广州城区大气细颗粒物粒谱分布特征分析

2008年10~11月,利用大气细粒子谱分析仪(FPM-I型)对广州城区5nm~10μm大气细粒子谱进行长期连续在线测量.同时,利用大气能见度仪、黑碳分析仪、气象参数仪获取了观测点的大气能见度、黑碳质量浓度和气象参数信息. 颗粒物谱型分析结果表明:整个观测期内,颗粒物数浓度谱、表面积谱及体积谱均呈双峰结构. 广州地区核模态(5~20nm)、爱根核模态(20~100nm)和积聚模态(0.1~1μm)粒子日平均浓度变化范围分别为1400~4300个/cm3、5000~12300个/cm3和1600~2600个/cm3.晴天和灰霾天气下颗粒物数浓度、黑碳浓度及大气能见度对比分析结果表明:广州地区大气能见度的高低受核模态和爱根核模态粒子浓度的影响较小,与积聚模态粒子浓度呈负相关关系;黑碳质量浓度峰值的出现位置与爱根核模态粒子浓度峰值位置相一致,表明爱根核模态粒子对黑碳浓度的贡献不能忽略.     

Characteristics of airborne particles inside southern California museums

The concentrations and chemical composition of suspended particulate matter were measured in both the fine and total size modes inside and outside five southern California museums over summer and winter periods. The seasonally averaged indoor/outdoor ratios for particulate matter mass concentrations ranged from 0.16 to 0.96 for fine particles and from 0.06 to 0.53 for coarse particles, with the lower values observed for buildings with sophisticated ventilation systems which include filters for particulate matter removal. Museums with deliberate particle filtration systems showed indoor fine particle concentrations generally averaging less than 10 μg m⁻³. One museum with no environmental control system showed indoor fine particle concentrations averaging nearly 60 μg m⁻³ in winter and coarse particle concentrations in the 30–40 μg m⁻³ range. Analyses of indoor vs outdoor concentrations of major chemical species indicated that indoor sources of organic matter may exist at all sites, but that none of the other measured species appear to have major indoor sources at the museums studied. Significant fractions of the dark-colored fine elemental (black) carbon and soil dust particles present in outdoor air are able to penetrate to the indoor atmosphere of the museums studied, and may constitute a soiling hazard to works of art displayed in museums.     

不同燃烧过程颗粒物粒径排放特征

采用荷电低压颗粒物撞击器(ELPI)和稀释采样系统研究重庆市工业源、交通源、生物质燃烧以及餐饮业油烟等各类燃烧过程的颗粒物排放特征.结果表明:燃煤锅炉以及各类柴油交通源颗粒物数浓度峰值都表现出单峰型的变化特征,峰值主要出现在0.20~0.48μm之间;生物质燃烧和餐饮业油烟颗粒物的数浓度都呈现出双峰型的变化趋势,分别出现在核模态(0.02~0.07μm)和积聚态(0.2μm);水泥窑炉的数浓度也出现双峰型变化特征,分别出现在积聚态(0.12μm)以及接近粗颗粒物态的1.23~1.96μm粒径范围处.各污染源颗粒物质量浓度峰值主要出现在粗粒径态,交通源排放的颗粒物质量浓度相对较高.各类污染源数浓度分布主要集中在积聚模态,粗颗粒态的数浓度累计贡献都不到1%;质量浓度主要分布在粗颗粒态,核模态的质量浓度贡献都小于0.1%.     

