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 15 毫秒
1.
Coastal tourism continues to be an important industry for many countries. Improper planning, however, frequently results in the deterioration of the coastal waters in newly opened tourist resorts. Avoidance of this situation can be achieved by predetermining the bearing capacity of the site, which is very costly and time consuming. After an extensive study, the author previously had developed an equation by which the effects of the increase in tourist population on coastal water quality can be determined. The microbial pollution, which is indicated by coliform concentration, is a function of human population, intensity of light, turbidity, temperature of seawater, human population density, and the coastal characteristics coefficients. By using the equation, the bering capacity of a site can be determined easily. The purpose of the present study is the verification of the equation. To achieve this, a study was conducted at another tourist resourt, Cesme, where 1764 observations were made. The results, regardless of the small differences in the coefficients obtained, indicate that the proposed method can be used to determine the bearing capacity of the system as well as the extent of microbial pollution. This accelerates and simplifies the prediction and the prevention of possible negative effects that can be caused by opening coastal areas to tourism.  相似文献   

2.
Effluent subsamples are usually aggregated into flow or time proportional samples before analysis. Although this provides information on average process conditions, that on process variability is lost by compositing. Fisher's information is defined and used to estimate the loss due to compositing. The results of simulations based on parameters derived from actual waste streams support the fact that random grabs serve as well as composite samples for monitoring purposes. These findings favor changes in regulatory practice to allow compliance to be demonstrated by grab sample averages. Reporting requirements based on moving averages are shown to be inferior to those based on averages taken over nonoverlapping time periods.  相似文献   

3.
Conservationists and environmental economists have promoted the extraction of non–timber forest products (NTFP) as an alternative to forest conversion and as a means to benefit forest peoples. This article discusses the development of NTFP economic analyses and some economic, biological and socio–cultural constraints on the use of forest resources and methodological limitations of NTFP investigations. Several case studies document the importance of the forest in both North and South America. While studies differ in their conclusions regarding the sustainability of NTFP extraction, most researchers agree that sustainable harvesting is rare. The article argues for additional considerations that transcend the biological and economic concerns. While forests provide the basis of material culture for peoples that inhabit them, they are also linked intrinsically to the religion, mythology, and psyche of native peoples. Conservationists have an ethical obligation to consider the needs and desires of these people in conjunction with conservation and management plans.  相似文献   

4.
花生、大豆与芝麻复合乳饮料的研制   总被引:1,自引:0,他引:1  
报道了以花生、大豆和芝麻为主要原料,并按一定比例制备出以花生为主体风味的复合蛋白乳保健饮料的基本工艺流程,同时对获得良好风味的花生、大豆与芝麻复合蛋白乳饮料的基本工艺条件、操作要求及影响产品质量的因素也作了简要探讨与说明。  相似文献   

5.
Studies of irrigation drainage in the Western United States have documented some of the effects of irrigating land without first understanding and then considering implications from the interdependent relationships of hydrology, geology, geochemistry, biology, climatology, land use and socio-economic issues. In studies completed in 26 areas, selenium is the trace element found most often at elevated concentrations in water, bottom material and biota. Boron, arsenic, mercury and pesticide residues have also been found at elevated levels in some areas. Bioaccumulation of constituents associated with irrigation drainage is common. As the world experiences an explosive population growth, particularly in poorer countries, demands for food production from marginal, submarginal and newly irrigated soils are likely to cause severe adverse environmental impacts from allocation of limited water resources and contamination from irrigation drainwater. Cultivated marginal land is highly susceptible to degradation from soil erosion, salinization and waterlogging, not withstanding release of contaminants from application of irrigation water.  相似文献   

6.
An urban population of ducks in Puyallup, Washington, USA was studied for 14 consecutive months beginning in November 1978. Observations were made weekly from four study sites where ducks would congregate at early morning hours. Factors contributing to the presence of waterfowl in Puyallyup included abundant food supplies and a creek corridor that connected fragmented habitats in the urban area to the larger rural populations of waterfowl. Mallards (Anas platyrhynchos) were the most abundant of the 13 species observed and were the only ducks remaining during the nesting season. Habitat size and complexity were important factors influencing the species diversity of a particular site. Nesting success of mallards was poor due to limited distribution of nesting habitat, intraspecific aggression, and human disturbance. Both site-specific and more broad-based strategies are suggested for managing and planning for duck populations in urban areas.  相似文献   

