Urban Pollution Control Research Articles

Perception of Users on the Environmental Impact Caused by Public Transport Operation

The objective of this article is to present a model for the assessment of the perception of users on the environmental impact of public transport operation. Public transport operations can contribute to urban pollution control. The research method was the survey with 300 users of public transport in a Brazilian city with 1,500,000 inhabitants. Previous research was used to calculate the sample. Environmental impact of public transportation is an observable set of consequences on the environment, due to the operation. It is treated as a systemic multivariate structure of latent constructs, obtained by literature review, and indicators. Experts in environmental and transport management deployed the constructs in twenty-nine formative and suggested ten reflective indicators that generated scales fulfilled by respondents. Final constructs were reorganized by exploratory factor analysis (EFA): atmospheric emissions; noise pollution; urban space; safety; and waste. Results were analyzed by structural equation modeling (SEM) with SmartPLS2.0 software. The reliability of constructs, the composite reliability, average variance extracted, and t-score were calculated. The main conclusion was: safety and atmospheric emissions of vehicles are the factors that most influence the perception of users about environmental impacts. Environmental image influences positively on the overall image of the service and on the satisfaction of the user, but satisfaction doesn´t increase proneness of users to increase ridership.

Ozone weekend effect in Santiago, Chile

The study examined weekday–weekend differences in ozone, NO x (NO and NO 2) and VOC concentrations in Santiago, Chile, from 1999 to 2007. The results provide evidence for the occurrence of an atmospheric phenomenon that produces higher ozone concentrations during weekends despite lower concentrations of ozone precursors. This phenomenon is known as the weekend effect (WE). The overall ozone decrease since the spring of 2004 was a consequence of the implementation of several urban pollution control measures. Although these measures caused a decline in the number of days that exceed the national standard from two-thirds to one-third of summer days, the WE, which became statistically significant beginning in September 2004, could not be eliminated. Furthermore, VOC/NO x ratios decreased during the same period (2004), especially in the most industrialized area of Santiago. Similarly, under these regimes, the VOC/NO x ratios were higher on Sundays than on weekdays and caused higher ozone concentrations on Sundays.

Use of environmental magnetic techniques to monitor urban pollution origins in Lanzhou, Northwest China

In this study, samples of dustfall collected monthly or semi-monthly, during 1997–1999, at two representative sites (Kexueguan: KLD and Gaolanxan: GLX) in Lanzhou, a typical industrial city in northwestern China, have been examined using environmental magnetic measurements. A set of magnetic parameters of 50 dustfall samples were analysed. Results demonstrate that Lanzhou City is heavily polluted, with the main pollution sources being anthropogenic activities and natural dust. The former poses a threat to human health all the year, which is different from the general opinion that natural dust is the main source of pollution in summer. This study extended the application of environmental magnetic techniques and can be regarded as a progressive step in exploring urban pollution problems using environmental magnetic techniques. The results from the present study have an important implication on the design of future urban pollution control strategies in Lanzhou, and the method could be applied to other urban cities in the world.

The influence of institutions and organizations on urban waste collection systems: An analysis of waste collection system in Accra, Ghana (1985–2000)

Urban waste collection system is a pivotal component of all waste management schemes around the world. Therefore, the efficient performance and the success of these schemes in urban pollution control rest on the ability of the collection systems to fully adapt to the prevailing cultural and social contexts within which they operate. Conceptually, institutions being the rules guiding the conduct of public service provision and routine social interactions, waste collection systems embedded in institutions can only realize their potentials if they fully evolve continuously to reflect evolving social and technical matrices underlying the cultures, organizations, institutions and social conditions they are designed to address. This paper is a product of an analysis of waste collection performance in Ghana under two different institutional and/or organizational regimes; from an initial entirely public sector dependence to a current mix of public–private sector participation drawing on actual planning data from 1985 to 2000. The analysis found that the overall performance of waste collection services in Ghana increased under the coupled system, with efficiency (in terms of total waste clearance and coverage of service provision) increasing rapidly with increased private-sector controls and levels of involvement, e.g. for solid waste, collection rate and disposal improved from 51% in 1998 to about 91% in the year 2000. However, such an increase in performance could not be sustained beyond 10 years of public–private partnerships. This analysis argues that the sustainability of improved waste collection efficiency is a function of the franchise and lease arrangements between private sector group on the one hand and public sector group (local authorities) on the other hand. The analysis therefore concludes that if such franchise and lease arrangements are not conceived out of an initial transparent process, such a provision could undermine the overall sustainability of private sector initiatives in collection services delivery in the long term, as in the case of the Accra example.

