Effects of seasonal climatic variability on several toxic contaminants in urban lakes: Implications for the impacts of climate change

Climate change is supposed to have influences on water quality and ecosystem. However, only few studies have assessed the effect of climate change on environmental toxic contaminants in urban lakes. In this research, response of several toxic contaminants in twelve urban lakes in Beijing, China, to the seasonal variations in climatic factors was studied. Fluorides, volatile phenols, arsenic, selenium, and other water quality parameters were analyzed monthly from2009 to 2012. Multivariate statistical methods including principle component analysis, cluster analysis, and multiple regression analysis were performed to study the relationship between contaminants and climatic factors including temperature, precipitation, wind speed, and sunshine duration. Fluoride and arsenic concentrations in most urban lakes exhibited a significant positive correlation with temperature/precipitation, which is mainly caused by rainfall induced diffuse pollution. A negative correlation was observed between volatile phenols and temperature/precipitation, and this could be explained by their enhanced volatilization and biodegradation rates caused by higher temperature. Selenium did not show a significant response to climatic factor variations, which was attributed to low selenium contents in the lakes and soils. Moreover, the response degrees of contaminants to climatic variations differ among lakes with different contamination levels. On average, temperature/precipitation contributed to 8%, 15%, and 12% of the variations in volatile phenols, arsenic, and fluorides,respectively. Beijing is undergoing increased temperature and heavy rainfall frequency during the past five decades. This study suggests that water quality related to fluoride and arsenic concentrations of most urban lakes in Beijing is becoming worse under this climate change trend.     

浅析融雪剂对城市环境的影响

融雪剂是一把双刃剑,在快速除雪保障交通畅通的同时,也给城市带来了一系列的环境问题。对融雪剂对城市环境的影响进行了探讨分析,并提出了今后使用融雪剂的建议和策略。     

A case for urban liveability from below: exploring the politics of water and land access for greater liveability in Kampala,Uganda

ABSTRACT

Improving urban liveability and prosperity is commonly set as a priority in urban development plans and policy around the world. Several annual reports produced by international consulting firms, media, and global agencies rank the liveability of cities based on a set of indicators, to represent the quality of life in these cities. The higher is the ranking, the more liveable is the city. In this paper, we argue that such quantitative approaches to framing and addressing urban liveability challenges leave little room to reflect on people's experiences of this liveability, which cannot be expressed through numbers. To illustrate our argument, we draw on empirical evidence of urban liveability challenges in access to water and land in Kampala, the capital city of Uganda, ranked recently as the most liveable East African city by various global agencies and media outlets. By showing that increasing the number of water connections does not guarantee improved access to water and sanitation in the long run, first, we demonstrate how urban liveability challenges are tightly linked with land-title issues in the city. Second, we highlight the political game-playing between the central government, the opposition, the traditional leadership, and the slum dwellers in governance processes of service delivery. Finally, by arguing that urban liveability can be enhanced by broadening political participation in city development planning, we discuss some of the strategies that can be used by communities to make collective claims towards improving their quality of life and the environment.     

Cooperative Game Among Cities in Urban Agglomerations and Economical Sustainable Development

Abstract

This paper analyses redounded profits of cooperation and non-cooperation among cities in urban agglomerations based on game theory. It discusses the problems of economical development among cities with feeble cooperation, and deduces the conclusion that only cooperation of cities produces the maximum profits and realizes Pareto efficiency for cities and urban agglomerations. The paper states that cooperation is the cornerstone of economic sustainable development in urban agglomerations in profits produced by cooperation among cities. Some suggestions to accelerate cooperation among cities are proposed.     