7.
Food is a basic human need and therefore a basic human right. While food output has increased to a level where there is enough food produced to feed the world, still millions starve. Using the concept of capitalist world economy as a framework, this paper provides a structural analysis of the food production and distribution system within monopoly capitalism and its implications for countries of the underdeveloped world. Focusing on the impact of a dominant world food supply system on indigenous systems (particularly through the rise of science, technology, and monopoly capital), considerations relating to environmental use and food production and distribution are raised. Finally a call is made for a new agricultural ethic.  相似文献   

8.
9.
This report briefly describes the implementation process involving nature conservation considerations in forestry, according to a recently passed law in Sweden. Described are the forestry and political systems in Sweden regarding nature conservation in forestry, as well as of the administrative process involved when a forest is going to be clearcut. Conclusions are based upon the conditions and outcome of two clearcutting cases outlined in this report, and are focused on the interactions and control functions among various agencies and levels of government. The policy on the consideration of nature in forestry is, to a large extent, formed at a very low level in the bureaucracy and is subject to negotiation from case to case. Checkups between different agencies as a form of concurrent government become important means of implementing environmental considerations in forestry, having the split roles and interests of the authorities in mind.  相似文献   

10.
Large-scale sample surveys to estimate abundance and distribution of organisms and their habitats are increasingly important in ecological studies. Multi-stage sampling (MSS) is especially suited to large-scale surveys because of the natural clustering of resources. To illustrate an application, we: (1) designed a stratified MSS to estimate late autumn abundance (kg/ha) of rice seeds in harvested fields as food for waterfowl wintering in the Mississippi Alluvial Valley (MAV); (2) investigated options for improving the MSS design; and (3) compared statistical and cost efficiency of MSS to simulated simple random sampling (SRS). During 2000-2002, we sampled 25-35 landowners per year, 1 or 2 fields per landowner per year, and measured seed mass in 10 soil cores collected within each field. Analysis of variance components and costs for each stage of the survey design indicated that collecting 10 soil cores per field was near the optimum of 11-15, whereas sampling >1 field per landowner provided few benefits because data from fields within landowners were highly correlated. Coefficients of variation (CV) of annual estimates of rice abundance ranged from 0.23 to 0.31 and were limited by variation among landowners and the number of landowners sampled. Design effects representing the statistical efficiency of MSS relative to SRS ranged from 3.2 to 9.0, and simulations indicated SRS would cost, on average, 1.4 times more than MSS because clustering of sample units in MSS decreased travel costs. We recommend MSS as a potential sampling strategy for large-scale natural resource surveys and specifically for future surveys of the availability of rice as food for waterfowl in the MAV and similar areas.  相似文献   

11.
Management of natural environment sites is becoming increasingly complex because of the influx of urbanized society into wildland areas. This worldwide phenomenon impacts a wide range of countries. In southern California ethnicity is often a major factor influencing recreation site use and behavior at sites in the wildland-urban interface. This study investigated the role of ethnicity and race on the use patterns, perception of environment, and recreation behaviors at an outdoor recreation site visited by an ethnically diverse population. Two research questions were asked: (1) What ethnic groups engage in outdoor recreation at this site, and (2) what differences can be assigned to these various groups? Data were collected from 250 recreationists during 1991. Three major ethnic groups were identified, and statistically significant differences were found in the importance of site attributes, activity participation, and in preferred and actual communication channels. Management implications and strategies based on group differences are discussed.  相似文献   

12.
Light has received very less attention as a selective factor, probably because the changing vertical light gradient makes light a rather complex factor when compared with the nutrient competition. In our study we modified an analytically tractable model based upon the Beer–Lambert law. The study aimed to predict the outcome of phytoplankton competition for light, on the basis of field measurements. When we considered competition theory, Fragilaria was found to be more competitive than other genera. The overall result shows that the trends flow in the following manner; Fragilaria > Gomphonema > Diatoma > Amphora > Achnanthes.  相似文献   

