Urban environmental geochemistry of trace metals

As the world's urban population continues to grow, it becomes increasingly imperative to understand the dynamic interactions between human activities and the urban environment. The development of urban environmental geochemistry has yielded a significant volume of scientific information about geochemical phenomena found uniquely in the urban environment, such as the distribution, dispersion, and geochemical characteristics of some toxic and potentially toxic trace metals. The aim of this paper is to provide an overview of the development of urban environmental geochemistry as a field of scientific study and highlight major transitions during the course of its development from its establishment to the major scientific interests in the field today. An extensive literature review is also conducted of trace metal contamination of the urban terrestrial environment, in particular of urban soils, in which the uniqueness of the urban environment and its influences on trace metal contamination are elaborated. Potential areas of future development in urban environmental geochemistry are identified and discussed.     

高邮市城区污染强度与北澄子河环境容量的相关性

根据2004年度高邮市主要纳污河流北澄子河流经城区后，污染物增加量、城区段河流的自净量及河流剩余环境容量，计算出城区段河流的总环境容量，再通过各年度河流流经城区后污染物增加量及自净量，计算出各年度城区段河流的剩余环境容量，分析城区污染强度与北澄子河环境容量的相关性，得到线性公式，从而可以根据城区污染强度推算环境容量的变化，或根据环境容量的变化推算城区污染强度。     

The study of urban metabolism and its applications to urban planning and design

Following formative work in the 1970s, disappearance in the 1980s, and reemergence in the 1990s, a chronological review shows that the past decade has witnessed increasing interest in the study of urban metabolism. The review finds that there are two related, non-conflicting, schools of urban metabolism: one following Odum describes metabolism in terms of energy equivalents; while the second more broadly expresses a city's flows of water, materials and nutrients in terms of mass fluxes. Four example applications of urban metabolism studies are discussed: urban sustainability indicators; inputs to urban greenhouse gas emissions calculation; mathematical models of urban metabolism for policy analysis; and as a basis for sustainable urban design. Future directions include fuller integration of social, health and economic indicators into the urban metabolism framework, while tackling the great sustainability challenge of reconstructing cities.     

城市轨道交通噪声的声源特性研究进展

分析了城市轨道交通噪声的主要类型、基本特性、传播规律及其影响因素;综述了国内外城市轨道交通噪声的预测及测量分析技术的研究成果,并对其进行了总结比较,阐述了各种方法的特点、主要成就和局限;最后探讨了城市轨道交通噪声领域今后的研究方向和发展趋势,为解决城市轨道交通发展中的噪声问题提供了参考.     

The potential contribution of urban runoff to surface sediments of the Passaic River: sources and chemical characteristics

Urban runoff has been reported as the second most frequent cause of surface water pollution in the United States. Due to the incidence of runoff in urban areas, it was of interest to estimate the impact runoff may have to recent sediment quality within the lower reaches of the Passaic River. Study objectives included i) review of recent urban runoff studies to determine the occurrence and pattern of distribution of chemicals in runoff; ii)comparison of the "fingerprints" from urban runoff studies to the contaminant distributions in surface sediments from the River; and iii) estimation of mass loadings to the surface sediments using surrogate data. The analyses showed that metals and PAH distributions in the sediments were similar to those observed in runoff from diverse locations, suggesting that urban runoff composition within the Passaic watershed is similar to other urban areas. Mass loading calculations demonstrated that urban runoff is a significant source of the metals observed in the sediments, and that PAH and DDT sediment loadings could, in some cases, be accounted for by urban runoff. Observed sediment loads for PCBs, however, were significantly higher than were estimated from urban runoff.     

The dust retention capacities of urban vegetation—a case study of Guangzhou, South China

Urban vegetation increasingly plays an important role in the improvement of the urban atmospheric environment. This paper deals with the dust retention capacities of four urban tree species (Ficus virens var. sublanceolata, Ficus microcarpa, Bauhinia blakeana, and Mangifera indica Linn) in Guangzhou. The dust-retaining capacities of four tree species are studied under different pollution intensities and for different seasons. Remote sensing imagery was used to estimate the total aboveground urban vegetation biomass in different functional areas of urban Guangzhou, information that was then used to estimate the dust-retaining capacities of the different functional areas and the total removal of airborne particulates in urban Guangzhou by foliage. The results showed that urban vegetation can remove dust from the atmosphere thereby improving air quality. The major findings are that dust retention, or capture, vary between the four species of tree studied; it also varied between season and between types of urban functional area, namely industrial, commercial/road traffic, residential, and clean areas. Dust accumulation over time was also studied and reached a maximum, and saturation, after about 24 days. The overall aboveground biomass of urban vegetation in Guangzhou was estimated to be 52.0?×?10⁵ t, its total leaf area 459.01 km², and the dust-retaining capacity was calculated at 8012.89 t per year. The present study demonstrated that the foliage of tree species used in urban greening make a substantial contribution to atmospheric dust removal and retention in urban Guangzhou.     

