Levels and major sources of PM2.5 and PM10 in Bangkok Metropolitan Region

This research was the first long-term attempt to concurrently measure and identify major sources of both PM(10) and PM(2.5) in Bangkok Metropolitan Region (BMR). Ambient PM(10) and PM(2.5) were evaluated at four monitoring stations and analyzed for elemental compositions, water-soluble ions, and total carbon during February 2002-January 2003. Fifteen chemical elements, four water-soluble ions, and total carbon were analyzed to assist major source identification by a receptor model approach, known as chemical mass balance. PM(10) and PM(2.5) were significantly different (p<0.05) at all sites and 24 h averages were high at traffic location while two separated residential sites were similar. Seasonal difference of PM(10) and PM(2.5) concentrations was distinct between dry and wet seasons. Major source of PM(10) at the traffic site indicated that automobile emissions and biomass burning-related sources contributed approximately 33% each. Automobiles contributed approximately 39 and 22% of PM(10) mass at two residential sites while biomass burning contributed about 36 and 28%. PM(10) from re-suspended soil and cooking sources accounted for 10 to 15% at a residential site. Major sources of PM(2.5) at traffic site were automobile and biomass burning, contributing approximately 32 and 26%, respectively. Biomass burning was the major source of PM(2.5) mass concentrations at residential sites. Meat cooking also accounted for 31% of PM(2.5) mass at a low impact site. Automobile, biomass burning, and road dust were less significant, contributed 10, 6, and 5%, respectively. Major sources identification at some location had difficulty to achieve performance criteria due to limited source profiles. Improved in characterize other sources profiles will help local authority to better air quality.     

Cancer risk assessment of selected hazardous air pollutants in Seattle

The risk estimates calculated from the conventional risk assessment method usually are compound specific and provide limited information for source-specific air quality control. We used a risk apportionment approach, which is a combination of receptor modeling and risk assessment, to estimate source-specific lifetime excess cancer risks of selected hazardous air pollutants. We analyzed the speciated PM(2.5) and VOCs data collected at the Beacon Hill in Seattle, WA between 2000 and 2004 with the Multilinear Engine to first quantify source contributions to the mixture of hazardous air pollutants (HAPs) in terms of mass concentrations. The cancer risk from exposure to each source was then calculated as the sum of all available species' cancer risks in the source feature. We also adopted the bootstrapping technique for the uncertainty analysis. The results showed that the overall cancer risk was 6.09 x 10(-5), with the background (1.61 x 10(-5)), diesel (9.82 x 10(-6)) and wood burning (9.45 x 10(-6)) sources being the primary risk sources. The PM(2.5) mass concentration contributed 20% of the total risk. The 5th percentile of the risk estimates of all sources other than marine and soil were higher than 110(-6). It was also found that the diesel and wood burning sources presented similar cancer risks although the diesel exhaust contributed less to the PM(2.5) mass concentration than the wood burning. This highlights the additional value from such a risk apportionment approach that could be utilized for prioritizing control strategies to reduce the highest population health risks from exposure to HAPs.     

Mutagenic and carcinogenic potency of extracts of diesel and related environmental emissions: Summary and discussion of the results

The proposed conversion from gasoline powered automobiles to diesel powered vehicels has prompted the Environmental Protection Agency to evaluate the potential health effects associated with exposure to diesel emissions. At present, there is no direct epidemiological link between this exposure and human health. Therefore, a research program was constructed to compare the health effects associated with diesel emissions with those from other emission sources for which epidemiological information was available. The emission sources chosen were cigarette smoke, roofing tar, and coke oven. An additional comparative emission source which was a gasoline catalyst engine. Respirable particles from a variety of combustion sources have the potential of being carcinogenic and mutagenic. The objective of these studies was to determine the relative biological activity of the organic material adsorbed on these particles in both in vitro mutagenesis and in vitro and in vivo bioassays. The organic extracts from the following series of emission sources were quantitatively bioassayed in a matrix of tests for their carcinogenic and mutagenic activity: (1) a light-duty Oldsmobile diesel 350 engine; (2) a heavy-duty Caterpillar diesel engine; (3) a light-duty Nissan engine; (4) a Volkswagen Rabbit diesel engine; (5) cigarette smoke; (6) roofing tar; (7) coke oven; and (8) a gasoline catalyst Mustang. The test matrix consisted of the following bioassay: reverse mutation in Salmonella typhimurium; mitotic recombination in Saccharomyces cerevisiae; DNA damage in Syrian hamster embryo cells (SHE); sister chromatid exchange in CHO cells; gene mutation in L5178Y mouse lymphoma cells, Balb/c 3T3 mouse embryo fibroblasts and CHO cells; viral enhancement of SHE cells; oncogenic transformation in Balb/c 3T3 cells; and skin tumor initiation in SENCAR and C57 black mice. The results of this test matrix are discussed.     

