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991.
992.
Thomas W. Sager Alfredo D. Vaquiax M. W. Hemphiil 《Journal of the Air & Waste Management Association (1995)》2013,63(2):199-205
Strategies for control of ozone aim at regulation of its chemical precursors, non-methane organic compounds (NMOC) and nitrogen oxides (NOx). It is therefore important to analyze how these precursors vary temporally and geographically. This study finds significant and important differences among four Texas ozone nonattainment sites, Dallas, Ft. Worth, El Paso, and Houston, for 1984, 1985, and 1986 for NMOC, NOx, and their ratio NNR. These differences were detected through nonparametric analysis of variance and Student-New-man-Keuls’s test for multiple comparisons on rank-transformed data. A noteworthy feature of the data analysis is its attention to the assumptions underlying the statistical methods. Classical models based on normal or lognormal theory had to be abandoned for lack of realism. It is demonstrated how alternative models may be applied to yield appropriate, rather than inappropriate, conclusions. 相似文献
993.
Edwin A. Korzun N. Thomas Stephens Howell H. Heck 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1544-1548
The State of Florida passed The Florida Solid Waste Management Act of 1988 mandating that county recycling programs be initiated by July 1, 1989. The legislation further expressed the goal that, at a minimum, recycling efforts reduce the amount of solid waste requiring final disposal or resource recovery by 30 percent by the end of 1994. This study was performed to determine the impact on recycle markets when the amounts of materials recycled from the municipal solid waste stream are increased by 30 percent in Florida. The composition of the municipal waste stream was quantified in terms of the amounts of paper, plastic, metals, glass, and rubber. The effect of a 30 percent increase in the recycle rate of each class of material was calculated and compared to existing recycle rates in the State of Florida. It was determined that there are few capacity constraints on the increase in recycle rates for aluminum, steel (i.e., tin cans), and color separated glass. There are, however, serious constraints on increasing recycle rates for paper, plastics and rubber tires. 相似文献
994.
Thomas D. Brown Dennis N. Smith Richard A. Hargis Jr. William J. O'Dowd 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1-97
ABSTRACT Based on the available evidence of health effects, the U.S. Environmental Protection Agency (EPA) has been evaluating the need to regulate mercury releases to the environment. In response to the congressional mandates in The 1990 Clean Air Act Amendments (CAAA), the EPA has issued the Mercury Study Report and the Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units Report. In spite of the enormous effort represented by these reports, as well as the efforts of both the U.S. Department of Energy (DOE) and the Electric Power Research Institute (EPRI), in conducting the field measurement programs that form the basis for these reports, a definitive answer on the need for mercury regulation has not been found. However, the EPA, as well as other regulatory agencies and health researchers, have suggested a “plausible link” between anthropogenic sources emitting mercury and the methylation, bioaccumulation in the food chain, and adverse health effects in humans and wildlife. Policy-makers have recognized that regulations must be based on good science and that a number of issues still remain. These issues can generally be grouped into four main categories: emissions inventory, control technology, fate of releases, and health effects. This paper will discuss recent, ongoing, and planned studies to address the remaining issues regarding the presence of mercury in the environment, with an emphasis on those studies that are directly related to the DOE/Federal Energy Technology Center’s (FETC) programmatic effort. 相似文献
995.
Thomas D. Durbin Joseph M. Norbeck 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1054-1063
Abstract A total of 77 On-Board Diagnostics II (OBDII)-equipped vehicles with illuminated malfunction indicator lights (MILs) and non-evaporative codes were tested before and after repair. The test cycles included the Federal Test Procedure (FTP), IM240, and steady-state cycles. A total of 17 vehicles were found with emissions greater than 1.5 times their respective FTP emissions standards. Repair of these vehicles resulted in dramatic reductions in overall emissions for all the cycles. A majority of the remaining vehicles were found to have emissions below the certification standard for the FTP both before and after repair. Repairs for the vehicles with emissions <1.5 times the standard resulted in some smaller but quantifiable emission reductions over the FTP and IM240 but larger reductions over the steady-state driving tests. Misfires, bad oxygen sensors, and exhaust gas recirculation (EGR) problems were the most common non-evaporative causes for triggering the MIL. The results show some fundamental differences between identifying malfunctioning vehicles using OBDII as opposed to more traditional dynamometer tests. In particular, for many systems, OBDII identifies components that are operating outside their design specification rather than for a specific emissions threshold. 相似文献
996.