上海工业区大气颗粒物中硫的化学形态和分布

用低压冲击式采样器 (DLPI) 采集了上海工业区和郊区大气中28nm~9.92μm粒径范围的颗粒物样品,用同步辐射X射线吸收近边结构谱(XANES)和X射线荧光分析(SRXRF) 对样品中硫的化学形态和含量进行了研究.结果表明,粗颗粒物和细颗粒物中的硫,大部分以硫酸盐形式存在;超细颗粒物中除了硫酸盐硫之外,一部分硫以低价的还原态形式存在,可能的化学形态为金属硫化物、噻吩类有机硫化物.细粒子中硫的质量浓度高于粗颗粒,约 70%的硫分布在细粒子中.硫的质量浓度呈多模态分布.工业区的超细颗粒物峰值出现在0.091~0.154μm;细颗粒的分布为积聚模,峰值出现在0.38~0.611μm;粗颗粒分布为粗模态,在1.59~3.98μm和6.57~9.92μm出现2个峰值.郊区的超细颗粒物中硫的质量分布不存在峰值;积聚模出现两个亚模态,分别为峰值在0.261~0.380μm的“凝结模态”和峰值在0.611~0.945μm的“液滴模态”;粗模态峰值在2.38~6.57μm.污染来源和颗粒物形成、转换机制以及不同采样时间的气象条件差异决定了2个地区颗粒物中硫的分布特性,工业区颗粒物中硫的来源有海盐源的贡献,而郊区较少受海洋源的影响.     

Estimate of municipal refuse incinerator contribution to Philadelphia aerosol using single particle analysis—II. Ambient measurements

In a study to differentiate between municipal refuse incinerator particles and other particles in urban air, samples were collected on Teflon and nuclepore filters in dichotomous samplers and analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry. The samples included ambient aerosol from two sites in the Philadelphia area, representing different meteorological conditions. The same samples were previously analyzed by bulk techniques including X-ray fluorescence and instrumental neutron activation analysis.Particles emitted from incinerators rich in Zn, Cl and K were clearly identified in ambient samples, both in the coarse (2.5–10 μm) and fine aerosol fraction (<2.5 μm). The contribution of incinerators emission was from zero up to 10% of the coarse aerosol mass. Similar particles that contained also Zn and Cl were observed, but they did not originate in refuse incineration. Minerals and biologicals were the most dominant components of the coarse aerosol fraction; sulfates dominate the fine fraction. One of the case studies provided evidence for the missing chlorine in the fine fraction. Apparently fine chlorides emitted from incinerators reacted with ambient sulfates to form mixed sulfates of Zn and K. Good agreement was obtained between the measured coarse aerosol mass concentration and the one estimated by electron microscopy.     

电厂除尘设施对PM10排放特征影响研究

在5个不同燃煤电厂除尘器进、出口进行了现场测试,对除尘器性能以及振打时对PM₁₀排放特征的影响进行了研究.试验系统由低压荷电捕集器(ELPI)、等速采样系统、稀释系统组成.结果表明:该试验系统可对燃煤排放的可吸入颗粒物进行在线测量,获得可吸入颗粒物的瞬时浓度、平均浓度和浓度分布,最小粒径达0.03μm,可广泛用于固定源采样;除尘器进口和出口的PM10粒数浓度均呈明显的双模态对数正态分布,峰值均分别出现在0.07～0.12μm和0.76～1.23μm;电除尘器和布袋除尘器对粗颗粒态的颗粒物去除效率均较好,最大穿透率均出现在0.1～1μm范围内,但布袋除尘器在该粒径区间的穿透率低于电除尘器,降低该区间颗粒物的穿透率有利于控制可吸入颗粒物的排放;PM10的粒数浓度主要取决于亚微米态的颗粒,针对粒数浓度而言,电除尘器对PM₁和PM_2.5的去除效率同样低于PM₁₀;除尘器的运行和操作条件对PM₁₀排放影响较大,电除尘器末电场振打清灰时,出口PM₁₀的质量和粒数浓度均明显增加;振打时电除尘器基于粒数和质量浓度的2种除尘效率均有不同程度的下降,下降幅度最大的是PM1.     

A preliminary comparison of atmospheric aerosols in urban and non-urban areas in Nanjing,China

Using a 10-stage cascade impactor, atmospheric aerosols were collected from urban and non-urban areas in Nanjing, China. The shapes of average mass distribution were multimodal for both the urban and non-urban samples. The average mass concentration of atmospheric aerosols in the industrial/agricultural area was larger than in city center and natural park areas. The mass median diameter (MMD) were 0.80 μm, 0.51 μm and 0.46 μm for the natural park, city center and industrial/agricultural samples, respectively. In both the urban and non-urban areas, the particles in accumulation and coarse modes were the main contributors to total mass concentration, the particles in Aitken nuclei mode were only a few percent of total mass.     

