基于EPAS技术的日照市大气单颗粒物理化学特性及来源研究

城市地区大气气溶胶颗粒的物理化学特性复杂,理清单颗粒精细的化学成分和混合状态对于大气污染溯源和精细治理具有重要意义。本研究利用被动式气溶胶采样器分别在山东省日照市城区和钢铁园区两个区域进行了定点采样,并利用智能扫描电镜环境颗粒物分析系统（IntelliSEM EPAS）对采集的大气单颗粒物样品进行分析。结果表明,日照市大气颗粒物主要由不规则碳质颗粒（C-rich）、含硫颗粒（Ca-S、Na-S-Ca）与矿物颗粒组成。其中,城区样品中C-rich颗粒数量贡献为53.5%,是钢铁园区样品的2.5倍,大于1 μm的颗粒物数量为9.0%,是钢铁园区样品的1.7倍,城区居民活动和工业过程是城市中大气颗粒物特别是二次细颗粒的主要来源。钢铁园区样品中含硫颗粒物数量贡献为72.9%,含硫颗粒物质量贡献为30.9%,富铁颗粒物质量贡献为5.3%,分别是城区样品的1.8倍、3.6倍和2.9倍,表明钢铁园区大气颗粒物的主要来源包括钢铁企业排放的一次污染物及其转化生成的二次细颗粒物。     

Trace elements in aerosol particles from Bermuda and Barbados: Concentrations,sources and relationships to aerosol sulfate

The concentrations of selected trace elements and non-sea salt sulfate were determined for aerosol particle samples collected over the open North Atlantic Ocean as part of the Atmosphere/Ocean Chemistry Experiment (AEROCE). The concentrations of atmospheric sea salt and mineral aerosol, which together dominate the mass of particulate material in the atmosphere, were higher at Barbados than at Bermuda. In contrast, the impact of pollution sources on trace element concentrations was more evident at Bermuda than at Barbados. At both sites Sb and Se were enriched significantly over the concentrations expected from mineral dust or from atmospheric sea salt. Moreover, the concentrations of Sb and Se were correlated, and the observed Sb/Se ratios often were similar to those resulting from anthropogenic emissions. At Bermuda, the concentrations of Sb and Se co-varied with non-sea salt sulfate, suggesting that a significant fraction of the non-sea salt sulfate is anthropogenic. In a broader context, the synthesis of results demonstrates that trace element data are useful for evaluating the relative contributions of anthropogenic vs. natural sources to the budgets of non-sea salt sulfate in acrosol particles.     

Elemental particle size distributions. Measured and estimated dry deposition in Sfax region (Tunisia)

Mass size distribution of the crustal elements (Al, Ca, Fe, Mg, Si, Ti), anthropogenic elements (Zn, Mn, Cr, Cu, K, P, Pb) and sea elements (Na, Cl) were obtained from measurements carried out with an inertial cascade impactor in Sfax. A fitting procedure by data inversion was applied to those data. This procedure yields accurate size distributions of aerosols in the diameter range 0.1–25 μm in two different sites. In a coastal industrial site, the mass distribution of the aerosol showed a bimodal structure; and in urban area, the lower particle mode cannot be observed. The elemental dry deposition flux was calculated as a function of particle size. The element flux size distribution increased rapidly with particle size. The modelling results indicate that the majority of the crustal and anthropogenic elements flux (>90%) was due to particles larger than 3 μm in diameter.     

Size distributions of ambient air particles and enrichment factor analyses of metallic elements at Taichung Harbor near the Taiwan Strait

This work attempts to characterize metallic elements associated with atmospheric particulate matter on a dry deposition plate, a TE-PUF high-volume air sampler and a universal air sampler. Dry deposition fluxes of particulates and concentrations of total suspended particulate, fine (PM_2.5) and coarse (PM_2.5–10) particulate matters were collected at Taichung harbor sampling sites from August 2004 to January 2005. Chemical analyses of metallic elements were made using a flame atomic absorption spectrophotometer coupled with hollow cathode lamps. Concentrations of metal elements in the forms of coarse particles and fine particles as well as the coarse/fine particulate ratios were presented. Statistical methods such as correlation analysis, principal component analysis and enrichment factor analysis were performed to compare the chemical components and identify possible emission sources at the sampling sites. Metallic elements of Cu, Zn, Pb, Cr, Ni and Mg had higher EF_crust ratios in winter and spring than in summer and autumn. Diurnal and nocturnal variations of metallic element concentrations in fine and coarse particles were also discussed.     

