Potential and Shortcomings of Numerical Weather Prediction Models in Providing Meteorological Data for Urban Air Pollution Forecasting

The last decade progress in numericalweather prediction (NWP) modelling and studies of urbanatmospheric processes for providing meteorological data forurban air pollution forecasting is analysed on examples ofseveral European meteorological centres. Modern nested NWP models are utilising land-use databasesdown to 1 km resolution or finer, and are approaching thenecessary horizontal and vertical resolution suitable forcity scale. The recent scientific developments in the fieldof urban atmospheric physics and the growing availabilityof high-resolution urban surface characteristics datapromise further improvements of the capability of NWPmodels for this aim. A strategy to improve NWP data forthe urban air pollution forecasting is suggested.     

Assessment of the status of municipal solid waste management in metro cities, state capitals, class I cities, and class II towns in India: an insight

Solid waste management is one of the most challenging issues in urban cities, which are facing a serious pollution problem due to the generation of huge quantities of solid waste. This paper presents an assessment of the existing situation of municipal solid waste management (MSWM) in major cities in India. The quantity and composition of MSW vary from place to place, and bear a rather consistent correlation with the average standard of living. Extensive field investigations were carried out for quantification, analysis of physical composition, and characterization of MSW in each of the identified cities. The MSW management status (per the MSW Rules, 2000) has also been assessed, and an action plan for better management has been formulated; both are presented in this paper. Studies carried out in 59 selected cities in India have revealed that there are many shortcomings in the existing practices used in managing the MSW. These shortcomings pertain mainly to inadequate manpower, financial resources, implements, and machinery required for effectively carrying out various activities for MSWM. To overcome the deficiencies in the existing MSWM systems, an indicative action plan has been presented incorporating strategies and guidelines. Based on this plan, municipal agencies can prepare specific action plans for their respective cities.     

Physical Modelling of Urban Roughness using Arrays of Regular Roughness Elements

The aerodynamic behaviour of large urbanagglomerations must be represented in increasingly greaterdetail, as large-scale numerical weather prediction and airpollution dispersion models are refined. The present studyprovides detailed measurements of the flow field in regulararrays of obstacles to obtain representative data on meanflow and turbulence statistics in urban-type areas. Obstacle arrays consisting of simple cubes and flat plateroughness commonly used in boundary layer simulations wereplaced in a simulated atmospheric boundary layer flow in ahydraulic flume. The scale factor was about 1:200 based onthe obstacle height (50 mm). The results show noappreciable `constant stress' region in the internalboundary layer above the buildings, since in any finite-length test array the boundary layer is always developing.However, if the RMS turbulence components are scaled by thelocal values of the shear stress, then there seems to be auniversal scaling, with _u/u_* = 2.1,_v/u_* = 1.65 and _w/u_* = 1.2. This greatly simplifies the parameterization of the first orderturbulence statistics in obstacle arrays. It was alsoobserved during the experiments that, compared to results inthe cube arrays, the turbulence kinetic energy and theReynolds stresses were almost doubled in the flat plateroughness arrays.     

Results from Three Field Tracer Experiments on the Neighbourhood Scale in the City of Birmingham UK

The physical processes governing flow and pollutantdispersion at the neighbourhood scale, a spatial scaleintermediate between the street scale and the city scale, is notwell understood. Furthermore, it is not clear whether a traditional approach using averaged characteristics such as theaerodynamic roughness length is sufficient to predict the concentration field at this scale. To investigate pollutant dispersion in a real urban area, three field experiments were designed within the UK-URGENT programme sponsored by NERC. Theexperiments were performed in the City of Birmingham using a finite duration release of inert, non-toxic and non-depositingtracers, vis. perfluoromethylcyclohexane (PMCH) and perfluoromethylcyclopentane (PMCP). Measurements were taken using air bag samplers placedin an arc at 3.5 km (first experiment) and 1 km (second andthird experiments) from the source; some trap samplers wereplaced outside the main arc in the outskirts of the city. Measurements were analysed in the laboratory using anovel gas-chromatography technique. Data so obtained werecompared with predictions from a simple steady-state modeland a time-dependent model. The concentration-time serieswere very asymmetrical with a sharp rise, a plateau followedby a relatively slow decrease and finally a long-livedplateau above (or possibly very slow decrease to) thebackground level.     

Theoretical Investigation of Urban Air Quality Management Systems Performance Towards Simplified Strategic Environmental Planning

Urban Air Quality Management Systems are software tools that combine air quality models with various software modules like geographical information systems, databases, expert systems and statistical analysis tools. Such systems try to interpret as accurately as possible the complex interactions between various atmospheric, emission, land use and topographic parameters involved in the air pollution management problem, in order to provide support for environmental strategic planning and decision making. As this process involves a huge set of parameters, some of which may only be roughly estimated, air quality management systems tend to aggregate parameters in order to simplify their analysis and make it more effective and operational. Yet, this aggregation may lead to deviations in the analysis results, as proved in this theoretical article, and thus influence the decision making and strategic planning process. According to the findings of this article, such a policy making process should focus primarily on short term measures when dealing with air pollution episode management.     