13.
Farmers in a southwestern Ontario watershed were surveyed to determine factors influencing their attitudes towards adoption of soil conservation practices. The majority of farmers in the watershed were internally motivated which indicates they believe that their own actions determine their successes and failures. Most respondents were also environmentally oriented. However, although many farmers in the study area have adopted crop rotations and cross-slope tillage, the adoption rate of conservation tillage is low. The survey suggests that the low adoption rate may be more a function of perceived economic risk associated with the tillage practice than lack of farmer motivation.  相似文献   

14.
/ Rivers transport sediment from eroding uplands to depositional areas near sea level. If the continuity of sediment transport is interrupted by dams or removal of sediment from the channel by gravel mining, the flow may become sediment-starved (hungry water) and prone to erode the channel bed and banks, producing channel incision (downcutting), coarsening of bed material, and loss of spawning gravels for salmon and trout (as smaller gravels are transported without replacement from upstream). Gravel is artificially added to the River Rhine to prevent further incision and to many other rivers in attempts to restore spawning habitat. It is possible to pass incoming sediment through some small reservoirs, thereby maintaining the continuity of sediment transport through the system. Damming and mining have reduced sediment delivery from rivers to many coastal areas, leading to accelerated beach erosion. Sand and gravel are mined for construction aggregate from river channel and floodplains. In-channel mining commonly causes incision, which may propagate up- and downstream of the mine, undermining bridges, inducing channel instability, and lowering alluvial water tables. Floodplain gravel pits have the potential to become wildlife habitat upon reclamation, but may be captured by the active channel and thereby become instream pits. Management of sand and gravel in rivers must be done on a regional basis, restoring the continuity of sediment transport where possible and encouraging alternatives to river-derived aggregate sources.KEY WORDS: Dams; Aquatic habitat; Sediment transport; Erosion; Sedimentation; Gravel mining  相似文献   

15.
Financial markets recognise maximisation of expected value (E), in an essentially risk-neutral context, as the main corporate financial objective of private enterprise. This may be valid for large, integrated mining companies. Yet, most junior and middle-size exploration companies behave in a risk-averse fashion when making decisions about progressively more expensive exploration programs. From their perspective, a potential increase in expected value from either an increase in target value or related probability of discovery, or both, may not be a sufficient incentive to embark in an exploration programme if the resultant increase in expected value is accompanied by a significant increase in possible maximum loss. Risk-averse explorers may be unwilling to bear larger, albeit less probable losses, when the cost of successive exploration programmes is taken into account. The paper provides a practical methodology for such explorers to optimise the decision whether to progress to the next stage of exploration or to farm out a risky project. It uses a decision-tree model incorporating the effectiveness of the proposed exploration programme, the explorer's risk tolerance and related utility values and the probability distribution of the possible value of the exploration target.  相似文献   

16.
A geo-referenced environmental fate model was developed for analyzing unsteady-state dispersion and distribution of chemicals in multimedia environmental systems. Chemical transport processes were formulated in seven environmental compartments of air, canopy, surface soil, root-zone soil, vadose-zone soil, surface water, and sediment. The model assumed that the compartments were completely mixed and chemical equilibrium was established instantaneously between the sub-compartments within each compartment. A fugacity approach was utilized to formulate the mechanisms of diffusion, advection, physical interfacial transport, and transformation reactions. The governing equations of chemical mass balances in the environmental compartments were solved simultaneously to reflect the interactions between the compartments. A geographic information system (GIS) database and geospatial analysis were integrated into the chemical transport simulation to provide spatially explicit estimations of model parameters at watershed scale. Temporal variations of the environmental properties and source emissions were also considered in the parameter estimations. The outputs of the model included time-dependent chemical concentrations in each compartment and its sub-compartments, and inter-media mass fluxes between adjacent compartments at daily time steps.  相似文献   

