CALIOP对一次秸秆焚烧后气溶胶光学特性的探测分析

采用星载激光雷达(Cloud - Aerosol LIdar with Orthogonal Polarization,CALIOP)资料研究了2008年6月2日华东秸秆焚烧排放气溶胶的光学特性,并与2006～2008年统计结果进行了对比.结果表明:1)CALIOP能够有效探测到气溶胶层,探测结果符合生物质燃烧气溶胶的...     

秸秆燃烧对北京秋季气溶胶浓度和短波辐射影响的模拟研究

利用地面细颗粒物（PM2.5）浓度和气象常规观测资料、地基 AERONET观测资料、GFED生物质燃烧排放清单和大气化学—天气耦合模式WRF-Chem,模拟研究了华北地区2014年10月气象要素和大气污染物的时空演变,重点关注北京10月7～11日的一次重霾事件及其天气形势、边界层气象特征、输送路径、PM2.5及其化学成分浓度变化等特征,以及秸秆燃烧对华北和北京地区细颗粒物浓度和地面短波辐射的影响。与观测资料的对比结果显示,模式可以很好地模拟北京地区地面气象要素和PM2.5质量浓度,考虑秸秆燃烧排放源可以明显改进北京PM2.5浓度模拟的准确性,但在重度污染情况下,模式总体上低估气溶胶光学厚度和高估地面短波辐射。10月7～11日北京地区重霾事件主要是不利气象条件下人为污染物累积和区域输送造成,也受到华北地区南部秸秆燃烧的影响。河南北部、河北南部和山东西部大面积秸秆燃烧释放的气态污染物和颗粒物在南风的作用下输送至北京,秸秆燃烧对北京地区地面PM2.5、有机碳（OC）、硝酸盐、铵盐、硫酸盐和黑碳（BC）的平均贡献率分别为24.6%、36.8%、23.2%、22.6%、7.1%和19.8%,秸秆燃烧产生的气溶胶可以导致北京地面平均短波辐射最大减小超过20 W m－2,约占总气溶胶导致地表短波辐射变化的24%。     

The sources and seasonal variations of organic compounds in PM<Subscript>2.5</Subscript> in Beijing and Shanghai

Fine aerosol samples were collected throughout spring, summer, and winter in 2004∼2005 at a major urban traffic junction (BNU) and a suburban location (MY) in Beijing and at a downtown site (SH) in Shanghai, China. Ten of the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs), seven fatty acids, levoglucosan, and cholesterol were identified and quantified. PAHs detected in Beijing and Shanghai were up to one order of magnitude higher than those reported in the developed countries either in urban or suburban areas, while levoglucosan was one order of magnitude lower than that in other countries for no biomass combustion in domestic heating in the mega-cities in China. PAHs showed the same seasonal trend in all sampling sites as the highest in winter and the lowest in summer, while fatty acids no pronounced seasonal variation. A significant fraction of levoglucosan from cooking with higher concentrations in urban than in suburban area contributed to the ambient atmosphere, indicating that the main source of levoglucosan in urban environment would be cooking rather than biomass burning. The relative contributions of coal combustion and vehicle exhaust sources to PAHs in fine aerosols were preliminarily estimated to be 1:2 in Beijing and 1:1 in Shanghai, revealing that the air pollution in these mega-cities in China was mainly the mixing of coal combustion with vehicle exhaust. Cooking was one of the major sources of organic aerosols in both Beijing and Shanghai.     

