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1.
An overview of the role of NO x in the formation of rural O3, regional transport and its potential impact on urban air quality is presented. An analysis of a specific O3 excursion in southeast Michigan (8-2-90) is performed based on a combined urban and regional-scale model. The regional component of the model represents transport and photochemistry from sources as far away as Texas. Results suggest that rural O3 and regional transport sensitive to NO x emissions and relatively insensitive to changes in volatile organic carbon (VOC) emissions. This differs from the situation in urban areas, where O3 is sensitive to both NO x and VOC. Regional transport and upwind NO x emissions have a significant impact on peak O3 in Detroit. Implications for urban and regional-scale abatement strategies are discussed.  相似文献   

2.
The primary object of this paper is to provide a preliminary assessment of the effectiveness of NO x vs Volatile Organic Compounds (VOC) emissions control options in improving O3 air quality over the New York metropolitan area. To this end, we have applied the Urban Airshed Model (UAM) with the Carbon Bond IV (CB-IV) chemical mechanism utilizing the results of the Regional Oxidant Model (ROM) for the specification of initial/boundary concentrations and wind fields to the UAM. After examining the sensitivity of the predicted O3 concentrations to initial/boundary conditions and biogenic emissions, we have evaluated the impact of various hypothetical emissions reduction options on O3 air quality. Nested ROM/UAM simulations with an across-the-board reduction of 75% in the NO x and VOC emissions from sources located within the New York metropolitan area indicate that the option of VOC-only control is superior to the NO x -only control in reducing not only peak O3 levels over the entire modeling domain but also population exposure to unhealthy O3 levels. The model predicts that the combined 75% NO x and VOC control option also reduces the peak O3 concentration, but the improvement in O3 air quality is less than that predicted for the 75% VOC-only control strategy. Additional modeling analyses with different mix and levels of emissions control and meteorological conditions are needed to confirm these preliminary findings.  相似文献   

3.
Regional oxidant distributions produced under various atmospheric conditions and emission scenarios are investigated using the Regional Acid Deposition Model (RADM). RADM is a complex, evolving three-dimensional Eulerian model that describes the chemistry, transport and deposition of tropospheric trace species including SO2, sulfate, NO x and volatile organic compounds as well as O3, other major oxidants and acids. The model calculates the short-term temporal evolution of atmospheric trace gas concentrations and their deposition on the regional scale. This study is focused on oxidant production in the eastern United States and southeastern Canada. The influence of atmospheric conditions is explored by comparing three characteristic winter, summer and spring/fall cases. Base-case 1985 emissions of SO x , NO x , volatile organic compounds (VOCs), NH3 and CO are specified using the comprehensive pollutant emissions inventory developed as part of the National Acid Precipitation Assessment Program (NAPAP). The perturbed case, which represents projected anthropogenic emission changes for 2010, indicates changes in daily total 80 km grid average NO x emissions ranging from increases of 75% to decreases of 45% and VOC emission changes ranging from increases of 65% to decreases of 20%. The largest NO x emission changes occur in the northeast, and the largest VOC changes occur in the Gulf Coast area. Ground level grid average midday O3 concentrations for the 1985 emission cases are highest (on the order of 70 to 100 ppb) in the New York City and Houston metropolitan areas for the summer and spring cases; the summer case also indicates relatively high grid average O3 concentrations of greater than 80 ppb in the southeast. Winter case values are much lower than summer O3 values throughout the region, with highs of 40 to 50 ppb occurring in the southeast and the Great Lakes area. Changes in NO x and other emissions under the complex 2010 emissions scenario for the summer case result in maximum O3 concentration reductions of 10% in the Houston area and increases in O3 of a few percent in some rural areas of the southeast. This study underscores the need for more comprehensive assessment of the complex relationships among regional emission changes, oxidant production and atmospheric conditions.  相似文献   