Urban Metal Management The Example of Lead

The metal metabolism of an urban region, the City ofVienna, was investigated to discuss urban metal management strategies in view of environmental protection and resource conservation. About 90% of the metal stock is located in Vienna's buildings and infrastructure, whilst only 10% is in the landfills. The city stock represents a potential source for diffusive emissions. However, the control of the current environmental policy concentrates mainly on landfill emissions. Diffusive emissions resulting from the losses over the use of metal containing goods in the city are widely dispersed and cannot be easily controlled due to numerous non-point sources. First investigations indicate that for certain applications, the diffusive stock emissions are as significant as other sources. At present, Vienna's known diffusive and point source lead emissions into air and water are about 40 to 50 times higher than comparable past loadings from geogenic Vienna. Furthermore, a life cycle approach from acid car batteries indicates that sustainable lead management should consider flows and stocks in the hinterland of the city too. The city metal stock also represents a potential resource. Leaded water pipes built-in in Vienna's city stock have the potential to produce 1.6 million traditional car batteries. In future such city mining strategies can partly replace ore mining.     

Three-Dimensional Numerical Simulation of Air Pollutant Dispersion in Street Canyons

The PHOENICS Computational Fluid Dynamics (CFD) software package has been used with a standard k- turbulence model to simulate the three-dimensional dispersion of air pollutants in an urban street canyon. In all cases, a vortex was formed within the street canyon, characterized by updrafts near the upwind buildings and down-drafts near the downwind buildings. Contours of pollutant concentrations over a transverse vertical plane at mid-canyon show pollutants circulating within the vortex, with higher concentrations at the leeward face than at the windward faces, and higher concentrations above downwind buildings than above upwind buildings. Longitudinal distributions of pollutant concentrations at leeward and windward faces are characterized by higher concentrations at mid-block and lower concentrations at the ends. These results agree qualitatively with previous wind tunnel findings such as those of Hoydysh and Dabberdt (1988) and Wedding et al. (1977). The results also suggest that the k- turbulence model is satisfactory for simulating the effect of turbulence on dispersion of pollutants in street canyons     

Improvements in Air Quality Modelling by Using Surface Boundary Layer Parameters derived from Satellite Land Cover Data

Many atmospheric dispersion models include only simpletreatment of surface features to estimate the wind profilesand stability parameters. Detailed characterisation of theland cover, particularly in large and complex urbanconurbations, is especially important, as the surfacefeatures can vary significantly over the area. This paperdiscusses the use of satellite land cover data to derivespatially resolved surface boundary layer (SBL) parameters.These parameters have been used in an air quality model,PEARL (Prediction Air Quality in Urban and RegionalLocations) for estimating monthly and annual COconcentrations. Land cover data, derived from LANDSATThematic Mapper Imagery, has been used to estimate SBLparameters (surface roughness length, albeedo, Bowen ratioand anthropogenic heat flux) for a study area of 10000km² encompassing Greater London and the surroundingcounties. The SBL parameters have been assigned according tomajor land cover types for the whole area at a spatialresolution of 1 × 1 km. Predictions from two versions of the PEARL model (one with land cover data and one without)have been compared with each other and with measured data forannual and monthly CO concentrations from seven London airquality monitoring sites. This comparison shows thatdifferences between predicted and observed values can bereduced by up to a factor of three. The use of SBLparameters derived from land cover data also yields moredetailed predicted annual CO spatial patterns especially inand around suburban areas. The performance of both versionsof the model for monthly CO concentrations has been comparedwith a range of statistical measures. This comparisonconfirms that improved agreement is observed betweenmodelled and measured monthly CO concentrations when use ismade of spatially resolved SBL parameters.     

Annual and Diurnal Wind Patterns in the City of São Paulo

The major topographic, mesoscale, and urban influences on the wind patterns of the City of São Paulo are characterized using one year of surface wind velocity data observed at 11 surface stations within its urban limits. The data was used to study the diurnal and annual variations of wind velocity and horizontal wind divergence within the city. Results showed that the circulation over the investigated area is dominated by three major factors: sea breeze; mountain-valley circulations; and urban effects, such as roughness, building-barrier, and urban heat island. The sea breeze was found to be the dominant feature of the monthly-averaged diurnal variation of São Paulo surface winds during the eight warmest months of the year. The sea breeze front induces a velocity minimum at the time of its passage and a post-frontal afternoon velocity maximum. Mountain-valley thermal effects on the flow can be seen in the temporal divergence/convergence patterns. These thermal effects tend to be more important during colder months, at night, and when the wind velocities are low. Nighttime downslope convergent flows are present over the city during winter and spring and daytime upslope divergent flows are present over the city during summer months.     