露天生物质燃烧对地面PM2.5浓度的影响评估

利用MODIS火点、土地类型、植被覆盖、生物质载荷和排放因子等数据产品,开发了露天生物质燃烧排放模型,并将其嵌入空气质量模式WRF-CUACE,通过敏感性试验定量评估了露天生物质燃烧对中国地面PM_2.5浓度的影响。研究设计了3种模拟方案,比较模式评估结果发现修订后的方案能更好地模拟PM_2.5浓度。结果表明:2014年10月露天生物质燃烧主要集中在我国东北、华南和西南地区,其对PM_2.5月平均浓度的贡献达30~60 μg·m-3,局地甚至超过100 μg·m-3;华北、华东和华南地区生物质燃烧对PM_2.5月平均浓度的贡献达5~20 μg·m-3。从相对贡献看,东北大部分地区生物质燃烧对地面PM_2.5浓度的贡献超过50%,华南地区达20%~50%,西南局部地区甚至超过60%;华北、华中以及华东地区相对较低,平均相对贡献达10%~20%。生物质燃烧越严重的地区,其产生的PM_2.5中二次气溶胶的贡献占比越小,反之亦然。     

CALIOP对一次秸秆焚烧后气溶胶光学特性的探测分析

采用星载激光雷达(Cloud-Aerosol LIdar with Orthogonal Polarization,CALIOP)资料研究了2008年6月2日华东秸秆焚烧排放气溶胶的光学特性,并与2006~2008年统计结果进行了对比。结果表明:1)CALIOP能够有效探测到气溶胶层,探测结果符合生物质燃烧气溶胶的典型特征;气溶胶分布及廓线特点可以由火点分布及大气环流形势做出解释。2)个例中气溶胶光学特性廓线与该地区2006~2008年全年平均和夏季平均都存在一定差异。个例中后向散射系数廓线的峰值显示出气溶胶垂直分布结构,对应高度上的退偏振率比平均偏大而双波长比则偏小,表明秸秆焚烧源气溶胶层由大量非球形的细粒子组成。3)个例中气溶胶粒子谱特征与3年夏季平均接近而与3年平均差别很大,显示出个例的季节特征。更多个例的统计分析和地基观测的验证有助于了解秸秆焚烧源气溶胶的普遍规律。     

Chemical composition of aerosols in the atmosphere of Mongolia

Presented are the results of studies of the component composition of atmospheric aerosols in Mongolia for the period of 2005?C2010. It is demonstrated that the local emissions mostly affect the composition of aerosols in industrial cities (Ulan Bator and Sükhbaatar), whereas the distant transport of pollutants and the wind regime of the area, in particular, the dust storms affect in small towns with the undeveloped industry (Baruun-Urt and Sainshand). Revealed is the dependence of the composition and concentration of suspended particles on the meteorological conditions in the research area. High concentrations of aerosols were observed on the days with strong winds and air masses transport from the deserts and industrial areas of China. Low concentrations of ions were observed during periods of calm weather and in case of the air masses transport from the territories of Russia and Kazakhstan.     

京津冀周边秸秆燃烧对PM2.5无机组分影响

华北平原是我国主要农作物产区,田间秸秆焚烧现象普遍存在,选取秋收季节（2014年10月）分析了秸秆燃烧的排放特征,利用区域化学传输模型WRF-Chem模拟研究了燃烧排放对气态前体物及其氧化产物的影响,以及最终导致的PM_2.5中硫酸盐、硝酸盐和铵盐的变化。研究表明:2014年秋收季节,河南和山东等省份的秸秆燃烧排放会在东南风的输送作用下影响京津冀地区;秸秆燃烧排放大量挥发性有机物（VOCs）,导致火点源及周边地区大气中主要氧化剂浓度上升,提升了区域大气氧化能力;当携带大量VOCs的秸秆燃烧烟羽与以化石燃料排放为主的城市气团相混合时,大气氧化性增强会加速城市地区人为源排放的NO_x和SO₂等气态前体物的氧化过程,提高硫酸盐和硝酸盐的形成速率、促进二次无机气溶胶的生成。     

可持续发展背景下的黑碳减排

 黑碳气溶胶是环境大气中浓度较低的一种气溶胶粒子组分,因其对光的吸收作用,及其对空气质量和人体健康的影响,而成为当前国际气候变化和环境研究中关注的热点问题之一。本文围绕黑碳的减排问题,介绍黑碳的来源、全球分布,讨论全球温室气体减排和区域空气质量控制对黑碳减排的影响,综述控制和改善燃烧条件、减少开放式生物质燃烧和黑碳封存等减排黑碳的措施。文章还分析了黑碳未能成为全球减排共识的原因,并对中国有关黑碳减排的政策选择提出了建议。     