4.
Hourly ozone, NO x and VOC concentrations, measured during 2001–2003 summer periods, are analyzed in order to examine the interaction patterns between the major photochemical pollutants in ?stanbul. 34 high ozone days throughout the summer periods of the three years are determined and examined in the study together with the meteorological parameters like temperature, wind and vertical structure of the atmosphere. The results show that high levels of ozone are observed mostly under anticyclonic conditions with relatively low wind speeds. High ozone days generally experienced maximum concentrations at afternoon hours and minimum concentrations are reached at rush hours due to NO x – titration by traffic emissions. High negative correlations with NO x up to -0.84 are observed at the Saraçhane station while higher correlations for VOC species, up to ?0.75, are calculated for Kadiköy station. Some individual episodes experiencing high ozone concentrations up to 310 μg m?3 in the early morning hours are also studied. It is found that decreasing inversion heights in the early hours of the day led to suppression of pollutants close to surface and thus, an increase in ozone concentrations was observed. Low wind speeds played a major role in the increase of pollution levels in the region. HYSPLIT model is applied to some particular episodes and the results show that the northeasterly transport to the region was dominant, especially in the early-morning maximums.  相似文献   

5.
Epidemiology studies relating health effects to ambient levels of ozone and fine particles have led to the modification of standards in the United States for these pollutants (substitution of an 8-h standard for ozone at 80 ppbv, and addition of 24-h and annual standards for fine particles). The interrelationships of these pollutants in the atmosphere suggest the need for an integrated, science-based strategy for their control. Secondary ozone formation has been controlled through emission controls on VOC and NOx precursors. Fine particles are secondary products largely resulting from the oxidation of precursors (SO2, NOx, and VOCs). The key intermediates in both types of secondary process are free radical species and the photochemically labile compounds that produce them in the atmosphere. However, due to the complex and nonlinear nature of the processes, reductions in precursors may lead to unexpected changes in ozone and fine particle formation rates. For example, reduction in NOx emissions may reduce ozone and nitric acid levels, but lead also to increased rates of sulfate formation in clouds and increased ammonia availability for neutralization of acidic sulfate aerosols. Reductions of SO2 may reduce aerosol sulfate levels in the summer, but have no effect in other seasons. Reductions in VOCs may reduce ozone levels in urban core areas, but not elsewhere. An integrated, regionally and seasonally specific, emission reduction strategy is needed to cost-effectively reduce both ozone and fine particle levels.  相似文献   

6.
In the present study, a three-dimensional Eulerian photochemical model was employed to estimate the impact that organic compounds have on tropospheric ozone formation in the Metropolitan Area of São Paulo (MASP). In the year 2000, base case simulations were conducted in two periods: August 22–24 and March 13–15. Based on the pollutant concentrations calculated by the model, the correlation coefficient relative to observations for ozone ranged from 0.91 to 0.93 in both periods. In the simulations employed to evaluate the ozone potential of individual VOCs, as well as the sensitivity of ozone to the VOC/NO x emission ratio, the variation in anthropogenic emissions was estimated at 15% (according to tests performed previously variations of 15% were stable). Although there were significant differences between the two periods, ozone concentrations were found to be much more sensitive to VOCs than to NO x in both periods and throughout the study domain. In addition, considering their individual rates of emission from vehicles, the species/classes that were most important for ozone formation were as follows: aromatics with a kOH?>?2?×?104 ppm?1 min?1; olefins with a kOH?<?7?×?104 ppm?1 min?1; olefins with a kOH?>?7?×?104 ppm?1 min?1; ethene; and formaldehyde, which are the principal species related to the production, transport, storage and combustion of fossil fuels.  相似文献   

7.
This investigation was conducted to compare the relative benefits of controlling emissions of VOC vs. NOx for reducing tropospheric O3 (smog) concentrations in the Northeast United States. Because of the nonlinear nature of O3 photochemistry, controls on NOx emissions could actually result in increases in O3 depending on the relative amount of VOC present and meteorological conditions. The Regional Oxidant Model (ROM) was used as the tool for estimating the impacts of different VOC and NO3 strategies. Scenarios simulated include a future baseline and separate strategies with controls on just NO, just VOC, and a combination of VOC and NOx controls. The results indicate that in general, NOx controls are more beneficial across the region than VOC controls. However, for several large urban areas, NOx controls were predicted to result in higher O3 than VOC controls. Also, the relative benefits of VOC and NOx controls varied from day-to-day suggesting a dependency on meteorological conditions. Given the variable nature of the effects of NOx controls, additional modeling using more spatially resolved models is warranted to identify specific strategies for attainment of the ozone NAAQS in individual areas.  相似文献   