On large-scale transport of dust storms and anthropogenic dust-falls over east Asia observed in central Korea in 2009

Dust air pollution has been routinely monitored in central Korea for the last two decades. In 2009, there were eight typical episodes of significant dust loadings in the air: four were caused by dust storms from deserts in Mongolia and Northern China, while the remaining were typical cases of anthropogenic air pollution masses arriving from the Yellow Sea and East China. These natural dust loadings occurred with cool northwesterly airflows in the forward side of an intense anticyclone coming from Mongolia and Siberia. The mean concentrations of the four natural dustfall cases for TSP, PM10 and PM2.5 were 632, 480 and 100 μg m^?3, respectively. In contrast, the anthropogenic dust-pollution episodes occurred with the warm westerly and southwesterly airflows in the rear side of an anticyclone. This produced a favorable atmospheric and chemical condition for the build-up of anthropogenic dust air pollution in the Yellow Sea. The mean concentrations of the four anthropogenic dust loadings for TSP, PM10 and PM2.5 were 224, 187 and 137 μg m^?3, respectively. The contents of fine dust loadings of PM2.5 were comparatively high in the cases of anthropogenic air pollution. High atmospheric concentrations of fine particles in the atmosphere cause poor visibility and constitute a health hazard. Satellite observations clearly showed the movement of dust-pollution masses from Mongolia and Northern China and from the Yellow Sea and East China that caused these dust pollution episodes in Korea.     

Reductions of PM<Subscript>2.5</Subscript> in Beijing-Tianjin-Hebei urban agglomerations during the 2008 Olympic Games

The Atmospheric Environmental Monitoring Network successfully undertook the task of monitoring the atmospheric quality of Beijing and its surrounding area during the 2008 Olympics.The results of this monitoring show that high concentrations of PM2.5 pollution exhibited a regional pattern during the monitoring period(1 June-30 October 2008).The PM2.5 mass concentrations were 53 μg m 3,66 μg m 3,and 82 μg m 3 at the background site,in Beijing,and in the Beijing-Tianjin-Hebei urban agglomerations,respectively.The PM2.5 levels were lowest during the 2008 Olympic Games(8-24 August):35 μg m 3 at the background site,42 μg m 3 in Beijing and 57 μg m 3 in the region.These levels represent decreases of 49%,48%,and 56%,respectively,compared to the prophase mean concentration before the Olympic Games.Emission control measures contributed 62%-82% of the declines observed in Beijing,and meteorological conditions represented 18%-38%.The concentration of fine particles met the goals set for a "Green Olympics."     

Heavy metals in aerosol samples from the Eastern Pamirs collected 2004–2006

This study measured the concentration of heavy metal elements in atmospheric aerosol samples collected between July 2004 and April 2006 at a remote site on Mt. Muztagata (38°17'N, 75°01'E, 4430 m), in the Eastern Pamirs. Inductively coupled plasma mass spectroscopy (ICP–MS) results show that the air at Muztagata contains low concentrations of As and heavy metal elements (Cr, Ni, Cu, Zn, Cd, Pb, and Bi), comparable with those in the Arctic — far lower than in heavily populated or industrialized areas. Observed enrichment factor (EF) values greater than 10 for those elements suggest partly anthropogenic sources. Seasonal variations in the concentrations of Zn, Cd, Pb, Bi, and As resemble those of crustal Al, with greater concentrations during the summer but lower ones in winter. Our results reveal that the background atmosphere in remote inner Asia is only weakly affected by anthropogenic pollution, and demonstrate that high heavy metal concentrations occur during summer but with greater EF values during the winter. The air mass back-trajectory analyses suggest that pollution from West Asia, Central Asia, and South Asia are the main possible source areas that contribute to the heavy metals in aerosols at Muztagata.     