17.
Habitat re-creation is one of the multiple faces of biodiversity restoration and encompasses the attempts to reconstruct an ecosystem on severely disturbed sites with little left to restore. Afforestation of abandoned or marginal agricultural land is an important tool for the re-creation of forest ecosystems and re-establishment of functional habitat networks for the maintenance of biodiversity. This study was performed in the context of the Danish-Lithuanian project ‘Afforestation of abandoned agricultural land based on sustainable land use planning and environmentally sound forest management’. The study assessed how habitat re-creation as designed in alternative afforestation plans for two administrative regions in Lithuania will affect the functionality of the landscapes for bird species of conservation concern. Spatial analysis of the forest cover was performed under existing and proposed conditions using general landscape ecological principles concerning core and edge habitats as well as nearest-neighbour metrics. The results show that the use of general criteria may result in proportionally negative changes in the availability of some forest habitats relative to changes in total forest cover, thus leading to less significant improvements in the habitats of many naturally occurring (and even protected) species compared to what would be expected from changes in forest cover alone. To solve this dilemma it is suggested that the requirements of focal species and quantitative conservation objectives should be considered in a spatially explicit – each main forest type. It is concluded that to ensure functionality of habitat networks, knowledge and experience from the fields of landscape ecology and conservation biology should be more commonly incorporated into afforestation planning.  相似文献   

18.
The Kabartal wetland situated in the upper Indo-Gangetic flood plains in northern India is significant because of its hydrological and ecological services, and the socio-economic and cultural values that it represents. Despite being designated as a wildlife sanctuary, this wetland is under threat from anthropogenic pressures. As in the case of most wetlands, the reason is incomplete information on its ecological services and functions, breakdown of traditional management structures and the lack of appropriate and recognized property rights. Our study assesses the economic linkages between the Kabartal wetland and the local people living around it, through socio-economic surveys and Contingent Valuation Method (CVM). The major objective of the study was to determine the importance of this wetland to the local people and to give an indication of the distribution of the benefits among various stakeholders. The people in the region are poor, have low literacy levels and high dependence on Kabartal and more than 50% want that the wetland should be drained and the land used for agriculture. However, they are willing to participate in collaborative management initiatives with the state. The willingness of people to accept compensation, as an alternative to access to Kabartal wetland, regressed on various socio-economic and attitudinal parameters, gave an estimated mean value of US $27,500 per household over a period of 60 years. This value is a pointer of the total value of access to Kabartal wetland to the surrounding villagers and would be useful when decisions to compensate people for lost access to Kabartal are made.  相似文献   

19.
In biologically mega-diverse countries that are undergoing rapid human landscape transformation, it is important to understand and model the patterns of land cover change. This problem is particularly acute in Colombia, where lowland forests are being rapidly cleared for cropping and ranching. We apply a conceptual model with a nested set of a priori predictions to analyse the spatial and temporal patterns of land cover change for six 50-100 km(2) case study areas in lowland ecosystems of Colombia. Our analysis included soil fertility, a cost-distance function, and neighbourhood of forest and secondary vegetation cover as independent variables. Deforestation and forest regrowth are tested using logistic regression analysis and an information criterion approach to rank the models and predictor variables. The results show that: (a) overall the process of deforestation is better predicted by the full model containing all variables, while for regrowth the model containing only the auto-correlated neighbourhood terms is a better predictor; (b) overall consistent patterns emerge, although there are variations across regions and time; and (c) during the transformation process, both the order of importance and significance of the drivers change. Forest cover follows a consistent logistic decline pattern across regions, with introduced pastures being the major replacement land cover type. Forest stabilizes at 2-10% of the original cover, with an average patch size of 15.4 (+/-9.2)ha. We discuss the implications of the observed patterns and rates of land cover change for conservation planning in countries with high rates of deforestation.  相似文献   

20.
Today world population lives in a new electromagnetic environment, characterized with (i) around the clock enforcement of chronic exposure of all age and gender groups to a wide range of modulated electromagnetic fields (EMF) from base stations; (ii) daily, repeated from early childhood throughout entire life exposure to EMF RF mobile phone the brain and vestibular receptor apparatus and auditory analyzers, located directly “under the EMF beam” in the inner ear. On the other hand, the world science and epidemiology is missing well-planned and executed research results of prolonged exposure of EMF RF on the brain. International recommendations and domestic guidelines do not include changing conditions of RF EMF on the population: the brain has become a critical organ, and the children entered the risk group. The population continues to actively use the mobile phone. In this situation the problem of assessing the risk of mobile communications has become a social and ethical.  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