南半球海洋大气气溶胶单颗粒的理化特性分析

运用透射电子显微镜-X射线能谱技术分析了中国第29次南极科考期间采集的大气气溶胶单颗粒样品,获得颗粒物的形貌特征、混合状态、成分组成及数量分布等信息.结果表明,航渡区域海洋上空的颗粒物主要表现为4类:海盐颗粒、矿物颗粒、富硫颗粒和含碳颗粒,其中海盐颗粒占主导,本研究将海盐颗粒又分为新鲜、部分老化及完全老化的海盐颗粒.部分和完全老化的海盐颗粒占海盐颗粒总数的86%,且部分老化的海盐颗粒表面及完全老化的海盐颗粒以长条状Na2SO4成分为主.同时,发现两处采样点(印度洋中东部和南极内陆)的样品中富硫颗粒较多,根据后向气团轨迹判断这些富硫颗粒主要来源于海洋地区,推测是由海洋表面浮游生物释放的二甲基硫(dimethyl sulfide,DMS)经过大气氧化形成.本研究表明,南半球海洋大气中海盐颗粒老化是由海洋表面释放的DMS控制,这不同于北半球海洋大气中人为源影响的海盐颗粒老化现象.     

南极菲尔德斯半岛植被微区CO2浓度的监测

在南极苔藓植被的微环境区内,CO₂的浓度在473.5mg·m^-3以上,大大高于全球CO2的平均浓度(356 mg·m^-3),可见苔藓等植被区可能是大气CO₂的源之一.这与特殊的南极条件下植被的生理生态特性有关.在苔藓分布区,CO₂浓度日变化的主要影响因素是光照和温度.菲尔德斯半岛变化无常的天气状况使得CO₂浓度昼夜变化规律出现局部波动,不同的天气状况也使CO₂浓度发生变化.研究表明:光照条件是CO₂浓度变化的主导影响因素,从CO₂浓度的季节变化中可以看出,CO₂浓度变化与大气温度呈负相关;与降水量和空气相对湿度呈正相关.本文首次给出了极地环境下植被微区的CO₂浓度变化及其影响因素,为极地温室气体的研究提供了新的材料.     

Variations in stable hydrogen and oxygen isotopes in atmospheric water vapor in the marine boundary layer across a wide latitude range

The newly-developed cavity ring-down laser absorption spectroscopy analyzer with special calibration protocols has enabled the direct measurement of atmospheric vapor isotopes at high spatial and temporal resolution. This paper presents real-time hydrogen and oxygen stable isotope data for atmospheric water vapor above the sea surface, over a wide range of latitudes spanning from 38°N to 69°S. Our results showed relatively higher values of 8180 and 82H in the subtropical regions than those in the tropical and high latitude regions, and also a notable decreasing trend in the Antarctic coastal region. By combining the hydrogen and oxygen isotope data with meteoric water line and backward trajectory model analysis, we explored the kinetic fractionation caused by subsiding air masses and related saturated vapor pressure in the subtropics, and the evaporation-driven kinetic fractionation in the Antarctic region. Simultaneous observations of meteorological and marine variables were used to interpret the isotopic composition characteristics and influential factors, indicating that d-excess is negatively correlated with humidity across a wide range of latitudes and weather conditions worldwide. Coincident with previous studies, d-excess is also positively correlated with sea surface temperature and air temperature （Tair）, with greater sensitivity to Tair. Thus, atmospheric vapor isotopes measured with high accuracy and good spatial- temporal resolution could act as informative tracers for exploring the water cycle at different regional scales. Such monitoring efforts should be undertaken over a longer time period and in different regions of the world.     

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.     

青岛大气颗粒物数浓度变化及对能见度的影响

为研究青岛地面大气颗粒物数浓度的变化及对能见度的影响,2010年9月~2011年8月使用便携式light house激光粒子计数器进行了大气颗粒物数浓度观测,利用Hysplit模式计算大气颗粒物的后向轨迹,运用统计分析方法初步探讨了气象因子对大气颗粒物数浓度和能见度的影响.结果表明,青岛大气颗粒物数浓度冬春最高,秋季次之,夏季最低;源自新疆、甘肃一带的气团颗粒物数浓度偏高,而来自于东北方向及海上的大气颗粒物数浓度较低;大气颗粒物数浓度变化与风速、相对湿度和混合层高度的变化呈现较好的负相关关系.当气团来源于西或西北方向,地面风向为南到东南风且混合层高度较低时,细粒子数浓度较高,容易出现低能见度现象.     

