城市雾天单个矿物颗粒物理和化学特征

应用场发射扫描电镜(FESEM)和带能谱的扫描电镜(SEM-EDX)对北京冬季雾天和正常天气下收集的4个样品进行研究.雾天中矿物颗粒的数量-粒度分布的峰值出现在0.1～0.3 μm和1～2.5 μm之间,并且发现雾天出现的二次矿物颗粒的数量百分含量(4.67%)高于正常天气条件(0.12%).单个矿物颗粒的EDX能谱显示,雾天和正常天气中单个矿物颗粒的主要化学成分有一定的差别,尤其是S元素.矿物颗粒分为9种不同类型:"富Si"、"富Ca"、"富S"、"富Fe""富Mg"、"富Al"、"富Ti"、"富K"和"富Cl",其中雾天"富Ca"中55%的颗粒含有Ca(50%±1.2%)和S(37%±1.6%),"富S"中72%的颗粒含有S(44%±1.5%)和Ca(33%±2%),说明了雾天中绝大部富集S的颗粒物中同时富集Ca,这在一定程度上说明了北京市大气中这些含Ca的碱性矿物对雾水酸性有一定的缓冲作用.雾天样品中S/Ca的平均比值为6.11,如果以冬季正常天气条件下S/Ca的均值0.73为背景值,雾天中S/Ca的比值是冬季正常天气的8倍,可见雾天中颗粒物表面的硫化现象相当严重,同时也显示出雾天SO2向硫酸盐的转化率比较高.     

内蒙古乌达-乌斯太工业园环境单颗粒研究

2015年夏季在内蒙古乌达-乌斯太工业园布点采集了大气颗粒物核孔膜样品16件,采用扫描电镜（SEM-EDX）共表征了1600个单颗粒的形貌和化学组成,结果表明,研究区单颗粒主要为矿物颗粒、燃烧产生颗粒和含硫颗粒3大类,其中矿物颗粒不仅含有硅铝酸盐和碳酸盐这类常见颗粒,还有风化煤矸石和沙尘颗粒这两种特殊颗粒;燃烧产生颗粒不仅有通常的燃煤飞灰、烟尘集合体和絮状碳质颗粒,还有原煤尘颗粒.统计表明,烟尘聚合体、硅铝酸盐和沙尘这三者占颗粒物总数的64%,风化煤矸石尘和原煤尘主要呈现为可吸入颗粒（2.5~10μm）;烟尘聚合体和沙尘则主要为超细颗粒（<1.0μm）.总之,单颗粒分析揭示该典型煤炭工业园区大气颗粒物主要来源：园内燃煤排放和交通,上风向矿区煤炭生产和上风向沙漠自然活动.     

内陆输送过程中沙尘单颗粒类型及其非均相反应

采用单颗粒分析方法对2004 年2~3 月发生在北京的3 次沙尘暴的样品中沙尘颗粒物的化学成分进行了测定.3 次沙尘暴的反向轨迹图显示,它们主要来自于中国北部、西北部和蒙古的戈壁沙漠地区,且这些沙尘颗粒主要通过高空长距离输送到下游区域.使用带能谱的扫描电镜对481 个沙尘颗粒进行分析,并根据成分特征,把这些沙尘颗粒划分为8 种类型,主要类型有“富Si”、“富Ca”、“富S”、“富Fe”.将北京样品分析结果与呼和浩特、塔克拉玛干和敦煌的结果进行对比,结果显示,长距离输送的沙尘颗粒表面发生了SO₂ 的非均相化学反应,导致部分颗粒局部的表面发生化学修改作用,且“富Ca”的碱性矿物为非均相化学反应提供了更有利的反应界面.     

北京市不同天气条件下单颗粒形貌及元素组成特征

使用透射电镜(TEM)对采自北京市2011年3~4月间不同天气条件下的气溶胶样品进行观察,并对比2010年3月沙尘天气和2010年11月18日雾天样品,对可吸入颗粒物PM10的基本形貌、矿物元素组成和硫化特征等做比较分析.结果表明,采样期间PM10主要包括烟尘集合体、飞灰、矿物颗粒、二次反应颗粒等,不同天气条件下颗粒类型并无明显差别.采样期间矿物颗粒以“富Si”颗粒(占总量46%)为主,“富Ca”(总量17%)、“富S”颗粒(总量13%)为次要,“富Fe”(总量7%)及较少“富Na” 颗粒(总量6%)和其他颗粒.沙尘天气中沙尘暴输入大量沙尘颗粒使占颗粒83% 的“富Si”颗粒含量明显高于阴天的36%和雾天的32%.仅在阴天和雾天发现大量“富S”颗粒,其中雾天26%,阴天10.7%,说明这2种天气二次反应强烈,易于生成富S二次颗粒,对颗粒物元素组成产生影响.对所有含S颗粒分析表明,不同天气含S矿物含量差异较大,阴天16%,雾天36%,晴天和沙尘天气则含量很低,说明一定的SO2浓度下,大气湿度越大,硫化现象越明显.雾天颗粒物表面的硫化现象相当严重,在含硫量较高的颗粒中,绝大部分同时含有Ca、Na、Si、Fe等元素,说明大气中含Ca、Na、Si、Fe的碱性矿物对雾水酸性有一定的缓冲作用.     