北京郊区农田夏季大气颗粒物质量和离子成分谱分布特征

农业活动是大气颗粒物的重要来源之一.为了研究北京郊区农田大气颗粒物质量和离子成分的分布,探讨其来源,本研究使用8级串联撞击式采样器MOUDI采集了2004年夏季北京远郊菜地的大气颗粒物样品,测量了0.18～18μm粒径段颗粒物质量和水溶性无机离子的粒径分布.细粒子的主要离子成分是SO₄^2-、NO₃^-和NH₄⁺,与温度、湿度和光照等条件相关,推测主要来自农田释放的NH₃与光化学生成的酸性物种的反应.细粒子中的K⁺可能来自植物的排放和生物质的燃烧.粗粒子中Ca²⁺、Mg²⁺、NO₃^-和SO₄^2-可能主要来自土壤颗粒物通过机械过程进入大气,以及其后酸性物种和土壤颗粒物表面的化学反应.研究结果表明,施用的化肥和土壤可能是决定农田大气中颗粒物的重要因素,北京远郊菜地对大气颗粒物可能有着重要的贡献.     

Dry deposition of atmospheric aerosols by dual tracer method — I. Area source

Aerosol deposition velocities can be estimated from measurements of the ratio of the concentration of a depositing species, such as Pb, to a non-depositing (conserved) species, such as CO, when both originate from the same source (dual tracer method). This method has been applied to size-segregated aerosol samples collected in Los Angeles, CA during the Southern California Air Quality Study, summer 1987. Lead size distributions were measured in ambient and tunnel samples using an eight-stage low pressure impactor. A new parameter, the fraction of aerosol remaining airborne, was directly determined. This fraction is of great importance receptor modelling. Dry deposition velocities calculated using a stirred atmosphere (box) model, varied over three orders of magnitude depending on particle size. The calculated deposition velocity for unit density particles > 0.5 μm, was approximately proportional to D_p² as expected for deposition by an interception mechanism (d_p = particle aerodynamic diameter).     

天津市典型城区大气碳质颗粒物的粒径分布特征和来源

为分析天津市典型城区大气碳质颗粒物的粒径分布及其来源,于2009年12月—2010年11月采用9级惯性撞击式分级采样器对大气颗粒物进行采样,采用热光碳分析仪分析了颗粒物中的EC(元素碳)和OC(有机碳)的质量浓度. 结果表明:天津市典型城区大气颗粒物中EC和OC主要存在于细颗粒物中,在≤2.1μm的4个细粒径段中,ρ(EC)的加和年均值为(2.6±0.9)μg/m3,占PM₉(空气动力学直径≤9.0μm)ρ(TEC)的72%;ρ(OC)为(21.5±7.7)μg/m3,占PM₉中ρ(TOC)的60%. ρ(EC)和ρ(OC)季节变化显著,在≤2.1μm粒径段中,春、夏、秋、冬季的ρ(EC)分别为(1.7±0.3)、(2.1±0.4)、(3.1±0.5)和(3.7±0.5)μg/m3;ρ(OC)分别为(17.6±0.4)、(14.4±1.1)、(21.9±1.8)和(32.1±2.5)μg/m3. ρ(EC)峰值分别出现在≤0.43、>0.65~1.1和>4.7~5.8μm 3个粒径段,其中最高值出现在≤0.43μm粒径段;ρ(OC)峰值分别出现在>0.65~1.1和>4.7~5.8μm 2个粒径段,最高值出现在>0.65~1.1μm粒径段. 天津市典型城区细颗粒物中的OC、EC主要来自燃煤、机动车和烹饪排放,粗颗粒物中的OC、EC则更多来自于路面和建筑扬尘.      