8.
The monitoring programs needed to design control strategies differ from those required to assess the impact of the strategies on air quality. The former are short-term and intensive. They are designed to obtain the data required to apply an urban-scale grid model, like the Urban Airshed Model, or a combination of an urban-scale and regional-scale model, like the Regional Oxidant Model, to an area without having to assume important input data. Such measurements include three-dimensional pollutant and meteorological measurements throughout the modeling domain. Detailed and accurate emissions inventories are also required. Model validation should compare not only the O3 predictions with actual data, but also include comparisons for NO x , individual volatile organic compounds (VOC), and if possible, additional species such as PAN, H2O2, formaldehyde, and HNO3. To assess the impact of control strategies, long-term monitoring networks that measure O3, NO x and speciated VOC are needed. O3 trends should be examined using robust, meteorologically-adjusted O3 statistics. Such statistics need to be related to a robust National Ambient Air Quality Standard.  相似文献   

9.
This paper documents the evolution of Environmental Protection Agency (EPA) policy concerning the relative roles that volatile organic compounds (VOCs) and oxides of nitrogen (NOx) emissions play in ozone nonattainment planning for State implementation plans (SIPs). It further discusses possible new control requirements, including NOx measures, that may be required as a result of pending Clean Air Act Amendments. In the early 1970's EPA guidance emphasized the use of VOC control measures to attain the ozone (formerly oxidant) ambient air quality standard. Little if any, control requirements applied to NOx emissions. EPA continued to focus guidance requirements upon the control of VOCs during the planning efforts associated with the 1977 Clean Air Act amendments... 1979 SIPs, 1982 plans for long-term problem areas (extension areas), and other revisions to SIPs. Preliminary air quality modeling work to support these later planning efforts revealed that, in certain cases, there were potential benefits of NOx control in addition to VOC. With this new insight, EPA's post-1987 policy proposal required states to look at the potential benefits of NOx controls in areas with a nonmethane organic compound to NOx ratio of 10∶1 or greater. In Clean Air Act Amendments currently being debated in the House and Senate, there is an uncertainty with regard to the role of NOx controls. Possibilities under consideration range from the application of reasonably available control technology for 100 ton sources of NOx to a clean fuel motor vehicle program within 42 months of enactment.  相似文献   

10.
This paper discusses trends and uncertainties in the anthropogenic emission inventory for VOC. EPA's trend analysis indicates that emissions increased almost across the board until about 1970. After 1970, emissions continued to increase for industrial solvents, but declined for transportation, nonindustrial solvents, and combustion and waste disposal. With the current emphasis on using grid models to define NOx and VOC control strategies, the uncertainty of emission inventories is becoming increasingly important. However, the volume of data in an emissions inventory makes the detailed assessment of uncertainty difficult if not impossible.  相似文献   

11.
Impacts of air pollutants and especially acidification in ecosystems have been of serious concern in the Nordic countries since the 1970s. The current approach to assess several pollutants (sulfur and nitrogen oxides, ammonia, volatile organic compounds) and their effects (acidification, eutrophication and ground-level ozone) simultaneously is extremely complex. This study explored the relative role of nitrogen oxides in environmental impacts in the Nordic countries. The share of NOx in the exceedances of critical loads, the long-term ecosystem protection targets, was found to be roughly 25% in acidification and 50% in eutrophication. The contribution of NOx emissions to ground-level ozone formation was considered important, as NOx is the limiting precursor in ozone formation in the Nordic countries. The comparison of observed and modeled accumulated ozone concentrations (AOT40) for the early 1990s shows noticeable differences in the Nordic area, partly due to the sensitivity of the AOT40 indicator to the 40 ppb threshold value.  相似文献   

12.
We explore the ability of a process-based space–time model to decompose 8-hour ozone on a given day and site into parts attributable to local emissions and regional transport, to provide space–time predictions, and to assess the efficacy of past and future emission controls. We model ozone as created plus transported plus an error with seasonally varying spatial covariance parameters. Created ozone is a function of the observed NO x concentration, the latent VOC concentration, and solar radiation surrogates. Transported ozone is a weighted average of the ozone observed at all sites on the previous day, where the weights are a function of wind speed and direction. The latent VOC process mean includes emissions, temperature, and a workday indicator, and the error has seasonally varying spatial covariance parameters. Using likelihood methods, we fit the model and obtain one set of predictions appropriate for prediction backward in time, and another appropriate for predicting under hypothetical emission scenarios. The first set of predictions has a lower root-mean-squared error (RMSE) when compared to point observations than do the 36 km gridcell averages from the Community Mesoscale Air Quality Model (CMAQ) used by the EPA; the second set has the same RMSE as CMAQ, but under-predicts high ozone values.  相似文献   

