一种以人为本的城市绿地评价方法及其应用——以南京市城市绿地质量评价为例

文章基于"以人为本"的理念,构建了从使用者角度对城市绿地质量评价的简明指标体系,采用多边形综合指标法及德尔菲法,兼顾科学性和可操作性,并应用该指标体系尝试分析南京市城市绿地质量。结果表明:南京城市绿地总体质量处于一般水平,其中公园绿地和风景名胜与自然保护区绿地质量较高。在各项评价指标中,南京居民对绿地管理质量满意度较低,视觉效果满意度、空间布局满意度较高。该评价体系从使用者角度展现了城市绿地的整体水平并直观反映出城市绿地所存在的问题,可为城市绿地规划与管理以及综合评价指标的构建提供重要的依据与参考。     

城市污泥及落叶蚯蚓处理最优条件因子实验研究

蚯蚓的环境生态作用具有促进微生物和其他土壤动物活动、消化分解土壤中重金属的功能,并且能够破碎与分解枯落物。通过城市污泥和城市落叶发酵后建立起蚯蚓养殖基床,以赤子爱胜蚓为主体,通过蚯蚓对污泥中重金属的富集作用实现城市污泥无害化,达到城市污泥与落叶资源化的目的。通过设计四因子四水平正交试验探索赤子爱胜蚓处理城市污泥及落叶的最优条件组合。实验结果表明:在落叶添加比例为35%,蚓床湿度为75%,培养温度为14℃,饲养密度为32mg/g时,赤子爱胜蚓对城市污泥和落叶的处理指标达到峰值,蚯蚓床对于污泥中重金属Cu和Zn的富集量分别为274.32μg/箱和420.98μg/箱,处理效果最佳。     

Integrated dynamic risk assessment of buried gas pipeline leakages in urban areas

In urban areas, buried gas pipeline leakages could potentially cause numerous casualties and massive damage. Traditional static analysis and dynamic probability-based quantitative risk assessment (QRA) methods have been widely used in various industries. However, dynamic QRA methods combined with probability and consequence are rarely used to evaluate gas pipelines buried in urban areas. Therefore, an integrated dynamic risk assessment approach was proposed. First, a failure rate calculation of buried gas pipelines was performed, where the corrosion failure rate dependent on time was calculated by integrating the subset simulation method. The relationship between failure probability and failure rate was considered, and a mechanical analysis model considering the corrosion growth model and multiple loads was used. The time-independent failure rates were calculated by the modification factor methods. Next, the overall evolution process from pipeline failures to accidents was proposed, with the accident rates subsequently updated. Then, the consequences of buried gas pipeline accidents corresponding to the accident types in the evolution process were modeled and analyzed. Finally, based on the above research, dynamic calculation and assessment methods for evaluating individual and social risks were established, and an overall application example was provided to demonstrate the capacity of the proposed approach. A reliable and practical theoretical basis and supporting information are provided for the integrity and emergency management of buried gas pipelines in urban areas, considering actual operational conditions.     

Urban water-related environmental transitions in Southeast Asia

This article reviews water-related urban environmental conditions in Southeast Asia. It argues that the development of urban environmental challenges in the region follows a unique pattern compared with those experienced in the now developed world. The new pattern is defined by the so called time–space telescoping of the development process. The process of time–space telescoping reduces the levels of income at which environmental challenges emerge and forces their appearance in a simultaneous fashion, as sets of problems. During previous eras, cities experienced sequential environmental transitions. Urban water-related environmental burdens emerged on local scales and expanded geographically and temporally in impact, with growing levels of affluence. Moreover, certain environmental challenges appeared later in economic growth because the technologies and practices that induced these problems emerged at higher levels of income. The article has two main findings. First, except for wealthy urban centers, for example Singapore, cities in the region are experiencing multi-scaled water burdens simultaneously. Second, low-income and middle-income cities are experiencing burdens at lower levels of income than did their contemporaries in the north.