基于Mie理论的带电沙尘媒质微波衰减特性研究

目的研究带电沙尘媒质中微波衰减特性。方法根据带电球形粒子Mie散射理论,分析带电沙尘粒子的散射特性及带电沙尘媒质的微波衰减。结果在同一频率下,消光系数随着沙粒半径增大而增大,带电沙粒的消光系数要大于不带电沙粒的消光系数。对于同一频率和能见度,带电沙的衰减要比不带电沙的衰减要大,且衰减随能见度的增大而减小。结论带电沙尘粒子对微波传播影响比中性沙尘粒子明显。     

Zeta电位法研究除草剂在土壤胶体中的吸附

应用Zeta(ζ)电位法研究比较了扑草净和扑灭通在4种土壤胶体中的吸附.结果表明,当带有正电荷的除草剂在负电荷土壤表面吸附后,土壤表面的ζ电位有所增加,甚至使ζ电位从负转变成正.通过零电荷点计算得到除草剂和土壤之间的吸附常数和Gibbs自由能,并由经典的振荡平衡法得到相近结果.     

基于TEM-EDS对四川盆地大气单颗粒气溶胶的研究

为了解四川盆地大气中单颗粒气溶胶理化特征,分别在该区域典型城市（成都市）和背景地区（峨眉山）进行了大气单颗粒样品采集.基于带能谱的透射电子显微镜（TEM-EDS）对两地累计3923个单颗粒的化学组成、形貌特征及混合状态等进行了全面观测和分析,并对两地颗粒物差异性进行了对比分析.结果发现：两地气溶胶颗粒主要包括有机物、富硫、矿物、烟尘和飞灰/金属颗粒,除了以单独的外混形式存在外,大多数颗粒以两种及两种以上颗粒类型混合（即内混）形式存在.通过对成都市不同污染状况下单颗粒特征对比发现,"污染天"的内混颗粒占比高于"清洁天",分别为74.2%和68.6%;相比"清洁天","污染天"颗粒物粒径分布范围更广且峰值区间更大,表明污染过程中颗粒物的大气混合趋于更强.对比成都市与峨眉山分析结果得知,成都市以内混的有机物-硫颗粒为主导（占比为50.2%）,而峨眉山以外混的有机物颗粒为主导（占比为50.5%）;成都市含硫类颗粒物（如有机物-硫颗粒）贡献高于峨眉山,而峨眉山两种含碳类颗粒（如烟尘和有机物-烟尘颗粒）占比高于成都市;此外,成都市与峨眉山两地大气颗粒物粒径分布范围及峰值区间均存在一定差异,进一步体现了两地颗粒物来源和老化混合的差异.在峨眉山,与非降雨天相比,一些易溶于水的颗粒物（如含硫类颗粒）在降雨天占比明显降低,而源自当地燃烧过程、粒径较小且疏水性强的颗粒物（如烟尘和有机物-烟尘颗粒）占比相应升高.     

Influence of floc dynamic protection layer on alleviating ultrafiltration membrane fouling induced by humic substances

Cake layer formation is inevitable over time for ultrafiltration (UF) membrane-based drinking water treatment. Although the cake layer is always considered to cause membrane fouling, it can also act as a “dynamic protection layer”, as it further adsorbs pollutants and dramatically reduces their chance of getting to the membrane surface. Here, the UF membrane fouling performance was investigated with pre-deposited loose flocs in the presence of humic acid (HA). The results showed that the floc dynamic protection layer played an important role in removing HA. The higher the solution pH, the more negative the floc charge, resulting in lower HA removal efficiency due to the electrostatic repulsion and large pore size of the floc layer. With decreasing solution pH, a positively charged floc dynamic protection layer was formed, and more HA molecules were adsorbed. The potential reasons were ascribed to the smaller floc size, greater positive charge, and higher roughness of the floc layer. However, similar membrane fouling performance was also observed for the negative and positive floc dynamic protection layers due to their strong looseness characteristics. In addition, the molecular weight (MW) distribution of HA also played an important role in UF membrane fouling behavior. For the small MW HA molecules, the chance of forming a loose cake layer was high with a negatively charged floc dynamic protection layer, while for the large MW HA molecules it was high with a positively charged floc dynamic protection layer. As a result, slight UF membrane fouling was induced.     

