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991.
Gary L. Johnson Lynda H. Wynn 《Journal of the Air & Waste Management Association (1995)》2013,63(5):733-737
The Management Systems Review is an important component of EPA’s quality assurance program. MSRs enable managers to assess the effectiveness of environmental data operations and the quality assurance/ quality control activities designed to ensure that the results are of the expected quality. These reviews inform managers about aspects of the environmental data operation that are working well and those which may warrant some improvement. A recent review of the Superfund remedial investigation/feasibility study (RI/FS) has shown that the MSR is an excellent tool for providing a systematic definition of complex environmental data operations and for enabling a thorough analysis of these operations. The MSR utilized information gathered from interviews of Regional staff and management and from case studies of recently completed RI/FSs. The findings indicated that environmental data play an important role in most RI/FS decisions and that thorough and structured scoping is critical to the effectiveness of the RI/ FS. Analysis of the RI/FS process using a comprehensive flow model identified several opportunities for changes that may increase efficiency in data collection and the reliability of RI/FS decisions. These changes provide for more effective scoping activities, a streamlined feasibility study, and increased use of treatability studies during the RI. A pilot demonstration of these process changes is being planned for a Regional RI/FS. 相似文献
992.
David L. Peterson Michael J. Arbaugh 《Journal of the Air & Waste Management Association (1995)》2013,63(7):921-927
Growth of ponderosa pines with visible symptoms of ozone injury was compared with that of asymptomatic trees in the southern Sierra Nevada, California. Time series analysis indicated that there was no significant reduction in annual radial increment of symptomatic trees during recent years compared to past growth and growth of asymptomatic trees. First order autocorrelation and climatic variables accounted for a large proportion of the variance in growth index, and winter precipitation was positively correlated with growth for all size and age classes. Although ozone concentrations are high enough to cause chlorosis and premature needle senescence in ponderosa pine, there has been no significant change in growth associated with ozone injury. 相似文献
993.
Robert R. Arnts Robert L. Seila Joseph J. Bufalini 《Journal of the Air & Waste Management Association (1995)》2013,63(4):453-460
A relative rate procedure was used to measure hydroxyl rate constants at room temperature in the presence of oxygen. The photolysis of methyl nitrite in the presence of nitric oxide was used to generate OH radicals. The rate of loss of the test compounds was measured relative to that of ethane (kOH = 2.74 × 10-13 cm3 molec-1 s-1). The rates obtained at 297 ± 2 K are: acetylene = (7.8 ± 1.6) × 10-13 cm3 molec-1 s-1,1,2-dichloroethane (2.8 ± Q.6) × 10-13 cm3 molec-1 s-1, 1,2-dibromoethane (2.4 ± 0.5) × 10-13 cm3 molec-1 s-1, p-dichlorobenzene (4.3 ± 0.9) × 10-13 cm3 molec-1 s-1 and carbon disulfide (29 ± 6) × 10-13 cm3 molec-1 s-1. Under a proposed EPA rule, this OH rate determination procedure could be used to determine if a given volatile organic will be subject to control for reduction of photochemical ozone. 相似文献
994.
Teri L. Conner William A. Lonneman Robert L. Seila 《Journal of the Air & Waste Management Association (1995)》2013,63(5):383-394
Abstract Samples representative of transportation-related hydrocarbon emissions were collected as part of the 1990 Atlanta Ozone Precursor Monitoring Study. Motor vehicle emissions were sampled in canisters beside a roadway in a tunnel-like underpass during periods of heavy traffic. Airport and aircraft emissions were approximated by canister samples obtained at a major airport facility. Three octane grades of gasoline were purchased from six major vendors in Atlanta. Canister samples were prepared using these fuels to approximate the whole gasoline and gasoline vapor composition of the fuels in use during the study. All samples were analyzed by gas chromatography/flame ionization detection (GC/FID) for their hydrocarbon content. Detailed speciated hydrocarbon profiles were developed from this source sampling and analysis program for use in the Chemical Mass Balance (CMB) model. Profiles presented and discussed here represent the hydrocarbon composition of emissions from a roadway, composite headspace gasoline at two temperatures, composite whole gasoline, whole gasoline at three octane grades, and an airport. The roadway profile is compared with similar profiles in the literature, and recommendations are made regarding its use in the CMB model. The roadway and fuel profiles are discussed in the context of the MOBILE5 model outputs. The headspace gasoline vapor profile presented here is compared with a headspace gasoline vapor profile calculated from the whole gasoline profile by means of Raoult’s law. Agreement between the measured and calculated headspace profiles is excellent. The airport profile demonstrates the importance of high molecular weight volatile hydrocarbons in airport and aircraft emissions. 相似文献
995.
Cynthia L. Gage Gary T. Rochelle 《Journal of the Air & Waste Management Association (1995)》2013,63(7):926-935
Batch limestone dissolution experiments were carried out in a pH stat apparatus at 55°C with CO2 sparging and dissolved sulfite. Particle size distribution, utilization, sulfite in solution, limestone type, and the approach to calcite equilibrium were all found to contribute to the limestone reactivity. In the absence of sulfite, limestone dissolution was controlled solely by mass transfer. For a given stone under mass transfer control, film thickness was found to be independent of pH. The dissolution rate in the presence of sulfite was controlled by a combined surface kinetics/mass transfer regime. SEM micrographs supported this conclusion. A surface rate correlation was developed which accounted for observed inhibition by an inverse dependence on calcium sulfite concentration at the limestone surface. While the form of the rate expression was applicable to all stones, the surface rate constant was stone dependent. A computer code which accounted for mass transfer with surface kinetics was tested against experimental observations of four limestone types. Changes in pH and the concentrations of calcium, carbonate, sulfite, sulfate, and adipic acid were accurately modeled. 相似文献
996.
