Determination and analysis of PM10 source apportionment during episodes of air pollution in Central Eastern European urban areas: The case of wintertime 2006

Source apportionment of air pollution due to particulate matter with an aerodynamic diameter <10 μm (PM₁₀) was investigated in Central Eastern European urban areas. A combination of four methods was developed to distinguish long-range transport (LRT) and regional transport (RT) from local pollution (LP) sources as well as to discern the involvement of traffic or residential sources in LP. Sources of PM₁₀ events of pollution were determined in January 2006 in representative Polish cities using monitored air quality and meteorological data, backward air mass trajectories, correlation and principal component analysis (PCA). Daily patterns of PM₁₀ levels show that several peak episodes were registered in Poland; January 21–30th being the most polluted days. Air mass back-trajectory analysis shows that all cities were under the influence of LRT from North-eastern origins (Russia–Belarus–Ukraine), most were also under LRT from Southern origin (Slovakia, Czech Republic), and northern cities were under national RT influence. PCA analysis shows that ion-sums of secondary inorganic aerosols account for LRT pollution while arsenic and chromium represents markers of RT (industrial) and LP (residential) sources of PM₁₀, respectively. Determination of several ratios (REG/UB, REG/TRAF, TRAF/UB) calculated between PM₁₀ levels measured at regional background (REG); urban background (UB) and traffic (TRAF) monitoring sites shows that, with ratios REG/UB ≥ 0.57, PM₁₀ episodes in both Szczecin and Warsaw bore a marked RT origin. The lower REG/UB ≤ 0.35 in the Southern cities of Cracow and Zabrze indicates that LP was the main contributor to the observed episodes. Only PM₁₀ episodes in Southern-western Poland (Jelenia Góra) were clearly of LP origin as characterized, by the lowest REG/UB ratio (<0.2). The high TRAF/UB ratios obtained for all cities (close to 1) indicate that there was a great uniformity of PM levels on an urban scale owing to the meteorologically stagnant conditions. A high correlation between PM₁₀, NO₂ and CO confirms that traffic emission represented a common and an important LP source of urban pollution in most Polish cities during January 2006. On the other hand PM₁₀ which is also highly correlated with SO₂ in 4 cities out of 6, indicates that coal combustion through domestic heating or industrial activities was also an important LP source of PM₁₀. Finally, extremely unfavourable meteorological conditions caused by the influence of a Siberian high-pressure system were found to be associated with the occurrence of severe PM₁₀ episodes of pollution.     

CFD modelling of hydrogen release, dispersion and combustion for automotive scenarios

The paper describes the analysis of the potential effects of releases from compressed gaseous hydrogen systems on commercial vehicles in urban and tunnel environments using computational fluid dynamics (CFD). Comparative releases from compressed natural gas systems are also included in the analysis.

This study is restricted to typical non-articulated single deck city buses. Hydrogen releases are considered from storage systems with nominal working pressures of 20, 35 and 70 MPa, and a comparative natural gas release (20 MPa). The cases investigated are based on the assumptions that either fire causes a release via a thermally activated pressure relief device(s) (PRD) and that the released gas vents without immediately igniting, or that a PRD fails. Various release strategies were taken into account. For each configuration some worst-case scenarios are considered.

By far the most critical case investigated in the urban environment, is a rapid release of the entire hydrogen or natural gas storage system such as the simultaneous opening of all PRDs. If ignition occurs, the effects could be expected to be similar to the 1983 Stockholm hydrogen accident [Venetsanos, A. G., Huld, T., Adams, P., & Bartzis, J. G. (2003). Source, dispersion and combustion modelling of an accidental release of hydrogen in an urban environment. Journal of Hazardous Materials, A105, 1–25]. In the cases where the hydrogen release is restricted, for example, by venting through a single PRD, the effects are relatively minor and localised close to the area of the flammable cloud. With increasing hydrogen storage pressure, the maximum energy available in a flammable cloud after a release increases, as do the predicted overpressures resulting from combustion. Even in the relatively confined environment considered, the effects on the combustion regime are closer to what would be expected in a more open environment, i.e. a slow deflagration should be expected.

