大气超细颗粒物观测和扩散模拟研究进展

总结了近年来不同地区对不同环境下大气超细颗粒物的观测和扩散模拟研究进展。大量的观测研究结果表明,大气超细颗粒物的时空分布、组成特征、形成和成长的特性因观测地区的不同而存在很大差异,受气象因素和局部污染源的影响很大;其来源主要包括固定、移动燃烧源的直接排放和大气中颗粒成核现象,前一种来源一般是局部的,而后一种来源则是区域性的。目前,大多数关于大气超细颗粒物扩散的模拟研究都是针对其质量浓度的,对其数浓度扩散的模拟研究主要集中在小范围(机动车排放烟云的研究方面),在城市区域范围上的研究和应用还很少。最后,探讨和展望了大气超细颗粒物今后的主要研究方向和研究中面临的挑战。     

Updating the conceptual model for fine particle mass emissions from combustion systems

Atmospheric transformations determine the contribution of emissions from combustion systems to fine particulate matter (PM) mass. For example, combustion systems emit vapors that condense onto existing particles or form new particles as the emissions are cooled and diluted. Upon entering the atmosphere, emissions are exposed to atmospheric oxidants and sunlight, which causes them to evolve chemically and physically, generating secondary PM. This review discusses these transformations, focusing on organic PM. Organic PM emissions are semi-volatile at atmospheric conditions and thus their partitioning varies continuously with changing temperature and concentration. Because organics contribute a large portion of the PM mass emitted by most combustion sources, these emissions cannot be represented using a traditional, static emission factor. Instead, knowledge of the volatility distribution of emissions is required to explicitly account for changes in gas-particle partitioning. This requires updating how PM emissions from combustion systems are measured and simulated from combustion systems. Secondary PM production often greatly exceeds the direct or primary PM emissions; therefore, secondary PM must be included in any assessment of the contribution of combustion systems to ambient PM concentrations. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary PM precursors that are poorly accounted for in inventories and models. The review concludes by discussing the implications that the dynamic nature of these PM emissions have on source testing for emission inventory development and regulatory purposes. This discussion highlights important linkages between primary and secondary PM, which could lead to simplified certification test procedures while capturing the emission components that contribute most to atmospheric PM mass.     

Lung cancer mortality and exposure to atmospheric aerosol particles in Guangzhou,China

In recent years, China and other emerging countries have been experiencing severe air pollution problems with high concentrations of atmospheric aerosol particles. Satellite measurements indicate that the aerosol loading of the atmosphere in highly populated regions of China is about 10 times higher than, for example, in Europe and in the Eastern United States. The exposure to extremely high aerosol concentrations might lead to important human health effects, including respiratory and cardiovascular diseases as well as lung cancers. Here, we analyze 52-year historical surface measurements of haze data in the Chinese city of Guangzhou, and show that the dramatic increase in the occurrence of air pollution events between 1954 and 2006 has been followed by a large enhancement in the incidence of lung cancer.     

大气中二（口/恶）（口/英）研究进展

二（口/恶）（口/英）是世界公认的强致癌物质,对人体健康危害极大.近年来,大气中二（口/恶）（口/英）的研究已成为各国环境化学家研究的热点.本文总结了近年来国际上有关大气中二（口/恶）（口/英）研究的进展情况,以及所取得的主要研究成果,并在此基础上指出了我国目前研究中存在的问题及以后所应开展的工作.     

Aerosol and ozone observations during six cruise campaigns across the Mediterranean basin: temporal,spatial, and seasonal variability

The Mediterranean basin, because of its semi-enclosed configuration, is one of the areas heavily affected by air pollutants. Despite implications on both human health and radiative budget involving an increasing interest, monitoring databases measuring air pollution directly over this area are yet relatively limited. Owing to this context, concentrations of fine (PM_2.5) and coarse (PM_2.5–10) particles along with other ancillary data, such as ozone levels and meteorological parameters, were measured during six cruise campaigns covering almost the whole Mediterranean basin. Elemental composition of both PM_2.5 and PM_2.5–10 was also determined to identify specific tracers for different classes of particles that can be found in the Mediterranean atmosphere. Outcomes resulting from the integration of a preliminary qualitative examination with a more quantitative analysis, based on receptor modelling, suggested that European continental influence, Saharan dust outbreaks, wildfire events, sea spray and fossil fuel combustion were the leading causes of the aerosol-ozone variations within the Mediterranean basin. Shipping emissions, consisting in both local harbours and maritime traffic across the basin, were also tested using the marker ratio of V/Ni. Peak values observed for coarse fraction have shown to be driven by the occurrence of African dust events. Considering the major influence of Continental pollution and wildfire events, the spatial variability resulted in larger fine particle concentrations and higher ozone levels over the Eastern Mediterranean side in comparison to the Western one.     

