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1.
本文在分析山一村农村产业结构的不同层次、调查该村产业结构的历年演变趋势、考虑该村资源的整体优势和部门潜力的基础上,参考萧山市社会经济发展综合规划,提出了山一村产业结构调整思路,列述了调整方案要点,并通过结构调整前后系统总负熵的计算,系统趋向有序。根据耗散结构理论,从系统总负熵值的降低,说明系统的有序度提高22%,从而验证了调整方案的合理性。  相似文献   

2.
本研究根据国家及地方有关固体废弃物管理政策的规定,结合常州市的实际,确定了常州市固体废弃物综合整治规划目标。按照尽量选用最佳实用技术,最新科学技术、区域传统有效的技术,显著削减固体废弃物产生量的技术等原则,制定了该市2000年、2010年固体废弃物综合整治规划备选方案。根据优化计算、可行性分析及其它综合比较、分析,确定了最优方案。从经济、技术、管理等方面对其进行了可行性分析。  相似文献   

3.
运用生态经济学原理,在对汉王乡生态经济系统进行现状分析、模型诊断和预测的基础上利用多目标规划方法,提出了该生态经济系统1995年和2000年生态农业建设规划方案,结果表明,按此方案实施后,系统现有资源将会得到持续,合理的利用、、生态和社会效益将显著提高。  相似文献   

4.
运用生态经济学原理,在对汉王乡生态经济系统进行现状分析、模型诊断和预测的基础上利用多目标规划方法,提出了该生态经济系统1995年和2000年生态农业建设规划方案。结果表明,按此方案实施后,系统现有资源将会得到持续、合理的利用,经济、生态和社会效益将显著提高。  相似文献   

5.
污泥处置方式对污水处理系统可持续性的影响   总被引:1,自引:0,他引:1  
脱水污泥的污染问题影响了城市污水处理厂的生存和发展,不同的中水处置方式对经济和环境的影响也不一样.将污水处理、脱水污泥和中水处置结合起来构建污水处理生态系统有利于研究污水处理的综合效益、探索促进污水处理事业可持续发展的途径.在考虑废物处理处置和排放的影响基础上,提出了针对污水处理生态系统的改进的能值分析方法和指标体系,即能值产出率(WEYR)、环境负载率(WELR) 和可持续发展指标(WESI), 指标反映了资源消耗和废物排放对系统可持续性的影响.以明镜滩污水处理生态系统作为案例,评价了"污水处理系统 污泥填埋系统 中水排放"(方案1)、"污水处理系统 陶粒生产系统 中水排放"(方案2)、"污水处理系统 聚合材料生产系统 中水排放"(方案3)和"污水处理系统 好氧堆肥生产系统 中水排放"(方案4)等4种方案的可持续性.方案1、2、3和4的WEYR分别为1.65、3.84、3.95和3.63, WELR分别为5.19、5.41、7.69和4.24,WESI分别为0.32、0.71、0.51和0.86.方案1由于未对污泥进行资源化利用,其能值产出率远远低于其他3个方案,故可持续性最低;其他三个方案的能值产出率比较接近,但方案4的环境负载率远远低于其他2个方案,故方案4的可持续性最高.结果表明,污泥利用可提高污水处理生态系统的可持续性,而不同废物利用方式由于对不可更新资源的消耗不同对污水处理生态系统的可持续性影响不一样;改进的能值分析方法适合于评价污水处理生态系统的可持续性.  相似文献   

6.
高校校园中水回用的研究与规划   总被引:22,自引:0,他引:22  
在分析某高校校园中水回用的必要性的基础上,对校园中水回用方案进行了比较,提出最佳适合高校校园中水回用的方案;同时研究了中水回用系统工艺,并对本中水回用项目的经济效益、社会效益和环境效益进行了详细的分析研究。  相似文献   

