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931.
在综合考虑各种社会经济影响因素的基础上,从景观格局、景观功能、景观受胁迫性等3方面构建评价指标体系,并据此开展规划实施的景观生态影响综合评价.利用计算机模型模拟各种规划替代方案的景观格局动态,并通过分析景观格局指数的变化实现对规划替代方案的比选,建立起规划环评中景观生态学方法应用的技术框架,进而应用于大连森林公园东区建设规划环境影响评价.研究结果表明,规划的实施有利于区域景观格局和功能的改善,但会导致人类对景观干扰和胁迫加重.采用以旅游经济为主导型方案(替代方案1),景观破碎化趋势明显;以生态优先主导型方案(替代方案2),景观向整合集约化趋势发展. 相似文献
932.
The source–pathway–receptor (SPR) approach to human exposure and risk assessment contains considerable uncertainty when using
the refined modelling approaches to pollutant transport and dispersal, not least in how compounds of concern might be prioritised,
proxy or indicator substances identified and the basic environmental and toxicological data collected. The impact of external
environmental variables, urban systems and lifestyle is still poorly understood. This determines exposure of individuals and
there are a number of methods being developed to provide more reliable spatial assessments. Within the human body, the dynamics
of pollutants and effects on target organs from diffuse, transient sources of exposure sets ambitious challenges for traditional
risk assessment approaches. Considerable potential exists in the application of, e.g. physiologically based pharmacokinetic
(PBPK) models. The reduction in uncertainties associated with the effects of contaminants on humans, transport and dynamics
influencing exposure, implications of adult versus child exposure and lifestyle and the development of realistic toxicological
and exposure data are all highlighted as urgent research needs. The potential to integrate environmental with toxicological
models provides the next phase of research opportunity and should be used to drive empirical and model assessments. 相似文献
933.
WARM (Water Accounting Rice Model) simulates paddy rice (Oryza sativa L.), based on temperature-driven development and radiation-driven crop growth. It also simulates: biomass partitioning, floodwater effect on temperature, spikelet sterility, floodwater and chemicals management, and soil hydrology. Biomass estimates from WARM were evaluated and compared with the ones from two generic crop models (CropSyst, WOFOST). The test-area was the Po Valley (Italy). Data collected at six sites from 1989 to 2004 from rice crops grown under flooded and non-limiting conditions were split into a calibration (to estimate some model parameters) and a validation set. For model evaluation, a fuzzy-logic based multiple-metrics indicator (MQI) was used: 0 (best) ≤ MQI ≤ 1 (worst). WARM estimates compared well with the actual data (mean MQI = 0.037 against 0.167 and 0.173 with CropSyst and WOFOST, respectively). On an average, the three models performed similarly for individual validation metrics such as modelling efficiency (EF > 0.90) and correlation coefficient (R > 0.98). WARM performed best in a weighed measure of the Akaike Information Criterion: (worst) 0<wk<1 (best), considering estimation accuracy and number of parameters required to achieve it (mean wk=0.983 against 0.007 and ∼0.000 with CropSyst and WOFOST, respectively). WARM results were sensitive to 30% of the model parameters (ratio being lower with both CropSyst, <10%, and WOFOST, <20%), but appeared the easiest model to use because of the lowest number of crop parameters required (10 against 15 and 34 with CropSyst and WOFOST, respectively). This study provides a concrete example of the possibilities offered using a range of assessment metrics to evaluate model estimates, predictive capabilities, and complexity. 相似文献
934.
The study described in this paper developed a model of animal movement, which explicitly recognised each individual as the central unit of measure. The model was developed by learning from a real dataset that measured and calculated, for individual cows in a herd, their linear and angular positions and directional and angular speeds. Two learning algorithms were implemented: a Hidden Markov model (HMM) and a long-term prediction algorithm. It is shown that a HMM can be used to describe the animal's movement and state transition behaviour within several “stay” areas where cows remained for long periods. Model parameters were estimated for hidden behaviour states such as relocating, foraging and bedding. For cows’ movement between the “stay” areas a long-term prediction algorithm was implemented. By combining these two algorithms it was possible to develop a successful model, which achieved similar results to the animal behaviour data collected. This modelling methodology could easily be applied to interactions of other animal species. 相似文献
935.
936.
