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1.
PM 2.5 sampling was conducted at a curbside location in Delhi city for summer and winter seasons, to evaluate the effect of PM 2.5 and its chemical components on the visibility impairment. The PM 2.5 concentrations were observed to be higher than the National Ambient Air Quality Standards (NAAQS), indicating poor air quality. The chemical constituents of PM 2.5 (the water-soluble ionic species SO 42-, NO 3?, Cl ?, and NH 4+, and carbonaceous species: organic carbon, elemental carbon) were analyzed to study their impact on visibility impairment by reconstructing the light extinction coefficient, b ext. The visibility was found to be negatively correlated with PM 2.5 and its components. The reconstructed b ext showed that organic matter was the largest contributor to b ext in both the seasons which may be attributed to combustion sources. In summer season, it was followed by elemental carbon and ammonium sulfate; however, in winter, major contributions were from ammonium nitrate and elemental carbon. Higher elemental carbon in both seasons may be attributed to traffic sources, while lower concentrations of nitrate during summer, may be attributed to volatility because of higher atmospheric temperatures. Implications: The chemical constituents of PM 2.5 that majorly effect the visibility impairment are organic matter and elemental carbon, both of which are products of combustion processes. Secondary formations that lead to ammonium sulfate and ammonium nitrate production also impair the visibility. 相似文献
2.
ABSTRACT Recent awareness of suspected adverse health effects from ambient particulate matter (PM) emission has prompted publication of new standards for fine PM with aerodynamic diameter less than 2.5 μm (PM 2.5). However, scientific data on fine PM emissions from various point sources and their characteristics are very limited. Source apportionment methods are applied to identify contributions of individual regional sources to tropospheric particulate concentrations. The existing industrial database developed using traditional source measurement techniques provides total emission rates only, with no details on chemical nature or size characteristics of particulates. This database is inadequate, in current form, to address source-receptor relationships. A source dilution system was developed for sampling and characterization of total PM, PM 2.5, and PM 10 (i.e., PM with aerodynamic diameter less than 10 μm) from residual oil and coal combustion. This new system has automatic control capabilities for key parameters, such as relative humidity (RH), temperature, and sample dilution. During optimization of the prototype equipment, three North American coal blends were burned using a 0.7-megawatt thermal (MW t) pulverized coal-fired, pilot-scale boiler. Characteristic emission profiles, including PM 2.5 and total PM soluble acids, and elemental and carbon concentrations for three coal blends are presented. 相似文献
3.
Continuous measurement of PM 10, PM 2.5 and carbon (organic, elemental composition) concentrations, and samples of PM 10 and PM 2.5 collected on a polycarbonate membrane filter (Nuclepore ®, pore size: 0.8 μm), were carried out during a period from December 1998 to January 1999 at Shinjuku in Tokyo in order to investigate the chemical characterization of particles in winter-night smog within a large area of the Japan Kanto Plain including the Tokyo Metropolitan area. These were measured using an ambient particulate monitor (tapered element oscillating microbalance—TEOM) and a carbon particulate monitor. Elemental compositions in the filter samples of PM 10 and PM 2.5 were determined by means of particle-induced X-ray emission (PIXE) analysis. Ionic species (anion: F −, Cl −, NO 3−, SO 42− and C 2O 42−; cation: Na +, NH 4+, K +, Ca 2+ and Mg 2+) in the filter samples were analyzed by ion chromatography. The temporal variation patterns of PM 2.5 were similar to those of PM 10 and carbon. PM 2.5 made up 90% of the PM 10 at a high concentration, and 70% at a low concentration. Concentrations of 22 elements in both the PM 10 and PM 2.5 samples were consistently determined by PIXE, and Na, Mg, Al, Si, S, Cl, K, Ca, Fe, Zn and Pb were found to be the major components. Among these S and Cl were the most dominant elements of the PM 2.5 and PM 10 at high concentrations. Ionic species were mainly composed of Cl −, NO 3−, SO 42− and NH 4+. The component proportion of carbon, the other elements (total amount of measured elements other than S and Cl) and secondary-formed particles of PM 2.5 was similar to that of PM 10. The major component was carbon particles at a low concentration and secondary-formed particles at a high concentration. The proportion of NH 4NO 3 and NH 4Cl plus HCl in secondary-formed particles at a high concentration, in particular, was as high as 90%. 相似文献
4.