Size Distributions and Elemental Compositions of Particulate Matter on Clear, Hazy and Foggy days in Beijing, China

Total suspended particulates(TSP)samples were collected using low pressure impactors(Andersen Series 20-800,USA)on typical clear,hazy and foggy days in Beijing in order to investigate the characteristics of size distributions and elemental compositions of particulate matter(PM)in different weather conditions. The concentrations of sixteen elements,including Na,Mg,Al,K,Ca,Mn,Fe,Ni,Cu,Zn,As,Se,Cd,Ba,Tl and Pb were detected using inductively coupled plasma mass spectrometry(ICP-MS).The results showed that Ca,Al,Fe,Mg and Ba on foggy days were 2.0-2.6 times higher than on clear days,and 2.3-2.9 times higher than on hazy days.Concentrations of Cu,Zn,As,Se and Pb on foggy days were 163.5,1186.7,65.9,32.0 and 708.2 ng m-3,respectively,in fine particles,and 68.1,289.5,19.8,1.6 and 103.8 ng m-3,respectively,in coarse particles.This was 1.0-8.4 times higher and 1.4-7.4 times higher than on clear and hazy days,respectively.It is then shown that Mg,Al,Fe,Ca and Ba were mainly associated with coarse particles,peaking at 4.7-5.8μm;that Cd,Se,Zn,As,Tl and Pb were most dominant in fine particles,peaking at 0.43-1.1μm;and that Na,K,Ni,Cu and Mn had a multi-mode distribution,with peaks at 0.43-1.1μm and 4.7-5.8μm.The enrichment factors indicated that coal combustion along with vehicle and industry emissions may be the main sources of pollution elements.     

上海市大气颗粒物与能见度的关系

大气能见度成为当前区域大气环境研究的重要指标,不同粒径的颗粒物对能见度的影响有着显著的区别。本研究在线连续监测了上海市嘉定区2008年11月—2009年1月不同粒径大气颗粒物质量浓度和粒子数浓度的日变化,同步收集了相同区域空气水平能见度的数据。比较不同粒径大气颗粒物质量浓度与空气水平能见度和颗粒物消光系数的相关性,结果表明：中值粒径为0.4 μm和0.65 μm的大气颗粒物对上海嘉定空气水平能见度的影响最显著;中值粒径为0.17 μm、0.26 μm、0.40 μm和0.65 μm的大气颗粒物对颗粒物的消光系数影响较大。该相关系数的分布趋势与各种组分(SO42-、NO3-、NH4+、OC和EC)的粒径分布十分一致,证明了这五种组分是影响大气颗粒物消光系数的重要原因。     

Trace elements in urban and suburban rainfall, Mersin, Northeastern Mediterranean

