Some Points on the Sustainable Cities Research

&nbsp; <dd>可持续城市建设是人类社会可持续发展的根本保障.本文系统地分析了可持续城市发展历程与内涵,总结了可持续城市的相关理论、方法和实践趋势,探讨了可持续城市的未来发展方向与关键,提出可持续城市建设需主动把握系统形态、结构、功能的高效及生态、社会、经济福利的可持续性,城市管理能力建设与政治创新是必要保障,是否具有朝向可持续城市发展的意愿及深入社区的公众对话是成败的关键.</dd

Distribution, availability, and sources of trace metals in different particle size fractions of urban soils in Hong Kong: Implications for assessing the risk to human health

The concentration and loading distribution of trace metals (Cu, Zn, Pb, Co, Ni, Cr, and Mn) and major elements (Al, Ca, Fe, and Mg) in different particle size fractions (2000&ndash;280, 280&ndash;100, 100&ndash;50, 50&ndash;10, 10&ndash;2, and &lt;2 &mu;m) of surface soils from highly urbanized areas in Hong Kong were studied. The enrichment of Pb, Cu, and Zn in the urban soils was strongly influenced by anthropogenic activities, and Pb accumulated in fine particles was mainly derived from past vehicular emissions as shown by Pb isotopic signatures. Trace metals primarily accumulated in clay, fine silt, and very fine sand fractions, and might pose potential health risks via the inhalation of resuspended soil particles in the air (PM10 or PM2.5), and ingestion of adhered soils through the hand-to-mouth pathway. The mobility, bioavailability, and human bioaccessibility of Pb and Zn in bulk soils correlated significantly with metal concentrations in fine silt and/or very fine sand fractions

Pollution characteristics of organic and elemental carbon in PM2.5 in Xiamen city, China

<p>Xiamen, located on the southeastern coastal line of China, is undergoing rapid urbanization and industrialization, so its air quality has a trend of degradation. However, studies on level, temporal and spatial changes of fine particles (PM_2.5) and their carbonaceous fractions are scarce. In this article, abundance, sources, seasonal and spatial variations, distribution of organic carbon (OC) and elemental carbon (EC) in PM_2.5, were studied at suburban, urban and industrial sites in Xiamen during four season-representative months in 2009&ndash;2010. PM_2.5 samples were collected with middle volume sampler and were analyzed for OC and EC with thermal optical transmittance (TOT) method. Results showed that the annual average PM_2.5 concentrations were 63.88&ndash;74.80 &mu;g/m³ at three sites. While OC and EC concentrations were in the range of 15.81&ndash;19.73 &mu;g/m³ and 2.74&ndash;3.49 &mu;g/m³, respectively, and clearly presented the summer minima and winter maxima in this study. The carbonaceous aerosol accounted for 42.8%&ndash;47.3% of the mass of PM_2.5. The annual average of secondary organic carbon (SOC) concentrations in Xiamen were 9.23&ndash;11.36 &mu;g/m³, accounting for approximately 56% of OC. Strong correlations between OC and EC was found in spring (<em>R</em>² = 0.50) and autumn (<em>R</em>² = 0.73), suggesting that there were similar emission and transport processes for carbonaceous aerosols in these two seasons, while weak correlations were found in summer (<em>R</em>² = 0.33) and winter (<em>R</em>² = 0.41). The OC/EC ratios in PM_2.5 varied from 2.1 to 8.7 with an annual average of 5.7, indicating that vehicle exhaust, coal smoke and biomass burning were main source apportionments of carbonaceous fractions in Xiamen.</p><!-- articleText --

Chemical Characteristics of Particulate Matter during a Heavy Dust Episode in a Coastal City, Xiamen, 2010