2004年北京秋季大气颗粒物的化学组分和来源特征

2004年9月在北京城区进行了大气颗粒物采样,样品用PIXE方法进行了分析,得到了20种元素的浓度及其谱分布。并对北京颗粒物的谱分布、富集因子和来源进行了分析研究。发现K元素浓度分布呈细粒态单峰谱分布,细粒态K富集因子较高,表明了生物质燃烧的主要贡献。因子分析结果还表明,土壤尘、生物质燃烧、煤烟尘、工业源和汽车尾气排放源对秋季北京局地排放源有明显贡献。     

Emissions of Polycyclic aromatic hydrocarbons by savanna fires

Although Polycyclic aromatic hydrocarbons (PAH) are known as anthropogenic compounds arising from the combustion or the pyrolysis of fossil fuels, they may be also emitted by the combustion of vegetation. A field study was carried out in January 1991 at Lamto (Ivory Coast) as part of the FOS DECAFE experiment (Fire Of Savanna). Some ground samplings were devoted to the qualitative and quantitative characterization of atmospheric emissions by savanna fires during prescribed burns and under background conditions. Specific collections for gaseous and particulate PAHs have shown that the African practice of burning the savanna biomass during the winter months is an important source of PAHs. These compounds are emitted mainly in gaseous form but a significant fraction, essentially heavy PAHs, is associated with fine carbonaceous particles and can therefore represent a hazard for human health, since some of these compounds are mutagenic and carcinogenic. Twelve compounds were identified during the fire episodes and in the atmospheric background. The total concentration in the fires is of the order of 10 ng m^–3 for the gas phase and from 0.1 to 1 ng m^–3 in the aerosols. In the atmospheric background the mean concentrations are regular, 0.15 ng m^–3 and 2 pg m^–3, respectively. These concentrations are comparable with what is observed in European rural zones. The particulate emissions of PAHs by the savanna fires are distinguished by the abundance of some compounds which can be considered as tracers, although they are also slightly emitted by fossil fuel sources. These compounds are essentially pyrene, chrysene and coronene. In the gas phase, although no individual PAH may be considered as specific of the biomass combustion emissions, the relative abundances of the main PAHs are characteristic of the biomass burning. The concentrations of pyrene and fluorene are always predominant; these compounds could be considered as characteristic emission products of smoldering and flaming episodes, respectively. In the background the PAH composition shows that in a tropical region the air consists of a mixture coming from the various sources, but the biomass combustion is by far the most important source.The fluxes of total PAH emitted by savanna biomass burning in Africa were estimated to be of the order of 17 and 600 ton yr^–1, respectively, for the particulate PAHs and the gaseous PAHs, respectively.     

Chemical composition of PM2.5 at an urban site of Chengdu in southwestern China

PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annual average of PM2.5 was 165g m－3, which is generally higher than measurements in other Chinese cities, suggesting serious particulate pollution issues in the city. Water soluble ions contributed 43.5% to the annual total PM2.5 mass, carbonaceous aerosols including elemental carbon and organic carbon contributed 32.0%, and trace elements contributed 13.8%. Distinct daily and seasonal variations were observed in the mass concentrations of PM2.5 and its components, reflecting the seasonal variations of different anthropogenic and natural sources. Weakly acidic to neutral particles were found for PM2.5. Major sources of PM2.5 identified from source apportionment analysis included coal combustion, traffic exhaust, biomass burning, soil dust, and construction dust emissions. The low nitrate: sulfate ratio suggested that stationary emissions were more important than vehicle emissions. The reconstructed masses of ammonium sulfate, ammonium nitrate, particulate carbonaceous matter, and fine soil accounted for 79% of the total measured PM2.5 mass; they also accounted for 92% of the total measured particle scattering.     

