非传统稳定同位素在大气颗粒物溯源中的应用

大气颗粒物对环境与人体健康都具有显著的负面影响,是当前严重的环境污染问题之一.准确判断大气颗粒物的来源是大气颗粒物污染控制的重要前提.近年来,基于天然稳定同位素的大气颗粒物溯源技术受到了广泛关注.本文综述了大气颗粒物中非传统稳定同位素(主要包括硅、锶、铁、锌、铜、钕、铅、汞、碘)的组成分析方法和溯源应用,总结了大气颗粒物中同位素组成的时空分布特征及各排放源同位素组成的差异性,并对非传统稳定同位素应用于大气颗粒物溯源的未来发展趋势进行了展望.     

原子荧光光谱法测定大气颗粒物中砷和汞

正大气颗粒物是指均匀地分散在空气中以气溶胶形式存在的固态或液态颗粒状物质的总称,具有粒径小、比表面积大、在空气中停留时间长和输送距离远的特点,能够大量吸附各种重金属离子、有毒的有机物和病菌等物质,是一种组成复杂、性质多样和危害巨大的大气污染物[1]。有研究表明大气颗粒物是造成空气污染和雾霾天气的主要原因,对城市居民     

NO2在矿物颗粒物表面的非均相反应

NO2在矿物颗粒物表面的非均相反应会改变矿物颗粒物的化学组成、粒径、形貌、吸湿性,进而影响矿物颗粒物的散射、反射、吸收等光学性质和成云能力,改变其直接和间接辐射强迫,最终对大气氧化性和气候变化产生重要的影响.本文综述了NO:在矿物颗粒物表面的非均相反应的研究体系和研究方法,阐述N02在氧化物颗粒物表面反应产物、反应机理的实验和推测结果,总结了测定的摄取系数,提出了NO2在矿物颗粒物表面非均相反应待深入研究的科学问题.     

现代分析技术在PM_(2.5)组份识别中的应用

以上海市闵行地区的大气细颗粒物PM_(2.5)为研究对象,综合多种分析测试手段对颗粒物的成份进行分析,以识别PM_(2.5)中主要污染物的来源。采用扫描电镜和透射电镜技术观察颗粒物的形貌特征,红外光谱技术识别颗粒物中的特征官能团,再结合碳分析仪,电感耦合等离子体质谱,离子色谱和气相色谱等技术对颗粒物中的元素碳和有机碳、无机金属元素、无机水溶性离子及有机化合物PAHs进行定量分析。结果表明PM_(2.5)是由大量的微米颗粒物及部分超细颗粒物组成,颗粒物主要以烟尘聚集体的形式存在;PM_(2.5)中有无机盐类和有机化合物的官能团共存在,有机官能团主要为羧基和芳烃化合物,无机化合物主要为硫酸盐和氨类化合物;各化学组份的质量分数表明了二次离子(SO_4~(2-),NO_3~-,NH_4~+)和有机碳是PM_(2.5)中的主要污染物,并明确解析了PM_(2.5)中各种污染来源的分担率。     

大气颗粒物中棕色碳的化学组成、来源和生成机制

大气颗粒物中棕色碳(BrC)在近紫外波段具有强吸光性,并因其显著的气候效应被广泛关注。BrC组成、来源、演变和光学性质的不确定性是造成气候模型估算气溶胶辐射强迫不确定性的重要因素。本文综述了大气颗粒物中BrC的化学组成、来源和生成机制,聚焦分子水平上BrC组成、二次生成机制和吸光间的关联。大气颗粒物中BrC的主要类别包括有机溶剂(甲醇)提取的碳质组分、水溶性有机碳及类腐殖质; 分子水平上,硝基芳香烃和含氮杂环有机物是BrC的主要发色团。BrC的来源包括生物质等不完全燃烧一次排放和挥发性有机物氧化二次生成; 二次生成途径主要包括人为源芳香烃氧化生成硝基芳香烃等含氮组分、羰基化合物与铵/胺反应生成含氮杂环组分或低聚物。前体物和反应条件影响二次生成BrC的组成和吸光性质; BrC在大气传输过程中还会发生“光漂白”现象。在分子水平上识别和阐明BrC的发色团、二次生成机制及其演变过程是未来该领域的重点研究方向。     

气候变化中的化学问题

气候变化是一个复杂体系中的科学问题。探讨大气中化学组分及化学过程的气候效应是目前这一研究的活跃领域。大气氧化剂和颗粒物是我国城市和区域大气中的关键污染物,在气候变化中也具有不容忽视的作用,分析和估算其直接和间接的气候效应,有助于丰富和完善对气候变化过程的科学认识。     