Abstract With the recent focus on fine particle matter (PM 2.5),new, self-consistent data are needed to characterize emissions from combustion sources. Such data are necessary for health assessment and air quality modeling. To address this need, emissions data for gas-fired combustors are presented here, using dilution sampling as the reference.The dilution method allows for collection of emitted particles under conditions simulating cooling and dilution during entry from the stack into the air. The sampling and analysis of the collected particles in the presence of precursor gases, SO 2, nitrogen oxide, volatile organic compound, and NH 3 is discussed; the results include data from eight gas fired units, including a dual-fuel institutional boiler and a diesel engine powered electricity generator. These data are compared with results in the literature for heavy-duty diesel vehicles and stationary sources using coal or wood as fuels. The results show that the gas-fired combustors have very low PM 2.5 mass emission rates in the range of ~10 -4 lb/million Btu (MMBTU) compared with the diesel backup generator with particle filter, with ~5 × 10 -3 lb/MMBTU. Even higher mass emission rates are found in coal-fired systems, with rates of ~0.07 lb/MMBTU for a bag-filter-controlled pilot unit burning eastern bituminous coal. The characterization of PM 2.5 chemical composition from the gas-fired units indicates that much of the measured primary particle mass in PM 2.5 samples is organic or elemental carbon and, to a much less extent, sulfate. Metal emissions are quite low compared with the diesel engines and the coal- or woodfueled combustors. The metals found in the gas-fired combustor particles are low in concentration, similar in concentration to ambient particles. The interpretation of the particulate carbon emissions is complicated by the fact that an approximately equal amount of particulate carbon (mainly organic carbon) is found on the particle collector and a backup filter. It is likely that measurement artifacts, mostly adsorption of volatile organic compounds on quartz filters, are positively biasing “true” particulate carbon emission results. 相似文献
5.
Atmospheric particles are a major problem that could lead to harmful effects on human health, especially in densely populated urban areas. Chiayi is a typical city with very high population and traffic density, as well as being located at the downwind side of several pollution sources. Multiple contributors for PM 2.5 (particulate matter with an aerodynamic diameter ≥2.5 μm) and ultrafine particles cause complicated air quality problems. This study focused on the inhibition of local emission sources by restricting the idling vehicles around a school area and evaluating the changes in surrounding atmospheric PM conditions. Two stationary sites were monitored, including a background site on the upwind side of the school and a campus site inside the school, to monitor the exposure level, before and after the idling prohibition. In the base condition, the PM 2.5 mass concentrations were found to increase 15% from the background, whereas the nitrate (NO 3?) content had a significant increase at the campus site. The anthropogenic metal contents in PM 2.5 were higher at the campus site than the background site. Mobile emissions were found to be the most likely contributor to the school hot spot area by chemical mass balance modeling (CMB8.2). On the other hand, the PM 2.5 in the school campus fell to only 2% after idling vehicle control, when the mobile source contribution reduced from 42.8% to 36.7%. The mobile monitoring also showed significant reductions in atmospheric PM 2.5, PM 0.1, polycyclic aromatic hydrocarbons (PAHs), and black carbon (BC) levels by 16.5%, 33.3%, 48.0%, and 11.5%, respectively. Consequently, the restriction of local idling emission was proven to significantly reduce PM and harmful pollutants in the hot spots around the school environment. Implications: The emission of idling vehicles strongly affects the levels of particles and relative pollutants in near-ground air around a school area. The PM 2.5 mass concentration at a campus site increased from the background site by 15%, whereas NO 3? and anthropogenic metals also significantly increased. Meanwhile, the PM 2.5 contribution from mobile source in the campus increased 6.6% from the upwind site. An idling prohibition took place and showed impressive results. Reductions of PM 2.5, ionic component, and non-natural metal contents were found after the idling prohibition. The mobile monitoring also pointed out a significant improvement with the spatial analysis of PM 2.5, PM 0.1, PAH, and black carbon concentrations. These findings are very useful to effectively improve the local air quality of a densely city during the rush hour. 相似文献
6.
