Organic aerosol formation downwind from the Deepwater Horizon oil spill

A large fraction of atmospheric aerosols are derived from organic compounds with various volatilities. A National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft made airborne measurements of the gaseous and aerosol composition of air over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico that occurred from April to August 2010. A narrow plume of hydrocarbons was observed downwind of DWH that is attributed to the evaporation of fresh oil on the sea surface. A much wider plume with high concentrations of organic aerosol (>25 micrograms per cubic meter) was attributed to the formation of secondary organic aerosol (SOA) from unmeasured, less volatile hydrocarbons that were emitted from a wider area around DWH. These observations provide direct and compelling evidence for the importance of formation of SOA from less volatile hydrocarbons.     

Organic aerosol growth mechanisms and their climate-forcing implications

Surface- and volume-limited chemical reactions on and in atmospheric aerosol particles cause growth while changing organic composition by 13 to 24% per day. Many of these particles contain carbonaceous components from mineral dust and combustion emissions in Africa, Asia, and North America and reveal reaction rates that are three times slower than those typically used in climate models. These slower rates for converting from volatile or hydrophobic to condensed and hygroscopic organic compounds increase carbonaceous particle burdens in climate models by 70%, producing organic aerosol climate forcings of as much as -0.8 watt per square meter cooling and +0.3 watt per square meter warming.     

面向服务的新农村信息资源整合研究——以浙江台州为例

近年来,我国农村信息化建设取得长足发展,成绩显著。但在信息化建设领域方面,由于刚刚起步,目前农村信息内容发展还存在许多问题。SOA（Service-Oriented Architecture）面向服务架构,作为新一代的体系结构,是当前解决异构系统整合、应用系统集成最理想的方案之一。提出了基于WebService技术的新农村信息资源整合的系统框架,并对如何利用该结构开展新农村信息资源整合给出了可行性方案。     

Urban ozone control and atmospheric reactivity of organic gases

Control strategies for urban ozone traditionally have been based on mass reductions in volatile organic compounds (VOCs). Studies show, however, that some organic gas species (such as alkanes and alcohols) form an order of magnitude less ozone than equal mass emissions of others (such as alkenes and aldehydes). Chemically detailed photochemical models are used to assess uncertainty and variability in reactivity quantification. VOC control strategies based on relative reactivity appear to be robust with respect to nationwide variations in environmental conditions and uncertainties in the atmospheric chemistry. Control of selective organic gas species on the basis of reactivity can offer cost savings over traditional strategies.     

Mount pinatubo aerosols, chlorofluorocarbons, and ozone depletion

The injection into the stratosphere of large quantities of sulfur during the June 1991 eruption of Mount Pinatubo (Philippines) and the subsequent formation of sulfate aerosol particles have generated a number of perturbations in the atmosphere with potential effects on the Earth's climate. Changes in the solar and infrared radiation budget caused by the eruption should produce a cooling of the troposphere and a warming of the lower stratosphere. These changes could affect atmospheric circulation. In addition, heterogeneous chemical reactions on the surface of sulfate aerosol particles render the ozone molecules more vulnerable to atmospheric chlorine and hence to man-made chlorofluorocarbons.     

Heterogeneous nucleation experiments bridging the scale from molecular ion clusters to nanoparticles

Generation, investigation, and manipulation of nanostructured materials are of fundamental and practical importance for several disciplines, including materials science and medicine. Recently, atmospheric new particle formation in the nanometer-size range has been found to be a global phenomenon. Still, its detailed mechanisms are mostly unknown, largely depending on the incapability to generate and measure nanoparticles in a controlled way. In our experiments, an organic vapor (n-propanol) condenses on molecular ions, as well as on charged and uncharged inorganic nanoparticles, via initial activation by heterogeneous nucleation. We found a smooth transition in activation behavior as a function of size and activation to occur well before the onset of homogeneous nucleation. Furthermore, nucleation enhancement for charged particles and a substantial negative sign preference were quantitatively detected.     

大气气溶胶遥感反演研究进展

大气气溶胶是悬浮在地球大气中的微粒混合物,它不仅对全球气候变化产生影响,而且影响到大气环境质量和人类身体健康。目前,大气气溶胶的研究已经成为国际研究热点之一。介绍了气溶胶参数遥感反演的国内外研究进展,对利用卫星遥感资料反演气溶胶参数的方法进行了总结,分析了方法中的各种假定条件,并对该领域内现存的问题与发展方向进行探讨。     

Emissions of methyl halides and methane from rice paddies

Methyl halide gases are important sources of atmospheric inorganic halogen compounds, which in turn are central reactants in many stratospheric and tropospheric chemical processes. By observing emissions of methyl chloride, methyl bromide, and methyl iodide from flooded California rice fields, we estimate the impact of rice agriculture on the atmospheric budgets of these gases. Factors influencing methyl halide emissions are stage of rice growth, soil organic content, halide concentrations, and field-water management. Extrapolating our data implies that about 1 percent of atmospheric methyl bromide and 5 percent of methyl iodide arise from rice fields worldwide. Unplanted flooded fields emit as much methyl chloride as planted, flooded rice fields.     