波长色散X射线荧光光谱法测定大气颗粒物中无机元素的质控方法探讨

正对大气颗粒物的化学组成进行来源识别和定量解析~([1])是制定针对性的政策并以此治理大气颗粒物污染的重要前提。无机物是大气颗粒的重要组成部分,目前测定环境空气颗粒物中无机物含量的方法主要有电感耦合等离子体原子发射光谱法~([2])、电感耦合等离子体质谱法~([3])、石墨炉原子吸收分光光度法~([4])、X射线荧光光谱法(XRFS)~([5])等。前3种方法存在前处理复杂、耗时长等缺点,而XRFS具有制样简单、分析速度快、精密度高等优点~([6])。现行环境质量标准HJ 830-2017《环境空气颗粒物中机元素的测定波长色散X射线荧光光谱法》主要采用聚丙烯膜、石英膜采集环境空气,用XRFS测定其中的28种元素(钠、镁、氯、硅、磷、硫、氯、钾、钙、钪、     

显微拉曼光谱用于研究大气单颗粒表面非均相反应

大气单颗粒表面的非均相反应研究因更接近大气实际条件,避免了堆积态研究中人为引入的误差,能够得到真实的反应过程与机理,获得反映大气实际条件的动力学参数.本研究建立了使用显微拉曼光谱研究大气单颗粒非均相反应的研究方法,并初步用于研究NO2与单颗粒CaCO3的非均相反应.研究结果表明显微拉曼光谱可同时获得颗粒物的化学组成和形貌变化,并能得到化学环境如相态的信息,对于研究反应过程很有帮助;而颗粒物沉降在基质上得到的拉曼光谱因不受形貌共振影响,有利于获得高质量的光谱.此外,将拉曼光谱研究单颗粒的方法与其他单颗粒非均相反应的研究方法进行了综合比较,表明显微拉曼光谱技术在单颗粒非均相反应研究中具有重要的特点和应用价值.     

大气颗粒物中有机物色谱分析的样品制备技术

大气颗粒物中有机物成分分析对深入研究大气颗粒物对人类健康、环境、气候、生态的影响,解析气溶胶来源,制定颗粒物控制相关法规,以及风险管理方法具有重要意义。由于颗粒物中的有机组分种类繁多,分析复杂,目前仅10%~20%的有机物得到了定性和定量分析。因此,大气细颗粒中有机物的分析已成为环境分析领域的优先发展方向。色谱是大气颗粒物中有机物分析的主要方法,而样品制备则是影响分析速度和精度的关键步骤。本文对颗粒物中有机组分色谱分析前的样品制备方法进行了综述,介绍了索氏提取、超声辅助提取、微波辅助提取、加压溶剂提取等溶剂提取方法以及热解吸提取方法,并重点介绍了这些方法在大气颗粒物样品处理中的应用,总结了各种方法的优缺点。     

大气二次细颗粒物形成机理的前沿研究

大气二次颗粒物是影响大气辐射强迫和全球气候变化最不确定的因素之一.本文总结了大气二次细颗粒物的形成机制以及吸湿增长因子的研究进展.近年来,OH·、NO3·和O3光化学氧化形成二次细颗粒物的机制较为清晰,海盐和大气矿尘表面多相反应形成硫酸盐和硝酸盐等二次无机细颗粒物的研究取得可喜进展,尤其是发现海盐和大气矿尘混合物完全不同于单组分的多相反应机制.然而,二次有机颗粒物形成过程中能够鉴定出的有机组分很少,多相酸催化对形成二次颗粒物的促进作用尚未完全确定,多组分混合大气颗粒物的吸湿增长特性亦需进一步深入研究.     

Methods for characterization of organic compounds in atmospheric aerosol particles

Atmospheric aerosol particles of primary or secondary, biogenic or anthropogenic origin are highly complex samples of changing composition in time and space. To assess their effects on climate or human health, the size-dependent chemical composition of these ubiquitous atmospheric constituents must be known. The development of novel analytical methods has enabled more detailed characterization of the organic composition of aerosols. This review gives an overview of the methods used in the chemical characterization of atmospheric aerosol particles, with a focus on mass-spectrometry techniques for organic compounds, either alone or in combination with chromatographic separation. Off-line, on-site, and on-line methods are covered, and the advantages and limitations of the different methods are discussed. The main emphasis is on methods used for detailed characterization of the composition of the organic compounds in aerosol particles. We address and summarize the current state of analytical methods used in aerosol research and discuss the importance of developing novel sampling strategies and analytical instrumentation.