Ambient suspended particulate (PM 2.5, PM 2.5–10, TSP) was collected from June 1998 to February 2001 in Taichung, central Taiwan. In addition, the related water-soluble ionic species (Cl −, NO 3−, SO 42−, Na +, NH 4+, K +, Mg 2+, Ca 2+) and metallic species (Fe, Zn, Pb, Ni) were also analyzed in this study. The results showed that the concentrations of particulate mass are higher in the traffic site (CCRT) than the other sampling sites in this study. Also, the fine particle (PM 2.5) concentration is the dominant species of the total suspended particles in Taichung, central Taiwan. The dominant species for PM 2.5 are sulfate and ammonium at all sampling sites during the period of 1998–2001. The results of diurnal variation at THUC sampling site are also discussed in this study. Overall, acidic and secondary aerosol (Cl −, NO 3−, SO 42− and NH 4+) is a more serious air pollutant issue in southern and central Taiwan than at several sites around the world. Therefore, ambient suspended particulate monitoring in Taichung, central Taiwan will be continuing in our following study to provide more information for the government to formulate environmental strategy. 相似文献
7.
Particulate matter, including coarse particles (PM 2.5–10, aerodynamic diameter of particle between 2.5 and 10 μm) and fine particles (PM 2.5, aerodynamic diameter of particle lower than 2.5 μm) and their compositions, including elemental carbon, organic carbon, and 11 water-soluble ionic species, and elements, were measured in a tunnel study. A comparison of the six-hour average of light-duty vehicle (LDV) flow of the two sampling periods showed that the peak hours over the weekend were higher than those on weekdays. However, the flow of heavy-duty vehicles (HDVs) on the weekdays was significant higher than that during the weekend in this study. EC and OC content were 49% for PM 2.5–10 and 47% for PM 2.5 in the tunnel center. EC content was higher than OC content in PM 2.5–10, but EC was about 2.3 times OC for PM 2.5. Sulfate, nitrate, ammonium were the main species for PM 2.5–10 and PM 2.5. The element contents of Na, Al, Ca, Fe and K were over 0.8 μg m ?3 in PM 2.5–10 and PM 2.5. In addition, the concentrations of S, Ba, Pb, and Zn were higher than 0.1 μg m ?3 for PM 2.5–10 and PM 2.5. The emission factors of PM 2.5–10 and PM 2.5 were 18 ± 6.5 and 39 ± 11 mg km ?1-vehicle, respectively. The emission factors of EC/OC were 3.6/2.7 mg km ?1-vehicle for PM 2.5–10 and 15/4.7 mg km ?1-vehicle for PM 2.5 Furthermore, the emission factors of water-soluble ions were 0.028(Mg 2+)–0.81(SO 42?) and 0.027(NO 2?)–0.97(SO 42?) mg km ?1-vehicle for PM 2.5–10 and PM 2.5, respectively. Elemental emission factors were 0.003(V)–1.6(Fe) and 0.001(Cd)–1.05(Na) mg km ?1-vehicle for PM 2.5–10 and PM 2.5, respectively. 相似文献
8.
