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761.
Walter F. Mcmichael John E. Sigsby Jr. 《Journal of the Air & Waste Management Association (1995)》2013,63(9):474-477
Randomly selected passenger automobiles were driven over a 7.5-mile composite route in Cincinnati, Ohio. Samples of the exhaust gases were collected from each car by means of a proportional sampler and analyzed for gross hydrocarbons, carbon monoxide, carbon dioxide, and oxides of nitrogen. In addition, detailed analysis of the hydrocarbons was made. This included parafins, 1 through 8 carbon, olefins, 2 through 6 carbon, and aromatics, 6 through 10 carbon. This paper compares the differences in these emissions immediately after starting with “cold” engines as opposed to emissions from cars started with engines already warmed up or “hot.” This determination was made under both cold and warm weather conditions. A comparison is also made in air pollutants emitted from cars driven under the summer as opposed to the winter conditions normally encountered in Cincinnati, Ohio. 相似文献
762.
763.
Walter F. McMichael Ronald E. Kruse Donald M. Hill 《Journal of the Air & Waste Management Association (1995)》2013,63(4):246-248
Road tests have been carried out in five different cities with a fleet of 300 passenger cars consisting of three different makes, half of which are equipped with the 1966 exhaust control devices required by the state of California. The performance of these devices during the first series of tests has been evaluated. All three makes of device-equipped cars produced significantly lower emissions of hydrocarbons and carbon monoxide than did similar cars tested in 1962 and 1963. There were no consistent differences among the three makes of cars with respect to carbon monoxide and hydrocarbon emissions. 相似文献
764.
Ralph I. Larsen Walter W. Heck 《Journal of the Air & Waste Management Association (1995)》2013,63(4):325-333
Acute leaf injury data are analyzed for 19 plant species exposed to ozone or sulfur dioxide. The data can be depicted by a new leaf injury mathematical model with two characteristics: (1) a constant percentage of leaf surface is injured by an air pollutant concentration that is inversely proportional to exposure duration raised to an exponent; (2) for a given exposure duration, the percent leaf injury as a function of pollutant concentration tends to fit a lognormal frequency distribution. Leaf injury as a function of laboratory exposure duration is modeled and compared with ambient air pollutant concentration measurements for various averaging times to determine which exposure durations are probably most important for setting ambient air quality standards to prevent or reduce visible leaf injury. The 8 hour average appears to be most important for most of the plants investigated for most sites, 1 hr concentrations are important for most plants at a few sites, and 3 hr S02 concentrations are important for some plants, especially those exposed to isolated point sources of the pollutant. The 1, 3, and 8 hr threshold injury concentrations are listed for each of the 19 plant species studied. To prevent or reduce acute leaf injury, fixed, nonoverlapping ambient air quality measurements and standards are recommended for averaging times of 1, 3, and 8hr. 相似文献
765.
Ralph I. Larsen Walter W. Heck 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1023-1034
A plant injury mathematical model, applied previously to acute and chronic leaf injury data, is used here to model National Crop Loss Assessment Network (NCLAN) data for 15 cultivars and to calculate species parameters from the cultivar analyses. Percent crop yield reduction is estimated as a function of a new parameter, the effective mean O3 concentration: me = [(Σ ch ?1/v)/n]?v, where ch is the hourly average ambient O3 concentration for each daytime hour (defined here as 9:00 A.M.–4:00 P.M., always standard time) of data available at an air sampling site for summer (defined here as June 1–August 31), n is the total number of such available hours, and v is an exposure time-concentration parameter, calculated here to be approximately –0.376. Crop yield reduction for soybean is calculated here as z = 0.478 In (tme 2-66) – 0.42, where z is the Gaussian transform of percent crop reduction, t is the hours of exposure (525 h is used here; 7 h/day for 75 days), and In indicates that the natural logarithm is taken of the quantity within parentheses. Crop yield reductions for seven plant species are estimated with similar equations for each of the 1824 site-years of 1981–1983 hourly O3 concentration data available in the National Aerometric Data Bank (NADB). County-average effective mean O3 concentrations are indicated by shading on a U.S. map. State-average O3 parameters and estimated percent crop yield reductions are tabulated. The National Ambient Air Quality Standard (NAAQS) for O3 specifies that, on the average, the second highest daily maximum 1-h average O3 concentration in a year shall not exceed 0.12 ppm. For years 1981-1983,71% of the NADB sites recorded annual second highest daily maximum 1-h average O3 concentrations below 0.125 ppm (for summer daytime hours). Ambient O3 concentrations reduced the total U.S. crop yield an estimated 5% for years 1981–1983. (Summer, daytime, and all acronyms are always used herein as defined above.) 相似文献
766.