夏季青岛大气粗细粒子中微量元素的浓度、溶解度及干沉降通量

利用2016年6~7月在青岛采集的PM_(2.5)和总悬浮颗粒物(TSP)样品,分析其中12种微量元素总态和溶解态浓度,讨论了微量元素在粗、细粒子中的浓度及溶解度的分布特征,并估算了微量元素的沉降通量.结果表明,青岛气溶胶中地壳元素Al、Fe、Sr、Mn、Ba总态浓度的55%~60%集中在粗粒子中,人为元素Cr、Ni、V、Zn、Pb、As、Cd的65%~85%集中在细粒子中.但无论是地壳元素还是人为元素其溶解态浓度均主要分布在细粒子中,Al、Fe、Mn、Ba在细粒子中的占比为50%~80%,Cr、Ni、V、Zn、Pb、As、Cd的为70%~90%.微量元素溶解度在细粒子中的高于粗粒子中的,细粒子中微量元素的溶解态浓度与酸组分呈显著正相关,溶解度与p H呈显著负相关,表明酸化作用可能是影响细粒子中微量元素溶解度的主控因子.不同微量元素的总沉降通量中溶解态部分的贡献不同,Al和Fe溶解态部分的贡献仅为1%~2%,Sr、Ba、Cr、Pb的约为30%~40%,Mn、Ni、V、Zn、As、Cd的约为50%~60%.大气沉降的溶解态Fe可支持(194±150)mg·(m2·d)-1浮游植物碳的生产,对黄海初级生产力的贡献约为10%.     

Effects of continuously regenerating diesel particulate filters on regulated emissions and number-size distribution of particles emitted from a diesel engine

The effects of continuously regenerating diesel particulate filter (CRDPF) systems on regulated gaseous emissions, and number-size distribution and mass of particles emanated from a diesel engine have been investigated in this study. Two CRDPF units (CRDPF-1 and CRDPF-2) with di erent specifications were separately retrofitted to the engine running with European steady-state cycle (ESC). An electrical low pressure impactor (ELPI) was used for particle number-size distribution measurement and mass estimation. The conversion/reduction rate (RCR) of hydrocarbons (HC) and carbon monoxide (CO) across CRDPF-1 was 83% and 96.3%, respectively. Similarly, the RCR of HC and CO and across CRDPF-2 was 91.8% and 99.1%, respectively. The number concentration of particles and their concentration peaks; nuclei mode, accumulation mode and total particles; and particle mass were highly reduced with the CRDPF units. The nuclei mode particles at downstream of CRDPF-1 and CRDPF-2 decreased by 99.9% to 100% and 97.8% to 99.8% respectively; and the particle mass reduced by 73% to 92.2% and 35.3% to 72.4%, respectively, depending on the engine conditions. In addition, nuclei mode particles increased with the increasing of engine speed due to the heterogeneous nucleation initiated by the higher exhaust temperature, while accumulation mode particles were higher at higher loads due to the decrease in the air-to-fuel ratio (A/F) at higher loads.     

北京冬、夏季颗粒物及其离子成分质量浓度谱分布

为认识北京大气颗粒物的重要特性之一的粒径谱分布,利用多级撞击式颗粒物采样器MOUDI对北京城区夏季和冬季大气颗粒物进行了4次为期1周的采样,采样时间分别是2001-07、2002-03、2002-07和2003-01.通过分析获得了颗粒物及其离子成分的质量浓度谱分布;发现北京城区颗粒物中细粒子占PM₁₀的40%～60%,已经成为PM₁₀的主要组成部分;但是细粒子和粗粒子的质量浓度与PM₁₀都有很强的相关性(R²>80%),仍然可以通过控制粗粒子的浓度来降低PM₁₀的浓度;在细粒子浓度高于70μg·m^-3时,硫酸盐、硝酸盐和铵盐在细粒子中所占比例之和大于70%,是颗粒物浓度升高的主要因素;并且观测到颗粒物的质量粒径谱分布在积聚模态存在2个亚模态以及积聚模态出现在1.0～1.8μm的粒径段的谱分布;对于积聚模态峰值出现在1.0～1.8μm粒径段的原因,进行了初步分析.     

