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

Sophie Sobanska  Cécile Coeur  Willy Maenhaut  Freddy Adams 《Journal of Atmospheric Chemistry》2003,44(3):299-322

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.  相似文献   

Products and Mechanism of the Gas Phase Reaction of Ozone with β-Pinene     

Richard Winterhalter  Peter Neeb  Dirk Grossmann  Antje Kolloff  Osamu Horie  Geert Moortgat 《Journal of Atmospheric Chemistry》2000,35(2):165-197

Gas phase ozonolysis of -pinene was performedin a 570 l static reactor at 730 Torr and 296 K insynthetic air and the products were analysed by acombination of gas phase FTIR spectroscopy, HPLC andIC analyses of gas phase and aerosol samples,respectively. The reaction mechanism was investigatedby adding HCHO, HCOOH and H₂O as Criegeeintermediate scavenger and cyclohexane as OH radicalscavenger. Main identified products (yields inparentheses) in the presence of cyclohexane as OHradical scavenger were HCHO (0.65 ± 0.04),nopinone (0.16 ± 0.04), 3-hydroxy-nopinone (0.15± 0.05), CO₂ (0.20 ± 0.04), CO (0.030± 0.002), HCOOH (0.020 ± 0.002), the secondaryozonide of -pinene (0.16 ± 0.05), andcis-pinic acid (0.02 ± 0.01). The decompositionof the primary ozonide was found to yieldpredominantly the excited C₉-Criegee intermediateand HCHO (0.84 ± 0.04) and to a minor extent theexcited CH₂OO intermediate and nopinone (0.16± 0.04). Roughly 40% of the excitedC₉-Criegee intermediate becomes stabilised andcould be shown to react with HCHO, HCOOH and H₂O. The atmospherically important reaction of thestabilised C₉-Criegee intermediate with H₂Owas found to result in a nopinone increase of (0.35± 0.05) and in the formation of H₂O₂(0.24 ± 0.03). Based on the observed products,the unimolecular decomposition/isomerisationchannels of the C₉-Criegee intermediate arediscussed in terms of the hydroperoxide and esterchannels. Subsequent reactions of the nopinonylradical, formed in the hydroperoxide channel, lead tomajor products like 3-hydroxy-nopinone but also tominor products like cis-pinic acid. A mechanismfor the formation of this dicarboxylic acid isproposed and its possible role in aerosol formationprocesses discussed.  相似文献   

松嫩平原西部碱尘气溶胶的元素特征分析     

胡克  陈兵  介冬梅  赵奎涛 《吉林大学学报(地球科学版)》2006,36(3):417-423

碱尘暴期间松嫩平原西部碱尘气溶胶的主要元素质量浓度排序为Na、Al、Fe、Ca、Mg、K、Ti、Ba、Zn,与当地盐碱化土壤的元素组成吻合,而与沙尘、城市气溶胶的元素组成有差别。风力对碱尘气溶胶元素组成有明显的影响,当风速在8.0~17.1 m/s时,元素组成的质量浓度排序为Na、Ca、Al、Fe、Mg、K、Ba、Ti、Zn。Na元素质量浓度的激增是碱尘暴元素组分的一大特征,明显富集元素为Na和B;相对于当地背景大气气溶胶的富集情况,Zn、Cu、Ba、B的富集因子值在碱尘暴期间明显降低;在各种天气情况下,B、Cu均具有较高的富集因子。碱尘中Ti元素的富集因子值均小于1,而Ca、Fe、K、Mg、Mn、Sr、V的富集因子值为1~4。两个采样点的Ca、Na、Al、Fe、Mg、Ti、Zn的富集因子近似,表明该区碱尘的主要元素具有特定的一致性;而B、Ba、Cu、V的富集因子相差较大,可以作为区分不同碱尘源的标志性元素。  相似文献   

