increased efficiency of fleet utilization. The simulations indicate that management considerations and the time horizon of the fishing strategy dominate the influence of altered population dynamics on the development of the stocks considered in the model.  相似文献   

2.
The framework of this article is modeling applied to fisheries. It aims at relating some classical stock–recruitment curves to a dynamic structured model, consisting of the adults stages of the stock and a pre-recruits stage (i.e., eggs, larvae, juveniles). The main result is that no functional stock–recruitment relationship can be found, unless further restrictive assumptions are added to the model (slow–fast dynamics and uniformity). Among the curves thus obtained is the Beverton–Holt curve, but not Ricker's.  相似文献   

3.
In recent years, China's fisheries economy has expanded dramatically. As a result, environmental pollution caused at least partially by such an expansion has endangered human health and the sustainable development of fisheries in some coastal regions. This paper establishes an indicator system for fisheries economic growth and environmental quality and evaluates the coordinated level of the two systems in 12 regions in China. Results show that i) it is necessary to expand the relative scale of fisheries economy, optimize the structure of fisheries industry, and improve the utilization capacity of pollutants; ii) the selected regions are evaluated as half each the fisheries economic lagging type and the environmental lagging type; iii) most of the selected regions exhibit a high coupling coordination degree, and the highest of those is Shandong. In the last section, the policy implications and further research directions are discussed.  相似文献   

4.
This paper unprecedentedly benchmarks the environmental and economic impacts of notable High-speed rail (HSR) networks. The goals are to (i) point out the environmental impacts from the HSR networks and (ii) evaluate the whole life cycle cost of HSR systems. The emphasis of this study is placed on five HSR networks from five countries to depict the effectiveness of sustainable transport policies in each particular country. Both life cycle assessment (LCA) and life cycle cost (LCC) models are adopted for a new critical framework capable of benchmarking the lifecycle sustainability of HSR networks. The new findings exhibit that CRC's system is the leader in energy-saving, who consumes only 67.55 GJ/km yearly, and emits lowest CO2 at an amount of 77,532.32 tCO2/km annually. These impressive results are stemmed from key enabling policies related to eco-friendly rolling stock design, sustainable construction, and green energy grids. With respect to the LCC analysis, the SCNF network takes advantage in the economy of scale and unleashes the lowest cost among other networks. It estimates that the SNCF network spends approximately 1,990,599.51 £/km annually at a % discount rate. The implications of these finding are discussed that the initial project has a high chance to be successful on economic than the late project due to an influence of the time value of money.  相似文献   

5.
Waterlogging and salinity due to seepage from canals have polluted land and environment in various parts of Pakistan. A sustainable environment requires urgent remedial measures for this problem. The research in this paper presents the impacts of the Fourth Drainage Project, Faisalabad on the twin problem of waterlogging and salinity. Monitoring of the project was made on regular basis. The key performance indicators for the project include the lowering of water table, improvement of water quality and soil salinity, increase in area under cultivation, cropping intensity, and socioeconomic status of the project population. Data regarding water levels and discharge from the drain pipes were collected to monitor the impact on waterlogging. Soil samples were tested to evaluate the impact of drainage on land. It has been found that the percentage of the contaminated land in the project area has considerably been decreased, while the cropping intensities have been increased.  相似文献   

6.
The multidisciplinary socio-economic study of fisheries in the bordering part of the Danube River between Serbia and Croatia (at the following sites: Apatin, Ba?ka Palanka, Ba?ko Novo Selo, Bezdan, and Sombor) that was performed in order to investigate various aspects of fish resource utilization (management, policy of protection and exploitation of freshwater fishery resources, present fisheries legislation, catch statistics), was realized during 2004 and 2005. Data were collected via survey with a structured interview. Socio-economic circumstances, together with ecological factors, have had an influence on the fish stock and number of commercial fishermen. Awareness of the occurring problems, both economic and ecological ones, is apparent, regardless of whether it is assessed in the field of commercial or recreational fishing. Fishery sector in Serbia is in a prolonged process of transition, with the enforcement of fishing regulations, but also the lack of control that leaves space for illegal commercial fishing. The statements, consciousness, experience and behavior of commercial fishermen represent a good basis for planning the sustainable development of fishing in this section of the Danube River.  相似文献   

7.
The ongoing urbanisation results in the decreased distance between residential areas and odour-generating municipal facilities. Odours are one of the crucial problems for people exposed to them, both locally and nationwide. Recently Syft Technologies company has been developing a new mobile device used for investigations of odorous compounds - Voice 200 Ultra. According to the manufacturer's declaration this device offers the possibility to carry out very precise odours measurements. Thus the attempt has been made to utilise that device for investigations of odorous compounds in one of Polish town.The primary goal of the research project has been to assess the applicability of the Voice 200Ultra method (developed by Syft Technologies) in the field odours measurements, in situ. That method is assumed to enable researchers to swiftly characterise and determine odorous chemical compounds in terms of quality and quantity.  相似文献   