A Summary of the APCA/EPA International Specialty Conference

Atmospheric change has emerged as a major global environmental issue of national and international concern in the 1990's. The dominance of the legislative and regulatory perception of atmospheric processes over their scientific understanding has left both regulators and atmospheric scientists ill-prepared to respond to emerging atmospheric-environmental issues. A view of clean air is presented whereby the legislative/regulatory and scientific perception of the physical and chemical processes of the atmosphere are linked to achieve the goal of a healthy atmosphere and sustainable environment.     

Extensive review of shale gas environmental impacts from scientific literature (2010–2015)

Extensive reviews and meta-analyses are essential to summarize emerging developments in a specific field and offering information on the current trends in the scientific literature. Shale gas exploration and exploitation has been extensively debated in literature, but a comprehensive review of recent studies on the environmental impacts has yet to be carried out. Therefore, the goal of this article is to systematically examine scientific articles published between 2010 and 2015 and identify recent advances and existing data gaps. The examined articles were classified into six main categories (water resources, atmospheric emissions, land use, induced seismicity, occupational and public health and safety, and other impacts). These categories are analyzed separately to identify specific challenges, possibly existing consensus and data gaps yet remained in the literature.     

Sources and concentration of nanoparticles (<10 nm diameter) in the urban atmosphere

Whilst limited information on particle size distributions and number concentrations in cities is available, very few data on the very smallest of particles, nanoparticles, have been recorded. Measurements in this study show that road traffic and stationary combustion sources generate a significant number of nanoparticles of diameter <10 nm. Measurements at the roadside (4 m from the kerb) and downwind from the traffic (more than 25 m from the kerb) show that nanoparticles (<10 nm diameter) accounted for more than 36–44% of the total particle number concentrations. Measurements designed to sample the plume of individual vehicles showed that both a diesel- and a petrol-fuelled vehicle generated nanoparticles (<10 nm diameter). The fraction of nanoparticles was even greater in a plume 350 m downwind of a stationary combustion source. On a few occasions, a temporal association between nanoparticles in the size range 3–7 nm and solar radiation was observed in urban background air at times when no other local sources were influential, which suggests that homogeneous nucleation can also be an important source of particles in the urban atmosphere.     

Synopsis of the temporal variation of particulate matter composition and size

A synopsis of the detailed temporal variation of the size and number distribution of particulate matter (PM) and its chemical composition on the basis of measurements performed by several regional research consortia funded by the U.S. Environmental Protection Agency (EPA) PM Supersite Program is presented. This program deployed and evaluated a variety of research and emerging commercial measurement technologies to investigate the physical and chemical properties of atmospheric aerosols at a level of detail never before achieved. Most notably these studies demonstrated that systematic size-segregated measurements of mass, number, and associated chemical composition of the fine (PM2.5) and ultrafine (PM0.1) fraction of ambient aerosol with a time resolution down to minutes and less is achievable. A wealth of new information on the temporal variation of aerosol has been added to the existing knowledge pool that can be mined to resolve outstanding research and policy-related questions. This paper explores the nature of temporal variations (on time scales from several minutes to hours) in the chemical and physical properties of PM and its implications in the identification of PM formation processes, and source attribution (primary versus secondary), the contribution of local versus transported PM and the development of effective PM control strategies. The PM Supersite results summarized indicate that location, time of day, and season significantly influence not only the mass and chemical composition but also the size-resolved chemical/elemental composition of PM. Ambient measurements also show that ultrafine particles have different compositions and make up only a small portion of the PM mass concentration compared with inhalable coarse and fine particles, but their number concentration is significantly larger than their coarse or fine counterparts. PM size classes show differences in the relative amounts of nitrates, sulfates, crustal materials, and most especially carbon as well as variations in seasonal and diurnal patterns.     

Health effects of fine particulate air pollution: lines that connect

Efforts to understand and mitigate thehealth effects of particulate matter (PM) air pollutionhave a rich and interesting history. This review focuseson six substantial lines of research that have been pursued since 1997 that have helped elucidate our understanding about the effects of PM on human health. There hasbeen substantial progress in the evaluation of PM health effects at different time-scales of exposure and in the exploration of the shape of the concentration-response function. There has also been emerging evidence of PM-related cardiovascular health effects and growing knowledge regarding interconnected general pathophysiological pathways that link PM exposure with cardiopulmonary morbidiity and mortality. Despite important gaps in scientific knowledge and continued reasons for some skepticism, a comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate air pollution has adverse effects on cardiopulmonaryhealth. Although much of this research has been motivated by environmental public health policy, these results have important scientific, medical, and public health implications that are broader than debates over legally mandated air quality standards.     