Atmospheric Mercury Pollution in Beijing

Abstract

The atmospheric mercury pollution in Beijing is a serious problem. Atmospheric mercury has three sources: natural emission, anthropogenic emission and previously deposited mercury reemission or recycling, composing elemental mercury, divalent mercury and particulate-phase mercury. Many studies showed that mercury in Beijing’s air was higher than the general level of mercury concentration in the atmosphere. Mercury emission sources were discussed. Industrial emissions, coal burning, vehicle exhaust emissions and waste incineration were thought to be the main sources of atmospheric mercury pollution in Beijing. And also meteorology has an effect on atmospheric mercury concentration in Beijing. Measures have been taken to control the emission of mercury into the air in recent years.     

Levels and major sources of PM2.5 and PM10 in Bangkok Metropolitan Region

This research was the first long-term attempt to concurrently measure and identify major sources of both PM₁₀ and PM_2.5 in Bangkok Metropolitan Region (BMR). Ambient PM₁₀ and PM_2.5 were evaluated at four monitoring stations and analyzed for elemental compositions, water-soluble ions, and total carbon during February 2002–January 2003. Fifteen chemical elements, four water-soluble ions, and total carbon were analyzed to assist major source identification by a receptor model approach, known as chemical mass balance. PM₁₀ and PM_2.5 were significantly different (p < 0.05) at all sites and 24 h averages were high at traffic location while two separated residential sites were similar. Seasonal difference of PM₁₀ and PM_2.5 concentrations was distinct between dry and wet seasons. Major source of PM₁₀ at the traffic site indicated that automobile emissions and biomass burning-related sources contributed approximately 33% each. Automobiles contributed approximately 39 and 22% of PM₁₀ mass at two residential sites while biomass burning contributed about 36 and 28%. PM₁₀ from re-suspended soil and cooking sources accounted for 10 to 15% at a residential site. Major sources of PM_2.5 at traffic site were automobile and biomass burning, contributing approximately 32 and 26%, respectively. Biomass burning was the major source of PM_2.5 mass concentrations at residential sites. Meat cooking also accounted for 31% of PM_2.5 mass at a low impact site. Automobile, biomass burning, and road dust were less significant, contributed 10, 6, and 5%, respectively. Major sources identification at some location had difficulty to achieve performance criteria due to limited source profiles. Improved in characterize other sources profiles will help local authority to better air quality.     

Primary and secondary components of PM2.5 in Milan (Italy)

In sampling campaigns--carried out by means of a high-volume gravimetric sampler--performed between August 2002 and December 2003, 24-h PM2.5 samples have been collected at an urban background site in downtown Milan and analyzed for elemental and organic carbon, ionic species (i.e., chloride, nitrates, sulfates and ammonium) and some elemental species. Chemical speciation data are evaluated also in terms of primary and secondary components of fine particulate matter: in particular, the contribution of secondary organic aerosols (SOA) and of the primary contribution from traffic to observed PM2.5 concentration levels are evaluated by means of the EC tracer method.     