7.
以中国石化股份公司长岭分公司的30×10^4t/a催化重汽油选择性加氢脱硫装置为例。阐述了保护压缩机的控制方案:采用了润滑油压低低三选二的紧急停车控制方案、电机定子温度高高联锁停机方案、润滑油压低不允许启动压缩机等控制方案.根据现场情况、及操作习惯将ESD系统安装在中控室内,便于工人操作及监控压缩机的运行状态.表1,参5.  相似文献   

8.
阐明了格尔木市周绿色屏障建设的重要意义及其具体可行性建设方案其中的城市污水综合处理变废为宝,可作为芦苇湿地灌溉水源,同时加以净化。  相似文献   

9.
本文依据生态经济学原理,以河北省沽源牧场为例,用系统工程的模型方法探讨实现坝上生态经济系统良性循环的途径。作者采用系统动态模型作为主干模型,表现整个系统的结构和主要反馈关系,用蒙特卡罗法模拟风蚀对土地肥力的影响,综合运用定性定量技术、系数模拟、灰色系统模型等方法进行预测,借助电子计算机建立一个能够反映坝上生态经济系统发展势态和变化规律的“生态经济实验室”;并以实际工作经验和定性分析为基础,制订若干方案,根据计算机仿真结果进行综合评判,寻求农牧业生产与自然环境相互促进,持续发展的策略和措施。  相似文献   

10.
运用描述系统循环过程中动力与阻力相互关系的数学模型,对河北省曲周县、邯郸市、马头镇、北京郊区窦店村、湖南桃源县观山村5个不同类型的农业生态系统的循环功能分别进行了分析与计算,发现模型中的系数K适于用来综合评价系统的循环功能。K值的大小取决于其他相关的指标,这些处于不同层次上的指标构成了一个简单实用的综合评价农业生态系统的指标体系。  相似文献   

11.
This paper presents a generic framework for assessing inherent climate change hazards in coastal environments through a combined coastal classification and hazard evaluation system. The framework is developed to be used at scales relevant for regional and national planning and aims to cover all coastal environments worldwide through a specially designed coastal classification system containing 113 generic coastal types. The framework provides information on the degree to which key climate change hazards are inherent in a particular coastal environment, and covers the hazards of ecosystem disruption, gradual inundation, salt water intrusion, erosion and flooding. The system includes a total of 565 individual hazard evaluations, each graduated into four different hazard levels based on a scientific literature review. The framework uses a simple assessment methodology with limited data and computing requirements, allowing for application in developing country settings. It is presented as a graphical tool—the Coastal Hazard Wheel—to ease its application for planning purposes.  相似文献   

12.
A generic ecosystem model has been developed for estimating the potential production of shellfish culture and the effect of that cultivation on the pelagic ecosystem in sheltered coastal waters. The model describes the dynamics of a simple food web, nutrient cycling and growth of shellfish. The design of the model is closely tied to the temporal and spatial scales that are important in determining the sustainable production level for a particular embayment. The pelagic ecosystem, mussel energetics, population dynamics and hydrodynamics are coupled to allow fully dynamic predictions of the effect of the shellfish density. When applied to Beatrix Bay, an intensive culture embayment in the Pelorus Sound of New Zealand, the model successfully captured main features of the observed system behaviour. The hydrodynamic regime of the bay controls mussel growth and production. Although high fluxes of water into the bay suppress nutrient and carbon cycling signals in the system, the model simulations demonstrated that the mussel cultivation can have considerable effects on the ecosystem of the bay including food depletion and nutrient cycling. One of the most obvious effects is nutrient enhancement through mussel excretion at low cultivation densities, which promotes primary production particularly during the N-limitation period in summer. The sensitivity analysis identified uncertainty in some parameters and indicated areas for which experimental studies could lead to model improvement. The modelling exercise has established a primary predictive tool for managing mussel aquaculture of a coastal embayment to estimate relationships between the stock level and the growth rate of mussels, and the potentially achievable harvest and stocking density.  相似文献   