AbstractTo determine the sources of particulate matter less than 2.5?μm (PM 2.5 in different ambient atmospheres (urban, roadside, industrial, and rural sites), the chemical components of PM 2.5 such as ions (Cl -, NO 3-, SO 42-, NH 4+, Na +, K +, Ca 2+, and Mg 2+), carbonaceous species, and elements (Al, As, Ba, Cd, Cu, Fe, Mn, Ni, Pb, Se, V, and Zn) were measured. The average mass concentrations of PM 2.5 at the urban, roadside, industrial, and rural sites were 31.5?±?14.8, 31.6?±?22.3, 31.4?±?16.0, and 25.8?±?12.4?μg/m 3, respectively. Except for secondary ammonium sulfate and ammonium nitrate, the model results showed that the traffic source (i.e., the sum of gasoline and diesel vehicle sources) was the most dominant source of PM 2.5 (17.1%) followed by biomass burning (13.8%) at the urban site. The major primary sources of PM 2.5 were consistent with the site characteristics (diesel vehicle source at the roadside site, coal-fired plants at the industrial site, and biomass burning at the rural site). Seasonal data from the urban site suggested that ammonium sulfate and ammonium nitrate were the most dominant sources of PM 2.5 during all seasons. Further, the contribution of road dust source to PM 2.5 increased during spring and fall seasons. We conclude that the determination of the major PM 2.5 sources is useful for establishing efficient control strategies for PM 2.5 in different regions and seasons. 相似文献
9.
In order to investigate the chemical characteristics of atmospheric aerosol measured during a severe winter haze event, 12-hr PM 2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) samples were collected at an urban site in Ulaanbaatar, Mongolia, from January 9 to February 17, 2008. On average, 12-hr PM 2.5 mass concentration was 105.1 ± 34.9 μg/m 3. Low PM 2.5 mass concentrations were measured when low pressure developed over central Mongolia. The 12-hr average organic mass by carbon (OMC) varied from 6.4 to 132.3 μg/m 3, with a mean of 54.9 ± 25.4 μg/m 3, whereas elemental carbon (EC) concentration ranged from 0.1 to 3.6 μgC/m 3, with a mean of 1.5 ± 0.8 μgC/m 3. Ammonium sulfate was found to be the most abundant water-soluble ionic component in Ulaanbaatar during the sampling period, with an average concentration of 11.3 ± 5.0 μg/m 3. In order to characterize the effect of air mass pathway on fine particulate matter characteristics, 5-day back-trajectory analysis was conducted, using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The haze level was classified into three categories, based on the 5-day air mass back trajectories, as Stagnant (ST), Continental (CT), and Low Pressure (LP) cases. PM 2.5 mass concentration during the Stagnant condition was approximately 2.5 times higher than that during the Low Pressure condition, mainly due to increased pollutant concentration of OMC and secondary ammonium sulfate. Implications: Mongolia is experiencing rapid rates of urbanization similar to other Asian countries, resulting in air pollution problems by the growing number of automobiles and industrialization. Ulaanbaatar, capital of Mongolia, is inherently vulnerable to air pollution because of its emission sources, topography, and meteorological characteristics. Very limited measurements on chemical characteristics of particulate matter have been carried out in Ulaanbaatar, Mongolia. 相似文献
10.
The present study investigated the comprehensive chemical composition [organic carbon (OC), elemental carbon (EC), water-soluble inorganic ionic components (WSICs), and major & trace elements] of particulate matter (PM 2.5) and scrutinized their emission sources for urban region of Delhi. The 135 PM 2.5 samples were collected from January 2013 to December 2014 and analyzed for chemical constituents for source apportionment study. The average concentration of PM 2.5 was recorded as 121.9 ± 93.2 μg m ?3 (range 25.1–429.8 μg m ?3), whereas the total concentration of trace elements (Na, Ca, Mg, Al, S, Cl, K, Cr, Si, Ti, As, Br, Pb, Fe, Zn, and Mn) was accounted for ~17% of PM 2.5. Strong seasonal variation was observed in PM 2.5 mass concentration and its chemical composition with maxima during winter and minima during monsoon seasons. The chemical composition of the PM 2.5 was reconstructed using IMPROVE equation, which was observed to be in good agreement with the gravimetric mass. Source apportionment of PM 2.5 was carried out using the following three different receptor models: principal component analysis with absolute principal component scores (PCA/APCS), which identified five major sources; UNMIX which identified four major sources; and positive matrix factorization (PMF), which explored seven major sources. The applied models were able to identify the major sources contributing to the PM 2.5 and re-confirmed that secondary aerosols (SAs), soil/road dust (SD), vehicular emissions (VEs), biomass burning (BB), fossil fuel combustion (FFC), and industrial emission (IE) were dominant contributors to PM 2.5 in Delhi. The influences of local and regional sources were also explored using 5-day backward air mass trajectory analysis, cluster analysis, and potential source contribution function (PSCF). Cluster and PSCF results indicated that local as well as long-transported PM 2.5 from the north-west India and Pakistan were mostly pertinent. 相似文献
11.