被动采样法观测研究京津冀区域大气中气态污染物

为了对京津冀区域的大气污染物进行观测,揭示污染物浓度和组分的时空分布和变化规律,深入了解区域复合型污染,从2007年12月开始使用造价低、操作简捷的被动采样方法对区域10个站点大气中的SO2、NO2、O3和NH3等主要污染物进行了监测,对被动采样方法的区域适用性进行了比较全面的评估并根据监测结果对污染物的浓度水平和区域分布进行了研究.方法适用性评估表明被动采样方法在污染较严重的京津冀区域能进行长时间采样,采样频率设定为每月1次;平行采样结果显示,SO2、NO2、O3和NH3的变异系数分别为6.4%、7.1%、4.2%和3.9%,方法表现出良好的稳定性;每月1次的被动采样浓度结果与主动采样仪器观测结果月平均值相比具有较好的一致性,SO2、NO2和O3这2种方法监测结果的相关系数达到0.91、0.88和0.93,拟合曲线斜率分别为1.25、0.98和0.93,平均相对标准偏差分别为23.3%、14.9%和8.5%,能基本满足大气采样的要求,NH3的短时监测也表明2种方法具有可比性.评估结果说明被动采样方法是一种可靠的大气污染监测方法,可用于区域污染的监测.2008年夏季京津冀区域10个站点SO2、NO2、O3和NH3的被动采样平均浓度分别(12.3±6.3)×10-9、(13.2±7.0)×10-9、(40.5±9.5)×10-9和(24.0±13.7)×10-9.浓度区域分布显示SO2和NO2在城市站点具有较高浓度,而NH3在农业站点的浓度较高,SO2、NO2和NH3的大气浓度水平明显受局地排放影响,浓度分布较直观的反应了站点的局地源排放;而O3除了背景站兴隆,在北京和天津周边的大小城市,平均浓度都在40×10-9左右,表现出区域协同污染特征.     

武汉城市圈城市化发展与环境空气质量关系探讨

城市化与环境空气的相互作用关系研究,是引导城市可持续发展和环境政策制定的重要依据。利用主成分分析法和集成的环境空气质量指数分别评价了城市化和环境空气质量水平,进而拟合了两者的最优高次多项式曲线。结果发现:12001年来,武汉城市圈的城市化综合水平表现出以武汉为核心,黄石和鄂州为次核心,咸宁、孝感等为边缘的层级结构;2城市圈空气污染的重心主要在武汉市和鄂东南的黄冈、鄂州、黄石等地区,PM10是首要污染物;3不同城市由于其自然地理背景、城市发展类型、经济产业结构的不同,环境空气效应(关系)存在差异,在武汉城市圈内主要表现为三类:武汉市的复合型空气污染,黄石、鄂州等煤烟型为主的空气污染,以及咸宁、天门等煤烟和机动车尾气混合型的转变空气污染。未来,城市圈在生态环保一体化的进程中,需加强空气污染的联合防治,也需结合城市的自身特点采取有针对性的污染治理措施。     

Black carbon (BC) in urban and surrounding rural soils of Beijing, China: spatial distribution and relationship with polycyclic aromatic hydrocarbons (PAHs)

The concentrations of black carbon (BC), total organic carbon (TOC) and polycyclic aromatic hydrocarbons (PAHs) have been determined in soils from urban and rural areas of Beijing. The rural area can be divided into plain and mountainous areas which are close to and relatively far from the urban area, respectively. Concentration of BC (5.83 ± 3.05 mg g⁻¹) and BC/TOC concentration ratio (0.37 ± 0.15) in Beijing’s urban soil are high compared with that in world background soils and rural soils of Beijing, suggesting the urban environment to be an essential source and sink of BC. Concentration of BC in the urban area decreases from the inner city to exterior areas, which correlates with the urbanization history of Beijing and infers accumulation of BC in old urban soils. Black carbon in Beijing soils mainly comes from fossil fuel combustion, especially traffic emission. Median PAH concentration in the urban area (502 ng g⁻¹) is one order of magnitude higher than that in the rural plain (148 ng g⁻¹) and mountainous area (146 ng g⁻¹) where PAHs are supposed to mainly come from atmospheric deposition from the urban area. Concentrations of BC correlate significantly with those of PAHs (p < 0.01, except naphthalene) in the urban area and with those of heavier 4-, 5- and 6- ring PAHs (p < 0.01) in the adjacent rural plain area, while there is no significant correlation with any PAH in the farther rural mountainous area.     