Philip M. Roth Thomas W. Tesche 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1558-1573
Abstract Despite the widespread application of photochemical air quality models (AQMs) in U.S. state implementation planning (SIP) for attainment of the ambient ozone standard, documentation for the reliability of projections has remained highly subjective. An “idealized” evaluation framework is proposed that provides a means for assessing reliability. Applied to 18 cases of regulatory modeling in the early 1990s in North America, a comparative review of these applications is reported. The intercomparisons suggest that more than two thirds of these AQM applications suffered from having inadequate air quality and meteorological databases. Emissions representations often were unreliable; uncertainties were too high. More than two thirds of the performance evaluation efforts were judged to be substandard compared with idealized goals. Meteorological conditions chosen according regulatory guidelines were limited to one or two cases and tended to be similar, thus limiting the extent to which public policy makers could be confident that the emission controls adopted would yield attainment for a broad range of adverse atmospheric conditions. More than half of the studies reviewed did not give sufficient attention to addressing the potential for compensating errors. Corroborative analyses were conducted in only one of the 18 studies reviewed. Insufficient attention was given to the estimation of model and/or input database errors, uncertainties, or variability in all of the cases examined. However, recent SIP and policy‐related regional modeling provides evidence of substantial improvements in the underlying science and available modeling systems used for regulatory decision making. Nevertheless, the availability of suitable databases to support increasingly sophisticated modeling continues to be a concern for many locations. Thus, AQM results may still be subject to significant uncertainties. The evaluative process used here provides a framework for modelers and public policy makers to assess the adequacy of contemporary and future modeling work. 相似文献
997.
Chun W. Lee Ravi K. Srivastava S. Behrooz Ghorishi Thomas W. Hastings Frank M. Stevens 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1560-1566
Abstract Selective catalytic reduction (SCR) technology increasingly is being applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury (Hg) in coal combustion flue gases. The speciation of Hg is an important factor influencing the control and environmental fate of Hg emissions from coal combustion. The vanadium and titanium oxides, used commonly in the vanadia-titania SCR catalyst for catalytic NOx reduction, promote the formation of oxidized mercury (Hg2+). The work reported in this paper focuses on the impact of SCR on elemental mercury (Hg0) oxidation. Bench-scale experiments were conducted to investigate Hg0 oxidation in the presence of simulated coal combustion flue gases and under SCR reaction conditions. Flue gas mixtures with different concentrations of hydrogen chloride (HCl) and sulfur dioxide (SO2) for simulating the combustion of bituminous coals and subbituminous coals were tested in these experiments. The effects of HCl and SO2 in the flue gases on Hg0 oxidation under SCR reaction conditions were studied. It was observed that HCl is the most critical flue gas component that causes conversion of Hg0 to Hg2+ under SCR reaction conditions. The importance of HCl for Hg0 oxidation found in the present study provides the scientific basis for the apparent coal-type dependence observed for Hg0 oxidation occurring across the SCR reactors in the field. 相似文献
998.