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Graphical Abstract Challenges in the atmospheric aerosol analytics

     

Analysis of anions in ambient aerosols by microchip capillary electrophoresis

We describe a microchip capillary electrophoresis method for the analysis of nitrate and sulfate in ambient aerosols. Investigating the chemical composition of ambient aerosol particles is essential for understanding their sources and effects. Significant progress has been made towards developing mass spectrometry-based instrumentation for rapid qualitative analysis of aerosols. Alternative methods for rapid quantification of selected high abundance compounds are needed to augment the capacity for widespread routine analysis. Such methods could provide much higher temporal and spatial resolution than can be achieved currently. Inorganic anions comprise a large percentage of particulate mass, with nitrate and sulfate among the most abundant species. While ion chromatography has proven very useful for analyzing extracts of time-integrated ambient aerosol samples collected on filters and for semi-continuous, on-line particle composition measurements, there is a growing need for development of new compact, inexpensive approaches to routine on-line aerosol ion analysis for deployment in spatially dense, atmospheric measurement networks. Microchip capillary electrophoresis provides the necessary speed and portability to address this need. In this report, on-column contact conductivity detection is used with hydrodynamic injection to create a simple microchip instrument for analysis of nitrate and sulfate. On-column contact conductivity detection was achieved using a Pd decoupler placed upstream from the working electrodes. Microchips containing two Au or Pd working electrodes showed a good linear range (5-500 microM) and low limits-of-detection for sulfate and nitrate, with Au providing the lowest detection limits (1 microM) for both ions. The completed microchip system was used to analyze ambient aerosol filter samples. Nitrate and sulfate concentrations measured by the microchip matched the concentrations measured by ion chromatography.     

Oxygenated interface on biomass burn tar balls determined by single particle scanning transmission X-ray microscopy

Carbonaceous particles originating from biomass burning can account for a large fraction of organic aerosols in a local environment. Presently, their composition, physical and chemical properties, as well as their environmental effects are largely unknown. Tar balls, a distinct type of highly spherical carbonaceous biomass burn particles, have been observed in a number of field campaigns. The Yosemite Aerosol Characterization Study that took place in summer 2002 occurred during an active fire season in the western United States; tar balls collected during this field campaign are described in this article. Scanning transmission X-ray microscopy and near-edge X-ray absorption fine structure spectroscopy are used to determine the shape, structure, and size-dependent chemical composition of approximately 150 individual spherical particles ranging in size from 0.15 to 1.2 mum. The elemental composition of tar balls is approximately 55% atomic carbon and approximately 45% atomic oxygen. Oxygen is present primarily as carboxylic carbonyls and oxygen-substituted alkyl (O-alkyl-C) functional groups, followed by moderate amounts of ketonic carbonyls. The observed chemical composition, density, and carbon functional groups are distinctly different from soot or black carbon and more closely resemble high molecular weight polymeric humic-like substances, which could account for their reported optical properties. A detailed examination of the carboxylic carbonyl and O-alkyl-C functional groups as a function of particle size reveals a thin oxygenated interface layer. The high oxygen content, as well as the presence of water-soluble carboxylic carbonyl groups, could account for the reported hygroscopic properties of tar balls. The presence of the oxygenated layer is attributed to atmospheric processing of biomass burn particles.     

Speciation of copper and zinc in size-fractionated atmospheric particulate matter using total reflection mode X-ray absorption near-edge structure spectrometry

The health effects of aerosol depend on the size distribution and the chemical composition of the particles. Heavy metals of anthropogenic origin are bound to the fine aerosol fraction (PM_2.5). The composition and speciation of aerosol particles can be variable in time, due to the time-dependence of anthropogenic sources as well as meteorological conditions. Synchrotron-radiation total reflection X-ray fluorescence (SR-TXRF) provides very high sensitivity for characterization of atmospheric particulate matter. X-ray absorption near-edge structure (XANES) spectrometry in conjunction with TXRF detection can deliver speciation information on heavy metals in aerosol particles collected directly on the reflector surface. The suitability of TXRF-XANES for copper and zinc speciation in size-fractionated atmospheric particulate matter from a short sampling period is presented. For high size resolution analysis, atmospheric aerosol particles were collected at different urban and rural locations using a 7-stage May cascade impactor having adapted for sampling on Si wafers. The thin stripe geometry formed by the particulate matter deposited on the May-impactor plates is ideally suited to SR-TXRF. Capabilities of the combination of the May-impactor sampling and TXRF-XANES measurements at HASYLAB Beamline L to Cu and Zn speciation in size-fractionated atmospheric particulate matter are demonstrated. Information on Cu and Zn speciation could be performed for elemental concentrations as low as 140 pg/m³. The Cu and Zn speciation in the different size fraction was found to be very distinctive for samples of different origin. Zn and Cu chemical state typical for soils was detected only in the largest particles studied (2–4 μm fraction). The fine particles, however, contained the metals of interest in the sulfate and nitrate forms.     