The ambient air of the Monterrey Metropolitan Area (MMA) in Mexico frequently exhibits high levels of PM 10 and PM 2.5. However, no information exists on the chemical composition of coarse particles (PM c = PM 10 – PM 2.5). A monitoring campaign was conducted during the summer of 2015, during which 24-hr average PM 10 and PM 2.5 samples were collected using high-volume filter-based instruments to chemically characterize the fine and coarse fractions of the PM. The collected samples were analyzed for anions (Cl –, NO 3–, SO 42–), cations (Na +, NH 4+, K +), organic carbon (OC), elemental carbon (EC), and 35 trace elements (Al to Pb). During the campaign, the average PM 2.5 concentrations did not showed significance differences among sampling sites, whereas the average PM c concentrations did. In addition, the PM c accounted for 75% to 90% of the PM 10 across the MMA. The average contribution of the main chemical species to the total mass indicated that geological material including Ca, Fe, Si, and Al (45%) and sulfates (11%) were the principal components of PM c, whereas sulfates (54%) and organic matter (30%) were the principal components of PM 2.5. The OC-to-EC ratio for PM c ranged from 4.4 to 13, whereas that for PM 2.5 ranged from 3.97 to 6.08. The estimated contribution of Secondary Organic Aerosol (SOA) to the total mass of organic aerosol in PM 2.5 was estimated to be around 70–80%; for PM c, the contribution was lower (20–50%). The enrichment factors (EF) for most of the trace elements exhibited high values for PM 2.5 (EF: 10–1000) and low values for PM c (EF: 1–10). Given the high contribution of crustal elements and the high values of EFs, PM c is heavily influenced by soil resuspension and PM 2.5 by anthropogenic sources. Finally, the airborne particles found in the eastern region of the MMA were chemically distinguishable from those in its western region. Implications: Concentration and chemical composition patterns of fine and coarse particles can vary significantly across the MMA. Public policy solutions have to be built based on these observations. There is clear evidence that the spatial variations in the MMA’s coarse fractions are influenced by clearly recognizable primary emission sources, while fine particles exhibit a homogeneous concentration field and a clear spatial pattern of increasing secondary contributions. Important reductions in the coarse fraction can come from primary particles’ emission controls; for fine particles, control of gaseous precursors—particularly sulfur-containing species and organic compounds—should be considered. 相似文献
12.
Biomass burning is a common agricultural practice, because it allows elimination of postharvesting residues; nevertheless, it involves an inefficient combustion process that generates atmospheric pollutants emission, which has implications on health and climate change. This work focuses on the estimation of emission factors (EFs) of PM 2.5, PM 10, organic carbon (OC), elemental carbon (EC), carbon monoxide (CO), carbon dioxide (CO 2), and methane (CH 4) of residues from burning alfalfa, barley, beans, cotton, maize, rice, sorghum, and wheat in Mexico. Chemical characteristics of the residues were determined to establish their relationship with EFs, as well as with the modified combustion efficiency (MCE). Essays were carried out in an open combustion chamber with isokinetic sampling, following modified EPA 201-A method. EFs did not present statistical differences among different varieties of the same crop, but were statistically different among different crops, showing that generic values of EFs for all the agricultural residues can introduce significant uncertainties when used for climatic and atmospheric pollutant inventories. EFs of PM 2.5 ranged from 1.19 to 11.30 g kg ?1, and of PM 10 from 1.77 to 21.56 g kg ?1. EFs of EC correlated with lignin content, whereas EFs of OC correlated inversely with carbon content. EFs of EC and OC in PM 2.5 ranged from 0.15 to 0.41 g kg ?1 and from 0.33 to 5.29 g kg ?1, respectively, and in PM 10, from 0.17 to 0.43 g kg ?1 and from 0.54 to 11.06 g kg ?1. CO 2 represented the largest gaseous emissions volume with 1053.35–1850.82 g kg ?1, whereas the lowest was CH 4 with 1.61–5.59 g kg ?1. CO ranged from 28.85 to 155.71 g kg ?1, correlating inversely with carbon content and MCE. EFs were used to calculate emissions from eight agricultural residues burning in the country during 2016, to know the potential mitigation of climatic and atmospheric pollutants, provided this practice was banned. Implications: The emission factors of particles, short-lived climatic pollutants, and atmospheric pollutants from the crop residues burning of eight agricultural wastes crops, determined in this study using a standardized method, provides better knowledge of the emissions of those species in Latin America and other developing countries, and can be used as inputs in air quality models and climatic studies. The EFs will allow the development of more accurate inventories of aerosols and gaseous pollutants, which will lead to the design of effective mitigation strategies and planning processes for sustainable agriculture. 相似文献
13.