Tin dioxide gas sensor as a tool for atmospheric pollution monitoring: Problems and possibilities for improvements

The monitoring of atmospheric pollution needs network of gas sensors in order to increase the number of measuring points. For this goal, tin dioxide sensors have been evaluated. Their potentials and limitations (selectivity and stability), are presented via on-site experiments of urban pollution control. The study shows that some global information indicating mainly the traffic pollution can be obtained. The general problem of long-term stability and selectivity of SnO2 sensors is discussed. Some specific solutions are proposed, for example, a chemical treatment in the case of instability due to SO2. The problem of the dual response to oxidising and reducing gases is discussed, especially in regard to CO/NO2 detection. To solve this problem, the use of active filters is proposed. For example, a thin film of rhodium deposited above the sensing material allows to filter NO2. The use of a platinum filter has also been applied to improve the selectivity for the reducing gases. The results point out the difficulty to control this type of device in thin film technology. On the contrary, with thick films obtained by screen-printing, the possibility to separate HC from VOC (CH4 from CO and C2H5OH) is demonstrated. Some preliminary results concerning the use of a MnO2 filter are also presented in order to control the ozone reaction. The possibilities offered by signal processing are finally discussed using a multi-variable approach with 90 days aged sensors. AC measurements are exploited to improve the selectivity for the oxidizing gases NO2 and O3. The results obtained with a model built with atmospheric air as carrier gas appear promising.

Approaches adopted by the European Union and selected Member States for the control of urban pollution

Several EU Directives have been adopted which have an influence on the control of urban pollution in particular the EU Urban Wastewater Treatment and the Integrated Pollution Control and Prevention Directive. In addition, the recently adopted Water Framework Directive (WFD) will have an additional impact on the control of urban pollution in particular related to storm overflows. The present paper provides a brief discussion of the EU legislation relevant to the control of urban pollution with special emphasis on the Urban Wastewater Treatment Directive (UWWTD) and its implementation in the Member States.The recently adopted WFD requires the achievement of good ecological and chemical status in all waters. The implementation of the UWWTD by the Member States, which should be achieved by 2005, will make a significant contribution towards achieving good ecological and chemical status. However, besides the discharge of sewage effluents, storm overflows can have a significant impact on the quality of surface waters and they will therefore require adequate control in order to achieve the final goal of good ecological and chemical status. The paper, therefore, also provides a brief analysis of the permitting requirements in the different countries and of the criteria currently applied by the EU Member States for the design of combined sewer overflow systems. Not all countries currently require a permit for storm overflows and the design criteria for combined sewer overflows are generally based on the spill frequency or treatment capacity in terms of dry weather flow, which do not take into account the effect on the receiving water. However, in the UK a method has been developed to assess the impact of combined sewer overflows on the quality of the receiving water, which is being applied to ensure the design of the storm overflow is adequate for the protection of the receiving water. Member States will need to adapt their methodologies used for the design of storm overflow to ensure the requirements of the WFD, the achievement of good ecological and chemical water quality, is being met.

