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411.
412.
George M. Hidy Charles L. Blanchard 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1261-1282
Numerous papers analyze ground-level ozone (O3) trends since the 1980s, but few have linked O3 trends with observed changes in nitrogen oxide (NOx) and volatile organic compound (VOC) emissions and ambient concentrations. This analysis of emissions and ambient measurements examines this linkage across the United States on multiple spatial scales from continental to urban. O3 concentrations follow the general decreases in both NOx and VOC emissions and ambient concentrations of precursors (nitrogen dioxide, NO2; nonmethane organic compounds, NMOCs). Annual fourth-highest daily peak 8-hr average ozone and annual average or 98th percentile daily maximum hourly NO2 concentrations show a statistically significant (p < 0.05) linear fit whose slope is less than 1:1 and intercept is in the 30 to >50 ppbv range. This empirical relationship is consistent with current understanding of O3 photochemistry. The linear O3–NO2 relationships found from our multispatial scale analysis can be used to extrapolate the rate of change of O3 with projected NOx emission reductions, which suggests that future declines in annual fourth-highest daily average 8-hr maximum O3 concentrations are unlikely to reach 65 ppbv or lower everywhere in the next decade. Measurements do not indicate increased annual reduction rates in (high) O3 concentrations beyond the multidecadal precursor proportionality, since aggressive measures for NOx and VOC reduction are in place and have not produced an accelerated O3 reduction rate beyond that prior to the mid-2000s. Empirically estimated changes in O3 with emissions suggest that O3 is less sensitive to precursor reductions than is found by the CAMx (v. 6.1) photochemical model. Options for increasing the rate of O3 change are limited by photochemical factors, including the increase in NOx sensitivity with time (NMOC/NOx ratio increase), increase in O3 production efficiency at lower NOx concentrations (higher O3/NOy ratio), and the presence of natural NOx and NMOC precursors and background O3.Implications:?This analysis demonstrates empirical relations between O3 and precursors based on long term trends in U.S. locations. The results indicate that ground-level O3 concentrations have responded predictably to reductions in VOC and NOx since the 1980s. The analysis reveals linear relations between the highest O3 and NO2 concentrations. Extrapolation of the historic trends to the future with expected continued precursor reductions suggest that achieving the 2014 proposed reduction in the U.S. National Ambient Air Quality Standard to a level between 65 and 70 ppbv is unlikely within the next decade. Comparison of measurements with national results from a regulatory photochemical model, CAMx, v. 6.1, suggests that model predictions are more sensitive to emissions changes than the observations would support. 相似文献
413.
Protection of the environment is critically dependent on the quality of data used in decision making. Whether the decisions are part of the scientific process or relate to application of the laws governing people and their living conditions, good quality data are required/needed by two disciplines with distinct differences. This paper examines some differences between science and the law, provides a brief history of science in law, discusses the effects of law on science, compares United States Environmental Protection Agency (U.S. EPA) guidance and U.S. Supreme Court credible science criteria. This paper further speculates on the future use of science data by the courts. 相似文献
414.
415.
George T. Wolff Paul J. Lioy 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1034-1038
A stepwise multiple regression procedure was employed to develop the best .fit equation relating maximum afternoon ozone concentrations to meteorological and emission factors along a 24h upwind air parcel trajectory. The equation was developed using ozone data from receptor sites in Northern New Jersey and the resulting correlation coefficient was 0.96. The four most significant variables were the upwind ozone maximum on the previous day, today’s maximum temperature, the previous day’s upwind maximum temperature and the mean wind speed from the surface to 1000 m. The model was also successfully tested at 5 other sites in the Northeastern Quadrant of the United States. The results indicate that the model could be a potentially useful tool for air pollution forecasters in predicting maximum ozone concentrations in this quadrant of the country. 相似文献
416.
George J. Nebel 《Journal of the Air & Waste Management Association (1995)》2013,63(4):391-392
The gas phase thermal decomposition rates of the C1 and C2-substituted peroxyacyl nitrates (RC(O)OONO2), PAN (R = CH3), PPN (R = C2H5) and vinyl-PAN (R = CH2 = CH-) have been measured at ambient temperature (288 - 299 K) and 1 atm. of air. Our results for PAN (k = A exp (-Ea/RT), log10 (A, s-1) = 16.2 ± 1.6, Ea = 26.9 ± 2.1 kcal / mol, k298 = 3.0 × 10?4S?1) are consistent with literature data. Thermal decomposition rates for PPN and vinyl-PAN are similar to that for PAN, with k298 = 3.0 × 10?4S?1 for PAN, 3.4 × 10?4S?1 for PPN and 3.0 × 10?4S?1 for vinyl-PAN. Implications for the atmospheric persistence of PPN and vinyl-PAN as compared to that of PAN are briefly discussed. 相似文献
417.