13.
Acidifying emissions from energy production and industry have decreased considerably during the last two decades in Finland. Especially the emissions of sulphur dioxide have dropped sharply with 85% in 1980–1998, although the energy use has increased 30% during the same period. The reduction has occurred through two mechanisms: by replacing the combustion of heavy fuel oil with cleaner energy carriers, and by direct emission reduction controls, e.g. flue gas desulphurization. In this study the Finnish cost curves for SO2 and NOx were first calculated to produce a consistent comprehensive view on further emission reduction costs and potentials. The data on technical and cost-related parameters were based on actual national experiences from power plants and industry. Most of the cost-efficient sulphur emission controls were already in use. For NOx, a large share of further reduction potential still remained. Second, a case on the emission reductions and costs for fuel switching in a 205 MWth peat power plant of Tampere Power Utility in Finland was studied. Fuel switching to natural gas was found less cost-efficient in SO2 and NOx emission reduction when compared to flue gas cleaning techniques. The findings provided new information on fuel switching as an alternative potential reduction measure, which is not considered in international assessments.  相似文献   

14.
Klimont  Z.  Cofala  J.  Schöpp  W.  Amann  M.  Streets  D.G.  Ichikawa  Y.  Fujita  S. 《Water, air, and soil pollution》2001,130(1-4):193-198
Starting from an inventory of SO2, NOx, VOC and NH3 emissions for the years 1990 and 1995 in East Asia (Japan, South and North Korea, China, Mongolia and Taiwan), the temporal development of the emissions of the four air pollutants is projected to the year 2030 based on scenarios of economic development. The projections are prepared at a regional level (prefectures or provinces of individual countries) and distinguish more than 100 source categories for each region. The emission estimates are presented with a spatial resolution of 1×1 degree longitude/latitude. First results suggest that, due to the emission control legislation taken in the region, SO2 emissions would only grow by about 46 percent until 2030. Emissions of NOx and VOC may increase by 95 and 65 percent, respectively, mainly driven by the expected increase in road traffic volume. Ammonia, mainly emitted from agriculture, is projected to double by 2030.  相似文献   

15.
Primary particulate matter is emitted directly into the atmosphere from various anthropogenic and natural sources such as power plants (combustion of fossil fuels) or forest fires. Secondary particles are formed by transformation of SO2, NOx, NH3, and VOC in the atmosphere. They both contribute to ambient particulate matter concentrations, which may have adverse effects on human health. Health hazards are caused by small particulate size, high number of especially fine (< 2.5 µm) and ultra-fine (< 0.1 µm) particles and/or their chemical composition. As part of an integrated assessment model developed at IIASA, a module on primary particulate matter (PM) emissions has been added to the existing SO2, NOx, NH3 and VOC sections. The module considers so far primary emissions of total suspended particles (TSP), PM10 and PM2.5 from aggregated stationary and mobile sources. A primary PM emission database has been established. Country specific emission factors for stationary sources have been calculated within the module using the ash content of solid fuels.  相似文献   

16.
Woo  J.-H.  Baek  J. M.  Kim  J.-W.  Carmichael  G. R.  Thongboonchoo  N.  Kim  S. T.  An  J. H. 《Water, air, and soil pollution》2003,148(1-4):259-278
Emissions in East Asia for 1993 by administrative units and source types are estimated to support regional emission assessments and transport modeling studies. Total emission of SOx, NOx, soil NOx, N2O, and NH3 are 24 150, 12 610, 1963, 908, and 8263 kton yr-1, respectively.China's emission contribution is the highest for every species.The area sources are the most significant source type for SOx and NOx, but the fraction due to mobile source is highest for NOx. Major LPSs are located from the middle to the east part of China, south and middle-west part of South Korea, and the east part of Japan. The area sources of SOx show a pattern similar to population density, whereas NH3 shows a strong landuse dependency. Detail emissions analysis reveals higher SOx emission `cores' within each province. The estimated emissions are used to estimate sulfur deposition in the regions. The seasonal average sulfur distribution amounts are estimated from the ATMOS2 chemical transport model. The results showed anti-correlation with temperature for sulfur (SO2 + SO4 -2) concentrations and a positive correlation with rainfall for deposition.  相似文献   