长江中游城市群区域一体化的测度与比较

实现长江中游城市集群区域一体化,既能承接东部地区产业转移,也能够向西部传递发展势能,缩小西部与中东部的差距。参照了世界银行从密度、距离与分割3个维度对区域一体化的界定,构建了区域一体化评价体系;采用2000～2010年数据,并结合层次分析法对长江中游城市集群内部区域一体化进行测度与比较分析。研究显示：（1）长株潭城市圈区域一体化水平最高,武汉城市圈次之,环鄱阳湖生态经济区最低,但三大城市群一体化水平都呈现逐渐增长趋势;（2）三大城市群在市场一体化、行政一体化及社会一体化变化水平差异明显但总体差距逐渐缩小;（3）武汉城市圈在“两型”社会建设推动下一体化水平稳步提升,长株潭城市群一体化水平进程最快,环鄱阳湖生态经济区后发优势明显。在此基础上,提出了构建长江中游城市集群经济发展联动机制的政策建议     

Liver histological changes and lipid peroxidation in the amphibian Ambystoma mexicanum induced by sediment elutriates from the Lake Xochimilco

Lacustrine sediments accumulate pollutants that input from the lake watershed and can be released to the water column by sediment resuspension; thus, pollutants can change their bioavailability and exert adverse effects to aquatic biota. Shallow-urban lakes are particularly susceptible to receive pollutants from urban discharges and sediment resuspension. Lake Xochimilco, in Mexico City, an urban-shallow lake, faces multiple problems: urban sprawl, overexploitation of aquifers, drying of springs, discharge of wastewater from treatment plants, and sediment resuspension. The aquatic biota living in this ecosystem is continuously exposed to the release of pollutants from the sediments. We assessed the risk that pollutants released from sediments from Lake Xochimilco, Touristic (TZ) and Agriculture zone (AZ), can exert on a native amphibian species of the lake (Ambystoma mexicanum) through exposure bioassays to sediment elutriates. We evaluate alterations in the amphibian by three approaches: biochemical (level of lipid peroxidation, LPO), cellular (ultrastructure) and the liver histology of A. mexicanum and we compare them with a batch control. Additionally, we assessed heavy metals (Pb, Cd and Hg) in elutriates. Elutriates from TZ showed the highest concentrations of the metals assessed. Organisms exposed to sediment elutriates from either study sites showed higher LPO values than control organisms (p < 0.05). Organisms exposed to elutriates from the TZ showed the most conspicuous damages: hepatic vasodilation of sinusoids, capillaries with erythrocytes, leukocyte infiltration and cytoplasmic vacuolation in hepatocytes. The biological responses assessed reflected the risk that faces A. mexicanum when is exposed for prolonged periods to sediment resuspension in Lake Xochimilco.     

A barrier to metal movement: Synchrotron study of iron plaque on roots of wetland plants

正A wetland with attractive plants hosting birds and other wildlife is an esthetically pleasing prospect that is gaining popularity as a way of stabilizing or remediating metalcontaminated soils and sediment(Weber and Gagnon,2014;     

Dynamic probability assessment of urban natural gas pipeline accidents considering integrated external activities

Urban gas pipelines usually have high structural vulnerability due to long service time. The locations across urban areas with high population density make the gas pipelines easily exposed to external activities. Recently, urban pipelines may also have been the target of terrorist attacks. Nevertheless, the intentional damage, i.e. terrorist attack, was seldom considered in previous risk analysis of urban gas pipelines. This work presents a dynamic risk analysis of external activities to urban gas pipelines, which integrates unintentional and intentional damage to pipelines in a unified framework. A Bayesian network mapping from the Bow-tie model is used to represent the evolution process of pipeline accidents initiating from intentional and unintentional hazards. The probabilities of basic events and safety barriers are estimated by adopting the Fuzzy set theory and hierarchical Bayesian analysis (HBA). The developed model enables assessment of the dynamic probabilities of consequences and identifies the most credible contributing factors to the risk, given observed evidence. It also captures both data and model uncertainties. Eventually, an industrial case is presented to illustrate the applicability and effectiveness of the developed methodology. It is observed that the proposed methodology helps to more accurately conduct risk assessment and management of urban natural gas pipelines.