<p style="margin-top: 0px; margin-bottom: 0px; text-indent: 12pt; line-height: 150%" class="MsoNormal" align="justify"><span><font size="2">Xiamen, as a southeastern coastal city, is hardly affected by dust storms (DSs) sourced from the arid and semiarid areas in North or Northwestern China in spring. Unfortunately, during 21&ndash;23 March, 2010, the heaviest DS that had been recorded in past 50 years affected air quality seriously. Continuous particulate matter monitor was employed for the observation of PM_2.5 (aerodynamic diameter less than 2.5 &mu;m) and PM₁₀ (aerodynamic diameter less than 10 &mu;m) during 20&ndash;24 March 2010. Total suspended particulate (TSP) samples during this episode were also collected and their characteristics of element species and water-soluble ions were illustrated to characterize the heavy pollution in Xiamen. The DS peaked on 21 March, with the highest concentrations of 454.51 &mu;g/m³ and 990.24 &mu;g/m³ for PM_2.5 and PM₁₀, respectively. The variations of ratio for PM_2.5/PM₁₀ indicated that PM₁₀ was the main particles that were influenced by DS. The higher ratios (DS/Non dust days) of Al, Fe, Mg, Mn, and Ba were over 5.0, which are primarily from a soil. However, the ratios of Zn, V, As, Ti, and Cr, mainly from anthropogenic sources, had a range of 1.3 to 3.4. These results suggested that the soil-sourced species made more contribution to DS particles compared to the anthropogenic species. The mass fractions of water-soluble ions in TSP indicated that the concentrations of K⁺, Ca²⁺, Mg²⁺, F^-, NO₂^-, and NO₃^- were evidently higher in DS samples than those of non-DS samples. The compositions of ions in dust aerosols showed that the multi-sources of aerosol were ubiquitous during the dust episode. The highest concentrations of sulfate and nitrate occurred in the day when dust ended in Xiamen, which demonstrated the formation of secondary pollutants from dust during the long-range transport, as well as from local environmental pollution.</font></span></p

城市化与植被碳储量的关系：以厦门为例

Rapid growth of the Chinese urban population and the expansion of urban areas have led to changes in urban forest structure and composition, and consequently changes in vegetation carbon storage. The purpose of this study is to quantify the effects of urbanization on vegetation carbon storage in Xiamen, a city located in southern China. Data used for this study were collected from 39,723 sample plots managed according to the forest management planning inventory program. Data from these plots were collected in 4 non-consecutive years: 1972, 1988, 1996 and 2006. The study area was divided into three zones, which were defined according to their level of urbanization: the urban core, the suburban zone, and the exurban zone. Total vegetation carbon storage and the vegetation carbon density for each study period were calculated for each zone. Our results show that urban vegetation carbon storage has increased by 865,589.71 t during the period from 1972 to 2006 (34 years) in Xiamen, with a rapid increase between 1972 and 1996, then relatively little change between 1996 and 2006. The increase in vegetation carbon storage is mainly due to the large percentages of the suburban and exurban areas which exist in Xiamen city, and the implementation of reforestation programs in these two zones. The percentage of total regional carbon storage in the city center (urban core), suburbs and exurbs was 5%, 23% and 72%, respectively. This demonstrates that the exurbs store the majority of vegetation carbon, and thus play a critical role in the vegetation carbon storage of the study area. The intensification of urbanization in the future will likely expand the urban core and reduce the area of the suburbs and exurbs, and thus potentially decrease total vegetation carbon storage. This article concludes with a discussion of the implications of these results for vegetation carbon management and urban landscape planning