Barriers to the implementation of urban sustainability

Much of the debate over urban sustainability has revolved around the key components of sustainable development, and this has resulted in the identification of key concepts and principles that should be followed. Very little attention has been given to the difficulties encountered in the implementation of urban sustainability. This paper sets out the background to urban sustainability within clearly parameters, namely land, energy and transport. Development principles are established, and the implementation issues are addressed at four levels: decisions relating to the use of existing resources; decisions relating to new development; decisions relating to transport; and decisions relating to increasing energy efficiency within urban areas. At each level, the objectives of sustainability, together with the key concerns and actions, are described. The barriers to implementation explain why progress towards urban sustainability has been slow. Recommendations are presented as to how these barriers can be overcome so that the objectives of urban sustainability can be matched with other objectives, such as improvement of the quality of life in urban areas.     

Impact of anthropogenic activities on urban stream water quality: a case study in Guangzhou,China

Anthropogenic activities are increasingly impacting the quality of urban surface water, particularly in regions undergoing intensive urbanization, such as Guangzhou of South China with a large urban stream network. To examine such impacts, we conducted field sampling on December 24, 2010, May 24, 2011, and August 28, 2011, representative of the low-, normal-, and high-flow periods, respectively. The first sampling was timed immediately after the closing of the 16th Asian Games (November 12–27, 2010) and the 10th Asian Para Games (December 12–19, 2010) held in Guangzhou. Assessments based on a pollution index method showed that the urban streams under investigation were extremely polluted, with direct discharge of untreated domestic sewage identified as the main pollution contributor. In addition, stream water quality around urban villages with high population densities was worse than that within business districts away from the urban villages. Pollution control measures implemented in preparation for the Asian Games were effective for urban streams within the business districts, but less effective for those adjacent to the urban villages. However, short-term efforts may not be able to achieve sustainable urban water quality improvements. In the case of Guangzhou, minimizing or even eliminating direct point-source inputs to the urban streams is perhaps the best option.     

Microbial biomass carbon and enzyme activities of urban soils in Beijing

Introduction  

To promote rational and sustainable use of soil resources and to maintain the urban soil quality, it is essential to assess urban ecosystem health. In this study, the microbiological properties of urban soils in Beijing and their spatial distribution patterns across the city were evaluated based on measurements of microbial biomass carbon and urease and invertase activities of the soils for the purpose of assessing the urban ecosystem health of Beijing.     

Urban expansion and the loss of prime agricultural lands in Puerto Rico

In many countries where the economy has shifted from mainly agricultural to industrial, abandoned agricultural lands are lost to urbanization. For more than 4 centuries the Puerto Rican economy depended almost entirely on agriculture, but sociopolitical changes early in the 20th century resulted in a shift to industry. This shift in the economy, and an increase in population, has resulted in an increase in urban areas. This study describes the rate and distribution of urban growth on the island of Puerto Rico from 1977 to 1994 and the resulting influence on potential agricultural lands. Urban extent and growth were determined by interpreting aerial photographs and satellite imagery. The 1994 urban coverage was combined with a soil coverage based on agricultural potential to determine the distribution of urban areas relative to potential farmlands. Analyses showed that in 1977, 11.3% of Puerto Rico was classified as urban. After 17 years, urban areas had increased by 27.4% and urban growth on soils suitable for agriculture had increased by 41.6%. This represents a loss of 6% of potential agricultural lands. If this pattern of encroachment by urban growth into potential farmlands continues, Puerto Rico's potential for food production in the future could be greatly limited.     

