人工土层快速渗滤法处理城市污水的模拟试验效果初探

应用土壤过滤技术,进行配比不同的人工土层快速渗滤系统,处理城市污水,结果表明:加入适量的砂粒及吸附剂可使该系统具有较高的水力负荷及对污染物的去除效应。各处理的平均渗滤速率为0.027～0.60 cm/min:对污水中 BOD_5的去除率为86.0%～96.9%:对 N,P的去除率分别为88.6%～97.1%及87.2%～92.4%:溶解氧增加10mg/L 左右;透光率由原来的69.8%提高到85.9%～96.1%:电导率由0.463mV/cm 下降到0.406～0.418mV/cm;臭味由强烈变为极弱或无。合理的干湿交替有助于维持较高的渗滤速率.     

人为侵入体对城市绿地土壤水分入渗特征的影响

在快速城市化过程中,人为侵入体大量混入绿地,改变了土壤的三相组成及孔隙特征,但其对城市绿地土壤的入渗影响仍不清楚。基于一维垂直土柱入渗模拟,以典型人为侵入体砖块和混凝土碎块为例,研究其对城市绿地土壤水分入渗的影响特征。结果表明:(1)人为侵入体的混入均会抑制城市绿地土壤水分下渗,导致其稳定入渗速率降低,累积入渗量、湿润锋距离和土壤体积含水量减小,深层土壤水分变化滞后。同一配比下,以混凝土碎块对土壤水分入渗的抑制作用更为明显(P0.1);(2)随着人为侵入体配比从10%增加到20%,土壤稳定入渗率、累积入渗量、湿润锋距离和土壤体积含水量仍持续减小或略有增加,但差异均不显著(P0.1),其对土壤水分下渗的抑制作用渐趋减弱。(3)不同类型人为侵入体及配比下,城市绿地土壤水分的入渗量随时间变化更加符合Kostiakov模型。研究结果可为未来海绵城市的高效建设提供科学依据。     

厦门城市边缘区旅游开发研究——以同安区为例

随着厦门旅游发展步伐的加快,边缘区旅游发展显得举足轻重。本文以厦门市同安区为例,在实地调研的基础上,通过对同安旅游条件和旅游市场的分析评价,探讨同安旅游的旅游开发。文章认为,城市边缘区开发旅游是市场的需求,政府应积极采取前瞻性促进策略。     

城市森林水流失率与水土流失率的探讨

水土保持是城市森林生态效益中最重要的一项,它是森林其它各种效益的基础。传统上研究和考察森林水土保持效益时,一般从土壤侵蚀角度出发,忽视了对水损失的考察。着重从水的损失出发,提出了用森林水保持率、水土保持率来考察城市森林的水土保持功能,并对北京、伦敦的城市森林和河南山区水保林的水流失率、水保持率进行了论证比较。     

An integrative method to quantify contaminant fluxes in the groundwater of urban areas

Background, Aims, and Scope  Groundwater in urban areas is often contaminated and emission sources can be located close to groundwater wells. The delineation of contaminant plumes is difficult because of the various potential emission sources. Thus, detection, quantification and remediation of contaminated sites in a city need more integrative approaches. Methods  A method has been developed which allows quantification of mass fluxes of contaminants in groundwater between control planes. Budget zones along the flow path are defined to calculate a contaminant balance and to quantitatively reveal input areas. Concentrations and water budgets are used to calculate mass balances for each contaminant. The city of Darmstadt (Germany) was chosen to evaluate the method. Results  The groundwater monitoring wells (GMWs) upstream of the city showed anthropogenically superposed background values for all naturally occurring inorganic species. The contaminant concentrations increased in the city (probably influenced by road traffic, gas stations, leaking sewers, etc.). Downstream from the city, concentrations usually decreased. Organic compounds typical for urban environments, such as polycyclic aromatic hydrocarbons (PAH), locally exceeded drinking water regulations. In GMWs with high concentrations of organic contaminants in the city or downstream from industrial areas, a significant increase in Fe²⁺ and Mn²⁺ could be observed, in some cases coinciding with a decrease in NO₃, SO₄ and an increase in NH₄. Discussion  For typical urban contaminants, a positive budget was calculated in several zones, which shows that emissions from urban sources are reaching the groundwater. Negative budgets can be mainly explained with diving plumes and degradation. The input calculated from the individual budget zones is usually higher than the input estimated from urban emissions. Differences between the calculated and the estimated input can be explained with additional sources or (bio)degradation processes. Conclusions  It was confirmed that high concentrations of contaminants do not necessarily correlate with high fluxes. Integrative approaches can reveal areas of high contaminant mass input. The results obtained with the new method are plausible compared to the land use and the estimated urban input. The concentration pattern of Fe²⁺, Mn²⁺, SO₄ and NO₃ is partly due to natural processes, triggered by the degradation of organic matter and organic contaminants. Recommendations  Since this method includes mass balances and flux calculations, avoiding an overestimation of single point contaminant concentration, it is recommended to use this approach to quantify groundwater contamination in cities. Further research is focusing on the role of urban soils as natural reservoirs for the input of contaminants.     