The Kidd Creek Cu–Zn sulfide mine is located near Timmins, Ontario. Mill tailings are thickened and deposited as a slurry in a circular impoundment with an area of approximately 1200 ha. Deposition of tailings as a thickened slurry from a central discharge ramp results in a conical-shaped tailings deposit with low perimeter dykes, a uniform grain-size distribution, uniform and low hydraulic conductivity, and a tension-saturated zone above the water table up to 5 to 6 m thick. These characteristics provide benefits over conventionally disposed tailings with respect to tailings management. The thick tension-saturated zone within the tailings limits the thickness of unsaturated tailings that are susceptible to rapid sulfide oxidation. The conical shape of the deposit results in the formation of a recharge area near the centre of the impoundment and discharge in the peripheral areas. In contrast, the elevated nature of many conventional, unthickened tailings impoundments results in recharge over most of the surface of the impoundment, with discharge occurring outside the impoundment through large containment dykes. Three-dimensional pore water flow modelling suggests that approximately 90% of the total discharge from the thickened tailings occurs within the tailings impoundment. When discharge is confined within the impoundment, there is improved control over low-quality effluent, and an opportunity to design passive control measures to reduce treatment costs and minimize environmental impacts. 相似文献
937.
关于中国西部“山川秀美”再造的思考——兼论西部生态安全建设中的防灾减灾 总被引:1,自引:0,他引:1
再造一个“山川秀美”的大西北 ,展现出一幅理想的人与自然依存的场景。笔者为此给出独特的思考和科学的见解 :要实现这一目标 ,必须研讨“山川秀美”的科学内涵 ,以恢复大西北自然生态安全环境为基础 ,以防灾减灾 ,保护人与自然为手段 ,依靠科技进步 ,坚持可持续发展战略 ,从长远利益并结合地区实际 ,才能真正实现人与自然和谐共存的“山川秀美” 相似文献
938.
A general mathematical model has been developed as a tool for environmental evaluation of industrial chemical processes. This model is based on the life cycle assessment (LCA) methodology and includes a modular and cumulative conceptual approximation. Accordingly, the model considers the potential effects on the environment caused by mass, energy and exergy flows. For environmental loads related with mass flows, two main categories are defined: pollution and perturbation environmental effects. Whereas for the environmental effect associated with energy flows, a factor defined as “energy dissipation” is employed, and similarly for exergy flows, a “exergy destruction” parameter is used. The measurement unit employed throughout the model is expressed in terms of “potential environmental impact units/hour”. As an example study case, the integrated production chain (IPC) for nitric acid production in the Colombian context is evaluated. This particular IPC includes the ammonia production plant, energy plants and main process plant. The results demonstrate that for environmental perturbation effects based on mass flows, the main contribution in the IPC corresponds to the energy plants. In the case of pollution environmental loads, the principal contribution relates to ammonia production. Regarding environmental effects associated with energy flows, the highest “energy dissipation” factor corresponds to the main process, followed in order by the ammonia process. Finally, for the effect denominated as “exergy destruction”, it could be established that Colombian energy plants show the highest contribution in the IPC. 相似文献
939.
Detection of discontinuities in landscape patterns is a crucial problem both in ecology and in environmental sciences since they may indicate substantial scale changes in generating and maintaining processes of landscape patches. This paper presents a statistical procedure for detecting distinct scales of pattern for irregular patch mosaics using fractal analysis. The method suggested is based on a piecewise regression model given by fitting different regression lines to different ranges of patches ordered according to patch size (area). Proper shift-points, where discontinuities occur, are then identified by means of an iterative procedure. Further statistical tests are applied in order to verify the statistical significance of the best models selected. Compared to the method proposed by Krummel et al. (1987), the procedure described here is not influenced by subjective choices of initial parameters. The procedure was applied to landscape pattern analysis of irregular patch mosaics (CORINE biotopes) of a watershed within the Map of the Italian Nature Project. Results for three different CORINE patch types are herein presented revealing different scaling properties with special pattern organizations linked to ecological traits of vegetation communities and human disturbance. 相似文献
940.
城市景观生态价值的边际效用分析法 总被引:4,自引:0,他引:4
宗跃光 《城市环境与城市生态》1998,(4)
本文从城市景观价值量的测定出发,引入经济学的效用和边际效用概念.提出城市景观价值量边际效用分析法,在理想状态下,以城市景观结构边际效用递减率为依据。通过面积-效益损益比,揭示城市景观经济效益与环境效益之间的内在联系.结果表明:在城市自然景观面积按比例递减的条件下,不但使环境效益损失趋于无穷大,而且使增加人工景观面积带来的城市经济效益锐减。 相似文献