城市居住空间形态变迁及其通勤效应研究——以住房市场化背景下的厦门为例

<p><span style="line-height: 150%; font-family: 宋体; font-size: 10pt">&nbsp;&nbsp;&nbsp; 改革开放以后，中国的城市化呈现出加速发展的趋势，在这个过程中城市的内部空间发生重构，其中居住空间在住房制度的市场化改革中发生了深刻变化。居住空间的变迁导致了居住分异、职住分离及其引发的交通拥堵等城市问题，影响到城市的可持续发展。目前对中国转型期住房制度市场化背景下的城市居住空间变迁过程以及由此引发的通勤问题已经有一定的研究，但是这些研究主要针对个别大城市，并且对整个变迁的过程及其通勤效应尚缺乏全面系统的分析。因此，本研究在对城市住房制度市场化改革回顾的基础上，以沿海经济特区厦门作为典型案例，结合宏观的历史资料、空间数据和社会经济数据以及微观的社会个体调查数据，对居住空间的物质形态和社会形态变迁进行了系统的分析与研究，并探讨了住房制度市场化改革背景下居住空间形态变迁对城市通勤的影响。</span></p><p><span style="line-height: 150%; font-family: 宋体; font-size: 10pt">&nbsp;&nbsp;&nbsp; 厦门市的住房制度改革整体上略滞后于全国的住房制度改革进程。根据资料分析，可以划分为筹划准备、初步实施、继续深化、全面改革和住房保障等五个阶段。与之相应的，城市居住空间的物质形态和社会形态都发生了深刻变化。在住房制度改革的影响下，厦门岛的城市居住空间在宏观上表现为在城市规划的约束下逐步向东向北的外延扩展，并在优势区位地段进行内涵填充；同时，随着城市化和工业化的持续推进，各种类型的城中村等特殊居住空间开始形成，成为厦门城市居住空间的重要组成部分。</span><span style="line-height: 150%; font-family: 宋体; font-size: 10pt">在微观上，典型住区及其格局定量分析表明，居住空间的变迁表现为总体开发规模的缩小和单个住区形态的多样化和高层化，总量指标总体上表现为递减的趋势，平均指标随着年代的推进大小变化较为平稳，而多样性指标随着年代总体上表现为上升的趋势。在住房制度改革的过程中，城市居民的总量与结构、收入与分层以及居住状况均发生了明显分化。结合住房制度改革过程和物质形态的变迁，可以将厦门岛<span>28</span>个调查居住区分为规划型住区和自发型住区，其中规划型住区又包括三类，分别代表住房制度改革不同阶段的住区形态；自发型住区既包括了改革开放之前自发形成的老城区，也包括改革开放之后逐步形成的城中村。对这些不同类型住区的社会形态进行分析，发现规划型住区与自发型住区以及两类住区内部的社会形态均存在显著差异，反映了住房制度改革对居住空间社会形态的影响。进一步通过因子分析发现，居住空间的社会形态主要受到<span>&ldquo;</span>居住因子<span>&rdquo;&ldquo;</span>阶层因子<span>&rdquo;&ldquo;</span>成熟因子<span>&rdquo;</span>等因素的影响，其中&ldquo;居住&rdquo;与&ldquo;阶层&rdquo;是两个最主要因子，反映了住房制度改革对居住空间社会形态变迁的影响。</span></p><p><span style="line-height: 150%; font-family: 宋体; font-size: 10pt">&nbsp;&nbsp;&nbsp; 对厦门出行调查的分析表明，住房制度改革前后出行方式和出行时耗均发生了变化，其中出行方式表现为机动化率的提高，公共交通出行的比例大幅增加，私家车出行比例增加到原来的十倍；与此同时，<span>2009</span>年调查的机动化方式的出行时耗却比住房制度改革之前的<span>1995</span>年明显增加了，特别是考虑到<span>2009</span>年的出行调查包括了岛外的样本，机动化率和出行时耗在厦门岛的增加就更为明显，在机动化率提高的同时出行时耗增加，一方面是机动化本身所带来的拥挤效应，另一方面也反映了城市空间的重构导致出行距离的增加。进一步分析代表居住空间物质形态和社会形态变迁典型变量的通勤特征，结果表明不同的住区类型、住房产权、收入水平和居住类型的通勤存在明显差异：从不同住区类型来看，随着住区形态的变迁机动化、高能耗的出行方式以及平均通勤时间和通勤距离表现为增加的趋势；住房产权的通勤特征表现为购房与租房、商品房与公房、非自建房与自建房的区别，机动化率、高能耗通勤率、平均通勤时间和平均通勤距离前者都明显高于后者，充分说明了住房制度改革后住区社会形态的变迁对通勤所产生的深刻影响；从收入水平来看，中等收入群体与其他收入群体相比机动化率相对较高，但是高能耗通勤率相对较低，平均通勤时间和平均通勤距离最长，反映了在住房制度市场化改革的影响下不同收入群体对居住质量、居住成本和通勤成本的综合平衡；与本地居民相比，外地居民的通勤表现为非机动化、短时间、短距离的特征，反映了其中大部分人作为外来居民的弱势地位。</span><span><font face="Times New Roman" size="3">&nbsp;</font></span> </p><p>&nbsp;</p><p style="text-indent: 24pt; margin: 0mm 0mm 0pt" class="MsoNormal"><span><font face="Times New Roman" size="2">After reform and opening up, China&rsquo;s urbanization shows an accelerating trend and the internal urban space is being reconstructed. In this course, the residential space is experiencing profound changes under the background of housing system marketization reform. Changes in residential space led to some urban problems such as the residential spatial differentiation, job-housing separation and traffic congestion, which affect the sustainable development of cities. There has been some research on the process of urban residential space changes and the consequent effect on commuting, but these studies focused on some big cities, and the whole process of residential space change and its effects on commuting are still lack of comprehensive and systematic analysis. Therefore, this dissertation firstly reviews the housing system reform and takes the coastal Special Economic Zone Xiamen as the typical case, combined with macro-historical materials, spatial and socio-economic data and micro-social individual survey data to study the process of physical and social pattern change of residential space and its effect on urban commuting.</font></span></p><p style="text-indent: 24pt; margin: 0mm 0mm 0pt" class="MsoNormal"><span><font face="Times New Roman"><font size="2"><span>&nbsp;</span>Housing system reform in Xiamen had minor lags behind the overall national process. According to the publication time of some landmark policy paper, the housing system reform in Xiamen can be divided into five stages: planning and preparation, initial implementation, continually deepening, comprehensive reform and housing security. Correspondingly, the physical form and social patterns of urban residential space have undergone profound changes. At the macro scale, the urban residential space gradually extended toward the north and east of Xiamen Island under the constraint of urban planning and filled the advantageous location. At the same time, with urbanization and industrialization, the special residential space of village-in-city began to form and became important part