Dispersion polymerizations in supercritical carbon dioxide

Conventional heterogeneous dispersion polymerizations of unsaturated monomers are performed in either aqueous or organic dispersing media with the addition of interfacially active agents to stabilize the colloidal dispersion that forms. Successful stabilization of the polymer colloid during polymerization results in the formation of high molar mass polymers with high rates of polymerization. An environmentally responsible alternative to aqueous and organic dispersing media for heterogeneous dispersion polymerizations is described in which supercritical carbon dioxide (CO(2)) is used in conjunction with molecularly engineered free radical initiators and amphipathic molecules that are specifically designed to be interfacially active in CO(2). Conventional lipophilic monomers, exemplified by methyl methacrylate, can be quantitatively (>90 percent) polymerized heterogeneously to very high degrees of polymerization (>3000) in supercritical CO(2) in the presence of an added stabilizer to form kinetically stable dispersions that result in micrometer-sized particles with a narrow size distribution.     

Organic globules in the Tagish Lake meteorite: remnants of the protosolar disk

Coordinated transmission electron microscopy and isotopic measurements of organic globules in the Tagish Lake meteorite shows that they have elevated ratios of nitrogen-15 to nitrogen-14 (1.2 to 2 times terrestrial) and of deuterium to hydrogen (2.5 to 9 times terrestrial). These isotopic anomalies are indicative of mass fractionation during chemical reactions at extremely low temperatures (10 to 20 kelvin), characteristic of cold molecular clouds and the outer protosolar disk. The globules probably originated as organic ice coatings on preexisting grains that were photochemically processed into refractory organic matter. The globules resemble cometary carbon, hydrogen, oxygen, and nitrogen (CHON) particles, suggesting that such grains were important constituents of the solar system starting materials.     

Gaseous nitrate radical: possible nighttime atmospheric sink for biogenic organic compounds

The gaseous nitrate (NO(3)) radical, which has recently been measured in nighttime ambient atmospheres over the United States and Europe at concentrations up to approximately 350 parts per trillion, has now been shown to react rapidly with the biogenically emitted organic compounds dimethyl sulfide (DMS), isoprene, and several monoterpenes. Computer simulations demonstrate that these reactions can dominate the atmospheric behavior of these organic compounds at night. Thus reaction with NO(3) radicals may be the unknown, nonphotochemical removal process for DMS recently invoked by Andreae and Raemdonck to explain the absence of a diurnal profile for DMS in maritime air influenced by continental air masses. Similarly, the nighttime reaction of NO(3) radicals with monoterpenes can be a dominant removal process, leading to very low monoterpene concentrations in ambient atmospheres during the early morning.     

典型气候/环境因子变化对九段沙湿地碳固定潜力的影响

利用人工气候室模拟长江口区域几种典型气候/环境因子的变化特征（全球变暖、CO2增加和海水无机氮污染加剧等）,并从植物生长量和土壤呼吸角度综合分析了这些气候/环境因素的变化对九段沙湿地土壤有机碳汇聚能力的影响。初步结果表明,在实验范围内,与对照相比,单方面的温度升高、无机氮污染加剧和CO2浓度升高会提高九段沙土壤的有机碳汇聚能力。无机氮污染加剧协同升温对土壤呼吸有一定的消减作用,从而提高了土壤有机碳汇聚能力;无机氮污染加剧协同CO2浓度升高会促使土壤有机碳的排放,使其碳汇聚能力下降;CO2浓度升高和全球升温的共同作用不会显著降低有机碳汇聚能力;无机氮污染加剧和CO2浓度升高的基础上加入升温的三因素交互作用会促进土壤有机碳的排放,使其碳汇聚能力下降。因此,要尽力避免海水中无机氮污染加剧和CO2浓度升高两个因素,以及在此基础上升温情况的同时发生。     

大气二氧化碳摩尔分数升高对土壤有机碳稳定性的影响

随着工业的不断发展，全球大气二氧化碳(CO₂)呈明显增加趋势。大气CO₂的增加将会影响土壤有机碳(SOC)转化和更新，进而改变土壤碳的稳定性。研究大气CO₂升高对SOC稳定性的影响，不但是评价陆地生态系统对气候变化反馈效应的重要环节，也对实现碳元素在土壤中的有效储存，对保持土壤肥力的可持续性具有重要意义。利用现有的文献资料，综述了大气CO₂升高对SOC稳定性的影响及其稳定性指标(生物指标、化学指标、其他指标等)，外源氮和大气CO₂升高的交互作用对SOC稳定性的影响，以及SOC稳定性随时间尺度的变化趋势等。总结发现:大气CO₂升高导致活性有机碳(溶解性有机碳、颗粒性有机碳、易氧化有机碳等)比例增多，SOC稳定性降低，尤其在氮限制的环境中，SOC稳定性更差。总结近年的研究成果发现:随着高CO₂处理时间的加长，SOC稳定性降低速率逐渐减小，表明土壤本身具有一定的适应能力和自我恢复能力。最后展望了SOC稳定性变化对植物生理、生长的反馈影响。未来大气CO₂升高对SOC稳定性的影响研究，应该着力于提高农田生态系统土壤肥力可持续性及提高农作物的产量产能。图1参74     

Identification of polymers as major components of atmospheric organic aerosols

Results from photooxidation of aromatic compounds in a reaction chamber show that a substantial fraction of the organic aerosol mass is composed of polymers. This polymerization results from reactions of carbonyls and their hydrates. After aging for more than 20 hours, about 50% of the particle mass consists of polymers with a molecular mass up to 1000 daltons. This results in a lower volatility of this secondary organic aerosol and a higher aerosol yield than a model using vapor pressures of individual organic species would predict.     

