Simulation of mixing depths incorporating the urban heat island effect

The main objective of this paper was to establish the effect of anthropogenic heat flux on the formation of mixing depth specially in urban areas. In this study an energy balance mixing depth model was developed for the simulation of mixing depth incorporating the heat island effect. To demonstrate the effect of heat island, mixing depths were simulated under two conditions. Under the first condition, hourly gridded anthropogenic heat flux and variant surface characteristics were considered, while under the second condition anthropogenic heat flux term was ignored and constant surface characteristics were considered throughout the modelling domain. The release of anthropogenic heat flux in the urban environment was found to be responsible for the growth of the unstable layer in the lower atmosphere even during the night. This resulted in higher mixing depth values in urban areas compared to the surrounding countryside. The maximum differential surfaces sensible heat flux between urban and rural areas was estimated as 130 W/m². From the simulation of mixing depth, it was revealed that the maximum increment in mixing depth in urban areas was 300 m due to the heat island effect. This increment in mixing depth in urban areas can provide an extra space for dilution and mixing of pollutants.     

Results from a national survey of Crown prosecutors and defense counsel on impaired driving in Canada: A “System Improvements” perspective

Introduction

This article summarizes the main findings from a study designed to examine the legal process in Canada as it applies to alcohol-impaired driving from the point of view of Crown prosecutors and defense counsel, and to identify evidentiary or procedural factors that may impact the legal process, the rights of the accused, and interactions of all parts in the legal process.

Method

The data in this study were collected by means of a survey that was mailed out to the population of Crown prosecutors and defense counsel in Canada. In total, 765 prosecutors and 270 defense lawyers or an estimated 33% of all Canadian prosecutors and 15% of defense lawyers completed and returned the questionnaire. The "systems improvement" paradigm was used to interpret the findings and draw conclusions. Such an approach acknowledges the importance of the context in which countermeasures are implemented and delivered and the structures or entities used to deliver countermeasures to a designated target group.

Results

Results on type of charges and breath alcohol concentration, caseload, case outcomes, case preparation time, conviction rate at trial and overall conviction rate, reasons for acquittals and time to resolve cases are described.

Discussion

The findings from this national survey suggest that there are important challenges within the criminal justice system that impede the effective and efficient processing of impaired driving cases. Some of these challenges occur as a function of practices and policies, while others occur as a function of legislation.

Impact on industry

This study illustrates that a "system improvements" approach that acknowledges the importance of all elements of the criminal justice system and the interaction between those elements, can be beneficial in overcoming the alcohol-impaired driving problem.     

The new gold rush: fueling ethanol production while protecting water quality

Renewable fuel production, particularly grain-based ethanol, is expanding rapidly in the USA. Although subsidized grain-based ethanol may provide a competitively priced transportation fuel, concerns exist about potential environmental impacts. This contribution focuses on potential water quality implications of expanded grain-based ethanol production and potential impacts of perennial-grass-based cellulosic ethanol. Expanded grain-based ethanol will increase and intensify corn production. Even with recommended fertilizer and land conservation measures, corn acreage can be a major source of N loss to water (20-40 kg ha(-1) yr(-1)). A greater acreage of corn is estimated to increase N and P loss to water by 37% (117 million kg) and 25% (9 million kg), respectively, and measures to encourage adoption of conservation practices are essential to mitigate water quality impairments. Dried distiller's grains remaining after ethanol production from corn grain are used as animal feed and can increase manure P content and may increase N content. Cellulosic fuel-stocks from perennials such as switchgrass and woody materials have the potential to produce ethanol. Although production, storage, and handling of cellulosic materials and conversion technology are limitations, accelerating development of cellulosic ethanol has the potential to reduce dependence on grain fuel-stocks and provide water quality and other environmental benefits. All alternative fuel production technologies could have environmental impacts. There is a need to understand these impacts to help guide policy and help make programmatic and scientific decisions that avoid or mitigate unintended environmental consequences of biofuel production.     