of urban residential space in Xiamen. At the micro scale, typical residential community and quantitative analysis shows that the total, average and diversity landscape indicators have the decreasing, stable and increasing trends respectively, which implies the decrease in development size and the internal morphology diversification of individual residential community pattern. </font></font></span></p><p style="text-indent: 24pt; margin: 0mm 0mm 0pt" class="MsoNormal"><span><font face="Times New Roman" size="2">In the process of housing system reform, urban residents have differentiated in total amount, structure, income stratification and housing condition. Considering the housing system reform course and changes of residential physical pattern, 28 residential communities surveyed in Xiamen Island can be classified into planned residential communities and spontaneous residential communities. The planned residential communities can be classified into three types which represent different form in different stage of housing system reform. The spontaneous communities include the old downtown formed spontaneously before reform and opening up and the village-in-city gradually formed after reform and opening up. Analysis on the social pattern of these different types of communities reveals the significant difference between planned communities and spontaneous communities and among the three types of these two kinds of communities respectively, which reflects the effect of housing system reform on the social pattern of residential space. The further factor analysis finds that social pattern of residential space mainly affected by the housing factor, class factor, maturity factor and so on and the the housing and class factors are the most important, which reflects the effect of housing system reform on the social pattern of residential space.</font></span></p><p style="text-indent: 24pt; margin: 0mm 0mm 0pt" class="MsoNormal"><span><font face="Times New Roman" size="2">According to the travel survey data, the travel modes and time consumption has changed. Motorization rate and proportion of public transport has increased significantly. Proportion of travel by car in 2009 is ten times of that in 1995. Meanwhile, travel time consumption of the motorized mode in 2009 is more than in 1995 before the housing system reform started in 1998. Considering that the travel survey in 2009 included a sample outsides the island, motorization rate and travel time consumption insides the island should increased more significantly. That travel time consumption increased with the promotion of motorization can be attributed to not only the congestion due to motorization itself but also the increase in travel distance due to the urban space reconstruction. </font></span></p><p style="text-indent: 24pt; margin: 0mm 0mm 0pt" class="MsoNormal"><span><font face="Times New Roman" size="2">Further analysis on the commuting characteristics of typical variables representing the physical form and social pattern changes of urban residential space showed that: (1)for different types of residential communities, the motorization rate, high energy commuter rate, average commuting time and average<span>&nbsp; </span>commuting distance have the increasing trend with the change of residential physical form and social pattern; (2) for different kinds of housing properties, the difference mainly existed between house bought and house rented, between commercial house and public house and between house self-built and house non-self-built, that is the motorization rate, high energy commuter rate, average commuting time and average<span>&nbsp; </span>commuting distance of the former are more than the latter, which reflects the impact of housing system reform on the urban residential space and commuting behavior; (3) for different income levels, compared with other income groups, the middle-income group has a higher motorization rate, but the proportion of high energy commuter rate is the highest and the average commuting time and average commuting distance are the longest, which reflects different income groups&rsquo; comprehensive balance among housing quality, housing cost and commuting cost under the influence of housing system reform; (4) compared with the local residents, foreign residents&rsquo; commuting has characteristics of non-motorization, short travel time and short travel distance, which reflects their weak position.</font></span></p

