Characterization of visibility and atmospheric aerosols in urban, suburban, and remote areas

Visibility data from over the past four decades accumulated from urban areas of central Taiwan indicated that air pollutants have significantly degraded visibility in recent years. Currently, the annual average visibility in urban areas of the same region is approximately 8-10 km, while the visibility in remote areas is approximately 25-30 km. To understand how aerosols affect the visibility in this region, here we selected three sites in central Taiwan to measure the soluble ionic and carbonaceous species of PM(2.5) and PM(2.5-10) during 1997-1998. A MOUDI cascade impactor was used to measure the size distributions of atmospheric sulfate, nitrate, and carbonaceous particles. The aerosol data were then analyzed together with meteorological and air quality data. Comparing the results obtained from urban, coastal suburban and remote sites revealed that sulfate, carbonaceous species and local wind speed significantly affected the visibility in the urban area. However, sulfate concentration and humidity influenced visibility in the coastal area of central Taiwan. The particulate concentration at the remote station was roughly one-fifth of that in the city. Regression analysis results indicated that humidity is a dominant factor affecting remote visibility.     

城市非建设用地对雨洪管理的影响

针对城市的防洪排涝控制、雨水安全排放等问题,探讨了如何构建高效的雨洪控制管理体系,详细介绍了城市雨洪管理的三种模式及自然水体在城市雨洪管理中的地位,并分析了LUCC对城市水安全问题的影响因素,以从根本上减少城市水安全问题。     

Drivers of urban sprawl in urban areas of Iran

During the recent decades, debates about urban sprawl have increased strongly in Iran. Literature review shows that there are few studies about causes of sprawl in urban areas of Iran. This paper analyses driving forces in creation or intensification of urban sprawl in Iranian cities. The methodology of the research is based on documentary and survey method. Results indicate that the most important drivers of urban sprawl are 22 factors in Iran. By using exploratory factor analysis, 22 factors are summarized in eight main factors. These factors include population growth, land value, political fragmentation, land speculation, transportation policies, exterior pressure, management system and land use. The eight main factors are able to explain an average of 76.9% of the urban sprawl phenomenon in Iran. The analysis of variance indicates that none of them can be effective in explaining urban sprawl alone in Iran that they were explained by each factor on urban sprawl. The population growth has the highest impact by 13% and land use has the lowest impact by about 7%. The margin of discrepancy between variance was explained by factors that suggest all of the eight extracted factors play a key role in the urban sprawl of Iran. Policies for controlling and reducing consequences of this phenomenon should be initiated by the government by considering the influential role of government in the urban sprawl of Iran. In particular, it can be helpful to establish integrated urban management, a compilation of comprehensive law about urban land and pay attention to worn-out textures and brownfield development.     

Transport in an urban context

There are three distinct kinds of problems with which the urban transport planner has to deal. Congestion is the one to which both analytical and policy making effort have been traditionally directed. More recently environmental objectives and a concern for the transport facilities available to disadvantaged groups have been given a higher priority. Unfortunately, neither of these objectives is adequately catered for by standard analytical methods or transport planning instruments and recent analytical and institutional developments embody attempts to rectify this defect. But the task of converting good intentions in these respects into good policies is complex and some of the apparently obvious solutions, such as public transport subsidy, may even be counterproductive. It would be unwise to expect any cheap and easy solutions to the problems to emerge.     

城区照明

Hess的投影反射系统具有光点影像分离功能。这个系统的照明光线不眩目．从根本上加强了街道和广场的气氛。新增的“Devio”墙体安装照明设备用于提供不对称光线。这种在墙上安装的型号可应用于三种多面系统：可用于街道照明、区域照明和辅助立面照明。为满足灯具数量不断增长的需要，Hess也设计了带有多个投影仪的设备模型。     