13.
The Reynolds transport theorem (RTT) from mathematics and engineering has a rich history of success in mass transport dynamics and traditional thermodynamics. This paper introduces RTT as a complementary approach to traditional compartmental methods used in ecological modeling and network analysis. A universal system equation for a generic flow quantity is developed into a generic open-system differential expression for conservation of energy. Nonadiabatic systems are defined and incorporated into control volume (CV) and control surface (CS) perspectives of RTT where reductive assumptions in empirical data are then formally introduced, reviewed, and appropriately implemented. Compartment models are abstract, time-dependent systems of simultaneous differential equations describing storage and flow of conservative quantities between interconnected entities (the compartments). As such, they represent a set of flexible and somewhat informal, assumptions, definitions, algebraic manipulations, and graphical depictions subject to influence and selectively parsed expression by the modeler. In comparison, RTT compartment models are more rigorous and formal integro-differential equations and graphics initiated by the RTT universal system equation, forcing an ordered identification of simplifying assumptions, ending with clearly identified depictions of the transfer and transport of conservative substances in physical space and time. They are less abstract in the rigor of their equation development leaving less ambiguity to modeler discretion. They achieve greater consistency with other RTT compartment style models while possibly generating greater conformity with physical reality. Characteristics of the RTT approach are compared with those of a traditional compartment model of energy flow in an intertidal oyster-reef community.  相似文献   

14.
This paper describes a procedure for evaluating the desertification risk in threatened areas. The procedure is based on an eight-equation dynamic model of a generic human–resource system that can be applied to different desertification syndromes. For each application, interest focuses on finding all the possible long-term final states of the system and on defining the conditions that mark out sustainability and long-term desertification by means of unambiguous specific parameter relations. The procedure is applied to three typified cases in Spain: (A) rainfed crops in areas with high soil erosion risk; (B) irrigated intensive agricultural systems; and (C) commercial rangelands. Results show that, in case A, high profit scenarios are responsible for the final extension of desertification but do not determine the specific threshold between sustainability and desertification. They do, however, in cases B and C.  相似文献   

15.
Population viability analysis (PVA) is useful in management of imperiled species. Applications range from research design, threat assessment, and development of management frameworks. Given the importance of PVAs, it is essential that they be rigorous and adhere to widely accepted guidelines; however, the quality of published PVAs is rarely assessed. We evaluated the quality of 160 PVAs of 144 species of birds and mammals published in peer-reviewed journals from 1990 to 2017. We hypothesized that PVA quality would be lower with generic programs than with custom-built programs; be higher for those developed for imperiled species; change over time; and be higher for those published in journals with high impact factors (IFs). Each included study was evaluated based on answers to an evaluation framework containing 32 questions reflecting whether and to what extent the PVA study adhered to published PVA guidelines or contained important PVA components. All measures of PVA quality were generally lower for studies based on generic programs. Conservation status of the species did not affect any measure of PVA quality, but PVAs published in high IF journals were of higher quality. Quality generally declined over time, suggesting the quantitative literacy of PVA practitioners has not increased over time or that PVAs developed by unskilled users are being published in peer-reviewed journals. Only 18.1% of studies were of high quality (score >75%), which is troubling because poor-quality PVAs could misinform conservation decisions. We call for increased scrutiny of PVAs by journal editors and reviewers. Our evaluation framework can be used for this purpose. Because poor-quality PVAs continue to be published, we recommend caution while using PVA results in conservation decision making without thoroughly assessing the PVA quality.  相似文献   

16.
Confusion abounds regarding the relative generic status of many member species of the squid family Loliginidae. A taxonomie reorganisation within the family has been proposed in whichLoligo species from the Indo-Pacific possessing photophores on the ink sac, includingLogligo edulis andLoligo chinensis, are removed to the newly created genusPhotololigo. This system of classification has not however gained general acceptance, and some authors have continued to refer to these species asLoligo. Here biochemical genetic data gathered using allozyme electrophoresis are presented supporting the assertion thatL. edulis andL. chinensis should indeed be positioned in a genus distinct from that characterised by the type speciesLoligo vulgaris vulgaris. Cluster analysis of allele frequency data from 22 putative enzyme-coding loci suggests thatL. edulis andL. chinensis are as genetically distant fromL. vulgaris vulgaris as are members of the confamilial generaAlloteuthis, Uroteuthis andSepioteuthis, and as such warrant separate generic status. We conclude that the genusPhotololigo is valid.  相似文献   