基于混合生命周期方法的私人电动汽车温室气体排放研究

近年来,电动汽车因其在行驶过程中无任何尾气排放,被各国政府视为推动交通部门清洁、低碳发展的重要途径,主要发达国家纷纷推出了各自的电动汽车发展战略。但是,由于电力属于二次能源,其上游电力生产阶段的能源消费是否清洁将对电动汽车的减排效果产生重要影响。考虑到目前中国绝大部分电力源于煤炭,电动汽车是否真正有益于减排还有待进一步验证。目前一些专家和学者基于传统的过程生命周期评价方法对电动汽车的能源消费、温室气体排放做了一些研究,但研究结果差异较大。为了对电动汽车的减排效果进行更精确的研究,本文采用混合生命周期方法对电动汽车的能源消费、温室气体排放进行了计算。同时,在考虑电动汽车的燃料生命周期、车辆制造生命周期的基础上,将相关配套充电设施建设生命周期纳入到电动汽车的全生命周期系统边界内,以使对电动汽车全生命周期的研究结果更加完整、精确。研究结果显示,纯电动汽车并非是"零排放"的,在燃料周期,虽然纯电动汽车的单位里程能源消费强度较小,约为传统汽油车的94.6%,但以煤为主的高碳电力结构导致目前纯电动汽车燃料周期的单位里程温室气体排放强度约为传统汽油车的1.12倍;车辆周期内,纯电动汽车的能源消费和温室气体排放量也略高于传统汽油车;此外,配套充电设施的建设也将增加纯电动汽车全生命周期的能源消费和温室气体排放量。综合燃料、车辆及充电设备的全生命周期,在当前的电源结构及技术条件下,电动汽车虽然具有较高的能源效率和较好的石油替代效果,但其全生命周期内的煤炭消费较高,导致其温室气体排放量高于传统汽油车,在当前的情况下大规模发展电动汽车并不利于温室气体减排。     

Mutagenic and carcinogenic potency of diesel and related environmental emissions: Salmonella bioassay

Due to the expected increase in the percentage of diesel vehicles in the United States, the Environmental Protection Agency must evaluate the health effects associated with exposure to diesel emissions. Respirable particles from a variety of combustion sources have the potential of being carcinogenic and mutagenic. The objective of these studies was to determine the relative biological activity of the organic material adsorbed on these particles in in vitro mutagenesis bioassays. The organic extracts from the following series of emission sources were bioassayed in the Salmonella assay for mutagenic activity: (1) a light-duty Oldsmobile diesel 350 engine; (2) a heavy-duty Caterpillar diesel engine; (3) a light-duty Nissan engine; (4) a Volkswagen Rabbit diesel engine; (5) cigarette smoke; (6) roofing tar; (7) coke oven; and (8) a gasoline catalyst Mustang. This paper provides a comparison of these sources within the Salmonella bioassay and also demonstrates how bacterial systems can be used as a quality assurance measure in in vivo testing.     

Airborne reduced nitrogen: ammonia emissions from agriculture and other sources

Ammonia is a basic gas and one of the most abundant nitrogen-containing compounds in the atmosphere. When emitted, ammonia reacts with oxides of nitrogen and sulfur to form particles, typically in the fine particle size range. Roughly half of the PM(2.5) mass in eastern United States is ammonium sulfate, according to the US EPA. Results from recent studies of PM(2.5) show that these fine particles are typically deposited deep in the lungs and may lead to increased morbidity and/or mortality. Also, these particles are in the size range that will degrade visibility. Ammonia emission inventories are usually constructed by multiplying an activity level by an experimentally determined emission factor for each source category. Typical sources of ammonia include livestock, fertilizer, soils, forest fires and slash burning, industry, vehicles, the oceans, humans, pets, wild animals, and waste disposal and recycling activities. Livestock is the largest source category in the United States, with waste from livestock responsible for about 3x10(9) kg of ammonia in 1995. Volatilization of ammonia from livestock waste is dependent on many parameters, and thus emission factors are difficult to predict. Despite a seasonal variation in these values, the emission factors for general livestock categories are usually annually averaged in current inventories. Activity levels for livestock are from the USDA Census of Agriculture, which does not give information about animal raising practices such as housing types and grazing times, waste handling systems, and approximate animal slurry spreading times or methods. Ammonia emissions in the United States in 1995 from sources other than livestock are much lower; for example, annual emissions are roughly 8x10(8) kg from fertilizer, 7x10(7) kg from industry, 5x10(7) kg from vehicles and 1x10(8) kg from humans. There is considerable uncertainty in the emissions from soil and vegetation, although this category may also be significant. Recommendations for future directions in ammonia research include designing experiments to improve emission factors and their resolution in all significant source categories, developing mass balance models, and refining of the livestock activity level data by eliciting judgment from experts in this field.     