荷电雾滴表面带电尘粒捕集的数值分析

通过数值计算分析了带电粉尘粒子在荷电雾滴上的捕集特性,主要考虑尘粒惯性和静电效应对于提高粒子捕集效率的相对强弱.结果表明,在不同粒径区间内,粒子的惯性效应和雾滴与粒子间的库仑力对强化粒子靶效率的作用需要仔细加以辨认,同时证明了当雾滴弱荷电时,对亚微米带电粒子捕集依然是有效的.     

自贡市大气颗粒物污染特征及来源解析

利用自贡市大气监测数据、同期气象数据以及颗粒物源解析在线监测资料,对颗粒物污染的特征及成因进行研究.结果表明:颗粒物年均浓度受浮尘天气影响明显,季均浓度呈冬高夏低变化,月均浓度呈"U"字形变化,日均浓度呈双峰型变化;颗粒物与降水、温度、气压、风速存在相关性,与相对湿度无相关性,PM10、CO、NO2、SO2、O3浓度对PM2.5浓度变化影响显著;PM2.5主要成分为元素碳、有机碳、富钾颗粒等,主要来源为机动车尾气、燃煤、工业工艺源等.     

Sources and characteristics of the atmospheric aerosol near Damascus,Syria

Coarse (>2 μm) and fine (<2 μm) atmospheric particulate material was collected in the Zabadani Valley, near Damascus, in August 1985, and analyzed for sulfate, nitrate, and about 40 elements. Individual particles were analyzed for chemical and morphological parameters. Particle number concentrations and size distributions were also measured. The physical aerosol characteristics, and particularly the chemical composition indicate that the airborne particles in this arid region are predominantly due to desert soil dispersion, but that there is also some contribution from anthropogenic sources. The crustal elements exhibit atmospheric concentrations which are comparable to those in urban and industrial areas. The anthropogenic elements, on the other hand, are clearly less abundant in the Zabadani Valley than in industrialized regions. The individual particle analysis indicated that there are two major soil dust components with respectively a shale-like and a limestone composition. The data set with the bulk atmospheric concentrations (sum of coarse and fine) was subjected to chemical mass balance receptor modeling in order to assess the impact of the various plausible aerosol sources. It was found that desert soil dispersion is responsible for at least 90% of the total suspended particulate mass concentration, and that the shale and limestone components contribute in about equal proportions.     

沈阳冬季灰霾日大气颗粒物元素粒径分布特征

为分析沈阳市冬季灰霾日大气颗粒物元素粒径分布特征,2009年1月14日─2月2日,用安德森分级撞击式采样器进行大气颗粒物分级采样,并用电感耦合等离子体质谱仪(ICP-MS)对各级样品中Na和K等30余种元素进行分析,讨论了灰霾日、非霾日及除夕日大气颗粒物元素质量浓度和富集因子的粒径分布特征及来源. 结果表明:灰霾日大气颗粒物及其元素的质量浓度均高于非霾日,粒径越细,质量浓度越高,越容易富集污染元素.Fe类元素以地壳元素为主,其质量浓度的粒径分布在非霾日呈双峰型,最高峰值出现在9.0～10 μm粗粒径段;该类元素的粒径分布在灰霾日和除夕日呈三峰型,质量浓度的最高峰值也在9.0～10 μm粗粒径段. Mn类元素在非霾日的质量浓度分布与Fe类元素相似,也呈双峰型,最高峰值出现在9.0～10 μm粗粒径段;但其在灰霾日和除夕日呈双峰型,最高峰值却出现在粒径<1.1 μm的细粒径段. K类和Zn类元素的质量浓度和富集因子的粒径分布均呈单峰型,峰值出现在粒径<1.1 μm的细粒径段. K类元素主要来源于烟花爆竹释放;Zn类元素主要源于人为污染,Pb和As等污染元素因其来源不同,在灰霾日和非霾日的表现也不相同.      