生物质燃烧颗粒物有机示踪化合物的测定和应用   总被引：2，自引：0，他引：2  

张烃刘咸德  董树屏祁辉 Hélène Cachier Magda Claeys 《岩矿测试》2006,25(2):107-113

使用气相色谱-质谱法对2002年7月-2003年7月的北京市大气粗、细颗粒物样品中的左旋葡聚糖等糖类化合物进行了测定。结果表明，左旋葡聚糖主要存在于细颗粒中，可以作为示踪化合物来研究生物质燃烧现象。生物质燃烧对北京市大气颗粒物有较重要的贡献。对应于12％-40％的PM2.5有机碳和10％-33％的PM10有机碳。北京市在2002年10月和11月受到明显的生物质燃烧的影响，可能由于农田秸杆焚烧和秋季落叶焚烧。2003年5月7日颗粒物样品受到直线距离约为1000km以外的内蒙古自治区呼伦贝尔市大兴安岭林区森林大火烟雾的影响。生物质燃烧事件具有突发性，可以长距离传输；生物质作为农村生物燃料的使用其燃烧排放具有经常性和持久性的特征。  相似文献   

云模式中气溶胶物理过程参数化方案研究概述   总被引：2，自引：1，他引：2  

刘校辰  刘奇俊 《气象》2006,32(6):3-12

介绍了大气气溶胶的浓度、气溶胶的谱形等物理性质对云的微物理过程造成的影响以及目前云模式中常用到的一些气溶胶物理过程的体积水、分档等参数化方案，并评述了这些参数化方案各自的特点。提出了在设计气溶胶物理过程参数化方案时需要注意和有待解决的几个问题，建议在设计气溶胶-云相互作用的模式时，要根据不同的研究目的选择合适的参数化方案。  相似文献   

国内外气溶胶观测网络发展进展及相关科学计划   总被引：16，自引：6，他引：16  

延昊  矫梅燕  毕宝贵  刘桂清 《气象科学》2006,26(1):110-117

气溶胶是气候变化研究中的一个极大的不确定性因素,国内外在此方面开展了大量的观测和科学研究。本文首先对当前全球两大气溶胶观测网络,世界气象组织(WMO)的全球大气观测计划(GAW)和气溶胶自动观测网(AERONET)的组织、规模、设备、数据和气溶胶网络的规范作了介绍,并对近年来国际上的重大气溶胶科学计划的目标、实验方法、步骤作了介绍,说明观测网络的重要性。在此基础上对中国气溶胶观测网络的地位做了分析,并指出其在正在开展的中国气溶胶科学研究中的重要性。  相似文献   

Characteristics of Aerosol Ionic Compositions in Summer 2003 at Lin''''an of Yangtze Delta Region   总被引：1，自引：0，他引：1       下载免费PDF全文

YAN Peng  ZHANG Yangmei  YANG Dongzhen  TANG Jie  ZHOU Xiuji 《Acta Meteorologica Sinica》2006,20(3):374-382

With the size-resolved aerosol mass and ion composition data obtained at Lin'an regional atmospheric pollution monitoring station in July 2003, the size distributions of aerosol mass and ionic components, and the correlations between major ion pairs were analyzed. The primary results indicate that in the period of in-situ measurement, the aerosols are mainly composed of fine particles. The mass of aerosols with size less than 2.1μm accounts for 66% of the total mass of all size ranges, in which about 50% of the mass is contributed by the particles with size less than 0.65μm. Similar to the size distributions of aerosol mass, the water-soluble ions are mainly concentrated in the size range of <0.65μm, accounting for about 77% of the sum of analyzed ions, and the ions within the range of <2.1μm reach 88%. The sulfate, ammonium, and potassium are the dominant ionic components in fine particles (particle size less than 2.1μm). Ion correlation analysis suggests that the sulfates in fine particles are mostly in the compounds of (NH4)2SO4, Na2SO4, and K2SO4, but for submicron particles the sulfates are mainly in the form of (NH4)2SO4.  相似文献   