C. Jean Bustard Kenneth M. Cushing Ramsay L. Chang 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1240-1249
Pulse-jet fabric filters (PJFFs) are widely used in U.S. industrial boiler applications and in utility and industrial boilers abroad. Their small size and reduced cost relative to more conventional reverse-gas baghouses makes the use of PJFFs appear to be an attractive particulate control option for utility boilers. This paper (Part 2 of a three-part series) summarizes the results of pilot PJFF studies sponsored by the Electric Power Research Institute at different utility sites in the United States. The purpose of these tests is to evaluate PJFF performance for U.S. fossil-fuel-fired applications. These data are also used to corroborate the results of a recent worldwide survey of PJFF user experience, as described in Part 1 of this series. Part 3 will provide a cost comparison of PJFFs to other particulate control options such as electrostatic precipitators and reverse-gas baghouses. 相似文献
997.
John A. Willemin Carl C. Nesbitt George R. Dewey John F. Sandell Lawrence L. Sutler 《Journal of the Air & Waste Management Association (1995)》2013,63(11):871-876
Abstract A completely mixed batch reactor leaching method utilizing flow injection analysis (the CMBR-FIA method) was developed to study the lead leaching characteristics of municipal waste combustor fly ash. Flow injection analysis (FIA) coupled with atomic absorption spectrophotometry enabled the determination of lead concentrations at one minute intervals. The pH and oxidation-reduction potential of the solution were continuously monitored to characterize the leaching conditions. Automatic titration was used to alter the solution pH to defined endpoints. The CMBR-FIA method offers the ability to immediately observe alterations to the leaching solution, and grants the freedom to study a number of parameters concurrently. The CMBR-FIA method is a rapid and reliable means to investigate leaching characteristics. This paper describes the method and demonstrates its use to monitor the leaching of lead from municipal solid waste combustor fly ash as a function of pH. Soluble lead concentrations are shown to increase quickly with decreasing pH. A maximum of 50% of the total lead concentration was available in solution at pH 2. This value gradually decreased with time to over 35% of the total. 相似文献
998.
Karen R. Anderson Edward L. Avol Scott A. Edwards Deborah A. Shamoo Ru-Chuan Peng William S. Linn 《Journal of the Air & Waste Management Association (1995)》2013,63(6):770-776
Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, we exposed 15 healthy and 15 asthmatic volunteers in a controlled- environment chamber (21°C, 50 percent relative humidity) to four test atmospheres: (i) clean air; (ii) 0.5-μm H2SO4 aerosol at =100 μg/m3, generated from water solution; (iii) 0,5-μm carbon aerosol at =250 μg/m3, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (iv) carbon as in (iii) plus =100 μg/m3 of ultrafine H2SO4 aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (iv) became attached to carbon particle surfaces, and that most particles remained in the sub-μm size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation =50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at endexposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H2SO4 or carbon, separate or interactive, on health measures. Group data showed no more than small equivocal effects of any exposure on any health measure. One individual's responses were consistent with a clinically significant excess airway constriction from H2SO4 plus carbon, and 2-3 others showed slight excess responses to the combined pollutants, but all these observations might have reflected chance variations. We conclude that coexisting carbon aerosol did not increase respiratory irritancy of H2SO4, in most healthy and asthmatic subjects exposed for 1 hr under simulated "worst-case" ambient conditions. 相似文献
999.
V. A. Cundy C. Lu C. A. Cook A. M. Sterling C. B. Leger A. L. Jakway 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1084-1094
Comparisons are made, for the first time, between the combustion characteristics of dichloromethane and xylene in an industrial rotary kiln incinerator. The comparisons are made under different operating conditions, including variable kiln rotation rate and operation both with and without turbulence air. Continuous gas composition and temperature measurements and batch gas composition measurements were obtained from two vertical locations hear the exit region of the rotary kiln. The measurements show that there is significant vertical stratification at the exit of the kiln. Addition of turbulence air enhanced combustion conditions throughout the kiln during xylene processing. During dichloromethane processing, however, the addition of turbulence air had minimal effect and only promoted greater bulk mixing; chlorinated compounds transported from the lower kiln during operation with turbulence air were not efficiently processed in the upper kiln. Evolution of test liquids from the bed was not constant but rather was characterized by intermittent peaks. The field-scale data of this work suggest that the evolution rate of the test liquid was increased as kiln rotation rate increased. Many of the differences between xylene and dichloromethane processing during these experiments are explained by a simple stoichiometric analysis. 相似文献
1000.
Lauraine G. Chestnut Robin L. Dennis 《Journal of the Air & Waste Management Association (1995)》2013,63(3):395-402
The Acid Rain Provisions (Title IV) of the Clean Air Act Amendments of 1990 call for about a 10 million ton reduction in annual SO2 emissions in the United States. Although the provisions apply nationwide, most of the reduction will occur in the eastern half of the country, where use of high-sulfur coal for electricity generation is most common. One potentially large benefit of Title IV is the expected improvement in visibility conditions in the eastern United States due to the reductions in secondary sul-fate aerosols. This paper combines available economic estimates of willingness to pay for improvements in visibility with current estimates of the difference between expected visibility conditions in the eastern United States with and without Title I V, to estimate the expected visibility benefits of Title IV. The results suggest an annual value of $2.3 billion (in 1994 dollars) in the year 2010, as a result of visibility improvements due to Title IV in residential areas of the eastern United States. The results also suggest a possible additional annual value for eastern U.S. residents of as much as $1-2 billion for visibility improvements at national parks in the Southeast. 相似文献