Spatial/temporal variabilities of rainwater constituents are examined based on soluble/insoluble trace elements, pH and electrical conductivity measurements in rainfall sampled during December 2003–May 2005 at two urban and two suburban sites in Mersin, an industrialized city of 850,000 inhabitants on the southern coast of Turkey. In the analyses, backward air mass trajectories for rainy days were used in addition to factor analyses, enrichment factors, phase distributions and correlations between trace elements. The pH varied from 4.8 to 8.5 with an average value of 6.2, reflecting a mainly alkaline regime. Mean concentrations of trace elements collected from urban and suburban sites are spatially variable. Based on the overall data, total concentrations of trace elements were ordered as Ca > Na > Fe > Al > Mg > K > Zn > Mn > Sr > Pb > Ni > Cr > Ba > Cu > Co > Cd. Mainly terrigeneous (Ca, Fe, Al) and, to a lesser extent, sea salt particles (Na, Mg) were shown to be the major source of trace elements. Excluding major cations, the solubilities of trace elements were found to be ordered as Sr > Zn > Ba > Mn > Cu > Ni > Cr > Fe > Al, confirming the lower solubility of crustal elements. Cd, Co and Pb were excluded from the above evaluation because of the low numbers of soluble samples allowing quantitative measurements. The solubilities of Al, Fe, Mn and particularly of Ni were found to be considerably lower than those reported for various sites around the world, most likely due to the effect of pH. During the entire sampling period, a total of 28 dust transport episodes associated with 31 red rain events were identified. Extremely high mean concentration ratios of Al (8.2), Fe (14.4) and Mn (13.1) were observed in red rain, compared to normal rain. The degree of this enhancement displayed a decrease from crustal to anthropogenic origin elements and the lowest enhancements were found for anthropogenic origin elements of Zn and Cd (both having a ratio of 1.1). Aerosol dust was found to be the main source of almost all analyzed elements in Mersin precipitation, regardless that they are crustal or anthropic derived elements. The magnitude of crustal source contribution to trace element budget of precipitation was at its highest levels for crustal originated elements, most probably due to much higher scavenging ratios of crustal elements compared to anthropogenic ones.     

SEM-EDX Characterisation of Tropospheric Aerosols in the Negev Desert (Israel)

Individual aerosol particles collected in the Negev desert in Israel during a summer and winter campaign in 1996–1997 were analysed by scanning electron microscopy with energy-dispersive X-ray analysis. Hierarchical cluster analysis was performed to interpret the data on the basis of particle diameter and composition. Eleven particle classes (groups) provided clues on sources and/or particle formation. The summer samples were enriched in sulphates and mineral dusts; the winter samples contained more sea salts, aged sea salts, and industrial particles. The fine size fraction below 1 m diameter was enriched in secondary particles and showed evidence of atmospheric processing. The secondary sulphate particles were mainly attributed to long-range transport. A regional conversion from calcite to calcium sulphate occurred during summer. Industrial particles originating from local pollution appeared during winter.     

Biomass Burning in Southern Africa: Individual Particle Characterization of Atmospheric Aerosols and Savanna Fire Samples

Ambient atmospheric aerosols and savanna fireparticulate emission samples from southern Africa werecharacterised in terms of particle classes and theirnumber abundance by electron probe X-ray microanalysis(EPXMA). About ten particle classes were identifiedfor each sample. The major classes werealuminosilicates and sea salts for ambient coarse(2–10 m equivalent aerodynamic diameter (EAD))samples, and K-S and S-only particles for ambient fine(<2 m EAD) samples. The K-S particles are oneof the major products of biomass burning. The EPXMAresults were found to be consistent with the resultsfrom bulk analyses on a sample by sample basis. Forsavanna fire fine samples, quantitative EPXMA revealedthat many particles had a composition of simple saltssuch as KCl. Some particles had a deviatingcomposition in the sense that more ionic species wereinvolved in sustaining the balance between cations andanions, and they were composite or mixed salts.Because of extensive processing during the atmospherictransport, the composition of the K-S particles in theambient samples was different from K₂SO₄,and such particles were enriched with S. The finepyrogenic KCl particles and the fine sea-saltparticles were much depleted in chlorine.     

Tests for individual Sulfate－Containing Particles in Urban Atmosphere in Beijing

Thin film methods and X ray energy dispersive technique were applied to analyze sulfate-containing particles in Beijing in order to examine their features and sources. Atmospheric aerosol particles were collected on electron mi-croscope meshes according to two size ranges: coarse particles (r>0.5μm) and fine particles (0.5μm≥r≥0.1μm) by using a two-stage impactor. It was found fiat more than seventy percent of the fine particles and about twenty percent of the coarse particles were sulfate-containing particles. These particles were formed mainly through heterogeneous nucleation. The element composition analyses revealed that the atmospheric aerosol particles in Beijing were domi-nated by crustal particles and construction dust.     