Analysis of Traffic Block in Downtown Area

With social and economic development in the past decades, the cities and towns was in rapid progress of urbanization. Under such circumstances, certain "urban concerns" causing serious problems in urban growth were arisen and attracted general attention. Located in the central plains in China, Zhengzhou has taken several strategies in its urbanization to ensure its urban development, including loop construction and "smooth transmit" program. However, the traffic block in downtown area always exists and has impact in certain level on the social and economic development in Zhengzhou, which is actually a common issue in other large cities of central and western China. Beginning with analysis of the patterns of urban spatial forms, in this paper, the main transportation issues of downtown area in Zhengzhou were discussed to find a way for its solution.     

城市景观建设的特性和生态意义

城市景观由众多因素综合而成,最基本的因素是人与自然。综合性地继承和发展天人合一的传统哲学理念,是城市建设的首要特征。在目前中国新一轮的城市改建浪潮中,需要明确城市景观设计必须以生态系统平衡为基础,以避免景观建设给自然生态系统带来危机。笔者拟从城市景观建设的特性入手,分析景观建设与生态系统的内部关系,探讨景观建设所产生的生态意义,从而使我们在城市景观建设中保护人文资源和自然资源,创造富有生态环境特色的城市风格和城市个性。     

城市流动人口合理规模的层次分析模型

以成都市为例,根据成都市的经济社会发展现状和2000年的战略纲要,通过分析影响城市流动人口合理规模的诸因素并在此基础上对指标加以选择、修正,建立起成都市流动人口合理规模的层次分析(AHP)模型,并最终判断选出最佳方案.     

江阴市环城公园规划方案

江阴市环城公园是指沿江阴市二环路两侧规划建设的环形带状绿地及由其串联的１４座园中之园所组成的市级综合性公园，全线长约２１ｋｍ，占地总面积约８４ｈｍ￣２。它的建成将使江阴市的城市绿化覆盖率和建成区绿地率均提高３．５９％，人均公共绿地增加２．１７ｍ￣２／人，从而可使江阴市的城市绿地考核指标接近（一项超过）国家园林城市标准。本文在探讨建设江阴市环城公园的必要性和可能性的基础上，对环城公园的性质和特点、规划指导思想、各景区和园中国的规划要点作了系统的论述。     

四川省城市土地集约利用空间差异研究

以四川省成都及17个地级市为研究区域,结合四川省实际,从土地投入水平、土地利用程度、土地利用效率和土地利用可持续度四个方面,构建城市土地集约利用评价指标体系,运用主成分分析法和聚类分析法等对四川省城市土地集约利用水平空间差异进行分析。结果表明,四川省城市土地集约度整体偏低,区域差异明显;集约利用水平在空间上由西南向东北呈现出低-高-低的特征;地形、城市地均GDP和生态环境建设等是影响城市土地集约度的重要原因。最后提出了提高四川省城市土地集约利用水平的对策与建议。