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1.
随着国家对流域水质改善要求的逐渐提高,流域污染源管理变得日益重要。提出了一种基于CPNTOOLS的辽河流域畜禽养殖行业污染源仿真技术,并采用CPNTOOLS软件对辽河流域内一家典型畜禽养殖基地进行了仿真研究,经过多次仿真与数据统计分析,分别得出了该畜禽养殖基地的CODCr,BOD5,NH3-N,TP,TN日排放量的正态分布均值在90%,95%,99%置信水平下的置信区间,并结合排水量分别计算出各污染物指标排放浓度的区间。结合BAT处理技术对污染物浓度削减进行了计算仿真,并得出了处理后CODCr,BOD5,NH3-N,TP,TN排放浓度的正态分布均值在90%,95%,99%置信水平下的置信区间以及排放浓度的极大值和极小值。  相似文献   
2.
针对城市热岛效应引起城区浅层土地温场升高这一观测结果,采用室内快速模拟试验方法,对城区酸性土壤腐蚀混凝土材料的温度效应开展了试验研究.试验研究了在温度为5℃、20℃和40℃条件下,混凝土试样在酸浓度分别为0%、5%和10%的沙土介质中放置30 d、90 d后的抗压强度变化规律,并对混凝土试样在腐蚀过程中的腐蚀系数变化规...  相似文献   
3.
中国城市绿化评价系统比较分析   总被引:1,自引:0,他引:1  
城市绿化在城市环境建设中起着至关重要的作用。为衡量城市绿化建设的水平和指导城市规划,有必要建立科学的绿化评价体系。分析和比较了中国现有的4种国家级城市绿化评价体系:国家园林城市标准、全国绿化模范城市标准、国家森林城市标准和国家生态园林城市标准,并从易得性、可比性、简易性、客观性等4个方面对具体的指标进行了分析。4种绿化...  相似文献   
4.
The quality of the waters collected from R. Arno was examined in the period September 1988 to December 1989. A first campaign in September/October 1988, during a period of low water, gives a general picture of pollution conditions along the river from the source to the mouth. the river appears to be heavily polluted immediately downstream of Florence and in the area of the textile industry.

In the second campaign, through the whole year 1989, particular attention has been given to the Florence area; the most significant results, compared with those from a previous investigation carried out in 1971, show only a small reduction of the pollution load, due to the shortage and inadequacy of wastewater depuration. Some considerations are reported on pollution drop with full spate.  相似文献   
5.
    
Urban forests deliver essential environmental services to the city in which they grow. Few entities are better positioned to provide consistent broad-scale maintenance and protection of urban trees than are large downtown landowners. We present a case study that investigates the structure and function of an urban forest growing on a large institutional property in Toronto, Canada, and determine a 1.35:1 economic benefit-to-cost ratio of investment in tree maintenance. The study provides a roadmap for institutional properties to use in assessing the ecological benefits of their current tree populations. We argue that municipal policies that incentivise tree care and maintenance are critical in order to safeguard and enhance the public benefits of trees growing on institutional land.  相似文献   
6.
城市规划与城镇土地定级之间的相互影响是多方面的。一是城市规划纲要、城市总体规划以及控制性详细规划的编制,分别从宏观和微观两方面影响着城镇土地定级工作;而城市规划的不同实施方式和不同实施程度对具体地块土地级别以及城镇土地级别空间分布格局有着直接和较大的影响。二是城镇土地级别现状和城镇土地级别变化趋势分析,潜在影响着城市规划方案设计、城市规划方案决策、城市规划实施和管理过程,并为其提供依据和指导。在此基础上,如何量化城市规划对城镇土地定级的影响值得进一步具体研究;发挥城镇土地定级工作的作用,更好地为城市规划服务,解决人们的住房问题,更值得深入思考。  相似文献   
7.
    
This study seeks to improve understanding of temperature patterns in reservoir outflows. We examined water temperatures in an irrigation storage reservoir, Island Park Reservoir, and its outflow, Henry’s Fork of the Snake River in eastern Idaho. Our objectives were to (1) quantify the extent to which daily temperature ranges in the reservoir outflow deviated from other reaches of the Henry’s Fork, and (2) test whether the reservoir’s net volume change during the summer — expressed as the volume of water remaining in the reservoir on September 1 — predicted mean summer temperature in the outflow. Two years of temperature data showed dampened diel temperature cycles in the reservoir outflow. Model selection with 17 years of climatic, hydrologic, and reservoir management variables found mean summer temperature in the outflow was best predicted by September 1 reservoir volume and average summer air temperature. Two years of weekly reservoir thermal profiles indicated large changes in reservoir volume eliminated cool hypolimnetic water and encouraged mixing, allowing warm epilimnetic water to be discharged into the outflow. Increases in future drought frequency and severity and increases in summer air temperatures could increase the frequency of occurrence of high mean summertime water temperatures in the outflow. Our study provides important information for local managers by quantifying influences on outflow temperatures and the downstream river ecosystem.  相似文献   
8.
    
Urban farming – a type of urban agriculture focused on entrepreneurial food production – serves multiple functions in neighbourhoods; yet these are not well delineated. Expectations for urban farming often centre on traditional measures of economic development, potentially overlooking other benefits. Through a qualitative case study conducted in Baltimore, Maryland, we sought to understand community perceptions regarding the ways in which urban farms can benefit cities. Interviews with residents, neighbourhood leaders, and urban farmers in three residential neighbourhoods with urban farms revealed the pathways by which community members view farms as improving neighbourhoods. Benefits stemmed from four primary changes urban farms made to study neighbourhoods: creation of public projects welcoming involvement, physical improvement of degraded space, production of local food, and creation of new businesses. These changes led to multiple perceived benefits including increased social connectedness, a transformed physical landscape, improved neighbourhood reputation, increased access to fresh produce, and educational, youth development, and employment opportunities. Our findings demonstrate the importance of a multifunctional paradigm that accounts for social and educational functions in assessing the value of urban farming and bring empirical evidence to the concept of multifunctional agriculture. Urban farms with strong social aims may appear to contribute little to economic development if measured using traditional indicators of success such as job creation or fiscal impacts, but provide numerous other benefits for community development.  相似文献   
9.
    
This paper evaluates the planning competences required to enact a managed transition to sustainability at the municipal level for cities facing population, economic and employment decline. Drawing on the ‘shrinking cities’ literature, we argue consolidation of the built environment can become a focal point for sustaining citizen welfare when transitioning cities that are facing decline, especially those previously reliant on resource industries. We evaluate the former coal mining city of Yubari, Japan, which is developing a consolidated urban form with the aim of creating a ‘sustainable’ future city. Findings from interviews and content analysis of Yubari’s planning policy indicate, however, that to translate ‘shrinking’ a city into a managed transition, spatial planning must be accompanied by a wider range of social policy measures and strong cross-sectoral engagement. We also caution that the unique geographical and political context of Yubari mean its model may not be directly replicable in other contexts.  相似文献   
10.
    
ABSTRACT: A review of methods for planning-level estimates of pollutant loads in urban stormwater focuses on transfer of charac. teristic runoff quality data to unmonitored sites, runoff monitoring, and simulation models. Load estimation by transfer of runoff quality data is the least expensive, but the accuracy of estimates is unknown. Runoff monitoring methods provide best estimates of existing loads, but cannot be used to predict load changes resulting from runoff controls, or other changes of the urban system. Simulation models require extensive calibration for reliable application. Models with optional formulations of pollutant build up, washoff, and transport can be better calibrated and the selection of options should be based on a statistical analysis of calibration data. Calibrated simulation models can be used for evaluation of control alternatives.  相似文献   
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