Mutagenic and carcinogenic potency of extracts from diesel related environmental emissions: Simultaneous morphological transformation and mutagenesis in BALB/c 3t3 cells

Particulate extracts from six different environmental emission sources were assayed for genotoxic activity in mouse BALB/c 3T3 clone A31-1 cells. All compounds were tested simultaneously for both transforming and mutagenic (induction of ouabain-resistance) potential with and without exogenous metabolic activation in the form of a 9000 × g postmitochondrial hepatic supernatant fraction from Aroclor-1254 induced Fischer 344 rats. Dichloromethane particulate extracts from the exhaust of two light duty diesel engines (Oldsmobile and Nissan), one heavy duty diesel engine (Caterpillar) and one late model gasoline engine (Mustang II) were assayed in an identical manner to particulate extracts from the emissions of a roofing tar pot and a coke oven. No clear dose-dependent responses were observed, but several of the samples showed significant transforming and mutagenic activity. A qualitative ranking system showed the activity of these particulate extracts for either mutagenesis or transformation was: coke oven = Mustang II gasoline engine > Nissan diesel engine > roofing tar. Particulate extracts from the Oldsmobile diesel engine and the Caterpillar diesel engine showed essentially no activity.     

京津冀PM_(2.5)的主要影响因素及内在关系研究

大气污染物的源排放是形成灰霾天气的内因,气象条件是形成灰霾天气的外因。本研究通过构建PM_(2.5)浓度的两段式分布滞后模型,结合自然环境因素及经济因素对PM_(2.5)的影响因素进行了综合分析。在第一段模型中构建了PM_(2.5)和大气污染物排放量的分布滞后模型,第二段模型中构建了不同的大气污染源对大气污染物排放量的影响因素模型。大气污染物排放源主要包括工业源、生活源、机动车源、集中式污染治理设施源。在工业源中,工业废气重度污染行业是大气污染物排放主要的贡献者;在生活源中,燃煤消费量对大气污染物排放影响很大,这也是冬季供暖期间PM_(2.5)剧增的原因;在机动车源中,尽管黄标车的保有量仅占汽车保有量的10%左右,但却占据了颗粒物排放量的绝大部分。利用京津冀代表性城市PM_(2.5)日度数据研究得出平均气温、平均风速、日照时数、平均气压、降雨量、平均相对湿度、沙尘暴等因素对PM_(2.5)浓度的负向与正向作用。研究发现,大气污染物排放量对PM_(2.5)浓度具有聚集的滞后效应,当期大气污染物排放量、滞后一期、滞后两期、滞后三期大气污染物对PM_(2.5)浓度具有显著的正向作用,且影响依次递减。构建的大气污染物排放量的污染源影响因素模型揭示一个地区煤炭消费量、工业废气重度污染行业工业增加值、黄标车保有量对该地区大气污染物排放量具有显著影响。本研究对优化能源消费结构和产业结构,减少空气污染物排放提出了对策建议。     