南黄海辐射沙脊群潮汐通道水流输运示踪模拟

将三维水动力模型MIKE3耦合粒子追踪模型,模拟辐射沙脊群海域西洋、陈家坞槽、苦水洋、黄沙洋四个主要潮汐通道和沙脊群顶点处的粒子运动轨迹,探讨潮汐通道间的水流运动、物质输运及交换特性。结果表明:潮汐通道内涨潮期表层粒子净位移大于落潮期;小潮期间,表、底层粒子运动轨迹相似,主要为潮汐通道内的往复运动;大潮期间,各通道粒子轨迹主要为往复运动和顺时针螺旋状横向运动两种形式,不同通道或同一通道的表、底层轨迹均不同,且不同的释放时刻粒子越出通道的程度也不同,表层粒子的运动范围更大,而底层相对集中。粒子运动轨迹由西洋通道的往复流和其余区域不同程度的旋转流所控制。与小潮相比,大潮期间潮汐通道的水体垂向环流及水体交换更为明显。通道内的水流横向输运能力主要取决于横向环流流速与纵向主流流速的相对强弱,同时也受局部地形影响。辐射沙脊群顶点处粒子大多数向岸,少量向南、北沿岸运动,表明近岸水流和物质迁移的主要向岸趋势。本研究结果可为辐射沙脊群海域水环境的管理提供理论支撑。     

南北极大气气溶胶单颗粒成分特点研究

运用定量电子探针微区分析技术(EPMA)分别测定了采自北极新奥尔松地区(78?55′N、11?56′E)和南极乔治王岛(62?13′S、58?47′W)极昼天气下PM10大气颗粒物样品.结果表明,北极和南极大气颗粒物化学成分存在很大差异,表现出各自不同的特点.北极的颗粒类型中,“反应的海盐”和“矿物尘”分别占颗粒总数的44%和27%,“新鲜海盐”所占的比例不到10%,“反应的海盐”中以含硝酸盐的颗粒为主,反映了外来物质或人为污染对该地气溶胶影响较大;南极的颗粒类型中,“新鲜海盐”占总数的74%左右,“反应的海盐”占19%,反应的海盐全部含硫酸盐、未发现含硝酸盐的颗粒,推测与海盐反应的含硫物质来源于海洋浮游生物代谢过程产生的二甲硫醚(DMS)及其降解产物,而与人为污染无关.     

鞍山市大气中多环芳烃健康影响评价

通过对鞍山市典型区域（6个污染源、4个居住区、一个对照点）大气颗粒物中PAHs的监测,采用BaP当量致毒系数TEF,研究了鞍山市大气颗粒物中典型PAHs毒性当量分布特征。研究结果表明,鞍山大气中典型PAHs污染主要以4～6环为主,不致癌BaP当量浓度为0．066ng/m3,致癌BaP当量浓度为12．7ng／m3,强致癌BaP当量浓度为8．1ng/m3,很强致癌BaP当量浓度为12．7ng／m3。BaP毒性当量浓度呈现出采暖期要远远高于非采暖期,工业区及工业区周边BaP毒性当量浓度要远远高于居住区和对照点。     

星形线电除尘器内EHD流动与粒子行为数值模拟

为了研究星形线电除尘器内电流体动力学（EHD）流动与荷电粒子运动行为及两者间相互作用,构建了线板式电除尘器（ESP）内关于EHD和带电粒子运动学的耦合数值模型.该模型采用有限体积法离散求解电场方程和空间电荷方程,在拉格朗日法下建立带电粒子运动方程,并与FLUENT湍流模型进行耦合.利用这一模型,对3种电场风速下星形线电除尘器内流动形态与粒子运动行为进行了细致模拟,并分析了二次流动对气流、粒子浓度分布的影响.结果表明,星形线电除尘通道内二次流动对流动形态和粒子浓度分布存在显著作用.随电场风速的降低,这一作用将越明显.EHD流动对细小荷电粒子运动的影响更为显著.二次流动产生涡旋并作用于主流来影响粒子运动行为.收尘板面的涡旋挤压粒子流远离壁面向流动中心运动,放电极下游的涡旋则促进粒子流向收尘板壁面靠近.此外,由于捕集通道中强二次流的存在,Deutsch计算式对除尘效率、特别是对于亚微米粒子捕集效率的计算并不准确.     