大气臭氧总量的经验计算方法   总被引：1，自引：0，他引：1  

白建辉 《南京气象学院学报》2006,29(6):799-805

依据臭氧生消与紫外辐射(UV)能量利用相互作用的观点,考虑与臭氧有关的主要因子UV、大气中物质在化学和光化学反应中对UV能量的吸收、气溶胶粒子的散射等,在分析1990—1992年臭氧总量、太阳辐射、气象资料的基础上,建立了计算臭氧总量的经验模式,其优点是所用资料均可由常规气象站获得。结果表明,计算值与观测值符合得比较好。利用该经验模式计算了北京地区1979年1月—1996年6月的臭氧总量,计算值与观测值同样比较一致,二者相对偏差的最大值、最小值、平均值分别为15.2%、0.05%和4.9%,相对偏差在±10%之内的比例为91.4%,因而该经验模式是合理、可行的。1991年之后北京地区臭氧的下降与Pinatubo火山气溶胶的影响有关。  相似文献   

Atmospheric Electrification in the Solar System     

Karen L. Aplin 《Surveys in Geophysics》2006,27(1):63-108

Atmospheric electrification is not a purely terrestrial phenomenon: all Solar System planetary atmospheres become slightly electrified by cosmic ray ionisation. There is evidence for lightning on Jupiter, Saturn, Uranus and Neptune, and it is possible on Mars, Venus and Titan. Controversy surrounds the role of atmospheric electricity in physical climate processes on Earth; here, a comparative approach is employed to review the role of electrification in the atmospheres of other planets and their moons. This paper reviews the theory, and, where available, measurements, of planetary atmospheric electricity which is taken to include ion production and ion–aerosol interactions. The conditions necessary for a planetary atmospheric electric circuit similar to Earth’s, and the likelihood of meeting these conditions in other planetary atmospheres, are briefly discussed. Atmospheric electrification could be important throughout the solar system, particularly at the outer planets which receive little solar radiation, increasing the relative significance of electrical forces. Nucleation onto atmospheric ions has been predicted to affect the evolution and lifetime of haze layers on Titan, Neptune and Triton. Atmospheric electrical processes on Titan, before the arrival of the Huygens probe, are summarised. For planets closer to Earth, heating from solar radiation dominates atmospheric circulations. However, Mars may have a global circuit analogous to the terrestrial model, but based on electrical discharges from dust storms. There is an increasing need for direct measurements of planetary atmospheric electrification, in particular on Mars, to assess the risk for future unmanned and manned missions. Theoretical understanding could be increased by cross-disciplinary work to modify and update models and parameterisations initially developed for a specific atmosphere, to make them more broadly applicable to other planetary atmospheres.  相似文献   

A numerical model of the partitioning of trace chemical solutes during drop freezing     

A. L. Stuart  M. Z. Jacobson 《Journal of Atmospheric Chemistry》2006,53(1):13-42

Partitioning of volatile chemicals among the gas, liquid, and solid phases during freezing of liquid water in clouds can impact trace chemical distributions in the troposphere and in precipitation. We describe here a numerical model of this partitioning during the freezing of a supercooled liquid drop. Our model includes the time-dependent calculation of the coupled processes of crystallization kinetics, heat transport, and solute mass transport, for a freezing hydrometeor particle. We demonstrate the model for tracer partitioning during the freezing of a 1000 μm radius drop on a 100 μm ice substrate, under a few ambient condition scenarios. The model effectively simulates particle freezing and solute transport, yielding results that are qualitatively and quantitatively consistent with previous experimental and theoretical work. Results suggest that the ice shell formation time is governed by heat loss to air and not by dendrite propagation, and that the location of ice nucleation is not important to freezing times or the effective partitioning of chemical solutes. Even for the case of nucleation at the center of the drop, we found that dendrites propagated rapidly to form surface ice. Freezing then proceeded from the outside in. Results also indicate that the solid-liquid interfacial surface area is not important to freezing times or the effective partitioning of chemical solutes, and that the rate aspects of trapping are more important than equilibrium solid-liquid partitioning to the effective partitioning resulting from freezing.  相似文献