Modeling and source apportionment of diesel particulate matter

The fine and ultra fine sizes of diesel particulate matter (DPM) are of greatest health concern. The composition of these primary and secondary fine and ultra fine particles is principally elemental carbon (EC) with adsorbed organic compounds, sulfate, nitrate, ammonia, metals, and other trace elements. The purpose of this study was to use an advanced air quality modeling technique to predict and analyze the emissions and the primary and secondary aerosols concentrations that come from diesel-fueled sources (DFS). The National Emissions Inventory for 1999 and a severe southeast ozone episode that occurred between August and September 1999 were used as reference. Five urban areas and one rural area in the Southeastern US were selected to compare the main results. For urban emissions, results showed that DFS contributed (77.9%+/-8.0) of EC, (16.8%+/-8.2) of organic aerosols, (14.3%+/-6.2) of nitrate, and (8.3%+/-6.6) of sulfate during the selected episodes. For the rural site, these contributions were lower. The highest DFS contribution on EC emissions was allocated in Memphis, due mainly to diesel non-road sources (60.9%). For ambient concentrations, DFS contributed (69.5%+/-6.5) of EC and (10.8%+/-2.4) of primary anthropogenic organic aerosols, where the highest DFS contributions on EC were allocated in Nashville and Memphis on that episode. The DFS contributed (8.3%+/-1.2) of the total ambient PM(2.5) at the analyzed sites. The maximum primary DPM concentration occurred in Atlanta (1.44 microg/m(3)), which was 3.8 times higher than that from the rural site. Non-linearity issues were encountered and recommendations were made for further research. The results indicated significant geographic variability in the EC contribution from DFS, and the main DPM sources in the Southeastern U.S. were the non-road DFS. The results of this work will be helpful in addressing policy issues targeted at designing control strategies on DFS in the Southeastern U.S.     

Combustion particles emitted during church services: Implications for human respiratory health

Burning candles and incense generate particulate matter (PM) that produces poor indoor air quality and may cause human pulmonary problems. This study physically characterised combustion particles collected in a church during services. In addition, the emissions from five types of candles and two types of incense were investigated using a combustion chamber. The plasmid scission assay was used to determine the oxidative capacities of these church particles. The corresponding risk factor (CRf) was derived from the emission factor (Ef) and the oxidative DNA damage, and used to evaluate the relative respiratory exposure risks. Real-time PM measurements in the church during candle–incense burning services showed that the levels (91.6 μg/m³ for PM₁₀; 38.9 μg/m³ for PM_2.5) exceeded the European Union (EU) air quality guidelines. The combustion chamber testing, using the same environmental conditions, showed that the incense Ef for both PM₁₀ (490.6–587.9 mg/g) and PM_2.5 (290.1–417.2 mg/g) exceeded that of candles; particularly the PM_2.5 emissions. These CRf results suggested that the exposure to significant amounts of incense PM could result in a higher risk of oxidative DNA adducts (27.4–32.8 times) than tobacco PM. The generation and subsequent inhalation of PM during church activities may therefore pose significant risks in terms of respiratory health effects.     

Effect of hydrogen addition to CNG in a biodiesel-operated dual-fuel engine

Alternative fuels for diesel engine applications are gaining more prominence as they have numerous advantages compared to fossil fuels. They are renewable, biodegradable; provide food and energy security and foreign exchange savings. They address environmental concerns and socio-economic issues as well. Gaseous fuels such as compressed natural gas and hydrogenated compressed natural gas (HCNG) appear more attractive fuels for diesel engine applications operated in dual-fuel mode. Such dual fuel engines can replace considerable amount of liquid-injected pilot fuels by gaseous fuels besides being friendly to the environment. A small quantity of liquid fuel injected towards the end of the compression stroke initiates combustion of the inducted gas in the dual-fuel engines. The main advantage of dual-fuel engines is their lower nitrogen oxides (NO_x) and particulate emissions. Hence renewable fuels such as biodiesels and gaseous fuels can be used predominantly for transportation and power generation applications. Gaseous fuels are clean burning and are more economical as well. A suitable carburettor was designed to supply a stoichiometric mixture of air and HCNG to the modified diesel engine operated in dual-fuel mode. The biodiesel used in this study is derived from Honge oil called the Honge oil methyl ester (HOME). This paper presents the performance, combustion and exhaust emission characteristics of a single cylinder, four stroke, direct injection, stationary diesel engine operated on HOME and HCNG in dual-fuel mode. From the results it is observed that HOME–HCNG combination gave lower brake thermal efficiency (BTE) and improved emission levels when compared with diesel/HOME in single fuel operation. Lower smoke and particulate matter were obtained with dual-fuel operation. Comparative measures of BTE, peak pressure, pressure–crank angle variation, smoke opacity, hydrocarbon, carbon monoxide and NO_x emissions have been made and analysed.     