Sustainable urban growth in peripheral areas

The monograph addresses the factors affecting the degree of sustainability exhibited by population growth in peripheral urban settlements. Development differentials between core and peripheral regions in countries of different size and various level of economic development are discussed and specifically, the following issues are considered: 1, core versus periphery: inequalities and development needs; 2, development peculiarities of peripheral urban settlements; 3, criteria for sustainable urban growth; 4, factors influencing urban growth in peripheral areas; and 5, planning strategies for regional development. Two major theoretical considerations are posited for discussion. First, that ‘sustainable population growth' of an urban settlement is defined according to the settlement's ability to attract newcomers and retain current residents (migration attractiveness). Second, that the preconditions which are essential for sustainable population growth in peripheral areas are not identical to those in the core. A set of analytical models designed to explain development peculiarities of peripheral settlements are suggested and several planning strategies are also proposed, aimed at enhancing the socio-economic sustainability of existing settlements in peripheral areas. These include: 1, the formation of compact development clusters; 2, the concentration of state and local financial resources on selected development settlements; 3, the adoption of a system of progressive economic incentives to promote private investment in peripheral areas; and 4, stricter regulation of land use in core regions.     

Understanding chronic poverty in urban areas

The problem of chronic poverty in urban areas has been given little attention despite an increasing interest in poverty and some recognition of the growing significance of urban populations. This paper reviews the literature to bring together what we know about the nature and scale of chronic poverty in urban areas. It begins with a consideration of the definition of chronic urban poverty and related issues of poverty measurement. The section also reports on some recent assessments of the scale and scope of urban poverty. Following sections report on the different nature of such poverty in specific kinds of urban settlements (small towns, urban peripheries and the inner city) and social groups that appear to be particularly vulnerable. The paper concludes by drawing out some of the factors that appear to be of significance in understanding the causes of chronic poverty in urban areas.     

雅库特共和国城市地区的环境地球化学(英文)

回顾了北部城市化特别是雅库特城市地区环境的化学研究结果。结果表明,不利的气候和工程地质条件增加了城市生态系统的压力,并在所有环境成分中检测到与人类活动有关的强烈的地球化学异常。城市化地区的独特特征是向下迁移的深层污染与活性层和冻土的盐性。     

Cultural buildings and urban areas

Even a cursory review of contemporary urban architecture and architectural urbanism attests that the field is largely driven by two contrasting dispositions. On the one hand, there is abundant work promoting ‘place-making’, whilst, on the other, there is ample output advocating a profound revaluation of the field. Notwithstanding the numerous variations of these two dispositions, what they generally seem to be missing is a sophisticated understating of the intricate and reciprocal relationship between architecture and the city. This failure is part and parcel of a distortion in the field as to our expectations from and appraisal of cultural buildings. In other words, since cultural buildings are typically deployed as keystones in urban strategies, they seem well-placed—if not inescapably positioned—to take on a role as protagonist, and thus to anchor and spearhead transformation in their host urban areas. Through a series of both theoretical and design references, this article examines the notion of the urban area in respect to its constituent elements. This takes place within a broader conception of the city of parts which frames an investigation of the strategic tension cultural buildings introduce within their respective areas.     

Impact of non-uniform urban surface temperature on pollution dispersion in urban areas

Airflow pattern through street canyons has been widely studied to understand the nature of pollution dispersion in order to develop guidelines for urban planners. One of the major contributing parameters in pollution dispersion is thermal-induced flow caused by surface and air temperature difference. However, most of the previous studies assumed isothermal condition for street canyons. Those addressed the thermal-induced flow, have assumed a uniform wall surface temperature distribution. The external building wall surface temperature distribution is not uniform, and is influenced by many factors including the wall surface characteristics, and shading. The non-uniform temperature distribution significantly impacts on 3-dimensional airflow within street canyons. Moreover, effect of intersection is barely considered in the literature where L/H<3 (L and H are respectively length and height of street canyon). This Paper reports the development of a 3-dimensional model to study the effect of non-uniform wall surface temperature distribution on the pollution dispersion and flow pattern within the short street canyons (L/H<3). For this purpose, a computational fluid dynamics (CFD) model is developed to investigate these effects on pollution dispersion in various prevailing wind velocities and directions. Moreover, active and passive techniques to reduce the level of concentration are examined. The study clearly shows that thermal-induced flow dominates during fair-weather condition.     