北京雾、霾天细粒子质量浓度垂直梯度变化的观测

近年来北京城市区域雾霾天气显著增加,不仅严重影响工农业生产和交通运输,还严重影响人体健康.2007年夏秋季节,北京325 m气象塔8、80和240m平台梯度观测结果表明,雾、霾、晴三种典型天气状况大气细粒子质量浓度垂直分布各有特点,雾天(11月5～6日)低层浓度明显偏高,6日从低到高3层PM2.5(空气动力学直径小于等于2.5μ的大气气溶胶)浓度日均值分别为352.6±79.3、224.7±69.0、214.8±32.8 μg·m~(-3);霾天(8月19～20日)细粒子上下混合均匀,19日从低到高3层PM2.5浓度分别为89.8±29.3、88.9±29.8、90.0±31.7 μg·m~(-3);晴天(8月22～23日)细粒子昼夜变化明显,夜间在80 m高度出现明显分层,23日80 m以下平均值为32.6±13.1μg·m~(-3),240 m平均值为27.4±13.5μg·m~(-3).雾天细粒子主要来源于局地,霾天细粒子污染表现为时空分布十分均匀的城市群区域污染特征且污染物积累;连续晴天细粒子明显被清除.     

Transformation of Aerosol Chemical Properties due to Transport Over a City

The change of the chemical composition of the near-ground level atmospheric aerosol was studied during two summer episodes by a Lagrangian type of experimental approach. Bulk and single-particle chemical analyses of ions and elements in the particulate phase were deployed. N(-III) and N(V) components were also measured in the gas-phase. The measurements were completed by particle size distributions.Secondary inorganic aerosols (SIA) and fine particles of ≈0.2–0.4 μm size were still elevated 50 km downwind of the city. The direct comparison of transport over the city in contrast to transport over the surrounding areas showed that SIA was formed from emission from the city within less than 3 h. Relative increases, i.e., enrichment during transport were observed for primary and secondary aerosol components. The degree of mixing on the individual particle level increased significantly during transport in the area. In particular, newly emitted carbonaceous particles became internally mixed within hours with pre-existing sulphate particles. Mostly due to secondary aerosol formation the average particle size (mass median diameter) of major constituents of the aerosol was significantly decreased while being transported over 13 h. Given recent insights which link fine particles number and mass concentrations with health risks, the results suggest that rural populations in areas which frequently are located within an urban plume might run an elevated health risk relative to populations in areas not affected by urban plumes.     

北京市夏季臭氧变化特征的观测研究

利用2002年7月至8月325m气象塔资料研究了北京市夏季近地层臭氧浓度变化特征及其与气象因子的关系。结果表明：北京市夏季边界层臭氧浓度日变化显著．臭氧浓度随高度增加而增加；臭氧多数为单峰型分布，双峰型仅分布在底层；臭氧峰值出现时间与气温峰值出现时间基本一致，或略有落后。     

Elemental composition and mixing properties of atmospheric mineral particles collected in Hohhot,China

Aerosol particles were collected during the period from 23 to 28 April 1991 at Hohhot in the Inner Mongolia Autonomous Region of China, which is in an urban area located near one of the source areas of atmospheric mineral particles. The four samples were examined by a transmission electron microscope equipped with an energy-dispersive X-ray (EDX) analyzer to obtain the size and elemental composition of individual mineral particles.On the basis of EDX analyses for 385 particles, mineral particles were present in an extremely high number (98%) of particles in the radius range of 0.1–3 μm. Particles mainly composed of silicates comprised 70% of mineral particles. “Ca-rich” particles were detected in 18% of all the particles. Most of Ca would be present as CaCO₃, although the internal mixture of CaCO₃ and CaSO₄ was also found. Particles mainly composed of halite (NaCl) were present in low percentages of about 2% of mineral particles, and most of the particles were modified. The sample collected in the situation of weak wind contained spherical fly ash particles with about 13% of the particles analyzed. For the samples other than this sample, the grand abundance of mineral particles other than fly ash particles was larger than 98%.The hygroscopic properties of mineral particles were examined by the dialysis (extraction) of water-soluble material with distilled water. The sample collected in the situation of anthropogenic influence showed the presence of water-soluble material in mineral particles. On the basis of the EDX analysis and the water dialysis, it is suggested that the formation of CaSO₄ has occurred through chemical reactions of CaCO₃ in mineral particles with sulfuric acid in the atmosphere of Hohhot.     