WATCH

Abstract

The characteristics of fine particulate pollution (PM₁₀ and PM_2.5) were measured at urban and suburban sites in Jinan during the 2008–2009 heating and non-heating seasons. The results showed that PM₁₀ and PM_2.5 pollution was quite serious, and PM mass concentration was higher during the heating season than the non-heating season. PM was the highest in the chemical factory and lowest in the development zone. The mass concentrations of PM₁₀ and PM_2.5 were linearly related, and the mass concentration ratio of PM_2.5/PM₁₀ was up to 0.59 in urban areas. PM pollution in Jinan was related to local meteorological factors: PM_2.5 mass concentration and humidity were positively correlated, and PM_2.5 mass concentration was negatively correlated with both click on the temperature and wind speed, although wind speed varied more.     

Characteristics and health implications of fine and coarse particulates at roadside, urban background and rural sites in UK

Recent studies have pointed to evidence that fine particles in the air could be significant contributors to respiratory and cardiovascular diseases and mortality. Epidemiologists looking at the health effects of particulate pollution need more information from various receptor locations to improve the understanding of this problem. Detailed information on temporal, spatial and size distributions of particulate pollution in urban areas is also important for air quality modellers as well as being an aid to decision and policy makers of local authorities. This paper presents a detailed analysis of temporal and seasonal variation of PM(10) and PM(2.5) levels at one urban roadside, one urban background and one rural monitoring location. Levels of PM(10), PM(2.5) and coarse fraction of particulates are compared. In addition, particulate levels are compared with NO(2) and CO concentrations. The study concludes that PM(10) and PM(2.5) are closely related at urban locations. Diurnal variation in PM(2.5)/PM(10) ratio shows the influence of vehicular emission and movement on size distribution. This ratio is higher in winter than in summer, indicating a build-up or longer residence time of finer particulates or washout due to wet weather in winter. In the second part of this study, a disease burden analysis is carried out based on the dose-response relationships recommended by the UK Committee on the Medical Effects of Air Pollution. The disease burden analysis indicates that if Marylebone Road (MR) levels of PM(10) were prevalent all over London, it will result in around 2.5% increase in death rates due to all causes. Whereas, if Bloomsbury (BB) levels were prevalent in London, which is more likely to occur as this is more representative of the urban background environment to which people in London are likely to be exposed, the corresponding increase would be around 1.7%. Considering this, in London, at Bloomsbury levels, 973 deaths and 1515 respiratory hospital admissions (RHA) are attributable to PM(10) while 2140 RHA are attributable to NO(2). After deducting the disease burden due to background levels at Rochester (RC), PM(10) emission caused by anthropogenic activities in London equates to 273 additional deaths and 410 additional RHA, while NO(2) account for additional 1205 incidences of RHA.     

Fine Particulate Pollution Characteristics in Jinan City

The characteristics of fine particulate pollution(PM10and PM25)were measured at urban and suburban sites in Jinan during the 2008-2009 heating and non-heating seasons.The results showed that PM10 and PM2.5 pollution was quite serious,and PM mass concentration was higher during the heating season than the non-heating season.PM was the highest in the chemical factory and lowest in the development zone.The mass concentrations of PM10 and PM2.5 were linearly related,and the mass concentration ratio of PM2.5/PM10 was up to 0.59 in urban areas.PM pollution in Jinan was related to local meteorological factors: PM2.5 mass concentration and humidity were positively correlated,and PM2.5mass concentration was negatively correlated with both click on the temperature and wind speed,although wind speed varied more.     