学校食堂、烤肉店PM2.5的微观形貌及粒度分布

使用带能谱的高分辨率场发射扫描电镜(FESEM)和图像分析技术对食堂和烤肉店PM_2.5(细颗粒物)进行微观形貌观察,研究其数量-粒度分布、体积-粒度分布特征. 结果表明:从微观形貌看,PM_2.5主要有矿物颗粒、烟尘集合体、球形颗粒、其他颗粒(生物质、食盐、纤维)4种,其中矿物颗粒有不规则和规则2种形态. 烤肉店的PM_2.5可观察到形成链状的烟尘集合体,而食堂的可观察到更细颗粒组成的链状烟尘集合体.食堂矿物颗粒分别占颗粒物总数和总体积的69.23%、80.13%;数量-粒度分布呈双峰,主要分布在0.2~0.4μm范围内,小于0.5μm的矿物颗粒占颗粒物总数的58.90%;体积-粒度分布呈单峰,集中在在1~2.5μm.烤肉店矿物颗粒和其他颗粒分别占颗粒物总数的45.67%、44.86%;数量-粒度分布主要集中在0.2~0.4μm,小于0.5μm的矿物颗粒占颗粒物总数的39.41%;从体积-粒度分布上看,1~2.5μm内的矿物颗粒体积占颗粒物总体积的比例(32.36%)最大.      

民用燃煤排放细颗粒中金属元素排放特征及单颗粒分析

通过模拟民用煤炭燃烧,采集了5种不同成熟度的典型块煤燃烧排放的单颗粒和PM_2.5样品.利用带能谱仪的透射电镜研究了金属颗粒的单颗粒特征,运用电感耦合等离子体质谱仪和发射光谱仪获得了PM_2.5样品中14种金属元素（包括8种重金属）的浓度特征.结果显示,民用燃煤排放的含金属元素的颗粒物主要有矿物颗粒、部分碳质颗粒、富K颗粒、富S[K]颗粒、富Fe颗粒、富Zn颗粒和富Pb颗粒共7种.5种民用燃煤排放的14种金属元素占PM_2.5的1.29%~15.54%,其中Al、Ca和Na占金属元素总量的57%~80%,是民用燃煤排放的主要的金属元素;V、Cr、Mn、Co、Ni、Cu、Zn和Pb这8种重金属元素占PM_2.5的0.09%~2.53%,其中Zn和Pb占重金属总量的54%~91%,在民用燃煤排放的重金属中占主导.单颗粒分析结果显示Zn和Pb元素主要富集在粒径小于1μm的富Zn和富Pb颗粒中,这些细颗粒能够直接进入人体,对人体健康造成威胁.因此,建议居民应通过使用精煤或天然气等清洁能源来减少重金属的排放.     

大气可吸入颗粒物(PM_(10))单颗粒硫化特征

使用SEM/EDX对哈尔滨市夏季不同时段采集的可吸入颗粒物单个矿物颗粒的成分和硫化特征进行研究.结果表明,哈尔滨市夏季PM10中可以鉴定出的矿物有29种,其中黏土矿物所占比例超过了40%;中午时段内的样品几乎没有发生硫化,但早晚时段内采集的样品具有普遍的硫化现象,且黏土矿物发生硫化的几率最高,样品S/Ca的平均比值为1.0,是中午时段样品S/Ca值的73倍,不同时段、气象条件下样品的硫化程度不同,显示其硫化机制各不相同;按矿物的元素含量不同,矿物颗粒分为5种类型:"富Si"、"富Ca"、"富S"、"富Fe"、"富Mg",显示矿物颗粒主要来自地壳源;各时段样品中的矿物颗粒具有同源性,说明早晚时段样品中富含的S只能是大气二次化学反应的结果,且规则石膏颗粒主要是由方解石等碳酸钙盐矿物发生的硫化作用形成的.     