Ralph I. Larsen Thomas R. McCurdy Pamela M. Johnson Walter W. Heck 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1497-1503
Soybean percent crop reduction was estimated as a function of ambient O3 concentrations for each of 80 agricultural sites in the National Aerometric Data Bank (NADB) for each available year of data for years 1981-1985. Fourteen O3 concentration statistics were calculated for each of the resulting 320 site-years of data. The two statistics that correlated best with estimated crop reduction were an effective mean O3 concentration (1 percent of variance unexplained) and an arithmetic mean O3 concentration (4 percent unexplained). The worst correlation of the 14 was for the statistic used in the present O3 National Ambient Air Quality Standard (NAAQS), the second highest daily maximum 1-h O3 concentration (42 percent unexplained). The number of site-years for estimated percent soybean yield reductions was plotted versus increasing O3 concentrations for each of the 14 O3 statistics. A maximum crop reduction line was drawn on each plot. These lines were used to estimate (and list) potential ambient O3 standards for each of the 14 statistics that would limit soybean crop reduction at agricultural. NADB sites to 5, 10, 15, or 20 percent. 相似文献
767.
Debra L. Bisson Danny R. Jackson Kenneth R. Williams Walter E. Grube 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1348-1354
WILT, ANS 16.1 and TCLP leach tests were performed on solidified/stabilized (s/s) wastes treated by Soliditech, Inc. of Houston, Texas as part of a U.S. EPA SITE demonstration project conducted in December 1988 at the Imperial Oil Company/ Champion Chemical Company Superfund site in Morganville, New Jersey. All three leaching tests performed on the s/s wastes indicated that the primary contaminants of concern (lead and PCBs) were not leachable. The ANS 16.1 static leach test for the s/s wastes provided diffusion coefficients (De) for Al, Ca, and Na that were comparable to those obtained from the WILT test. However, plots of the ANS 16.1 data indicated that wetting of the samples confounded the static leaching process. The large column WILT De was used to estimate that less than 0.8 μg/cm2 lead would leach from a one-cubic yard block of s/s waste in contact with groundwater over a 60-month leaching period. This corresponds to concentrations less than 10 μg/L lead in the water contacting the block of s/s waste. 相似文献
768.
Environmental Management - Cattle degrade streams by increasing sediment, nutrient, and fecal bacteria levels. Riparian fencing is one best management practice that may protect water quality within... 相似文献
769.
Combined monitoring and modeling indicate the most effective agricultural best management practices 总被引:1,自引:0,他引:1
Although water quality problems associated with agricultural nonpoint source (NPS) pollution have prompted the rapid and widespread adoption of a variety of so called "best management practices" (BMPs), there have been few realistic efforts to assess their combined effectiveness in reducing NPS pollution. This study used the Variable Source Loading Function (VSLF) model, a distributed watershed model, to simulate phosphorus (P) loading from an upstate New York dairy farm before and after the implementation of a suite of BMPs. With minimal calibration, the model calculates the dissolved P (DP) losses from impervious surfaces (e.g., barnyards), the plant/soil complex, field-applied manure, and loads associated with baseflow conditions. The simulated DP loads agreed well with measured loads for both the pre-BMP and post-BMP periods. More importantly, results showed that BMPs reduced DP loads by 35%, which is over half of the expected reduction if all manure was removed from the watershed, i.e., approximately 50% reduction. The model results indicate that had no BMPs been installed DP loads would be approximately 37% greater than observed at the watershed outlet. The most effective BMPs were those that disassociated pollutant loading areas from areas prone to generating runoff, i.e., hydrologically sensitive areas. By contrast, attempts to reduce P content in manure were somewhat less effective. This study demonstrates that a combination of distributed, mechanistic modeling and long-term monitoring provides better insights into the effectiveness of water quality protection efforts than either individually. 相似文献
770.
Chemical and toxicologic assessment of organic contaminants in surface water using passive samplers 总被引:1,自引:0,他引:1
Alvarez DA Cranor WL Perkins SD Clark RC Smith SB 《Journal of environmental quality》2008,37(3):1024-1033
Passive sampling methodologies were used to conduct a chemical and toxicologic assessment of organic contaminants in the surface waters of three geographically distinct agricultural watersheds. A selection of current-use agrochemicals and persistent organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides, were targeted using the polar organic chemical integrative sampler (POCIS) and the semipermeable membrane device passive samplers. In addition to the chemical analysis, the Microtox assay for acute toxicity and the yeast estrogen screen (YES) were conducted as potential assessment tools in combination with the passive samplers. During the spring of 2004, the passive samplers were deployed for 29 to 65 d at Leary Weber Ditch, IN; Morgan Creek, MD; and DR2 Drain, WA. Chemical analysis of the sampler extracts identified the agrochemicals predominantly used in those areas, including atrazine, simazine, acetochlor, and metolachlor. Other chemicals identified included deethylatrazine and deisopropylatrazine, trifluralin, fluoranthene, pyrene, cis- and trans-nonachlor, and pentachloroanisole. Screening using Microtox resulted in no acutely toxic samples. POCIS samples screened by the YES assay failed to elicit a positive estrogenic response. 相似文献