8.
The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones: Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow soils from the Roraima and Rondonia highlands. A consistent east–west decline in biomass carbon in the Rio Negro Basin sector is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting C stocks in Amazonia when such great pedological variability is not taken into account.  相似文献   

9.
Because they contribute little to climate change, fisheries, aquaculture and other uses of marine renewable resources and environment have limited means to mitigate climate impacts. Adaptation is, therefore, critical. Though likely effects on oceans and fisheries can be identified, few can be quantified and, thus, priorized. Consequently, adaptation strategies should aim at enhancing the resilience of marine renewable resources and their uses and the current capacity to respond to surprises. Already, these uses are characterized by massive over-capacities, excessive resource exploitation, and pervasive conflicts within and between uses. Two complementary adaptation strategies are available. The first consists in adjusting conventional management systems to the new conditions of resource scarcity. The second aims at reducing the current resource constraint by promoting the development of aquaculture and a better utilization of fishery and aquaculture harvests. In this respect, small-scale and large-scale production systems, and developing and developed countries, have different capabilities. In summary, climate change does not modify, but enhances, existing priorities of environment and fisheries management and aquaculture development.  相似文献   

10.
深圳滨海大道工程的生态影响与生态补偿   总被引:4,自引:0,他引:4  
通过运用景观生态学原理对滨海大道工程中生态环境的损失及生态补偿的阐述,指出了道路工程的实施必须充分考虑生态环境损失及相应的生态建设,以利于区域内生态环境良好发展.  相似文献   

11.
The growing commercial demand for products with medicinal use has caused overexploitation of several plant species worldwide. To prevent the decline of these populations, the collection of these resources should be done in a sustainable way considering the time of its replacement in natural stocks. This study was designed to identify the relationship between different intensities of extraction of bark from the trunk of Stryphnodendron rotundifolium Mart. and its regeneration speed. For this, we selected two areas of Cerrado in the Northeast of Brazil, where a monitoring experiment with duration of 24 months was performed. This experiment consisted in simulating different extractive damage to assess the regeneration of bark. In each area, we selected 20 individuals, among which four treatments with five repetitions were implemented. The data showed that in both study areas, the trees regenerated their shells faster when subjected to higher collection intensities. However, this regeneration was not related to variations in rainfall in the environment.  相似文献   

12.
The availability of wetlands and shallow water habitats significantly influences Gulf of Mexico (GOM) penaeid shrimp fishery productivity. However, the GOM region has the highest rate of wetland loss in the USA. Protection and management of these vital GOM habitats are critical to sustainable shrimp fisheries. Brown shrimp (Farfantepenaeus aztecus) are a major component of GOM fisheries. We present an approach for estimating the areal extent of suitable habitat for post-larval and juvenile brown shrimp in Mobile Bay, Alabama, using an existing habitat suitability index model for the northern GOM calculated from probabilistic survey of water quality and sediment data, land cover data, and submerged aquatic vegetation coverages. This estuarine scale approach is intended to support targeted protection and restoration of these habitats. These analyses indicate that approximately 60% of the area of Mobile Bay is categorized as suitable to near optimal for post-larval and juvenile shrimp and 38% of the area is marginally to minimally suitable. We identify potential units within Mobile Bay for targeted restoration to improve habitat suitability.  相似文献   

13.
Coastal waters in South Johore, Malaysia are polluted to various degrees. The major pollution sources are domestric wastes from human settlements, agro-based wastes from palm oil mills and rubber processing factories, industrial effluents from industrial estates and discharges from animal farms. These pollution problems have adversely affected resources such as fisheries, recreational potential as well as the general aesthetic quality of the coastal environment particularly the Inner Johore Strait. Hence proper management and control measures are urgently needed to protect and further enhance the water quality to ensure environmentally sustainable development. This study examines various management options to control the pollution in the Inner Johore Strait. The options involve partial opening as well as complete removal of the Causeway to improve the tidal flow for more effective dilution and dispersion of pollutants. Computer simulation models are used to assess the impacts of the proposed options.  相似文献   

14.
We review ways in which the new discipline of ecoinformatics is changing how environmental monitoring data are managed, synthesized, and analyzed. Rapid improvements in information technology and strong interest in biodiversity and sustainable ecosystems are driving a vigorous phase of development in ecological databases. Emerging data standards and protocols enable these data to be shared in ways that have previously been difficult. We use the U.S. Environmental Protection Agency’s National Coastal Assessment (NCA) as an example. The NCA has collected biological, chemical, and physical data from thousands of stations around the U.S. coasts since 1990. NCA data that were collected primarily to assess the ecological condition of the U.S. coasts can be used in innovative ways, such as biogeographical studies to analyze species invasions. NCA application of ecoinformatics tools leads to new possibilities for integrating the hundreds of thousands of NCA species records with other databases to address broad-scale and long-term questions such as environmental impacts, global climate change, and species invasions.  相似文献   