Ross C. Beier Michael E. Hume Robin C. Anderson Christy E. Oliver Todd R. Callaway Thomas S. Edrington 《Journal of environmental science and health. Part. B》2013,48(6):717-726
Salmonella and Escherichia coli are two bacteria that are important causes of human and animal disease worldwide. Chlorate is converted in the cell to chlorite, which is lethal to these bacteria. An HPLC procedure was developed for the rapid analysis of chlorate (ClO3 ?), nitrate (NO3 ?), and nitrite (NO2 ?) ions in bovine ruminal fluid samples. Standard curves for chlorite, nitrite, nitrate, and chlorate were well defined linear curves with R2 values of 0.99846, 0.99106, 0.99854, and 0.99138, respectively. Concentrations of chlorite could not be accurately determined in bovine ruminal fluid because chlorite reacts with or binds a component(s) or is reduced to chloride in bovine ruminal fluid resulting in low chlorite measurements. A standard curve ranging from 25 to 150 ppm ClO3 ? ion was used to measure chlorate fortified into ruminal fluid. The concentration of chlorate was more rapidly lowered (P < 0.01) under anaerobic compared to aerobic incubation conditions. Chlorate alone or chlorate supplemented with the reductants sodium lactate or glycerol were bactericidal in anaerobic incubations. In anaerobic culture, the addition of sodium formate to chlorate-fortified ruminal fluid appeared to decrease chlorate concentrations; however, formate also appeared to moderate the bactericidal effect of chlorate against E. coli. Addition of the reductants, glycerol or lactate, to chlorate-fortified ruminal fluid did not increase the killing of E. coli at 24 h, but may be useful when the reducing equivalents are limiting as in waste holding reservoirs or composting systems required for intense animal production. 相似文献
999.
Marie E. DeLorenzo Sarah C. Wallace Loren E. Danese Thomas D. Baird 《Journal of environmental science and health. Part. B》2013,48(5):455-460
This study investigated the effects of increased temperature and salinity, two potential impacts of global climate change, on the toxicity of two common pesticides to the estuarine grass shrimp, Palaemonetes pugio. Larval and adult grass shrimp were exposed to the fungicide chlorothalonil and the insecticide Scourge® under standard toxicity test conditions, a 10°C increase in temperature, a 10 ppt increase in salinity, and a combined increased temperature and salinity exposure. Toxicity of the fungicide chlorothalonil increased with temperature and salinity. Toxicity of the insecticide Scourge® also increased with temperature; while increased salinity reduced Scourge® toxicity, but only in adult shrimp. These findings suggest that changes in temperature and salinity may alter the toxicity of certain pesticides, and that the nature of the effect will depend on both the organism's life stage and the chemical contaminant. Standard toxicity bioassays may not be predictive of actual pesticide toxicity under variable environmental conditions, and testing under a wider range of exposure conditions could improve the accuracy of chemical risk assessments. 相似文献
1000.
Li-Tse Ou John E. Thomas L. Hartwell Allen Jr Joseph C. Vu Donald W. Dickson 《Journal of environmental science and health. Part. B》2013,48(5):376-381
The purpose of this study was to conduct a field study at a Florida field site on surface emissions and subsurface distribution of cis-and trans-1,3-dichloropropene (1,3-D) and chloropicrin (CP) in raised beds injected with Telone C35 with four replications. A total of 16 beds were applied with Telone C35 by chisel injection and covered with four different plastic films, 4 beds for each film. Each bed was installed with five 20-cm long soil pore air probes and a surface air collection pan at arbitrarily locations along the length of each bed for sampling soil pore air and surface air, respectively, for analysis of the three biologically active compounds, cis- and trans-1,3-D and CP. We found that average concentrations of the three compounds at 20-cm depth among the beds covered with four different plastic films generally were not statistically different. Among the four beds covered with the same plastic film, average concentrations of the three compounds were statistically different only in the four metallic PE covered beds at 5 and 24 hours after injection. Volatilization rates of the three compounds among the beds covered with four different plastic films, with the exception of CP at 48 hours after injection, were not statistically different. It appeared that initial upward diffusion and volatilization flux were influenced by solar radiation. Initial subsurface concentrations of the three compounds and volatilization flux, especially cis-1,3-D, were greater in the beds on the east side of the field than that in the beds on the west side of the field. Whether or not difference in initial subsurface concentrations of the compounds between east side beds and west side beds may influence fumigant efficacy remains to be determined. 相似文献