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871.
Jon M. Heuss Dennis F. Kahlbaum George T. Wolff 《Journal of the Air & Waste Management Association (1995)》2013,63(7):772-788
Abstract A national analysis of weekday/weekend ozone (O3) differences demonstrates significant variation across the country. Weekend 1-hr or 8-hr maximum O3 varies from 15% lower than weekday levels to 30% higher. The weekend O3 increases are primarily found in and around large coastal cities in California and large cities in the Midwest and Northeast Corridor. Both the average and the 95th percentile of the daily 1-hr and 8-hr maxima exhibit the same general pattern. Many sites that have elevated O3 also have higher O3 on weekends even though traffic and O3 precursor levels are substantially reduced on weekends. Detailed studies of this phenomenon indicate that the primary cause of the higher O3 on weekends is the reduction in oxides of nitrogen (NOx) emissions on weekends in a volatile organic compound (VOC)-limited chemical regime. In contrast, the lower O3 on weekends in other locations is probably a result of NOx reductions in a NOx-limited regime. The NOx reduction explanation is supported by a wide range of ambient analyses and several photochemical modeling studies. Changes in the timing and location of emissions and meteorological factors play smaller roles in weekend O3 behavior. Weekday/weekend temperature differences do not explain the weekend effect but may modify it. 相似文献
872.
L.-W. Antony Chen Judith C. Chow Bruce G. Doddridge Russell R. Dickerson William F. Ryan Peter K. Mueller 《Journal of the Air & Waste Management Association (1995)》2013,63(8):946-956
Abstract Observations of the mass and chemical composition of particles less than 2.5 μm in aerodynamic diameter (PM2.5), light extinction, and meteorology in the urban Baltimore-Washington corridor during July 1999 and July 2000 are presented and analyzed to study summertime haze formation in the mid-Atlantic region. The mass fraction of ammoniated sulfate (SO4 2-) and carbonaceous material in PM2.5 were each ~50% for cleaner air (PM2.5 < 10 μg/m3) but changed to ~60% and ~20%, respectively, for more polluted air (PM2.5 > 30 μg/m3). This signifies the role of SO4 2- in haze formation. Comparisons of data from this study with the Interagency Monitoring of Protected Visual Environments network suggest that SO4 2? is more regional than carbonaceous material and originates in part from upwind source regions. The light extinction coefficient is well correlated to PM2.5 mass plus water associated with inorganic salt, leading to a mass extinction efficiency of 7.6 ± 1.7 m2/g for hydrated aerosol. The most serious haze episode occurring between July 15 and 19, 1999, was characterized by westerly transport and recirculation slowing removal of pollutants. At the peak of this episode, 1-hr PM2.5 concentration reached ~45 μg/m3, visual range dropped to ~5 km, and aerosol water likely contributed to ~40% of the light extinction coefficient. 相似文献
873.
D. Bruce Henschel Roy C. Fortmann Nancy F. Roache Xiaoyu Liu 《Journal of the Air & Waste Management Association (1995)》2013,63(5):708-717
ABSTRACT A laboratory thermal desorption apparatus was used to measure emissions from a number of nominally identical photocopier toners—manufactured to meet the specifications of one specific model copier—when these toners were heated to fuser temperature (180-200 °C). The objective was to assess how potential volatile organic compound (VOC) emissions from the toner for a given copier can vary, depending upon the production run and the supplier. Tests were performed on a series of toner (and associated raw polymer feedstock) samples obtained directly from a toner manufacturer, representing two production runs using a nonvented extrusion process, and on toner cartridges purchased from two local retailers, representing three different production lots (histories unknown). The results showed that the retailer toners consistently had up to 350% higher emissions of some major compounds (expressed as |ig of compound emit-ted/g of toner), and up to 100% lower emissions of others, relative to the manufacturer toners (p ≤ 0.01). The manufacturer toners from one production run had emissions of certain compounds, and of total VOCs, that were modestly higher (13-18%) than those from the other run (p ≤ 0.01). The emission differences between the retailer and manufacturer toners are probably due to differences 相似文献
874.
Aron D. Jazcilevich Agustín R. García L. Gerardo Ruiz-Suárez Xóchitl Cruz-Nuñez Javier C. Delgado Carlos Tellez 《Journal of the Air & Waste Management Association (1995)》2013,63(3):366-378
Abstract Using an air quality model, two future urban scenarios induced by the construction of the new international airport for Mexico City are compared at a regional level. The air quality model couples the meteorology model MM5 and state-of-the-art photochemistry. The air quality comparison is made using metrics for the criterion gases selected for the study. From the two urban scenarios compared, the option for Tizayuca is moderately better than the option for Texcoco, because relative reductions in O3 and other photochemical pollutants are achieved over highly populated areas. Regardless of the site, the air quality for the central region of Mexico in the future will deteriorate. In the region of central Mexico, SO2 and NO2 will become important pollutants. 相似文献
875.