Preventive conservation strategies for sustainable urban pollution control in museums

The last 40 years have seen major changes in the sources and concentrations of urban pollution (nitrogen dioxide, sulphur dioxide, hydrogen sulphide and particles). During this time, research has advanced our understanding of the impact of pollutants on objects in urban museums. As a consequence, pollutant control has become an important aspect of preventive conservation. There is also increased awareness of the need for pollution control strategies that are sustainable at an organizational and global level. This paper, prepared by a chemist, a conservator and two building scientists, reviews strategies for minimizing the impact of urban pollution on museum collections. The results of new research funded by the UK government identify current (1999) internal pollution levels in both naturally ventilated and air-conditioned museums with particle and gaseous filtration, in relation to external concentrations, ventilation strategies, and the characteristics of the internal fabric and finishes of these buildings.

Gas detection for automotive pollution control

The detection of the gases produced by the cars becomes an important objective for different applications as urban pollution control or for the development of car exhaust devices. The use of gas sensors can contribute to reach such objectives. At the moment, the performances of the gas sensors available on the market especially SnO 2 sensors are often not sufficient to satisfy these needs. The major limitations are dependent on their poor selectivity and stability. Some examples of such problems are presented through field experiments in both types of applications and some feasible improvements of the sensors are discussed. In urban pollution monitoring, it is necessary to take into account the irreversible action of SO 2. The dual response to oxidising or reducing gases is a difficult problem to solve, especially for the NO x gases. Solutions with metallic filters above the sensing material are currently studied. In order to be able to use directly the sensors in the car exhausts, new types of sensors are developed mainly on the basis of electrochemical devices. An example of such new sensor is exposed with experimental results obtained on car exhausts.

VEGETATION AND SUSTAINABLE CITIES

Summary The value of trees in urban areas has long been established. Trees offer significant opportunities as buffers of pollution on the pollution pathway. Pruning strategies of local authorities will affect the ability of trees to act as a target for pollutants. Within the United Kingdom current trends for overpruning to control water use ignore the potential for trees to be an integral part of urban pollution control. The impact of cyclical pruning policies upon human health, plant/animal communities and structures could be significant. ‘Fog everywhere. Fog up the river, where it flows among green aits and meadows, fog down the river, where it rolls defiled among the tiers of shipping and the waterside pollutions of the great (and dirty) city. Fog on the Essex marshes, fog on the Kentish heights. Fog lying out on the yards and hovering on the rigs of great ships. Fog in the eyes and throats of ancient Greenwich pensioners, wheezing by the firesides.’ Bleak House. Charles Dickens

Analytical Determination of Polycyclic Aromatic Hydrocarbons in Gases from Coal Conversion by Synchronous Fluorescence Spectrometry.

Abstract A method to analyze the most hazardous Polyclyclic Aromatic Hydrocarbons (PAH) (acenaphtene, anthracene, benzo(a) anthracene, benzo(a)pyrene, biphenyl, coronene, chrysene, dibenzo (a,h) anthracene, phenantrene, fluoranthene, fluorene, naphtalene and pyrene), by using excitation and energy constant synchronic fluorescence has been researched in depth in this study. Spectral studies carried out allow characteristic peaks to be obtained for the qualitative identification of 8 from 11 PAH tested. From the quantitative and interference studies, the most important analytical characteristics (linear range, detection limit and reproduciblity) for the determination of ten of these compounds have been obtained. The method was applied to the PAH determination in two different samples: 1) air filter samples for urban pollution control and 2) air samples from a laboratory scale coal carbonization oven. Fluorene (in the first type) and benzo (a) pyrene (in the second type), were identified and quantified.

Two Dimensional Numerical Modeling of Hydrodynamics and Pollutant Transport in a Wet Detention Pond

A vertically averaged two-dimensional hydrodynamic model was developed to simulate water movements in a small shallow unstratified impoundment. The hydrodynamic model was then coupled with a two-dimensional pollutant transport model to calculate the mass fluxes of pollutant. The differential equations were numerically solved on a space staggered grid using a two-level time ADI integration scheme. The model was used to simulate the flow and pollutant transport and to assess the pollutant removal performance of an urban detention pond located in Charlottesville, VA. Results of the simulation were compared to field data taken at the site. The model was successfully utilized in simulating pollutant transport and trapping, making it useful in analyzing wet detention pond modification for urban pollution control.