Animal feeding operations (AFOs) produce particulate matter (PM) and gaseous pollutants. Investigation of the chemical composition of PM 2.5 inside and in the local vicinity of AFOs can help to understand the impact of the AFO emissions on ambient secondary PM formation. This study was conducted on a commercial egg production farm in North Carolina. Samples of PM 2.5 were collected from five stations, with one located in an egg production house and the other four located in the vicinity of the farm along four wind directions. The major ions of NH 4+, Na +, K +, SO 42?, Cl ?, and NO 3? were analyzed using ion chromatography (IC). In the house, the mostly abundant ions were SO 42?, Cl ?, and K +. At ambient stations, SO 42?, and NH 4+ were the two most abundant ions. In the house, NH 4+, SO 42?, and NO 3? accounted for only 10% of the PM 2.5 mass; at ambient locations, NH 4+, SO 42?, and NO 3? accounted for 36–41% of the PM 2.5 mass. In the house, NH 4+ had small seasonal variations indicating that gas-phase NH 3 was not the only major force driving its gas–particle partitioning. At the ambient stations, NH 4+ had the highest concentrations in summer. In the house, K +, Na +, and Cl ? were highly correlated with each other. In ambient locations, SO 42? and NH 4+ had a strong correlation, whereas in the house, SO 42? and NH 4+ had a very weak correlation. Ambient temperature and solar radiation were positively correlated with NH 4+ and SO 42?. This study suggests that secondary PM formation inside the animal house was not an important source of PM 2.5. In the vicinity, NH 3 emissions had greater impact on PM 2.5 formation. ImplicationsThe chemical composition of PM 2.5 inside and in the local vicinity of AFOs showed the impact of the AFO emissions on ambient secondary PM 2.5 formation, and the fate and transport of air pollutants associated with AFOs. The results may help to manage in-house animal facility air quality, and to develop regional air quality control strategies and policies, especially in animal agriculture-concentrated areas. 相似文献
14.
This research was executed between March 2009 and March 2010 to monitor particulate matter size distribution and its composition in Istanbul. Particulate matter composition was determined using ion chromatography and inductively coupled plasma optical emission spectrometry. The sampling point is adjacent to a crowded road and the Bosporus Strait. Two prevailing particulate modes are found throughout PM 10 by sampling with a nine-stage low-volume cascade impactor. First mode in the fine mode is found to be between 0.43 and 0.65 μm, whereas the other peak was observed between 3.3 and 4.7 μm, referring to the coarse mode. The mean PM 10 concentration was determined as 41.2 μg/m 3, with a standard deviation of 16.92 μg/m 3. PM 0.43 had the highest mean concentration value of 10.67 μg/m 3, making up nearly one fourth of the total PM 10 mass. For determining the effect of traffic on particulate matter (PM) composition and distribution, four different sampling cycles were applied: entire day, nighttime, rush hour, and rush hour at weekdays. SO 4 ?2 and organic carbon/elemental carbon proportions are found to be lower in night samples, representing a decrease in traffic. The long-range transports of dust storms were observed during the sampling periods. Their effects were determined analytically and their route models were run by the HYSPLIT model and validated through satellite photographs taken by the NASA Earth Observatory. 相似文献
15.