云南宣威地区燃煤排放PM10的微观形貌和粒度特征

宣威地区肺癌发病率居全国首位,并且肺癌与室内燃煤关系密切. 为了解宣威地区室内燃煤排放PM₁₀的微观形貌和粒度特征,使用小流量Minivol采样器,分别于2011年1月、3月和12月对宣威地区6个代表性乡镇的18个农户及对照点——贵州六盘水幸福村2个农户室内、外的PM₁₀进行采样. 采用扫描电子显微镜分析样品的微观形貌,并对颗粒物粒度进行统计分析. 根据微观形貌特征将PM₁₀分为烟尘集合体(链状、蓬松状、密实状)、球形颗粒(燃煤飞灰和焦油球)、矿物颗粒(规则和不规则状)、生物颗粒及超细未知颗粒. 结果表明:宣威地区室内PM₁₀微观形貌差别较大;室、内外PM₁₀的粒度分布在0.1~0.4μm内的颗粒数量所占比例较大,而1μm以上颗粒体积所占比例较大;小粒径颗粒对颗粒物数量贡献较大,而少数大粒径颗粒对体积贡献较大;宣威地区和对照点室内的PM₁₀数量-粒度和体积-粒度分布相似,室外PM₁₀数量-粒度特征相似但体积-粒度分布有所差异. 宣威地区室内的烟尘集合体和球形颗粒分别占颗粒物总数的10.5%和23.6%,高于对照点 (分别为7.7%和11.3%).      

北京PM10中矿物颗粒的微观形貌及粒度分布

使用高分辨率环境扫描电镜和图像分析技术对北京PM10中矿物颗粒的微观形貌和粒度分布特征进行了研究．结果表明，北京PM10中的矿物颗粒按其形貌、组成特点可以分为单矿物和矿物集合体2类；矿物颗粒多以不规则的形态出现；形态规则的矿物主要是硫酸盐类矿物，是大气化学反应的产物，形态不规则的矿物是来自扬尘的原生矿物．不同类型污染产生的PM10中矿物颗粒的粒度分布特征表现不同，在沙尘暴样品和道路扬尘样品中矿物颗粒的粒度峰值在1～2．5μm；在局地扬尘的样品中，矿物颗粒的粒度较粗．主要分布在1—2．5μm和2．5—10μm．     

硅砂中主要矿物的化学物相分析

<正> 硅砂的主要矿物为石英、长石、高岭石、云母等,分别准确测定它们的含量,对于矿床的评价和矿产资源的综合利用,均有重要作用。这些矿物大都属硅铝酸盐,彼此性质极为相近。对它们进行概略测定一般是采用X射线衍射分析。本     

Size, composition, and mixing state of individual aerosol particles in a South China coastal city

Aerosol samples were collected in summer in Macao,a coastal city of the Pearl River Delta Region in China.Morphology,size,elemental composition,and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray(SEM/EDX) and transmission electron microscopy(TEM).Based on the morphologies of 5711 aerosol particles,they consist of soot(32%),mineral(17%),secondary(22%),and unknown fine particles(29%).The sizes of these particles were mostly distributed between 0.1 and 0.4 μm.Compositions of 202 mineral particles were obtained by SEM/EDX.Mineral particles were mainly classified into three types:Si-rich,Ca-rich,and Na-rich.The compositions of typical mineral particles can indicate their sources in sampling location.For example,mineral particles,collected along the main street,were associated with trace amounts of heavy metals,such as Zn,Ti,Mn,Ba,Pb,and As.TEM observations indicate that most Na-rich particles were aged sea salt particles(e.g.,Na2SO4 and NaNO3) which formed through heterogeneous chemical reactions between sea salt and acidic gases.Additionally,aging time of soot was short in Macao due to high humidity,high temperature,and high levels of sunlight in Macao.Most of soot and fine mineral dust particles were internally mixed with secondary particles.     

运用单颗粒气溶胶质谱技术初步研究广州大气矿尘污染

自主研发的单颗粒气溶胶飞行时间质谱仪(Single Particle Aerosol Mass Spectrometer,SPAMS)采用空气动力学透镜、双激光测径系统以及双极飞行时间质量分析器,并用其对广州市大气细颗粒物进行在线分析,实现了矿尘颗粒物的空气动力学直径和化学组成的同时检测. 在连续4 d的采样中,共采集到249 057个粒径在0.2～1.2 μm且同时含有正负质谱信息的颗粒物,其中矿尘颗粒物占7.9%. 结果表明:矿尘颗粒物的正离子成分以Ca2+,K+>/sup>,Fe2+和Na+>/sup>为主,同时还含有Li+>/sup>,Mg2+,V>/sup>5+,Ba2+和Ti4+等;负离子成分以NO₃->/sup> 和NO₂->/sup>为主,另外还含有HSO₄->/sup>,SiO₃->/sup>和PO₃->/sup>等. 在广州市大气细颗粒物中,矿尘贡献不如含碳颗粒物和生物质燃烧颗粒物,且在矿尘颗粒物中贡献较大的几类(如含钙、含铁、含钠钾颗粒物等)大多是老化的成分.      