Numerical simulation of the urban boundary layer over the complex terrain of Hong Kong

Due to the complexity of the underlying surface, urban boundary layers may exhibit very different wind-temperature field structures compared with rural areas. In this study, an urban boundary layer model with a resolution of 500 m is applied to Hong Kong, a place characterized by complex topography with high mountains and dense urban developments. Five surface land use types are considered; grass and shrub land, trees, water, old urban areas and new town developments. The urban boundary layer model is embedded into the National Center for Atmospheric Research (NCAR) Mesoscale Model, version 5 (MM5). The initial and boundary conditions are obtained from the National Centers for Environmental Prediction (NCEP)/NCAR reanalysis dataset. The modeling approach therefore takes into account both the mesoscale background field and the urban underlying surface. The model is applied to the simulation of a pollution episode in Hong Kong. Results show good agreement with meteorological data for the surface winds and temperature. The model successfully simulates the urban heat island and the occurrence of a sea–land breeze circulation, and their impact on air pollutant transport and dispersion.     

城市产业水污染控制优化研究——以株洲市为例

针对城市产业水污染状况，应用产业结构和工业行业结构优化模型，试图找出城市产业结构调整方法。研究以株洲市为例，根据株洲市产业结构和行业结构特点对模型进行改进和最优化计算。计算结果表明，产业和行业生产用水的调整可以减少废水排放量和实现经济增长。在此基础上，提出了株洲市产业和行业凋整方案，以期实现城市经济发展与环境保护协调发雇。     

城市产业水污染控制优化研究--以株洲市为例

针对城市产业水污染状况,应用产业结构和工业行业结构优化模型,试图找出城市产业结构调整方法.研究以株洲市为例,根据株洲市产业结构和行业结构特点对模型进行改进和最优化计算.计算结果表明,产业和行业生产用水的调整可以减少废水排放量和实现经济增长.在此基础上,提出了株洲市产业和行业调整方案,以期实现城市经济发展与环境保护协调发展.     

中国九十年代城市环境污染控制战略(下)

80年代是我国城市社会经济发展最快的时期,城市化水平由1981年的14.3％提高到1990年的21％,城市规模结构趋向合理,形成了以大城市为中心,中等城市为骨干和小城市为纽带的城市结构。但应该清醒的是,我国绝大部分城市的经济发展水平与工业     

Urban sustainability science: prospects for innovations through a system’s perspective,relational and transformations’ approaches: This article belongs to Ambio’s 50th Anniversary Collection. Theme: Urbanization

In this perspective, we present how three initial landmark papers on urban sustainability research contributed to the larger sustainability science scholarship and paved the way for the continued development of urban sustainability research. Based on this, we propose three conceptual innovation pathways to trace the progression of urban sustainability science: First, urban sustainability from a system’s perspective, meaning that urban sustainability requires integrative solutions to work in the tripled social-ecological-technological system setting. Second, urban sustainability from a (people and place) relational perspective, meaning urban sustainability is a contested and dynamic social-ecological contract of cities. As a governance mission, urban sustainability requires evidence from research that can inform coordinated action to bridge people, places, meanings, visions and ecosystems. Third, urban sustainability from a transformative science perspective, meaning that for urban sustainability to be achieved and progressed, deep transformations are required in systems, relations, policies and governance approaches. Our proposal for the future of urban sustainability science centres on emphasizing the relevance and policy applicability of systems’ thinking, value and place thinking and transitions/transformations thinking as fundamental to how knowledge is co-produced by research science, policy and society and becomes actionable.     

Assessing urban habitat quality based on specific leaf area and stomatal characteristics of Plantago lanceolata L

This study has evaluated urban habitat quality by studying specific leaf area (SLA) and stomatal characteristics of the common herb Plantago lanceolata L. SLA and stomatal density, pore surface and resistance were measured at 169 locations in the city of Gent (Belgium), distributed over four land use classes, i.e., sub-urban green, urban green, urban and industry. SLA and stomatal density significantly increased from sub-urban green towards more urbanised land use classes, while the reverse was observed for stomatal pore surface. Stomatal resistance increased in the urban and industrial land use class in comparison with the (sub-) urban green, but differences between land use classes were less pronounced. Spatial distribution maps for these leaf characteristics showed a high spatial variation, related to differences in habitat quality within the city. Hence, stomatal density and stomatal pore surface are assumed to be potentially good bio-indicators for urban habitat quality.     