Representative profiles for particulate matter particles less than or equal to 2.5 µm (PM 2.5) are developed from the Kansas City Light-Duty Vehicle Emissions Study for use in the U.S. Environmental Protection Agency (EPA) vehicle emission model, the Motor Vehicle Emission Simulator (MOVES), and for inclusion in the EPA SPECIATE database for speciation profiles. The profiles are compatible with the inputs of current photochemical air quality models, including the Community Multiscale Air Quality Aerosol Module Version 6 (AE6). The composition of light-duty gasoline PM 2.5 emissions differs significantly between cold start and hot stabilized running emissions, and between older and newer vehicles, reflecting both impacts of aging/deterioration and changes in vehicle technology. Fleet-average PM 2.5 profiles are estimated for cold start and hot stabilized running emission processes. Fleet-average profiles are calculated to include emissions from deteriorated high-emitting vehicles that are expected to continue to contribute disproportionately to the fleet-wide PM 2.5 emissions into the future. The profiles are calculated using a weighted average of the PM 2.5 composition according to the contribution of PM 2.5 emissions from each class of vehicles in the on-road gasoline fleet in the Kansas City Metropolitan Statistical Area. The paper introduces methods to exclude insignificant measurements, correct for organic carbon positive artifact, and control for contamination from the testing infrastructure in developing speciation profiles. The uncertainty of the PM 2.5 species fraction in each profile is quantified using sampling survey analysis methods. The primary use of the profiles is to develop PM 2.5 emissions inventories for the United States, but the profiles may also be used in source apportionment, atmospheric modeling, and exposure assessment, and as a basis for light-duty gasoline emission profiles for countries with limited data. Implications: PM 2.5 speciation profiles were developed from a large sample of light-duty gasoline vehicles tested in the Kansas City area. Separate PM 2.5 profiles represent cold start and hot stabilized running emission processes to distinguish important differences in chemical composition. Statistical analysis was used to construct profiles that represent PM 2.5 emissions from the U.S. vehicle fleet based on vehicles tested from the 2005 calendar year Kansas City metropolitan area. The profiles have been incorporated into the EPA MOVES emissions model, as well as the EPA SPECIATE database, to improve emission inventories and provide the PM 2.5 chemical characterization needed by CMAQv5.0 for atmospheric chemistry modeling. 相似文献
16.
Abstract This paper presents measurements of daily sampling of fine particulate matter (PM 2.5) and its major chemical components at three urban and one rural locations in North Carolina during 2002. At both urban and rural sites, the major insoluble component of PM 2.5 is organic matter, and the major soluble components are sulfate (SO 4 2?), ammonium (NH 4 +), and nitrate (NO 3 ?). NH 4 + is neutralized mainly by SO 4 2? rather than by NO 3 ?, except in winter when SO 4 2? concentration is relatively low, whereas NO 3 ? concentration is high. The equivalent ratio of NH 4 + to the sum of SO 4 2? and NO 3 ? is <1, suggesting that SO 4 2?and NO 3 ?are not completely neutralized by NH 4 +. At both rural and urban sites, SO 4 2?concentration displays a maximum in summer and a minimum in winter, whereas NO 3 ?displays an opposite seasonal trend. Mass ratio of NO 3 ? to SO 4 2?is consistently <1 at all sites, suggesting that stationary source emissions may play an important role in PM 2.5 formation in those areas. Organic carbon and elemental carbon are well correlated at three urban sites although they are poorly correlated at the agriculture site. Other than the daily samples, hourly samples were measured at one urban site. PM 2.5 mass concen trations display a peak in early morning, and a second peak in late afternoon. Back trajectory analysis shows that air masses with lower PM 2.5 mass content mainly originate from the marine environment or from a continental environment but with a strong subsidence from the upper troposphere. Air masses with high PM 2.5 mass concentrations are largely from continental sources. Our study of fine particulate matter and its chemical composition in North Carolina provides crucial information that may be used to determine the efficacy of the new National Ambient Air Quality Standard (NAAQS) for PM fine. Moreover, the gas-to-particle conversion processes provide improved prediction of long-range transport of pollutants and air quality. 相似文献
17.