Characterization of coal burning-derived individual particles emitted from an experimental domestic stove

Coal combustion in the domestic stoves, which is common in most parts of the Chinese countryside, can release harmful substances into the air and cause health issues. In this study, particles emitted from laboratory stove combustion of the raw powder coals were analyzed for morphologies and chemical compositions by using transmission electron microscopy(TEM) coupled with energy-dispersive X-ray spectrometry(EDX). The coal burning-derived individual particles were classified into two groups: carbonaceous particles(including soot aggregates and organic particles) and non-carbonaceous particles(including sulfate, mineral and metal particles). The non-carbonaceous particles, which constituted a majority of the coal burning-derived emissions, were subdivided into Si-rich, S-rich, K-rich,Ca-rich, and Fe-rich particles according to the elemental compositions. The Si-rich, S-rich and K-rich particles are commonly observed in the coal burning emission. The proportions for particles of different types exhibit obvious coal-issue dependence. Burning of coal with high ash yield could emit more non-carbonaceous particles, and burning of coal with high sulfur content can emit more S-rich particles. By comparing the S-rich particles from this coal burning experiment with those in the atmosphere, we draw a conclusion that some S-rich particles in the atmosphere in China could be mainly sourced from coal combustion.     

Individual particle analysis of aerosols collected at Lhasa City in the Tibetan Plateau

To understand the composition and major sources of aerosol particles in Lhasa City on the Tibetan Plateau (TP), individual particles were collected from 2 February to 8 March, 2013 in Tibet University. The mean concentrations of both PM_2.5 and PM₁₀ during the sampling were 25.7 ± 21.7 and 57.2 ± 46.7 μg/m³, respectively, much lower than those of other cities in East and South Asia, but higher than those in the remote region in TP like Nam Co, indicating minor urban pollution. Combining the observations with the meteorological parameters and back trajectory analysis, it was concluded that local sources controlled the pollution during the sampling. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectra (EDS) was used to study 408 particles sampled on four days. Based on the EDS analysis, a total of 8 different particle categories were classified for all 408 particles, including Si-rich, Ca-rich, soot, K-rich, Fe-rich, Pb-rich, Al-rich and other particles. The dominant elements were Si, Al and Ca, which were mainly attributed to mineral dust in the earth's crust such as feldspar and clay. Fe-, Pb-, K-, Al-rich particles and soot mainly originated from anthropogenic sources like firework combustion and biomass burning during the sampling. During the sampling, the pollution mainly came from mineral dust, while the celebration ceremony and religious ritual produced a large quantity of anthropogenic metal-bearing particles on 9 and 25 February 2013. Cement particles also had a minor influence. The data obtained in this study can be useful for developing pollution control strategies.     

北极夏季大气气溶胶单颗粒研究

为研究北极地区大气气溶胶颗粒的物理化学特性,于2013年8月8~12日环Svalbard岛收集大气气溶胶样品,利用带能谱的透射电子显微镜(TEM-EDS)共分析2530个单颗粒,并获得颗粒物的形貌特征和化学组成.结果表明,北极地区颗粒物主要表现为5种类型,分别为海盐颗粒、富S颗粒、富Fe颗粒、含碳颗粒和矿物颗粒.后向气流轨迹显示,采样期间大气污染物主要来自于北极点周边的海洋上空和附近格陵兰岛地区.来自海洋上空的大气中主要包含海盐颗粒,所占数量比例为54.7%;经过陆地的大气样品中95.4%为矿物颗粒.利用时间密度因子法估算出北极地区PM2.5质量浓度范围为0.55~0.72mg/m3.     

Seasonal features of aerosol particles recorded in snow from Mt. Qomolangma （Everest） and their environmental implications

To assess the seasonality of aerosol deposition and anthropogenic effects on central Himalayas, a 1.85-m deep snow pit was dug on the northern slope of Mr. Qomolangma (Everest). Based on the morphology and energy dispersive X-ray (EDX) signal, totally 1500 particles were classed into 7 groups: soot; aluminosilicates; fly ash; calcium sulfates; Ca/Mg carbonates; metal oxides; and biological particles and carbon fragments. The size distribution and number fractions of different particle groups exhibited distinct seasonal variations between non-monsoon and monsoon periods, which are clearly related to the differences in air mass pathways. Specifically, the relative abundance of soot in non-monsoon period (25%) was much higher than that in monsoon period (14%), indicating Mr. Qomolangma region received more anthropogenic influence in non-monsoon than monsoon period.