Isaac Schifter Luis Díaz Esteban López-Salinas 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1289-1297
Abstract Environmental agencies are currently in the process of implementing a new air management program, which includes the improvement of fuel quality. In this work, exhaust emissions data and estimated relative risk for various fuels testing in-use vehicles, equipped with three different exhaust emission control technologies, are presented. Aromatics, sulfur, and olefins contents; type of oxygenated compound; and Reid vapor pressure were varied. The aim also includes calculating the ozone (O3)of forming potential and a relative cancer risk of emissions from current and formulated gasoline blends in Mexico. The proposed gasoline decreases carbon monoxide, total hydrocarbons (THC), and nitrogen oxides emissions by 18 and 14%, respectively, when compared with gasoline sold in the rest of the country and within ozone nonattainment metropolitan areas in Mexico, respectively. 相似文献
876.
877.
Ronald F. Lewis 《Journal of the Air & Waste Management Association (1995)》2013,63(4):503-508
This paper summarizes a joint Superfund Innovative Technology Evaluation (SITE) project on slurry-phase biodegradation and a project to collect information for the data base on Best Demonstrated Available Technologies (BOAT). In this 12-week study, a creosote contaminated soil from the Burlington Northern Superfund site in Brainerd, Minnesota was used to evaluate the effectiveness of the bioslurry reactors. During the demonstration, five 64-liter stainless steel bioreactors, equipped with agitation, aeration and temperature controls were used. The pilot scale study employed a 30 percent slurry, an inoculum of indigenous polynuclear aromatic hydrocarbon (PAH) degraders, and inorganic nutrients. Total PAH degradation averaged 93.4 ± 3.2 percent over all five operating reactors in the 12 weeks with 97.4 percent degradation of the 2- and 3-ring PAHs and 90 percent degradation of the 4- to 6-ring PAHs. A study of the air emissions, both semivolatile compounds such as naphthalene, anthracene, and phenanthrene and volatile compounds such as toluene, xylene, and benzene, from the units showed that the greatest amount of emissions occurred during the loading of the reactors and during the first few days of operation. Therefore, it may not be cost-effective to require elaborate emissions controls unless there are significant quantities of volatile compounds present in the soil or water to be treated in a bioslurry reactor system. 相似文献
878.
Pedro Bueno Remedios Yañez Sebastian Caparrós Manuel Jesús Díaz 《Journal of the Air & Waste Management Association (1995)》2013,63(7):790-800
Abstract A neural fuzzy system was used to investigate the influence of environmental variables (time, aeration, moisture, and particle size) on composting parameters (pH, organic matter [OM], nitrogen [N], ammonium nitrogen [NH4 +-N] and nitrate nitrogen [NO3 --N]). This was to determine the best composting conditions to ensure the maximum quality on the composts obtained with the minimum ammonium losses. A central composite experimental design was used to obtain the neural fuzzy model for each dependent variable. These models, consisting of the four independent process variables, were found to accurately describe the composting process (the differences between the experimental values and those estimated by using the equations never exceeded 5–10% of the former). Results of the modeling showed that creating a product with acceptable chemical properties (pH, NH4 +-N and NO3 --N) entails operating at medium moisture content (55%) and medium to high particle size (3–5 cm). Moderate to low aeration (0.2 L air/min · kg) would be the best compromise to compost this residue because of the scant statistical influence of this independent variable. 相似文献
879.
J.F. Karlik A.J. Downer 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1361-1367
ABSTRACT Five different models of dosimeters were compared in the Chernobyl Inner Exclusion Zone by measuring gamma radiation in 12 locations. We used an instrument made by Mirion Technologies, Inc., as the reference, since that instrument had an NIST-traceable calibration. Two models of dosimeters gave radiation values similar to the Mirion at all levels of radiation encountered. Two other models gave similar values to the Mirion instrument at low radiation levels but not at higher radiation levels encountered. These results offer a caution regarding the accuracy of inexpensive commercially available radiation instruments. Implications: Comparison of gamma ray dosimeters in the Chernobyl Exclusion Zone showed varying agreement with an NIST-calibrated instrument, as well as varying linearity of response to ambient radiation. These results suggest caution regarding accuracy of inexpensive dosimeters. However, dosimeters used that were manufactured in Ukraine exhibited good agreement with the reference instrument. 相似文献
880.
Dan Venables Nick F. Pidgeon Karen A. Parkhill Karen L. Henwood Peter Simmons 《Journal of environmental psychology》2012
Previous research notes that sense of place may intensify, and that levels of public risk perception may decrease with proximity to an established hazardous or stigmatised site. In addition, the literature suggests that sense of place may act either to mediate or moderate community perceptions of risk in such localities. This study comprised a major household survey (n = 1326) and an interview study (n = 39) and was conducted close to the nuclear power stations at Oldbury and Hinkley Point, both in the UK. It investigated the roles of perceptions of place and hazard proximity in considering (a) perceptions of risk and (b) public attitudes towards the building of a new nuclear power station in the nearby area. In addition, a novel scale was developed to measure the perceived contribution of the nearby nuclear power station to sense of place. The results suggest first, that sense of place mediates (but does not moderate) perceptions of risk in very proximate communities, and second, that public attitudes to new build in communities situated very close to established nuclear sites may be largely dependent on the extent to which the existing facility is perceived to contribute towards sense of place. The implications of these results for existing theory are discussed. 相似文献