电网规划环境影响评价应关注的几个要点

广州市城市高压电网规划环境影响评价是国家环境保护总局全国规划环境影响评价的试点项目,结合该专项规划环境影响评价在评价指标体系设计、评价标准、评价技术方法等方面的探索和研究成果,提出电网规划环境影响评价应关注的几个要点。     

我国化工园区布局性环境风险及对策建议

介绍了我国化工园区基本情况和布局现状,指出了化工园区布局不合理、城市规划源头缺少环境风险控制要求、后期规划实施和控制不利导致环境风险累积、已属末端的园区规划环评无法改变不合理的空间布局等问题,提出了科学布局新建化工园区、从城市规划源头控制环境风险、推动城市规划环境影响评价并针对现有城市开展环境安全评估、推进现有园区清理整顿等对策建议。     

Analysis of the St. Petersburg Traffic Data using the OSPM Model

Since October 1998 two DOAS instruments were installed at the level of the first floor and at the top of a building located in St. Petersburg at Pestelya Street. The collected datacovers the time period of December 1998–March 2001, and include concentrations of benzene, toluene, NO and NO₂, ozone and SO₂. There is also an additional information about the traffic intensity and meteorological conditions. The results of the analysis of this data set, using the OSPM model, are presented here with the goal to understand the features of the air pollution dispersion in this street canyon and to analyse the information about the emission factors of the vehicles. In particular, the model results are used for the solution of the inverse problem of reconstructing the emission factors from measured concentrations. The results obtained indicate that most of the concentrations are well inside the Russian standards with the only exception of NO₂ (mean and 98-th percentile are equal to 57.8 and 119.2 g m^-3 for the street level). The same values for benzene are 18.5 and 62.6, respectively. Emission estimates show that there is a possibility that the NO_x and benzene basic emission factors recommended by the Russian national guidelines could result in overestimating the traffic emissions. These considerations are supplemented with the model sensitivity tests carried out in connection with the problem of predictability of NO₂ concentrations in the street canyon. Tests indicate that NO₂ concentrations are not very sensitive to NO_x emissions because of the usually low urban background ozone levels.     

An Evaluation of Daumod Model in Estimating Urban Background Concentrations

This article presents an evaluation of the performance of the urban atmospheric dispersion model (DAUMOD) in estimating nitrogen oxides (NO_x) background concentrations in Copenhagen. Estimations of hourly average (averaged over a year), mean daily and mean monthly concentrations of NO_x are compared with observed values for two years of data. The model slightly underestimates low hourly average values and overestimates high values. The cumulative frequency distribution of mean daily concentration obtained from model estimations is in good agreement with the obtained from observed data. We performed a statistical analysis to determine the agreement between estimated and observed concentration values. The results show that 95.8% of hourly average estimations, 86.8% of mean daily and 100% of monthly average concentrations are within a factor of two of the observed values. The normalised mean square error of predictions is +0.13 for hourly average estimations, +0.22 for mean daily values and +0.02 for monthly mean concentrations. The fractional bias values are: –0.049 for hourly mean estimations, –0.047 for mean daily values and –0.053 for monthly average estimations. The values of the statistical parameters allow us to consider that though estimations are lightly larger than the observed values, the model performance is acceptable.     

Air Quality in Major Portuguese Urban Agglomerations

This paper presents some recent research work that has beendeveloped for the major Portuguese agglomerations. Threemain topics are developed: the methodology used in Portugalto limit agglomerations (as they are defined by theEuropean Air Quality Framework Directive 96/62/EC), thepreliminary assessment of the air quality levels in themost densely populated agglomerations over the last fiveyears and their influence on the air quality levels acrossthe country (a requirement by Directive 96/62/EC), and theuse of an air quality index to raise public awareness aboutair quality levels. It is concluded that particulate matteris the critical pollutant in Portuguese populated urbanareas. In Lisbon and Oporto, based in 1999 data, in allmonitoring stations, the daily average limit value of 50g m^-3 for particulate matter (PM₁₀) isexceeded more times during a year period then allowed byDirective 99/30/EC. In the same areas, nitrogen dioxideconcentrations are above the annual limit value of 40g m^-3 for the protection of human health set byDirective 99/30/EC, and influence pollution concentrationswithin a few tens of kilometres surrounding the urbanareas.     

某市河道底泥污染工程总体设计方案

为截流和处理某市内河的外来污染源,河道综合整治工程是某市内河水系底泥污染系统综合开发工程的重要工程之一,主要内容包括:河道工程、截污工程、底泥疏浚、景观工程等。截污工程采取“沿河截污,超量溢流”的工程方案沿河敷设截污管道,并在河道交汇处设置合流污水调蓄池。     

Serving the unserved: informal refuse collection in Mexico.