All-Carbon Molecules: Evidence for the Generation of Cyclo[18]carbon from a Stable Organic Precursor

The unambiguous structural characterization of a single-sized all-carbon molecule requires its chemical synthesis. For cyclo[18]carbon, ab initio calculations predict a relatively stable, cyclic D9h ground state geometry with alternating C-C (1.36 angstroms) and C identical withC (1.20 angstroms) bonds. The synthesis and x-ray crystal structure of a direct precursor to C(18) are described. The analysis of laser flash heating experiments on this precursor by time-of-flight mass spectroscopy shows a sequence of retro-Diels-Alder reactions leading to C(18) as the predominant fragmentation pattern. Structural evidence is provided for the generation of an all-carbon molecule from a well-characterized organic precursor.     

园林植物对大气细颗粒物浓度的正负作用评价

针对于园林绿地对城市大气环境中发挥的双重作用,本研究综合评价不同植物种类对消减PM2.5污染的能力差异,以期为城市绿地功能优化与提升提供科学依据。以北京市常用园林绿化植物为试验材料,在目前构建的植物叶片滞留细颗粒物质量的计算模型的基础上,考虑植物释放VOCs对大气颗粒物浓度的贡献量作为一个影响因子参与计算,对植物个体消减细颗粒物的净效益进行研究。结果表明：（1）植物个体之间滞留PM2.5能力有很大的差异,单位叶面积PM2.5滞留量较多的植物有元宝枫、大叶黄杨、胡枝子、锦带花、樱花,较少的为黄栌、旱柳、油松、七叶树;（2）油松、黄栌、圆柏3种植物由于释放α-蒎烯的量较高,对生成SOA的贡献较高;（3）综合评价植物消减细颗粒物的净效益,黄栌与油松2种植物对PM2.5没有消减作用,反而增加空气PM2.5浓度,其余13种植物对PM2.5具有消减作用,其中锦带花与元宝枫2种植物单位叶面积对PM2.5的消减能力最强。     

SO2在矿质颗粒物表面非均相反应研究进展

我国秋冬季雾霾频发,对人类健康造成巨大威胁。大气中SO_2经系列物理化学反应产生的硫酸盐气溶胶是雾霾产生的元凶,其中矿质颗粒物参与的SO_2表面非均相反应尤为重要,因此,厘清矿质颗粒物表面硫酸盐的形成机制是解析大气雾霾形成的关键科学问题。本文综述了SO_2在不同类型氧化型矿质颗粒物表面非均相反应的研究进展,讨论了多污染物共存体系、湿度和光照对SO_2非均相反应的影响,并对目前矿质颗粒物表面非均相反应研究中存在的问题进行了评述,旨在加深对矿质颗粒物促进硫酸盐形成机制的认识,助力揭示我国雾霾的成因,进而为雾霾治理提供理论指导。     

Atmospheric influence of Earth's earliest sulfur cycle

Mass-independent isotopic signatures for delta(33)S, delta(34)S, and delta(36)S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal. Atmospheric fractionation processes should be considered in the use of sulfur isotopes to study the onset and consequences of microbial fractionation processes in Earth's early history.     

基于半导体光放大器的光学向量矩阵乘法器的实现方法

提出了一种基于半导体光放大器(SOA)的光学向量矩阵乘法器(OVMM)的实现方法。与传统的向量矩阵乘法器相比,本文方法采用的是非空间光的实现方案,且SOA的增益补偿作用可对计算所得的光功率进行校正,从而提高计算精度。对提出的方法进行了1×2向量与2×2矩阵乘法运算的实验验证,结果表明可以实现向量矩阵乘法器的运算功能。利用SOA的大范围增益可调特性,可有效提高信号动态范围,利于多路信号间均匀性的改善,且易于集成。     

The process of tholin formation in Titan's upper atmosphere

Titan's lower atmosphere has long been known to harbor organic aerosols (tholins) presumed to have been formed from simple molecules, such as methane and nitrogen (CH4 and N2). Up to now, it has been assumed that tholins were formed at altitudes of several hundred kilometers by processes as yet unobserved. Using measurements from a combination of mass/charge and energy/charge spectrometers on the Cassini spacecraft, we have obtained evidence for tholin formation at high altitudes (approximately 1000 kilometers) in Titan's atmosphere. The observed chemical mix strongly implies a series of chemical reactions and physical processes that lead from simple molecules (CH4 and N2) to larger, more complex molecules (80 to 350 daltons) to negatively charged massive molecules (approximately 8000 daltons), which we identify as tholins. That the process involves massive negatively charged molecules and aerosols is completely unexpected.