Study on pollution characteristics of particulate matter in indoor air

为获得室内空气颗粒物污染特征,2009年8月18～24日在某单位工作及生活区选取4个室内点和1个室外点进行颗粒物采样和成分分析。结果表明,室内粗颗粒（PM10）符合《室内空气质量标准》（GB/T 18883&mdash;2002）,而细粒子（PM2.5）的浓度水平较高,表明室内PM2.5的污染较重;室内与室外PM2.5比值显示,PM2.5污染没有明显的室内源;食堂和会议室PM2.5中的有机碳与元素碳（OC/EC）浓度较其他3个室内采样点要高,与厨房烹饪和室内装修有关,二次有机气溶胶对5个采样点颗粒物浓度都有较大的贡献;Cr、Mn、Cu、Zn、Ni、Pb、Mg、Fe、Al 9种重金属在室外颗粒物中的浓度基本高于室内,富集因子计算结果显示,室内外PM2.5中Cr、Cu、Ni 3种重金属元素均有显著富集。NO-3、SO24-、Na＋、NH＋4为PM2.5中主要的水溶性离子

Trace metal contamination in urban soils of China

The contamination of urban soils can affect the health of people living in urban areas, and the surrounding ecosystems. Urbanization in China has taken place at an unprecedented pace in the last three decades. This paper provides an overview of studies on the quality of urban soils in China with special reference to trace metal contamination. It summarizes the characteristics of accumulation, spatial and temporal distribution, and major sources of various toxic or potentially toxic trace metals in urban soils as reported in recent literature. Levels of pollution in urban soil and road dust were discussed using the concentrations, enrichment factors, pollution indexes, and chemical fractionation of trace metals in major cities of China, and compared with other countries. In future studies, more pollutants in urban environments need to be included in multi-compartmental environmental surveillance for potential risk assessments. In addition to routine urban soil surveys by a harmonized methodology, a comprehensive assessment of soil quality is needed for the control and management of many urban brownfield sites. Taking into consideration pathways of exposure and site characteristics, risk assessment frameworks for major pollutants in urban soils, which integrate land use type and environmental availability, may be developed in the future

The analysis of socio-economic driving forces on built-up area expansion in Xiamen

<font size="2"><font face="Times New Roman"><span>Based on the grey relational analysis and stepwise regression, this study analyzed the socio-economic driving forces of Xiamen since the reform and opening of China. The research was aimed to explore the deep dynamic mechanism of urban space expansion of Xiamen and provide scientific support for</span><span> its </span><span>sustainable development. The result</span><span>s</span><span> indicated resource consumption factors and population factors have</span><span> a</span><span> significant driving effect on the expansion of built-up area, more contributively</span><span> </span><span>than the economic development factors. It was revealed </span><span>that </span><span>the main urban socio-economic driving forces ha</span><span>ve</span><span> been gradually changing </span><span>during </span><span>the mid and late stage of urbanization,</span><span> and</span><span> the city </span><span>has</span><span> also shifted from the original construction and develop</span><span>ing</span><span> city type into a more spatially stable </span><span>develop</span><span>ed</span><span> city type.</span></font></font

Inconsistency and comprehensiveness of risk assessments for heavy metals in urban surface sediments

Numerous indices have been developed to assess environmental risk of heavy metals in surface sediments, including the total content based geoaccumulation index (Igeo), exchangeable fraction based risk assessment code (RAC), and biological toxicity test based sediment quality guidelines (SQGs). In this study, the three indices were applied to freshwater surface sediments from 10 sections along an urbanization gradient of the Grand Canal, China to assess the environmental risks of heavy metals (Cu, Pb, Zn, Cd, and Cr) and to understand discrepancies of risk assessment indices and urbanization effects regarding heavy metal contamination. Results showed that Cd, Zn, and Pb were the most enriched metals in urban sections assessed by Igeo and over 95% of the samples exceeded the Zn and Pb thresholds of the effect range low (ERL) of SQGs. According to RAC, Cu, Zn, Cd, and Cr had high risks of adversely affecting the water quality of the Grand Canal due to their remarkable portions of exchangeable fraction in surface sediment. However, Pb showed a relative low risk, and was largely bounded to Fe/Mn oxides in the urban surface sediments. Obviously, the three assessment indices were not consistent with each other in terms of predicting environmental risks attributed to heavy metals in the freshwater surface sediments of this study. It is recommended that risk assessment by SQGs should be revised according to availability and site specificity. However, the combination of the three indices gave us a comprehensive understanding of heavy metal risks in the urban surface sediments of the Grand Canal