南京市大气细颗粒物化学成分分析

为了解南京大气细粒子的污染水平和污染特征,在南京市中心鼓楼和北郊南京信息工程大学校内进行了连续1a、每季度5d的大气气溶胶同步采样。用称重法、离子色谱法和电感耦合等离子质谱法分别测得细颗粒物的质量浓度、水溶性离子和元素组成。结果表明,南京地区PM2.1污染比较严重,水溶性离子是细粒子的重要组分,所测6种离子质量浓度总和分别占市区和北郊PM2.1的46.99％、42.32％。PM2.1中的各离子最高浓度都出现在冬季。NH^＋4与SO^2-4的相关性好,可能主要以（NH4）2SO4形式存在。温度对SOR和NOR的影响显著,温度升高时SOR值增大而NOR显著减小。通过计算NO^-3与SO^2-4的质量比发现,南京市SO2和NOx主要来自于固定源（如煤的燃烧）。分析细颗粒物中元素含量和富集因子结果表明,Pb、As、Zn、Hg、Cu、Cr、Ni元素的人为污染较明显,且北郊的污染重于市区。比较PM2.1和PM3.3中的离子成分发现,SO^2-4、NH^＋4在PM2.1中占据绝对优势,F^-、Cl^-、NO^-2、NO^-3等不在细粒子中占明显优势。从元素组成来看,Pb、Zn在PM2.1细粒子中含量显著,而Ca、Mg、Na等在粗粒子中富集。     

2004年北京秋季大气颗粒物的化学组分和来源特征

2004年9月在北京城区进行了大气颗粒物采样,样品用PIXE方法进行了分析,得到了20种元素的浓度及其谱分布。并对北京颗粒物的谱分布、富集因子和来源进行了分析研究。发现K元素浓度分布呈细粒态单峰谱分布,细粒态K富集因子较高,表明了生物质燃烧的主要贡献。因子分析结果还表明,土壤尘、生物质燃烧、煤烟尘、工业源和汽车尾气排放源对秋季北京局地排放源有明显贡献。     

2007和2008年夏季北京奥运馆大气PM10与PM2.5质量浓度变化特征

为了监测北京奥运主场馆附近大气颗粒物的污染状况以及评估奥运污染源减排措施对北京大气颗粒物质量浓度变化的影响,利用颗粒物在线监测仪器TEOM于2007年和2008年夏季,在奥运主场馆附近的中国科学院遥感应用研究所办公楼楼顶对大气颗粒物PM10和PM2.5进行了连续同步观测。结果表明,2007年夏季监测点附近大气PM10与PM2.5质量浓度的平均值分别为153.9和71.2μg.m-3,而2008年夏季PM10与PM2.5质量浓度的平均值分别为85.2和52.8μg.m-3。与奥运前一年同时段相比,奥运时段大气PM10和PM2.5的质量浓度分别下降44.5%和25.1%。对比分析奥运前后的2次典型污染过程发现,空气相对湿度的增加和偏南气流输送的共同影响易造成大气颗粒物的累积增长,而降雨的湿清除作用和偏北气流则会使大气颗粒物浓度迅速降低。在相近的气象条件下,奥运前后的污染过程中,大气细粒子的日均增长速率分别为25.1和13.9μg.m-3.d-1,而大气粗粒子的日均增长速率分别为20.8和2.2μg.m-3.d-1,奥运时段污染累积过程中大气粗、细粒子的增长速率分别显著低于和略低于奥运前同时段污染过程中颗粒物的增长速率。污染源减排措施的实施是奥运期间大气颗粒物质量浓度降低的主要原因,从控制效果来看,奥运期间实施的污染源减排措施对大气粗粒子的控制效果明显好于大气细粒子。