17.
Allometric equations allow aboveground tree biomass and carbon stock to be estimated from tree size. The allometric scaling theory suggests the existence of a universal power-law relationship between tree biomass and tree diameter with a fixed scaling exponent close to 8/3. In addition, generic empirical models, like Chave's or Brown's models, have been proposed for tropical forests in America and Asia. These generic models have been used to estimate forest biomass and carbon worldwide. However, tree allometry depends on environmental and genetic factors that vary from region to region. Consequently, theoretical models that include too few ecological explicative variables or empirical generic models that have been calibrated at particular sites are unlikely to yield accurate tree biomass estimates at other sites. In this study, we based our analysis on a destructive sample of 481 trees in Madagascar spiny dry and moist forests characterized by a high rate of endemism (> 95%). We show that, among the available generic allometric models, Chave's model including diameter, height, and wood specific gravity as explicative variables for a particular forest type (dry, moist, or wet tropical forest) was the only one that gave accurate tree biomass estimates for Madagascar (R2 > 83%, bias < 6%), with estimates comparable to those obtained with regional allometric models. When biomass allometric models are not available for a given forest site, this result shows that a simple height-diameter allometry is needed to accurately estimate biomass and carbon stock from plot inventories.  相似文献   

18.
In the present study, we demonstrate an integrated modeling approach for predicting internal tissue concentrations of chemicals by coupling a multimedia environmental model and a generic physiologically based pharmacokinetic (PBPK) model. A case study was designed for a region situated on the Seine river watershed, downstream of the Paris megacity, and for benzo(a)pyrene emitted from industrial zones in the region. In this case study, these two models are linked only by water intake from riverine system for the multimedia model into human body for the PBPK model. The limited monitoring data sets of B(a)P concentrations in bottom sediment and in raw river water, obtained at the downstream of Paris, were used to re-construct long-term daily concentrations of B(a)P in river water. The re-construction of long-term series of B(a)P level played a key role for the intermediate model calibration (conducted in multimedia model) and thus for improving model input to PBPK model. In order to take into account the parametric uncertainty in the model inputs, some input parameters relevant for the multimedia model were given by probability density functions (PDFs); some generic PDFs were updated with site-specific measurements by a Bayesian approach. The results of this study showed that the multimedia model fits well with actual annual measurements in sediments over one decade. No accumulation of B(a)P in the organs was observed. In conclusion, this case study demonstrated the feasibility of a full-chain assessment combining multimedia environmental predictions and PBPK modeling, including uncertainty and sensitivity analyses.  相似文献   

19.
Although problems may occur in the implementation of environmental management systems (EMS) in agriculture, an EMS can be a suitable farm management tool. In the past, pilot projects have revealed that the environmental audit as a base analysis still contains methodical weak points. A uniform procedure for the implementation process is not possible due to variations in the structure of farms in Germany with respect to size, employee structure and capital resources. While the resource costs which occur on larger farms can lead to a benefit due to increased efficiency, this has not yet been established for smaller farms. In these cases, other measures such as the implementation of generic management systems (especially environment and quality) or a farm-specific implementation of a management system without the cost-intensive certification may be a possible alternative.  相似文献   

20.
孙万国 《生态环境》2011,20(12):1966-1969
科学合理的制度安排必然是建立在对现存制度不合理的批判之上。湿地恢复补偿制度改革必须以现行湿地恢复补偿制度的现实性存在为基础和出发点,通过对现行湿地恢复补偿制度设计的目标和制度缺陷进行理性分析,为新的湿地恢复补偿制度设计与安排提供价值坐标,以保障湿地恢复补偿制度价值的实现。现行湿地恢复补偿制度规定存在着合法性、合理性和权威性等诸多悖论,成为湿地恢复补偿实践产生冲突的制度根源,并已构成当前环境友好型和资源节约型社会实践推进的严重障碍。  相似文献   

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