The incomplete collection of municipal solid waste is a significant problem in the cities of many developing countries. Mexican cities collect less than 75% of the waste generated. The uncollected waste generates pollution and poses risks to human health and the environment. Low-income communities comprise most areas that lack refuse collection. In many of the areas where there is no official collection service, informal collectors provide this service for a fee. This paper analyses informal refuse collection in three Mexican cities, and argues that it can supplement municipal collection, create jobs, benefit the economy and help clean up the urban environment.     

Spatial and Temporal Comparison of Polycyclic Aromatic Hydrocarbons and Spheroidal Carbonaceous Particles in Remote European Lakes

Spheroidal carbonaceous particles (SCP) and polycyclicaromatic hydrocarbons (PAH) have been measured in the dated sediment cores of 10 remote lakes distributed across Europe. The geographic trends were evaluated by examination of the superficial sediment fluxes and total sediment inventories. The highest levels of both markers were observed in the Eastern European lakes whereas the minimal values corresponded to the lake located in the Arctic. However, this SCP-PAH correlation was not observed after exclusion of the end member lakes from the series. The temporal trends of both pollutant markers are consistent with the history of pyrolytic emissions over Europe. However, the downcore SCP distributions are shorter than the PAH profiles in nearly all lakes. The differences are probably related to the different size particle fractions involved in the measurement of each marker, >5 and >1 m for SCP and PAH, respectively. Thus, the two proxies probably reflect pollution inputs from closer (SCP) and more distant sites (PAH).     

Measurement of Traffic Related Toxic Air Pollutants in an Urban Atmosphere

Nose-level measurements of air toxics were made along a busy urban street in Ottawa, Canada for 2 hr periods during morning, noon, and afternoon rush hours in the winter and summer of 2000. Measurements were also made in a commuter car and a transit bus during morning and afternoon commutes in 2000. The main objectives of the study were to establish a database, to determine temporal and seasonal variations and to determine the contribution of motor vehicle traffic to the measured toxic substance concentrations. Ottawa is an appropriate choice of location for the measurement of motor vehicle related toxic and reactive compounds, as it has virtually no industrial sources that could be contributing to the ambient loadings. Samples were collected for a total of 165 volatile organic compounds and 25 carbonyl compounds. Sampling and analytical methodologyare discussed and results are presented. Toluene, ethylene andformaldehyde were the most abundant pollutants in Ottawa during both winter and summer. Total non-methane hydrocarbon concentrationwas measured as 100 g m^-3 at nose-level measurements in Ottawa.     

Vertical Distribution of Atmospheric Pollution Lead in Swedish Boreal Forest Soils

In order to understand the fate of anthropogenic lead (Pb)pollution in boreal forest soils, and to predict future trends, it is important to know where in the soil the pollution Pb is accumulated and how large the pollution and natural Pb inventories are in different soil horizons. We combined stable Pb isotope (²⁰⁶Pb/²⁰⁷Pb ratios) and concentration analyses to study Pb in podzol profiles and mor samples from old-growth forest stands at seven sites distributed from southern to northern Sweden. Additional samples were taken from managed forests, and from an agricultural field, to give some idea of the effects of land-use. Pb concentrations are typically 60–100 g g^-1 dry mass in the mor layer in southern Sweden and about 30 g g^-1 in northern Sweden. Pb isotope analyses show that virtually all of this Pb is pollution Pb. The isotope composition also shows that pollution Pb has penetrated downwards between 20–60 cm in the forest soils. The total pollution Pb inventories vary between 0.7–3.0 g m^-2 ground surface, with larger inventories in southern compared to northern Sweden. Although the highest Pb concentrations occur in the mor layer, the largest inventories of pollution Pb are found in the Bs-horizon. The limited investigation of Pb distribution and inventories in soils from managed forests did not point to any major difference compared to the old-growth forests. The agricultural field revealed, however, a completely deviating Pb profile with all pollution Pb evenly distributed in the 20 cm thick top-soil.     

有机污染土壤原位化学氧化药剂投加方式的综述

原位化学氧化技术是修复有机污染土壤最经济有效的技术之一。药剂的投加与分散技术是原位化学氧化修复技术的核心。药剂投加与分散方式的选择与污染场地的土壤渗透性、特征水平、污染深度、氧化剂性质、修复费用等相关。阐述了直压式注射法、注射井法、土壤置换法和高压-旋喷注射法等药剂投加与分散技术的适用性、控制参数及优缺点等,引用工程实例对药剂投加与分散技术在原位化学氧化修复过程中的应用情况进行了论证。