Health effects from Sahara dust episodes in Europe: Literature review and research gaps

The adverse consequences of particulate matter (PM) on human health have been well documented. Recently, special attention has been given to mineral dust particles, which may be a serious health threat. The main global source of atmospheric mineral dust is the Sahara desert, which produces about half of the annual mineral dust. Sahara dust transport can lead to PM levels that substantially exceed the established limit values. A review was undertaken using the ISI web of knowledge database with the objective to identify all studies presenting results on the potential health impact from Sahara dust particles. The review of the literature shows that the association of fine particles, PM_2.5, with total or cause‐specific daily mortality is not significant during Saharan dust intrusions. However, regarding coarser fractions PM₁₀ and PM_2.5–10 an explicit answer cannot be given. Some of the published studies state that they increase mortality during Sahara dust days while other studies find no association between mortality and PM₁₀ or PM_2.5–10. The main conclusion of this review is that health impact of Saharan dust outbreaks needs to be further explored. Considering the diverse outcomes for PM₁₀ and PM_2.5–10, future studies should focus on the chemical characterization and potential toxicity of coarse particles transported from Sahara desert mixed or not with anthropogenic pollutants. The results of this review may be considered to establish the objectives and strategies of a new European directive on ambient air quality. An implication for public policy in Europe is that to protect public health, anthropogenic sources of particulate pollution need to be more rigorously controlled in areas highly impacted by the Sahara dust.     

Seasonal distribution and modeling of diesel particulate matter in the Southeast US

The fine and ultra fine size of diesel particulate mater (DPM) are of great health concern and significantly contribute to the overall cancer risk. In addition, diesel particles may contribute a warming effect on the planet's climate. The composition of these particles is composed principally of elemental carbon (EC) with adsorbed organic compounds, sulfate, nitrate, ammonia, metals, and other trace elements. The purpose of this study was to depict the seasonality and modeling of particulate matter in the Southeastern US produced by the diesel fueled sources (DFSs). The modeling results came from four one-month cases including March, June, September, and December to represent different seasons in 2003 by linking Models-3/CMAQ and SMOKE. The 1999 National Emissions Inventory Version 3 (NEI99) was used in this analysis for point, area, and non-road sources, whereas the National Mobile Inventory Model (NMIM) was used to create the on-road emissions. Three urban areas, Atlanta, Birmingham, and Nashville were selected to analyze the DPM emissions and concentrations. Even though the model performance was not very strong, it could be considered satisfactory to conduct seasonal distribution analysis for DPM. Important hourly DPM seasonality was observed in each city, of which higher values occurred at the morning traffic rush hours. The EC contributions of primary DPM were similar for all three sites (~ 74%). The results showed that there is no significant daily seasonality of DPM contribution to PM_2.5 for any of these three cities in 2003. The annual DPM contribution to total PM_2.5 for Atlanta, Nashville, and Birmingham were 3.7%, 2.5%, and 2.2%, respectively.     

安徽省冬季PM2.5污染来源及其成因分析

随着中国城市化和工业化的加速发展,大气污染的问题日益突出,严重危害公众身体健康。基于安徽省逐小时PM2.5浓度监测数据,采用后向轨迹模式、潜在源因子分析法（PSCF）和权重浓度分析法（CWT）,构建PM2.5来源分析模型,分析了安徽省PM2.5的来源,并结合地理探测器辨析了影响PM2.5本底贡献浓度的驱动因子。结果表明：（1）本底贡献、本底外溢和外地输送这3个动态过程对安徽省PM2.5浓度的时空变化有重要的影响;（2）PM2.5月累计逐小时测量浓度、总浓度、外地输送浓度、本底贡献浓度、本底外溢浓度和月均PM2.5本底排放贡献率,均在整体呈现出西南高、东北低的分布趋势,但前3项在安徽西北部的阜阳、亳州和淮北等地出现高值区;（3）安徽省约97.5%的面积外地输送贡献率>50%,下辖市PM2.5本底排放贡献率在30%~50%,说明1月污染以外地输送为主;（4）工厂密度、车辆保有量密度和人口密度对PM2.5月累计本底贡献浓度的解释力q值分别为0.33、0.47和0.61,通过与PM2.5月累计测量浓度地理探测分析结果的比较,表明人为要素与PM2.5月累计本底贡献浓度的关系更加密切。研究结果可为区域大气污染治理提供科学的参考依据。