15.
When population is increasing, characterizing the optimal water consumption path is complicated by the fact that the underlying dynamics of the water stock is contingent on the level of the stock itself. We propose a method of constructing the optimal path in this case. Since population is increasing, the optimal consumption path may involve refraining at times from consuming the totality of the surface water flow in order to restock in groundwater for future consumption. The aquifer then serves as a means to achieve welfare increasing intertemporal transfers of surface water. Therefore the aquifer itself, as distinct from the stock of water it serves to store, may have value and the marginal valuation of water when groundwater stocks are being drawn upon should, for this reason, differ at times from the marginal valuation of water when it is drawn strictly from surface water.  相似文献   

16.
The increase of train speed and axle load is an essential goal to make the railway transport more and more competitive for passengers and freights. On this basis, the unevenness of the railway track is crucial for the safety of the railway due to the high speed of the vehicle. Although ballasted tracks represent by far the most used railway track substructure, in recent years the modernization process has led the development of the ballastless track substructures.In deciding between the use of ballasted or ballastless track substructure there are many important technical, economical and environmental factors that have to be addressed. Based on the above, the principal objective of this study was to evaluate the environmental impact of different railway track substructures including ballast, cast-in sleeper and embedded track systems on the short, medium and long term. To accomplish this task, a life cycle assessment (LCA) was carried out throughout the entire life cycle of the railway infrastructure by using the ReCiPe (H) method. Although such approach is commonly included in the environmental assessment of building products and buildings, it was rarely applied in the analysis of the environmental impacts of railway track substructure.Thus, the result of these LCA showed that ballasted tracks cause the lowest environmental impact for service lives of up to 75 years. On the other hand, the embedded track beds cause the highest environmental impacts, regardless of their service life. The highest contributor for the environmental impacts of the track beds was the steel production.The results of this study will provide relevant environmental information for engineers and decision makers to select the most adequate railway track substructures for addressing issues related to the pursuit of sustainable development.  相似文献   

17.
新疆水能、风能、光能资源丰富,合理开发利用资源,大力开发新能源、可再生能源和节能、提高能效是新疆实施可持续发展的需要。开发清洁发展机制(CDM)项目有着巨大潜力,对降低一次能源消耗,减少环境污染,促进节能减排具有重要意义。本文对此进行了论述。  相似文献   

18.
Atmospheric acidification in the Asian region is discussed from the perspectives of currently available regional measurements, and the knowledge now available from several decades of acidic deposition research in the northern mid-latitudes. The main conclusions emerge: (1) that there is insufficient information currently available to enable a quantitative assessment of the present state or future potential for atmospheric acidification across the whole region; and (2) that within the limitations imposed by (1) the possibility of future acidification in certain areas cannot be ruled out if economic development and energy use on a per capita basis evolve to the levels of the major industrial countries. These two conclusions point to the need for systematic, multidisciplinary studies covering the whole region. The studies should assess quantitatively the current levels of acidic and alkaline emissions (both natural and anthropogenic) to the atmosphere, identify the relevant chemical transformations and transport/deposition pathways in the regional atmosphere, and assess the susceptibility of regional plants, soils and groundwaters to acidification.Plenary speaker.  相似文献   

19.
环境一号卫星环境应用系统工程及其关键技术研究进展   总被引:3,自引:1,他引:2  
简介长达11年的国家重点项目“环境一号卫星环境应用系统工程及其关键技术研究”的核心内容及其重要研究成果,对环境一号卫星系统需求分析、设计理论、研制发射和运行应用全过程进行了完整的研究与实践,为环境一号卫星系统的建设、应用和业务运行奠定了重要基础。  相似文献   

20.
The occurrence and fate of polyfluoroalkyl compounds (PFCs) in the aquatic environment has been recognized as one of the emerging issues in environmental chemistry. PFCs comprise a diverse group of chemicals that are widely used as processing additives during fluoropolymer production and as surfactants in consumer applications for over 50 years. PFCs are known to be persistent, bioaccumulative and have possible adverse effects on humans and wildlife. As a result, perfluorooctane sulfonate (PFOS) has been added to the persistent organic pollutants (POPs) list of the Stockholm Convention in May 2009. However, their homologues, neutral precursor compounds and new PFCs classes continue to be produced. In general, several PFCs from different classes have been detected ubiquitously in the aqueous environment while the concentrations usually range between pg and ng per litre for individual compounds. Sources of PFCs into the aqueous environment are both point sources (e.g., wastewater treatment plant effluents) and nonpoint sources (e.g., surface runoff). The detected congener composition in environmental samples depends on their physicochemical characteristics and may provide information to their sources and transport pathways. However, the dominant transport pathways of individual PFCs to remote regions have not been conclusively characterised to date. The objective of this article is to give an overview on existing knowledge of the occurrence, fate and processes of PFCs in the aquatic environment. Finally, this article identifies knowledge gaps, presents conclusions and recommendations for future work.  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