Multivariate statistical techniques are applied to particulate matter (PM) and meteorological data to identify the sources responsible for evening PM spikes at Sunland Park, NM (USA). The statistical techniques applied are principal components analysis (PCA), redundancy analysis (RDA), and absolute principal components scores analysis (APCSA), and the data evaluated are 3-h average (6–9 p.m.) PM 2.5 mass and chemical composition and 1-h average PM 2.5 and PM 10 mass and environmental data collected in the winter of 2002. Although the interpretation of the data was complicated by the presence of sources which are likely changing in time (e.g. brick kilns), the multivariate analyses indicate that the evening high PM 2.5 is associated with burning-activities occurring to the south of Sunland Park, and these emissions are characterized by elevated Sb, Cl −, and elemental carbon; ∼68% of the PM 2.5 mass can be attributed to this source. The PM 10 evening peaks, on the other hand, are mainly caused by resuspended dust generated by vehicular movements south of the site and transported by the local terrain-induced drainage flow. 相似文献
19.
PM 2.5 (particulate matter with an aerodynamic diameter <2.5 μm) samples ( n = 58) collected every sixth day in Xi’an, China, from 5 July 2008 to 27 June 2009 are analyzed for levoglucosan (1,6-anhydro-β- d-glucopyranose) to evaluate the impacts of biomass combustion on ambient concentrations. Twenty-four-hour levoglucosan concentrations displayed clear summer minima and winter maxima that ranged from 46 to 1889 ng m ?3, with an average of 428 ± 399 ng m ?3. Besides agricultural burning, biomass/biofuel combustion for household heating with straws and branches appears to be of regional importance during the heating season in northwestern China. Good correlations (0.70 < R < 0.91) were found between levoglucosan relative to water-soluble K +, Cl ?, organic carbon (OC), elemental carbon (EC), and glyoxal. The highest levoglucosan/OC ratio of 2.3% was found in winter, followed by autumn (1.5%). Biomass burning contributed to 5.1–43.8% of OC (with an average of 17.6 ± 8.4%).Implications: ?PM2.5 levoglucosan concentrations and the correlation between levoglucosan relative to other compounds during four seasons in Xi’an showed that the influence of biomass burning is maximum during the residential heating season (winter), although some important influences may be detected in spring (field preparation burnings) and autumn (corn stalks and wheat straw burning, fallen dead leaves burning) at Xi’an and surrounding areas. Household heating with biomass during winter was quite widespread in Guanzhong Plain. Therefore, the control of biomass/biofuel combustion could be an effective method to reduce pollutant emission on a regional scale. 相似文献
20.
ABSTRACT Ambient particulates of PM 2.5 were sampled at three sites in Kaohsiung, Taiwan, during February and March 1999. In addition, resuspended PM 2.5 collected from traffic tunnels, paved roads, fly ash of a municipal solid waste (MSW) incinerator, and seawater was obtained. All the samples were analyzed for twenty constituents, including water-soluble ions, organic carbon (OC), elemental carbon (EC), and metallic elements. In conjunction with local source profiles and the source profiles in the model library SPECIATE EPA, the receptor model based on chemical mass balance (CMB) was then applied to determine the source contributions to ambient PM 2.5. The mean concentration of ambient PM 2.5 was 42.6953.68 μj.g/m 3 for the sampling period. The abundant species in ambient PM 2.5 in the mass fraction for three sites were OC (12.7-14.2%), SO 4 2- (12.8-15.1%), NO 3 - (8.110.3%), NH 4+ (6.7-7.5%), and EC (5.3-8.5%). Results of CMB modeling show that major pollution sources for ambient PM 2.5 are traffic exhaust (18-54%), secondary aerosols (30-41% from SO 4 2- and NO 3 -), and outdoor burning of agriculture wastes (13-17%). 相似文献
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