A new urban boundary layer and dispersion parameterization for an emergency response modeling system: Tests with the Joint Urban 2003 data set

A new urban parameterization for a fast-running dispersion prediction modeling system suitable for emergency response situations is introduced. The parameterization represents the urban convective boundary layer in the dispersion prediction system developed by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory. The performance of the modeling system is tested with data collected during the field campaign Joint Urban 2003 (JU03), held in July 2003 in Oklahoma City, Oklahoma. Tests were performed using data from three intense operating periods held during daytime slightly unstable to unstable conditions. The system was run in operational mode using the meteorological data that would be available operationally at NARAC to test its effectiveness in emergency response conditions. The new parameterization considerably improves the performance of the original modeling system, by producing a better degree of pattern of correspondence between predictions and observations (as measured by Taylor diagrams), considerably reducing bias, and better capturing directional effects resulting in plume predictions whose shape and size better resemble the observations (via the measure of effectiveness). Furthermore, the new parameterization shows similar skills to urban modeling systems of similar or greater complexity. The parameterization performs the best at the three JU03 sensor arcs (1, 2, and 4 km downwind the release points), with fractional bias values ranging from 0.13 to 0.4, correlation values from 0.45 to 0.71, and centered root-mean-square error being reduced more than 50% in most cases. The urban parameterization has been tested with grid increments of 125, 250, 500 and 1000 m, performing best at 250 and 500 m. Finally, it has been found that representing the point source by a Gaussian distribution with an initial spread of particles leads to a better representation of the initial spread induced by near-source buildings, resulting in lower bias and improved correlation in downtown Oklahoma City.     

Metabolic responses of Eisenia fetida after sub-lethal exposure to organic contaminants with different toxic modes of action

Nuclear magnetic resonance (NMR) - based metabolomics has the potential to identify toxic responses of contaminants within a mixture in contaminated soil. This study evaluated the metabolic response of Eisenia fetida after exposure to an array of organic compounds to determine whether contaminant-specific responses could be identified. The compounds investigated in contact tests included: two pesticides (carbaryl and chlorpyrifos), three pharmaceuticals (carbamazephine, estrone and caffeine), two persistent organohalogens (Aroclor 1254 and PBDE 209) and two industrial compounds (nonylphenol and dimethyl phthalate). Control and contaminant-exposed metabolic profiles were distinguished using principal component analysis and potential contaminant-specific biomarkers of exposure were found for several contaminants. These results suggest that NMR-based metabolomics offers considerable promise for differentiating between the different toxic modes of action (MOA) associated with sub-lethal toxicity to earthworms.     

Comparison of modelled and measured ozone concentrations and meteorology for a site in south-west Sweden: implications for ozone uptake calculations

Measurements of ground-level ozone concentrations and meteorology (temperature, vapour pressure deficit (VPD), solar radiation) at the monitoring site Ostad (south-west Sweden) were compared to data from the corresponding grid in the EMEP photo-oxidant model for 1997, 1999 and 2000. The influence of synoptic weather on the agreement between model and measurements was studied. Implications of differences between modelled and observed inputs for ozone flux calculations for wheat and potato were investigated. The EMEP model output of ozone, temperature and VPD correlated well with measurements during daytime. Deviations were larger during the night, especially in calm conditions, attributed to local climatological conditions at the monitoring site deviating from average conditions of the grid. These differences did not lead to significant differences in calculated ozone uptake, which was reproduced remarkably well. The uptake calculations were sensitive to errors in the ozone and temperature input data, especially when including a flux threshold.     

Siting a Fully Integrated Waste Management Facility in Alberta

The development of a special (hazardous) waste management system is well under way in Alberta, Canada, and completion of an integrated treatment and disposal facility near Swan Hills is expected in 1988. The facility will handle both inorganic and organic waste streams in a physical/chemical treatment plant and high temperature incinerator. Treated liquid residues will be disposed of in a deep well, and treated solid residues in a secure landfill. The chosen treatment technology and the established hydrogeological conditions of the site ensure the maintenance of environmental quality. An intensive site selection and public participation program provided that only locations which were environmentally and socially suitable for this development were considered. Through awareness of the problems of waste and the solutions for its management, and full citizen involvement in the site selection process, the siting and public participation programs accomplished the difficult task of selecting a location for North America’s first fully integrated special waste treatment and disposal facility.     