华南高山背景地区黑碳云内清除特征

基于2020年南岭背景高山地区的3个典型云事件,利用地用逆流虚拟撞击器采集云中颗粒物,结合单颗粒黑碳光度计和激光雾滴谱仪分析黑碳浓度及云参数特征,探讨黑碳云内清除率及其影响因素.结果表明：进入云内的黑碳约占整体的20%,而云中含黑碳云滴的占比（4.67%）则少于含黑碳间隙颗粒的占比（15.31%）;黑碳的分粒径质量清除率和数量清除率接近,变化范围均为28%~59%;高液态含水量和云滴数浓度有利于黑碳云内清除率的增加,而黑碳云内清除率会随黑碳总浓度的增加而降低,各因素对于黑碳云内清除的影响由大到小为：云滴数浓度>液态含水量>总黑碳浓度.     

Mass and trace element size distributions of aerosols emitted by a hospital refuse incinerator

Mass and elemental size distributions of hospital refuse incineration aerosols were measured in the aerodynamic particle size range 0.02–17 μm with an in-stack compressible flow, low pressure impactor. Oil was used as a supplementary fuel in the refuse combustion process and flue gases were cleaned with a cyclone. Mass size distributions were bimodal. The geometric aerodynamic mean diameter of the fine mode varied between 0.1 and 0.2 μm and the corresponding coarse mode mean between 6 and 10 μm. Mg, Al, Cl, Ti and Fe were found only in coarse mode particles. Elemental size distributions of Na, K, Zn, Cd, Pb and S were bimodal. Over 90% of the particle phase of S, 20–80% of Zn, 62–77% of Cd and 7–74% of Pb, respectively, were found in the fine mode particles. This existence of the fine mode peak in the size distributions of Na, K, Zn, Cd, Pb and S indicates that at least part of these elements vaporizes during the refuse incineration process.     

2004年春季北京一次沙尘暴的理化特性分析

2004-03-27～2004-03-29北京发生沙尘暴天气期间,监测了气溶胶TSP、PM10和PM2.5的浓度,利用撞击式采样器采集了8级膜样品,并用ICP-MS分析了气溶胶中元素的含量,同时监测了地面辐射和风速的变化.结果显示,此次沙尘暴导致TSP浓度比平时增加3～4倍,PM10浓度增加2～3倍,PM2.5浓度有所降低.研究还表明:地壳元素Na、Mg、Al、Mn和Fe主要分布在粗粒子上.而污染元素Zn、Pb主要分布在细粒子上,污染元素主要是本地源.沙尘暴对总辐射有明显的影响,导致地面总辐射衰减了37.8%.受大风影响粗粒子浓度增加显著,细粒子浓度明显减少.     

Aerosols in Santiago de Chile: A study using receptor modeling with X-ray fluorescence and single particle analysis

Between 15 January and 26 February 1987, 51 fine and coarse mode aerosol samples were collected at the Universidad de Santiago de Chile Planetarium using a dichotomous sampler. The samples were analyzed by X-ray fluorescence for up to 17 elements (Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br and Pb). Aerosol particles were individually studied by Electron Probe Microanalysis (EPMA) and Laser Microprobe Mass Analysis (LAMMA). The data set consisting of aerosol elemental concentrations and meteorological variables was subjected to Principal Factor Analysis (PFA), allowing the identification of six fine mode particle source classes (soil, industrial, sulfate particles, traffic, residual oil, wood-burnings), and five coarse mode particle source classes (soil, industrial, traffic, residual oil, sulfate particles). Both PFA solutions explained about 81 and 90% of the total variance in the data set, respectively. The regression of elemental mass concentrations on the Absolute Principal Factor Scores allowed the estimation of the contribution of the different source classes to the Santiago aerosol. Within the fine fraction, secondary SO₄²⁻ particles were responsible for about 49% of the fine mode aerosol mass concentration, while 26, 13, 6.4 and 5.6% were attributed to wood-burning/car exhausts, residual oil combustion, soil dust/metallurgical, and soil dust/wood-burning releases, respectively. The coarse fraction source apportionment was mainly dominated by soil dust, accounting for 74% of the coarse mode aerosol mass concentration. A composite of soil dust and industrial release accounted for 13%; a composite of secondary sulfates contributed with 9%; a composite of soil dust and automotive emissions, and secondary sulfates were responsible for 4 and 0.03% of the coarse aerosol mass concentration, respectively. EPMA results are in satisfactory agreement with those from the bulk analysis and allowed the identification of eight particle types in both fine and coarse mode aerosols, pertaining to different source classes, namely soil, seaspray, secondary SO₄²⁻, metallurgical emissions and biomass burning release. EPMA also evidenced that one of the most abundant particle types corresponded to marine aerosol, having an average diameter of 0.7 μm for the fine mode and 2.2 μm for the coarse mode aerosol. LAMMA results indicate that, in fact, seaspray has been transported into the city of Santiago de Chile airshed, suffering several transformations and a sulfur enrichment. This analytical technique also provided evidence of the abundance of carbon-rich particles, which were not detected by either the bulk X-ray analysis or EPMA; they are probably due to fossil-fuel combustion releases.     