Among the cases studied the most severe one was a rapid release of the entire hydrogen (40 kg) or natural gas (168 kg) storage system within the confines of a tunnel. In this case there was minimal difference between a release from a 20 MPa natural gas system or a 20 MPa hydrogen system, however, a similar release from a 35 MPa hydrogen system was significantly more severe and particularly in terms of predicted overpressures. The present study has also highlighted that the ignition point significantly affects the combustion regime in confined environments. The results have indicated that critical cases in tunnels may tend towards a fast deflagration, or where there are turbulence generating features, e.g. multiple obstacles, there is the possibility that the combustion regime could progress to a detonation.

When comparing the urban and tunnel environments, a similar release of hydrogen is significantly more severe in a tunnel, and the energy available in the flammable cloud is greater and remains for a longer period in tunnels. When comparing hydrogen and natural gas releases, for the cases and environments investigated and within the limits of the assumptions, it appears that hydrogen requires different mitigation measures in order that the potential effects are similar to those of natural gas in case of an accident. With respect to a PRD opening strategy, hydrogen storage systems should be designed to avoid simultaneous opening of all PRD, and that for the consequences of the released energy to be mitigated, either the number of PRDs opening should be limited or their vents to atmosphere should be restricted (the latter point would require validation by a comprehensive risk assessment).     

Identification,Abundance and Origin of Aliphatic Hydrocarbons in the Fine Atmospheric Particulate Matter of Athens,Greece

The organic chemical composition of the fine fraction of atmospheric particulate matter in Athens has been studied, in order to establish emission sources. The results of the analyses of the aliphatic fraction indicate that all samples contain n-alkanes ranging from C₁₄ to C₃₂, with C₂₅, C₂₆, C₂₇ and C₂₉ being the more abundant congeners. Fossil fuels biomarkers such as extended tricyclic terpanes (hopanes, steranes) and isoprenoid hydrocarbons (pristane, phytane) were observed in our samples on a daily basis. Source reconciliation was conducted using molecular diagnostic ratios (such as the carbon preference index – CPI). The mean CPI value (1.84) indicates the mixed origin of the Athenian fine particles. The notable presence of an unresolved complex mixture or “hump” of hydrocarbons in our gas chromatograms is indicative of petrogenic hydrocarbon inputs. An approximate measure of this kind of contamination is the ratio of the concentrations of unresolved components to the resolved n-alkanes and other major compounds (U:R). The high U:R value of 25.25 further confirmed the major contribution of fossil fuels. Yet, the percent contribution of leaf wax n-alkanes (25.15%) indicated the parallel contribution of biogenic sources. This work supports the conclusion that vehicular emissions were the major source of aliphatic organic compounds with a smaller contribution of biogenic n-alkanes during the study period in Athens.     

Fuzzy pricing for urban water resources: model construction and application

A rational water price system plays a crucial role in the optimal allocation of water resources. In this paper, a fuzzy pricing model for urban water resources is presented, which consists of a multi-criteria fuzzy evaluation model and a water resources price (WRP) computation model. Various factors affecting WRP are comprehensively evaluated with multiple levels and objectives in the multi-criteria fuzzy evaluation model, while the price vectors of water resources are constructed in the WRP computation model according to the definition of the bearing water price index, and then WRP is calculated. With the incorporation of an operator's knowledge, it considers iterative weights and subjective preference of operators for weight-assessment. The weights determined are more rational and the evaluation results are more realistic. Particularly, dual water supply is considered in the study. Different prices being fixed for water resources with different qualities conforms to the law of water resources value (WRV) itself. A high-quality groundwater price computation model is also proposed to provide optimal water allocation and to meet higher living standards. The developed model is applied in Jinan for evaluating its validity. The method presented in this paper offers some new directions in the research of WRP.     