Particle size distributions of polycyclic aromatic hydrocarbons in rural and urban atmosphere of Tianjin, China

The size distributions of 16 polycyclic aromatic hydrocarbons (PAHs) and particle mass less than 10 microm in aerodynamic diameter (Dp) were measured using a nine-stage low-volume cascade impactor at rural and urban sites in Tianjin, China in the winter of 2003-2004. The particles exhibited the trimodal distribution with the major peaks occurring at 0.43-2.1 and 9.0-10.0 microm for both urban and rural sites. The concentrations of the total PAH (sum of 16 PAH compound) at rural site were generally less than those of urban site. Mean fraction of 76.5% and 63.9% of the total PAH were associated with particles of 0.43-2.1 microm at rural and urban sites, respectively. Precipitation, temperature, wind speed and direction were the important meteorological factors influencing the concentration of PAHs in rural and urban sites. The distributions of PAHs concentration with respect to particle size were similar for rural and urban samples. The PAHs concentrations at the height of 40 m were higher than both of 20 and 60 m at urban site, but the mass median diameter (MMD) of total PAH increased with the increasing height. The mid-high molecular weight (278 >or= MW >or= 202) PAHs were mainly associated with fine particles (Dp or=MW >or=178) PAHs were distributed in both of fine and coarse particle. The fraction of PAHs associated with coarse particles (Dp>2.1 microm) decreased with increasing molecular weight. The relatively consistent distribution of PAHs seemed to indicate the similar combustion source of PAHs at both of rural and urban sites. The fine differences of concentration and distribution of PAHs at different levels at urban site suggested that the different source and transportation path of particulate PAHs.     

Microbial indicators of heavy metal contamination in urban and rural soils

Urban soils and especially their microbiology have been a neglected area of study. In this paper, we report on microbial properties of urban soils compared to rural soils of similar lithogenic origin in the vicinity of Aberdeen city. Significant differences in basal respiration rates, microbial biomass and ecophysiological parameters were found in urban soils compared to rural soils. Analysis of community level physiological profiles (CLPP) of micro-organisms showed they consumed C sources faster in urban soils to maintain the same level activity as those in rural soils. Cu, Pb, Zn and Ni were the principal elements that had accumulated in urban soils compared with their rural counterparts with Pb being the most significant metal to distinguish urban soils from rural soils. Sequential extraction showed the final residue after extraction was normally the highest proportion except for Pb, for which the hydroxylamine-hydrochloride extractable Pb was the largest part. Acetic acid extractable fraction of Cd, Cu, Ni, Pb and Zn were higher in urban soils and aqua regia extractable fraction were lower suggesting an elevated availability of heavy metals in urban soils. Correlation analyses between different microbial indicators (basal respiration, biomass-C, and sole C source tests) and heavy metal fractions indicated that basal respiration was negatively correlated with soil Cd, Cu, Ni and Zn inputs while soil microbial biomass was only significantly correlated with Pb. However, both exchangeable and iron- and manganese-bound Ni fractions were mostly responsible for shift of the soil microbial community level physiological profiles (sole C source tests). These data suggest soil microbial indicators can be useful indicators of pollutant heavy metal stress on the health of urban soils.     

Urban forests and pollution mitigation: analyzing ecosystem services and disservices

The purpose of this paper is to integrate the concepts of ecosystem services and disservices when assessing the efficacy of using urban forests for mitigating pollution. A brief review of the literature identifies some pollution mitigation ecosystem services provided by urban forests. Existing ecosystem services definitions and typologies from the economics and ecological literature are adapted and applied to urban forest management and the concepts of ecosystem disservices from natural and semi-natural systems are discussed. Examples of the urban forest ecosystem services of air quality and carbon dioxide sequestration are used to illustrate issues associated with assessing their efficacy in mitigating urban pollution. Development of urban forest management alternatives that mitigate pollution should consider scale, contexts, heterogeneity, management intensities and other social and economic co-benefits, tradeoffs, and costs affecting stakeholders and urban sustainability goals.     

昆明主城区城市地表径流污染特征分析

昆明市位于滇池上游,城市地表径流污染负荷对滇池水质具有直接影响。通过对昆明主城区内不同功能区12个监测点7次降雨径流过程水样的采集与分析,研究了昆明主城区城市地表径流污染特征。结果表明,昆明主城区城市地表径流中TSS、COD、TN和TP的多场降雨平均浓度分别为182.8、138.2、2.37和0.43 mg/L。不同功能区的地表径流水质存在显著差异(p<0.05);各功能区径流污染负荷顺序为:公路区>商业区>住宅区>文教区;不同功能区单场降雨径流水质动态变化规律是:污染物浓度在降雨径流初期相对较高,中后期浓度快速下降,并逐渐趋于稳定;地表利用功能、降雨特征和交通流量是影响城市地表径流水质的主要因素;城市地表径流中COD、TN、TP与TSS之间有较好的相关性,说明大部分的污染物质是以颗粒吸附态存在。