Michael D. Durham George A. Rinard Donald E. Rugg Leslie E. Sparks 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1132-1136
A charging/collecting device for high-resistivity fly ash has been developed which controls back ionization by cooling the collector electrode internally with water. The device consists of parallel 6.0 cm pipes with corona wires suspended between the pipes. The pipes provide a simple means of interfacing with a cooling water system and also minimizing the collector area needing to be cooled. By cooling the pipes with 38°C (100°F) water, back ionization is eliminated and average field strengths of 7 kV/cm can be achieved with fly ash having a resistivity > 1012 ω-cm. Results of tests on an actual flue gas stream and plans for future testing are described. Initial tests using heated instead of cooled electrodes are described as well as other tests that lead to the present design. The results of tests with the heated electrode show the kind of improvements in performance that can be obtained when resistivity is controlled in only a small collection area. 相似文献
418.
George F. Antonious Zachary M. Ray Louie Rivers Jr 《Journal of environmental science and health. Part. B》2013,48(1):9-14
Dimethoate [O, O-dimethyl-S-(N-methylcarbamoyl-methyl) phosphorodithioate] is a broad-spectrum systemic insecticide currently used worldwide and on many vegetables in Kentucky. Dimethoate is a hydrophilic compound (log KOW = 0.7) and has the potential of offsite movement from the application site into runoff and infiltration water. The dissipation patterns of dimethoate residues were studied on spring broccoli leaves and heads under field conditions. Following foliar application of Dimethoate 4E on broccoli foliage at the rate of 0.47 L acre?1, dimethoate residues were monitored in soil, runoff water collected down the land slope, and in infiltration water collected from the vadose zone. The study was conducted on a Lowell silty loam soil (pH 6.9) planted with broccoli under three soil management practices: (i) soil mixed with municipal sewage sludge, (ii) soil mixed with yard waste compost, and (iii) no-mulch rototilled bare soil. The main objective of this investigation was to study the effect of mixing native soil with municipal sewage sludge or yard waste compost, having considerable amounts of organic matter, on off-site movement of dimethoate residues into runoff and infiltration water following spring rainfall. The initial deposits of dimethoate were 6.2 and 21.4 μ g g?1 on broccoli heads and leaves, respectively. These residues dissipated rapidly and fell below the maximum residue limit of 2 μ g g?1 on the heads and leaves after 10 and 14 d, respectively, with half-lives of 5.7 d on broccoli heads and 3.9 d on the leaves. Dimethoate residues detected in top 15 cm of soil (due to droplet drift and wash off residues from broccoli foliage) one day (d) following spraying, were 30.5 ng g?1 dry soil in the sewage sludge treatment, and 46.1 and 134.5 ng g?1 dry soil in the yard waste and no mulch treatments, respectively. Water infiltration was greater from yard waste compost treatment than from no mulch treatment, however concentrations of dimethoate in the vadose zone of the three soil treatments did not differ. 相似文献
419.
Charles W. Gruber George A. Jutze Norman A. Huey 《Journal of the Air & Waste Management Association (1995)》2013,63(4):327-330
Abstract An airborne lidar was used to study the smoke plume from the burning of a controlled oil spill on the ocean. The ratio of the amount of light (at a wavelength, λ, of 0.532 u.m) backscattered by the smoke to the amount of light extinguished by the smoke was determined by measuring the strength of a laser beam after it had passed through the smoke plume, been reflected from the ocean, and passed through the smoke plume again, and comparing this to the strength of the laser beam reflected directly from the ocean. The optical depth of the smoke (at λ = 0.532 µm) was typically between 0.2 and 0.5. The mass fluxes of smoke particles that passed through four vertical cross sections of the (nonsteady state) smoke plume were estimated from lidar measurements to be 142, 175, 423, and 414 g s-1, compared to an average smoke mass production rate of ~770 g s-1. The spatial distribution of smoke mass along the long axis of the plume was also estimated from the lidar measurements; derived smoke mass concentrations were generally <300 µg m-3, with a few isolated values up to ~800 µg m-3. 相似文献
420.