Comment on “Measuring Air Quality Levels Inexpensively at Multiple Locations by Random Sampling”

ABSTRACT

In order to evaluate the spatial variation of aerosol (particulate matter with aerodynamic diameter ≤10 μm [PM₁₀]) and ozone (O₃) concentrations and characterize the atmospheric conditions that lead to O₃ and PM₁₀-rich episodes in southern Italy during summer 2007, an intensive sampling campaign was simultaneously performed, from middle of July to the end of August, at three ground-based sites (marine, urban, and high-altitude monitoring stations) in Calabria region. A cluster analysis, based on the prevailing air mass backward trajectories, was performed, allowing to discriminate the contribution of different air masses origin and paths. Results showed that both PM₁₀ and O₃ levels reached similar high values when air masses originated from the industrialized continental Europe as well as under the influence of wildfire emissions. Among natural sources, dust intrusion and wildfire events seem to involve a marked impact on the recorded data. Typical fair weather of Mediterranean summer and persisting anticyclone system at synoptic scale were indeed favorable conditions to the arrival of heavily dust-loaded air masses over three periods of consecutive days and more than half of the observed PM₁₀ daily exceedances have been attributed to Saharan dust events. During the identified dust outbreaks, a consistent increase in PM₁₀ levels with a concurrent decrease in O₃ values was also observed and discussed.

IMPLICATIONS In the summertime, the central-southern Mediterranean Basin is heavily affected by Saharan dust outbreaks and wildfire events. A focus on their significant influence on either oxidizing capacity of the atmosphere and air quality over Calabria, southern Italy, was here presented. Similar studies for most regions surrounding the Mediterranean Basin are needed to implement effective emission reduction measures, to prevent apparent air quality parameter exceedances and to define an appropriate health alert system. Because the frequency of these events is expected to increase due to climate change, these studies could even be a valid effort to better understand and characterize such atmospheric variations.     

Fatigued and drowsy driving: a survey of attitudes, opinions and behaviors

INTRODUCTION: There is evidence suggesting that the problem of fatigued or drowsy driving is an important contributor to road crashes. However, not much is known about public perceptions of the issue. The purpose of this study was to obtain information on attitudes, opinions, and professed practices related to fatigued or drowsy driving. METHODS: The data were gathered by means of a public opinion poll among a representative sample of 750 Ontario drivers. RESULTS: A majority of drivers (58.6%) admitted that they occasionally drive while fatigued or drowsy. Of greater importance, 14.5% of respondents admitted that they had fallen asleep or "nodded off" while driving during the past year. Nearly 2% were involved in a fatigue or drowsy driving related crash in the past year. Respondents were also asked about measures they take to overcome fatigue or drowsiness. Results indicate that relatively ineffective measures such as opening the window or playing music are the most popular; the most effective preventive measure--taking a rest--is the least popular. DISCUSSION: The prevalence of the behavior, coupled with the ineffective prevention measures favored by the public suggest there is a need for increasing their level of awareness and knowledge about the problem. IMPACT ON INDUSTRY: Results from this study further emphasize the importance of increasing the fatigued and drowsy driving knowledge base and the need to educate the public about it.     

Aggressive driving: a survey of attitudes, opinions and behaviors

INTRODUCTION: Aggressive driving encompasses a continuum of behaviors that range from extreme acts, such as shootings, to less severe manifestations, such as arguments and gestures. It is clear from the available data that aggressive driving is not uncommon and very risky. However, little is known about the opinions and practices of drivers. The purpose of this study was to help bridge these gaps. METHODS: The data were gathered by means of a public opinion poll among a representative sample of 1,201 Canadian drivers. Univariate frequency distributions and 95% confidence intervals were calculated and logistic regression and generalized linear latent models were used to summarize the data. RESULTS: It was found that the issue of aggressive driving is a significant one as a considerable percentage of drivers admits to it. The results coming from the logistic regression and the generalized linear latent model suggest that male and younger drivers are more likely to behave aggressively in traffic and that behaving more aggressively is associated with a history of traffic tickets. DISCUSSION: When gauging people's attitudes, opinions, and behaviors, it becomes clear that aggressive driving is a considerable problem. There also seems to be a need for a better understanding of which specific behaviors respondents associate with the generic term "aggressive driving." IMPACT ON INDUSTRY: Results from this study further emphasize the need of increasing the aggressive driving knowledge base.