Oxygenated polycyclic aromatic hydrocarbons in atmospheric particulate matter: Molecular characterization and occurrence

Particulate matter (PM) has become a major research issue receiving increasing attention because of its significant negative impact on human health. There are main indicators that next to the morphological characteristics of the particle, also the chemical composition plays an important role in the adverse health effects of PM. In this context, the rather polar organic fraction of PM is expected to play a major role, and advanced analytical techniques are developed to improve the knowledge on the molecular composition of this fraction. One component class that deserves major attention consists of the oxygenated polycyclic aromatic hydrocarbons (PAHs). Those compounds are considered to be among the key compounds in PM toxicity. This paper presents a comprehensive review focusing on the analysis, fate and behavior of oxygenated PAHs in the atmosphere. The first part of the paper briefly introduces (i) the main sources and atmospheric pathways of oxygenated PAHs, (ii) available physical–chemical properties and (iii) their health effects. The second and main part of this paper gives a thorough discussion on the entire analytical sequence necessary to identify and quantify oxygenated PAHs on atmospheric PM. Special attention is given to critical parameters and innovations related to (i) sampling, (ii) sample preparation including both extraction and clean-up, and (iii) separation and detection. Third, the state-of-the-art knowledge about the atmospheric occurrence of oxygenated PAHs is discussed, including an extended overview of reported concentrations presented as a function of sampling season and geographical location. A clear seasonal effect is observed with the median of the oxygenated PAHs concentrations during winter being a factor of 3–4 higher than during summer. However, the oxygenated PAH/parent PAH ratio is about 20 times higher during summer, indicating the importance of photochemical activity in the atmosphere.     

Challenges in quantifying biosphere-atmosphere exchange of nitrogen species

Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended on improved methodologies, while ongoing challenges include gas-aerosol interactions, organic nitrogen and N(2) fluxes. The NEU strategy applies a 3-tier Flux Network together with a Manipulation Network of global-change experiments, linked by common protocols to facilitate model application. Substantial progress has been made in modelling N fluxes, especially for N(2)O, NO and bi-directional NH(3) exchange. Landscape analysis represents an emerging challenge to address the spatial interactions between farms, fields, ecosystems, catchments and air dispersion/deposition. European up-scaling of N fluxes is highly uncertain and a key priority is for better data on agricultural practices. Finally, attention is needed to develop N flux verification procedures to assess compliance with international protocols.     

Chapter two: methodologies for characterisation of combustion sources and for quantification of their emissions

Emissions from the combustion of biomass and fossil fuels result in generation of a large number of particle and gaseous products in outdoor and/or indoor air, which create health and environmental risks. Of particular importance are the very small particles that are emitted in large quantities from all the combustion sources, and that could be potentially more significant in terms of their impact on health and the environment than larger particles. It is important to quantify particle emissions from combustion sources for regulatory and control purposes in relation to air quality. This paper is a review of particle characteristics that are used as source signatures, their general advantages and limitations, as well as a review of source signatures of the most common combustion pollution sources including road transport, industrial facilities, small household combustion devices, environmental tobacco smoke, and vegetation burning. The current methods for measuring particle physical characteristics (mass and number concentrations) and principles of methodologies for measuring emission factors are discussed in the paper as well. Finally, the paper presents the recommendations for the future techniques for measurements of combustion products.     

Environmental Appraisal: And Oxides of Nitrogen Oxidants,Hydrocarbons

The relationships between criteria, standards, and control of air pollutants involve complex multidisciplinary interactions. Their over-all impact on the public health and welfare is directly related to the confidence level held by members of government, industry, and universities in the validity of the data upon which these criteria are based. The Environmental Appraisal section of the preliminary draft of the Air Quality Criteria Document “Photochemical Oxidant” prepared by the State of California, Department of Public Health, is reviewed. In general, it is a thoughtful and extensive effort to present the current status of information concerning the physical and chemical aspects of photochemical oxidant. Suggestions as to how it might be extended, revised, or updated are presented along with a brief discussion of two new research areas of possible interest, singlet molecular oxygen as a possible environmental oxidant, and the photochemistry of mixed lead halides in the atmosphere.     

Health Effects of Fine Particulate Air Pollution: Lines that Connect

Abstract

Efforts to understand and mitigate the health effects of particulate matter (PM) air pollution have a rich and interesting history. This review focuses on six substantial lines of research that have been pursued since 1997 that have helped elucidate our understanding about the effects of PM on human health. There has been substantial progress in the evaluation of PM health effects at different time-scales of exposure and in the exploration of the shape of the concentration-response function. There has also been emerging evidence of PM-related cardiovascular health effects and growing knowledge regarding interconnected general pathophysiological pathways that link PM exposure with cardiopulmonary morbidity and mortality. Despite important gaps in scientific knowledge and continued reasons for some skepticism, a comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate air pollution has adverse effects on cardiopulmonary health. Although much of this research has been motivated by environmental public health policy, these results have important scientific, medical, and public health implications that are broader than debates over legally mandated air quality standards.     