Superhydrophobic surfaces from sustainable colloidal systems

In recent decades, sustainable superhydrophobic surfaces from natural materials and sustainable processes have attracted increased interest due to their lower environmental footprint and potential applications in self-cleaning surfaces and biomedical devices. Although there is significant progress on selecting suitable nano and micro particles to prepare superhydrophobic surfaces, a comprehensive review on the direct use of sustainable colloidal particles (SCPs) is lacking. In this review, we highlight the recent advances on sustainable superhydrophobic surfaces using SCPs. The composition and properties, extraction methods, and chemical modifications are described, including cellulose nanocrystals, chitin/chitosan nanoparticles, and lignin nanoparticles. In addition to the physico–chemical properties and tunable dimensionality, the fabrication methodologies of superhydrophobic surfaces using modified colloids are described. Finally, the potential applications of these sustainable superhydrophobic surfaces ranging from oil/water separation, biomedical, water harvesting, biofabrication, microfluidic reactor, and food packaging are discussed together with a future perspective on the advances made.     

Molecular chemistry of organic aerosols through the application of high resolution mass spectrometry

Understanding the molecular composition and fundamental chemical transformations of organic aerosols (OA) during their formation and aging is both a major challenge and the area of great uncertainty in atmospheric research. Particularly, little is known about fundamental relationship between the chemical composition and physicochemical properties of OA, their atmospheric history, evolution, and the impact on the environment. Ambient soft-ionization methods combined with high-resolution mass spectrometry (HR-MS) analysis provide detailed information on the molecular content of OA that is pivotal for improving the understanding of their complex composition, multi-phase aging chemistry, direct (light absorption and scattering) and indirect (aerosol-cloud interactions) effects on atmospheric radiation and climate, health effects. The HR-MS methods can detect thousands of individual OA constituents at once, provide their elemental formulae from accurate mass measurements and structural information based on tandem mass spectrometry. Integration with additional analytical tools, such as chromatography and UV/Vis absorption spectroscopy, makes it possible to further separate OA compounds by their polarity and ability to absorb solar radiation. The goal of this perspective is to describe contemporary HR-MS methods, review recent applications in field and laboratory studies of OA, and explain how the information obtained from HR-MS methods can be translated into an improved understanding of OA chemistry.     

The use of nuclear techniques in source apportionment studies, exemplified by recent studies in Turkey

Nuclear analytical methods are very important atmospheric tools as they provide multielement data, which is essential for receptor modeling. In this study, the application of receptor modeling is discussed on rural data to determine source regions affecting chemical composition of aerosols in the Eastern Mediterranean. The factor analysis revealed 4 sources, two of which represent anthropogenic component in aerosol mass. The source regions that determine the composition of particles is investigated using trajectory statistics. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development and certification of the new NIES CRM 28: urban aerosols for the determination of multielements

A new environmental certified reference material (CRM) for the determination of multielements in aerosol particulate matter has been developed and certified by the National Institute for Environmental Studies (NIES), Japan, based on analyses by a network of laboratories using a wide range of methods. The origin of the material was atmospheric particulate matter collected on filters in a central ventilating system in a building in Beijing city centre. The homogeneity and stability of this material were sufficient for its use as a reference material. Values for elemental mass fractions in the material were statistically determined based on the analytical results of the participating laboratories. Eighteen certified values and 14 reference values were obtained. The diameters, obtained from a micrographic image using image analysis software, of 99% of the particles were less than 10 μm, demonstrating that almost all the particles in the material could be classified as particles of 10 μm or less in aerodynamic diameter. The chemical composition and particle size distribution of this material were close to those of an authentic aerosol collected in Beijing. NIES CRM 28 is appropriate for use in analytical quality control and in the evaluation of methods used in the analysis of aerosols, particularly those collected in urban environments in northeast Asia Figure New NIES CRM 28 Urban Aerosols and photo micrograph of the material     

Atmospheric aerosols: composition, transformation, climate and health effects

Aerosols are of central importance for atmospheric chemistry and physics, the biosphere, climate, and public health. The airborne solid and liquid particles in the nanometer to micrometer size range influence the energy balance of the Earth, the hydrological cycle, atmospheric circulation, and the abundance of greenhouse and reactive trace gases. Moreover, they play important roles in the reproduction of biological organisms and can cause or enhance diseases. The primary parameters that determine the environmental and health effects of aerosol particles are their concentration, size, structure, and chemical composition. These parameters, however, are spatially and temporally highly variable. The quantification and identification of biological particles and carbonaceous components of fine particulate matter in the air (organic compounds and black or elemental carbon, respectively) represent demanding analytical challenges. This Review outlines the current state of knowledge, major open questions, and research perspectives on the properties and interactions of atmospheric aerosols and their effects on climate and human health.