17.
This paper describes a computational system developed for the compilation of an anthropogenic emission inventory of gaseous pollutants for Greece. The inventory was developed using a geographical information system integrated with SQL programming language to provide high temporal gridded emission fields for CO, NO2, NO, SO2, NH3 and 23 non-methane volatile organic compounds (NMVOCs) species for the reference year 2003. Activity and statistical data from national sources were used for the quantification of emissions from the road transport, the other mobile sources and machinery sectors and from range activities using top-down or bottom-up methodologies. Annual emission data from existing national and European emission databases were also used. The emission data were spatially and temporally disaggregated using source-specific spatiotemporal indicators. On national scale, the road transport sector produces about 60% of the annual CO and NMVOC total emissions, with gasoline vehicles being the main CO and NMVOC emissions source. The road transport is responsible for approximately half of the higher alkanes and for more than half of the ethene and toluene emissions. The maritime sector accounts for about 40% of the annual total NOx emissions, most of which are emitted by the international shipping subsector, whilst SO2 is emitted mainly by the energy sector. The evaluation of the emissions inventory suggests that it provides a good representation of the amounts of gaseous pollutants emitted on national scale and a good characterisation of the relative composition of CO and NOx emission in the large urban centres.  相似文献   

18.
Ground-level dynamics of O3, NO x and benzene, toluene, ethylbenzene and xylenes were characterised at rural sites in the medium Ebro River Basin (Northern Spain) from April to September (2003–2007) and by means of automated and passive monitoring. The study registered high O3 levels within the area, which were influenced by traffic emissions, and a monthly evolution of these levels consistent with the occurrence of a broad summer maximum, typical of polluted areas. The mean ozone concentration registered in the studied area by means of passive sampling was 87?±?12 μg m?3. The 2008/50/EC objective value for the protection of vegetation was widely exceeded during this study (AOT40?=?57,147?±?14,114 μg m?3 h), suggesting that current ambient levels may pose a risk for crops and vegetation in this important agroindustrial region.  相似文献   

19.
Solberg  S.  Lazaridis  M.  Walker  S.-E.  Knudsen  S.  Semb  A. 《Water, air, and soil pollution》2003,148(1-4):289-321
A photochemical puff-trajectory model (Fotoplume) has been applied to simulate emissions, atmospheric transport and chemical transformations of pollutants from offshore oil and gas production in the North Sea. The above model was used in conjunction with the European Monitoring and Evaluation Programme (EMEP) regional Lagrangian oxidant model. The Fotoplume and EMEP models were used to evaluate the effects of the atmospheric emissions from the oil and gas exploration activity in the Norwegian sector of the North Sea. Deposition of nitrogen and formation of boundary level ozone in Southern Norway due to North Sea emissions of nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOC) have been studied. The petroleum activity in the North Sea is calculated to contribute approximately 20% of the nitrogen deposition in the coastal areas of Norway in 1992. In addition, the models were used to estimate the AOT40 ozone exposure levels. The results indicate that emissions from British and Norwegian oil and gas exploitation sector separately contribute to less than 5% each of the AOT40 values for coniferous forests and meadows. Comparison of model calculations with experimental measurements is quite satisfactory and the models show realistic results for both the nitrogen deposition and AOT40 values.  相似文献   

20.
In the frame of the climatological project REKLIPwhich involves part of Switzerland, Germany and Franceand concerns the upper Rhine valley, an atmosphericemission inventory has been established with a spatialresolution of a square kilometer and a time resolutionup to one hour. Anthropogenic emissions of SO2, NOx,CO, HCl and volatile organic compounds (VOC) divided into thirty compounds or group of compounds as well as biogenic emissions of NMVOC have been taken into account for the year 1990. This inventory has been updated for the following years until 1993 and some hourly emissions inventories have been derived for a period of several days of September 1992,corresponding to a REKLIP intensive measurement campaign.  相似文献   

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