浅谈滨水地区城市设计

通过对滨水地区城市设计的介绍,结合在实际工作中的生态系统规划实例,论述了关于滨水地区城市设计中的一些注意事项及滨水区城市设计对城市形象和经营的直接作用,以使人们对滨水地区的发展有更清晰的认识。     

A regression-based method for mapping traffic-related air pollution: application and testing in four contrasting urban environments

Accurate, high-resolution maps of traffic-related air pollution are needed both as a basis for assessing exposures as part of epidemiological studies, and to inform urban air-quality policy and traffic management. This paper assesses the use of a GIS-based, regression mapping technique to model spatial patterns of traffic-related air pollution. The model--developed using data from 80 passive sampler sites in Huddersfield, as part of the SAVIAH (Small Area Variations in Air Quality and Health) project--uses data on traffic flows and land cover in the 300-m buffer zone around each site, and altitude of the site, as predictors of NO2 concentrations. It was tested here by application in four urban areas in the UK: Huddersfield (for the year following that used for initial model development), Sheffield, Northampton, and part of London. In each case, a GIS was built in ArcInfo, integrating relevant data on road traffic, urban land use and topography. Monitoring of NO2 was undertaken using replicate passive samplers (in London, data were obtained from surveys carried out as part of the London network). In Huddersfield, Sheffield and Northampton, the model was first calibrated by comparing modelled results with monitored NO2 concentrations at 10 randomly selected sites; the calibrated model was then validated against data from a further 10-28 sites. In London, where data for only 11 sites were available, validation was not undertaken. Results showed that the model performed well in all cases. After local calibration, the model gave estimates of mean annual NO2 concentrations within a factor of 1.5 of the actual mean (approx. 70-90%) of the time and within a factor of 2 between 70 and 100% of the time. r2 values between modelled and observed concentrations are in the range of 0.58-0.76. These results are comparable to those achieved by more sophisticated dispersion models. The model also has several advantages over dispersion modelling. It is able, for example, to provide high-resolution maps across a whole urban area without the need to interpolate between receptor points. It also offers substantially reduced costs and processing times compared to formal dispersion modelling. It is concluded that the model might thus be used as a means of mapping long-term air pollution concentrations either in support of local authority air-quality management strategies, or in epidemiological studies.     

Monitoring Pt and Rh in urban aerosols from Buenos Aires, Argentina

Vehicular traffic is the main source of platinum group elements (PGEs) in highly populated urban areas like Buenos Aires where a traffic density of 1,500,000 vehicles day(-1) (corresponding to 7,500 vehicles km(-2)) is estimated. Since there is no information on the levels of PGEs in Buenos Aires, a pilot study was undertaken to ascertain the amount of two major PGEs, namely Pt and Rh, in the atmosphere of this city. To this end, 49 samples of PM-10 particulate matter were collected during 7 days in seven representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km(2). The collection of particulate matter was performed on ash-free glass-fiber filters using high volume samplers with PM-10 sampling heads. Filters loaded with the particulate matter were subjected to microwave (MW)-assisted acid digestion using a combination of HNO(3), HF and HClO(4). The resulting solutions were evaporated and then diluted with 0.1 mol l(-1) HCl. Analyses were performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) and special attention was paid to the control of mass interferences. Statistical analysis was performed on the experimental data obtained for the element concentrations taking also into account local meteorological data for the monitored period. The highest concentrations of Pt and Rh were detected at two sites (Hospital Alemán and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars. The Pt content (in pg m(-3)) in airborne particulate matter was found to vary from 2.3 to 47.7, with a mean value of 12.9+/-7, and that of Rh from 0.3 to 16.8, with a mean value of 3.9+/-2.8. These concentrations are by far below the levels for which adverse health effects might be expected to occur, i.e., around 100 ng m(-3). On the other hand, monitoring of PGEs should be carried out in a systematic fashion to detect possible dramatic increases from today's levels.     

浅论滨水地区城市设计

简述了世界范围内的滨水区的发展历程、建设的经验以及滨水区景观开发的需要和可能性,从城市设计的角度入手,在滨水区城市形态研究的基础上,针对目前我国及国外滨水区开发现状,提出一些解决问题的方法和思路,对于指导滨水地区和整个城市的建设具有重要意义。