Implementing landscape fragmentation as an indicator in the Swiss Monitoring System Of Sustainable Development (Monet)

There is an increasing need and interest in including indicators of landscape fragmentation in monitoring systems of sustainable landscape management. Landscape fragmentation due to transportation infrastructure and urban development threatens human and environmental well-being by noise and pollution from traffic, reducing the size and viability of wildlife populations, facilitating the spread of invasive species, and impairing the scenic and recreational qualities of the landscape. This paper provides the rationale, method, and data for including landscape fragmentation in monitoring systems, using as an example the Swiss Monitoring System of Sustainable Development (Monet). We defined and compared four levels of fragmentation analysis, or fragmentation geometries (FGs), each based on different fragmenting elements, e.g., only anthropogenic, or combinations of anthropogenic and natural elements. As each FG has specific strengths and weaknesses, the most appropriate choice of FG depends on the context and objectives of a study. We present data on the current degree of landscape fragmentation for the five ecoregions and 26 cantons in Switzerland for all four FGs. Our results show that the degree of landscape fragmentation as quantified by the effective mesh size method is strongly supported by the postulates and indicator selection criteria of Monet, and we identify the most suitable FG focusing on the land area below 2100 m (e.g., excluding lakes) and allowing for an equitable comparison of fragmentation degrees among regions that differ in area covered by lakes and high mountains. For a more detailed analysis of landscape fragmentation in the context of environmental impact assessments and strategic environmental assessments, a combination of all four FGs may provide a more informative tool than any single FG.     

Private Sector Participation in Urban Water and Sanitation Provision in Ghana: Experiences from the Tamale Metropolitan Area (TMA)

African governments, like most countries in the developing world, face daunting tasks in their attempts to provide effective and equitable water and sanitation services for their ever increasing urban populations. Consequently, the past few years have witnessed increased private sector participation in urban water and sanitation provision, as many African governments strive to improve access to water and sanitation services for their citizens in line with Millennium Development Goal 7 (MDG7). Since the early 1990s, the government of Ghana and many local authorities have entered into various forms of public-private partnerships in urban water and sanitation provision. This article examines the outcome of such partnerships using the Tamale Metropolitan Area (TMA) as a case study with the aim of providing policy guidelines for the way forward. The article argues that the public-private arrangement for water supply and sanitation infrastructure management in the Tamale Metropolis has done nothing that an invigorated public sector could not have possibly achieved. It concludes that there can be no sustainable improvement in water and sanitation provision without political commitment, stakeholder ownership, and strong support for community driven initiatives.     

城市河涌污染治理技术的研究进展

随着经济的高速发展,大量污染物排放于城市河涌,导致城市河涌受到严重的污染。采取有效的技术措施治理河涌污染势在必行。结合近年来国内外河涌治理的研究成果,综述了河涌治理的主要技术的原理、特点、存在的问题,并指出目前各项技术的研究重点。     

戈尔膜过滤器在采油废水处理中的应用

"聚合物驱"采油技术在提高原油采收率的同时也产生了大量的采油废水。传统处理工艺多采用核桃壳过滤,处理效果不理想。戈尔膜过滤器因其具有效率高、运行稳定、易于维修以及全自动化控制等优点,更适合现行处理工艺的改造需求,在采油废水处理中避免了一些生物与化学处理所引起的二次污染等问题,具有较高的推广价值。     

桥梁-道路建设对西南山地城市扩展影响机制研究——以重庆嘉陵江两桥为例

交通因素对城市空间扩展的影响是一个研究热点,但国内外关于桥梁-道路建设对山地城市扩展影响机制的研究还不多见。基于桥梁-道路对城市待开发区域区位的影响,提出了点状辐射、线状辐射和环状辐射3种影响机制。以重庆嘉陵江大桥和黄花园大桥建设对嘉陵江北岸影响为例,将研究区划分为5个分区,基于Arc GIS软件提取各分区城市建成区与河岸的空间分布关系,并通过5个分区1940~2009年城市扩展差异比较印证3种影响机制。研究结果表明,桥梁和道路建设促进研究区建成区迅速扩张,但对不同分区的建成区扩展速度的影响有差异;第3分区城市扩展反映了桥梁-道路对城市扩展的点状辐射和线状辐射,而第4分区城市扩展反映了桥梁-道路对城市扩展的环状辐射。结论表明研究提出的点状辐射、线状辐射和环状辐射符合桥梁-道路建设对西南山地城市扩展的影响机制。