上呼吸道内可吸入颗粒物运动及沉降的模拟研究

建立了一个从人体口腔到前3级支气管的上呼吸道3维几何模型和流场计算模型以及可吸入颗粒物运动模型.将数值模拟结果与相关的实验数据进行了对比,表明数值模拟结果与实验结果基本吻合.在此基础上,在拉格朗日框架下追踪研究了可吸入颗粒物的运动轨迹,并统计了颗粒物在气道内不同部位的沉积分数;对人体上呼吸道内可吸入颗粒物的运动及沉积过程以及影响因素进行了分析.结果表明,可吸入颗粒物在上呼吸道内不同部位的沉积与呼吸强度、颗粒物密度以及粒径等因素密切相关;高呼吸强度时颗粒物在气管内的沉积分数明显升高,且随粒径的增大呈下降趋势;颗粒物在喉部的沉积分数最大,可以达到35%左右,但沉积分数受呼吸强度和粒径的影响相对较小;颗粒物在支气管内的沉积分数随粒径增大呈明显下降趋势;中小呼吸强度下颗粒物在支气管内的沉积分数明显高于高呼吸强度下的沉积分数.研究成果可以为可吸入颗粒物对人体健康影响的研究以及医学中气溶胶吸入疗法的研究等提供一定的依据.     

西安泾河夏季黑碳气溶胶及其吸收特性的观测研究

为研究西安泾河夏季黑碳气溶胶及其吸收特性,利用2011年夏季西安远郊泾河大气成分站观测的黑碳气溶胶浓度、颗粒物质量浓度、探空资料、地面气象资料,计算边界层顶高度、气溶胶吸收系数、大气消光系数,导出单次散射反照率,并对其进行分析讨论.结果表明:西安夏季黑碳气溶胶浓度为6.07μg/m3;黑碳气溶胶占颗粒物质量浓度PM1.0比值为21.9%,黑碳气溶胶与颗粒物质量浓度PM1.0、PM2.5、PM10相关系数分别为0.69、0.85、0.91;黑碳气溶胶浓度受城市边界层顶高度影响,风向、风速对泾河黑碳气溶胶的堆积输送有不同作用;气溶胶吸收系数和大气消光系数日变化显著,气溶胶吸收系数占大气消光系数比值范围在12%~30%;季单次散射反照率平均值为0.76,变化范围在0.70~0.84.     

不同粒径大气颗粒物中有机碳(OC)和元素碳(EC)的分布

使用Andersen六段分级大流量采样器(粒径:7.2～10,3.0～7.2,1.5～3.0,0.95～1.5,0.49～0.95,＜0.49μm)采集了广州市荔湾区冬季的大气颗粒物样品,并用美国Sunset碳分析仪分析了其中的有机碳(OC)和元素碳(EC)组分.研究表明:OC和EC主要存在于细粒子中,与OC相比,EC则相对更集中于＜0.49 μm粒径上;PM10中二次有机碳占总有机碳(ρ(OCsec)/ρ(OC.))比例的平均值为卵%,OC,EC的对数模型图都为双峰型.对ρ(OCtot),ρ(OCpri)(一次有机碳质量浓度)与ρ(EC)进行相关性分析,结果表明,只用ρ(OC)/ρ(EC)值来评价二次污染是不充分的.