计算机控制扫描电镜技术(CCSEM)在大气颗粒物表征及源解析中的应用

近年来,我国环境空气质量不断改善,在此背景下准确掌握大气颗粒物的理化性质及其来源是精准治污的重要基础. 计算机控制扫描电镜技术(CCSEM)的快速发展大幅提高了单颗粒分析效率,为实现颗粒物精细化源解析提供新的技术手段. 本文介绍了CCSEM技术的原理、特点、测试流程及技术发展,梳理了CCSEM在大气颗粒物的理化性质、来源解析及健康效应中的研究成果,总结了CCSEM的发展前景及局限性. 结果表明:CCSEM可通过自动化测试快速获取更全面的颗粒物信息,后处理功能便于快速掌握颗粒物污染源精细化信息,寻找部分隐匿的污染源,对比不同区域颗粒物类型的差异,并获取颗粒物精细化源解析结果. CCSEM对重金属等有潜在健康危害的高原子序数元素有较高的识别效率,可应用于颗粒物健康效应研究. 因此,CCSEM在大气颗粒物精细化源解析及健康效应研究等方面有较好的应用前景. 但是,CCSEM在颗粒物识别、分类标准及分析时效性等方面有一定的局限性,在未来应通过加强CCSEM形貌识别提高颗粒物的识别效率,结合单颗粒源谱数据库制定更科学的颗粒物分类规则,以及加强采样、测试及分析的连贯性以提高分析时效性.      

Highly time-resolved aerosol characteristics during springtime in Weizhou Island

A single particle aerosol mass spectrometer was deployed to measure the changes of single particle species and sizes during March 2015 in Weizhou Island of the Beibu Gulf, Guangxi province, South China. In this campaign, a total of 3,100,597 particles were sized, and 25.8%particles with both positive and negative mass spectrum were collected and 24.8%characterized in combination with the ART-2 a neural network algorithm. The distribution of sized particles was mainly in from 520 to 600 nm, and the diameters ranging from 340 to1000 nm accounted for above 90%. Eight types of particles were classified: Elemental Carbon containing(EC), Organic Carbon containing(OC), EC and OC combined containing particles,Na containing particles, K containing particles(K), Levoglucosan containing particles,mineral containing particles, and Heavy Metal containing particles(HM). EC, OC and K were the major containing particles, which accounted for 84.3% in the eight types particles. The relative ratio and size distribution of the three types were EC(48.1%, 620 nm), OC(12.7%,440 nm), and K(23.5%, 600 nm), respectively. The three types of particles were a bit increasing ratios compared with those in clean periods during haze pollution periods.Combined with the back-trajectory results from the Hysplit-4 model and local pollution sources revealed that the ambient air quality on the Weizhou Island may be influenced by biomass burning in the Indochina Peninsula(biomass burning in the Indochina Peninsula)from the transportation on higher level atmospheric layer and by mainland of south China located northeast of Weizhou Island on the ground.     

夏收时段农村大气亚微米颗粒物数浓度分布特征

为了从源区的角度研究华北平原夏收时段大气亚微米颗粒物粒径谱分布,采用扫描电迁移率粒径谱仪,于2017年6月对华北平原典型农村点位亚微米颗粒物数浓度进行连续观测.结果表明,观测期间大气亚微米颗粒物粒径分布主要集中在小于300nm处,平均数浓度为28371cm^-3.不同模态颗粒物数浓度分布差异明显,核模态（< 20nm）呈线性分布,爱根核模态（20~100nm）呈多项分布,积聚模态（>100nm）呈对数分布.48h后向轨迹聚类结果表明,观测点位气团受其东部的江苏省、山东省和安徽省生物质燃烧传输影响时,颗粒物总数浓度增加66.7%.潜在源贡献因子法和浓度权重轨迹法,表明潜在源区为观测点位以东的区域,且以粒径小于100nm的颗粒物为主.