The toxicity of titanium dioxide nanopowder to early life stages of the Japanese medaka (Oryzias latipes)

In this study, fertilized Japanese medaka (Oryzias latipes) embryos were exposed from fertilization to 5 d post-hatch using static non-renewal assays to aqueous suspensions of titanium dioxide nanoparticles (nTiO₂) ranging in nominal concentrations between 0 and 14 μg mL⁻¹. The average size of the nTiO₂ in the stock solution before addition to the test treatments was 87 nm (±14 nm). TiO₂ materials accumulated in a concentration dependent manner on the chorionic filaments of developing medaka embryos with evidence of pericardial edema occurring during embryo development. However, no significant (p > 0.05) increases in mortality relative to control treatments were observed for the nTiO₂ exposed embryos. A concentration dependent increase in cumulative percent hatch was observed at 11 d, indicating that exposure to increasing concentrations of nTiO₂ resulted in the premature hatch of medaka embryos. Post-hatch, a significant proportion of sac fry from the nTiO₂ exposure groups exhibited moribund swimming behavior and these individuals also experienced greater mortality at 15 d post-hatch. Combined, these results demonstrate that exposure to nTiO₂ can impact the development of early life stages of fish.     

Urban regeneration and democratization of information access: CitiStat experience in Baltimore

This article explores the potential of a GIS-based approach to city management - Baltimore's CitiStat e-government program - for meeting the goals of sustainable urban regeneration. The argument advocated here builds on the widely held recognition that the application of ICTs in general can lead to both new forms of inclusion and exclusion of citizens. Therefore attending to the 'digital divide' is a relevant issue because cities are complex environments where outcomes of interventions are uncertain and widening participative arenas to different actors can increase the possibilities to regenerate declining urban areas in a more democratic way.     

Polychlorinated biphenyls contamination in urban soil of Shanghai: level, compositional profiles and source identification

Surface soil samples taken from 55 sampling sites at the urban areas of Shanghai were collected and analyzed for the occurrence of 144 polychlorinated biphenyls (PCBs) by GC-μECD. The results showed that totally 74 PCB congeners were identified and the mean concentration of total PCBs was 3057 ng kg⁻¹ with a range of 232 to 11325 ng kg⁻¹. Compared with the related reports, the level of PCBs contamination in this study was approximately equal to the global background value in soils, but higher than Chinese background for rural and urban soils. According to the compositional profiles of PCBs homologues, a higher proportion of low chlorinated (from tri-CBs to hexa-CBs) was observed. The results indicated that PCB15 + 13, PCB18, PCB28, PCB104 + 47 and PCB153 were the most dominant congeners among the identified PCBs. Through homologues analysis, cluster analysis and principal component analysis (PCA), it was found that PCBs were stretched from mixed local sources, and appeared to be mostly originated by Aroclor 1260- and 1254-like mixtures as well as some samples influenced by Aroclor 1232 and 1242. The correlation analysis showed the relatively good correlation among the PCB homologues and soil total organic carbon (TOC), suggesting important influence of soil TOC on PCBs contamination in soil matrix in Shanghai region. The toxic equivalency (TEQ) concentrations of these six dioxin-like PCBs detected in urban soil samples range from 2.71 to 24.9 pg kg⁻¹-PCDDeq with a mean 8.18 pg kg⁻¹-PCDDeq.