Megacities and Large Urban Agglomerations in the Coastal Zone: Interactions Between Atmosphere, Land, and Marine Ecosystems

Megacities are not only important drivers for socio-economic development but also sources of environmental challenges. Many megacities and large urban agglomerations are located in the coastal zone where land, atmosphere, and ocean meet, posing multiple environmental challenges which we consider here. The atmospheric flow around megacities is complicated by urban heat island effects and topographic flows and sea breezes and influences air pollution and human health. The outflow of polluted air over the ocean perturbs biogeochemical processes. Contaminant inputs can damage downstream coastal zone ecosystem function and resources including fisheries, induce harmful algal blooms and feedback to the atmosphere via marine emissions. The scale of influence of megacities in the coastal zone is hundreds to thousands of kilometers in the atmosphere and tens to hundreds of kilometers in the ocean. We list research needs to further our understanding of coastal megacities with the ultimate aim to improve their environmental management.     

Modelling aerosol number distributions from a vehicle exhaust with an aerosol CFD model

Vehicular traffic contributes significantly to the aerosol number concentrations at the local scale by emitting primary soot particles and forming secondary nucleated nanoparticles. Because of their potential health effects, more attention is paid to the traffic induced aerosol number distributions.The aim of this work is to explain the phenomenology leading to the formation and the evolution of the aerosol number distributions in the vicinity of a vehicle exhaust using numerical modelling. The emissions are representative of those of a light-duty diesel truck without a diesel particle filter. The atmospheric flow is modelled with a computational fluid dynamics (CFD) code to describe the dispersion of pollutants at the local scale. The CFD code, coupled to a modal aerosol model (MAM) describing the aerosol dynamics, is used to model the tailpipe plume of a vehicle with emissions corresponding to urban driving conditions. On the basis of available measurements in Schauer et al. (1999), three surrogate species are chosen to treat the semi-volatile organic compounds in the emissions.The model simulates the formation of the aerosol distribution in the exhaust plume of a vehicle as follows. After emission to the atmosphere, particles are formed by nucleation of sulphuric acid and water vapour depending strongly on the thermodynamic state of the atmosphere and on the dilution conditions. The semi-volatile organic compounds are critical for the rapid growth of nanoparticles through condensation. The semi-volatile organic compounds are also important for the evolution of primary soot particles and can contribute substantially to their chemical composition.The most influential parameters for particle formation are the sulphur fuel content, the semi-volatile organic emissions and also the mass and initial diameter of the soot particles emitted. The model is able to take into account the complex competition between nucleation, condensation and dilution, as well as the interactions among the different aerosol modes. This type of model is a useful tool to better understand the dynamics leading to the formation of traffic induced aerosol distributions. However, some key issues such as the turbulence in the exhaust plume and in the wake of the car, the magnitude and chemical composition of semi-volatile organic emissions and the possible nucleation of organic species need to be investigated further to improve our understanding of ultrafine particle formation.     

Short-chain oxygenated VOCs: Emission and uptake by plants and atmospheric sources,sinks, and concentrations

Emissions of volatile organic compounds (VOCs) have multiple atmospheric implications and play many roles in plant physiology and ecology. Among these VOCs, growing interest is being devoted to a group of short-chain oxygenated VOCs (oxVOCs). Technology improvements such as proton transfer reaction-mass spectrometry are facilitating the study of these hydrocarbons and new data regarding these compounds is continuously appearing. Here we review current knowledge of the emissions of these oxVOCs by plants and the factors that control them, and also provide an overview of sources, sinks, and concentrations found in the atmosphere.The oxVOCs reviewed here are formic and acetic acids, acetone, formaldehyde, acetaldehyde, methanol, and ethanol. In general, because of their water solubility (low gas–liquid partitioning coefficient), the plant-atmosphere exchange is stomatal-dependent, although it can also take place via the cuticle. This exchange is also determined by atmospheric mixing ratios. These compounds have relatively long atmospheric half-lives and reach considerable concentrations in the atmosphere in the range of ppbv. Likewise, under non-stressed conditions plants can emit all of these oxVOCs together at fluxes ranging from 0.2 up to 4.8 μg(C)g⁻¹(leaf dry weight)h⁻¹ and at rates that increase several-fold when under stress.Gaps in our knowledge regarding the processes involved in the synthesis, emission, uptake, and atmospheric reactivity of oxVOCs precludes the clarification of exactly what is conditioning plant-atmosphere exchange—and also when, how, and why this occurs—and these lacunae therefore warrant further research in this field.