Satellite and ground-based remote sensing of aerosols during intense haze event of October 2013 over lahore,Pakistan

Due to increase in population and economic development, the mega-cities are facing increased haze events which are causing important effects on the regional environment and climate. In order to understand these effects, we require an in-depth knowledge of optical and physical properties of aerosols in intense haze conditions. In this paper an effort has been made to analyze the microphysical and optical properties of aerosols during intense haze event over mega-city of Lahore by using remote sensing data obtained from satellites (Terra/Aqua Moderate-resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)) and ground based instrument (AErosol RObotic NETwork (AERONET)) during 6-14 October 2013. The instantaneous highest value of Aerosol Optical Depth (AOD) is observed to be 3.70 on 9 October 2013 followed by 3.12 on 8 October 2013. The primary cause of such high values is large scale crop residue burning and urban-industrial emissions in the study region. AERONET observations show daily mean AOD of 2.36 which is eight times higher than the observed values on normal day. The observed fine mode volume concentration is more than 1.5 times greater than the coarse mode volume concentration on the high aerosol burden day. We also find high values (~0.95) of Single Scattering Albedo (SSA) on 9 October 2013. Scatter-plot between AOD (500 nm) and Angstrom exponent (440-870 nm) reveals that biomass burning/urban-industrial aerosols are the dominant aerosol type on the heavy aerosol loading day over Lahore. MODIS fire activity image suggests that the areas in the southeast of Lahore across the border with India are dominated by biomass burning activities. A Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model backward trajectory showed that the winds at 1000 m above the ground are responsible for transport from southeast region of biomass burning to Lahore. CALIPSO derived sub-types of aerosols with vertical profile taken on 10 October 2013 segregates the wide spread aerosol burden as smoke, polluted continental and dust aerosols.     

Source attribution of urban smog episodes caused by coal combustion

Stable weather conditions together with extensive use of coal combustion often lead to severe smog episodes in certain urban environments, especially in Eastern Europe. In order to identify the specific sources that cause the smog episodes in such environments, and to better understand the mixing state and atmospheric processing of aerosols, both single particle and bulk chemical characterization analysis of aerosols were performed in Krakow, Poland, during winter 2005.Real-time measurements of the bulk PM10 aerosol during a severe smog episode (PM10 mass > 400 µg m^− 3) showed a stable concentration of black carbon in the aerosol, and an increase in the sulphate and chlorine mass contributions towards the end of the episode. Chemical characterization of single particles further helped to identify residential coal burning as the main source that caused this severe smog episode, consisting of single particles with major signals for carbon with simultaneous absence of sulphate, chlorine and calcium. Particles from industrial coal combustion gained importance towards the end of that episode, after residential coal combustion was switched off, indicated by an increase of the percentage of sulphate and chlorine containing particles. Traffic was not a significant source during the severe smog episode. During a lighter smog episode, residential and industrial coal combustion was still predominant, with an increased contribution of traffic and processed/aged aerosols. On a clean day, particle classes containing nitrate were the most abundant. In addition, the aerosol was more internally mixed showing that there were more sources contributing to the total aerosol population.     

A Case Study of the Impacts of Dust Aerosols on Surface Atmospheric Variables and Energy Budgets in a Semi-Arid Region of China

The authors present a case study investigating the impacts of dust aerosols on surface atmospheric variables and energy budgets in a semi-arid region of China. Enhanced observational meteorological data, radiative fluxes, near-surface heat fluxes, and concentrations of dust aerosols were collected from Tongyu station, one of the reference sites of the International Coordinated Energy and Water Cycle Observations Project (CEOP), during a typical dust storm event in June 2006. A comprehensive analysis of these data show that in this semi-arid area, higher wind velocities and a continuously reduced air pressure were identified during the dust storm period. Dust storm events are usually associated with low relative humidity weather conditions, which result in low latent heat flux values. Dust aerosols suspended in the air decrease the net radiation, mainly by reducing the direct solar radiation reaching the land surface. This reduction in net radiation results in a decrease in soil temperatures at a depth of 2 cm. The combination of increased air temperature and decreased soil temperature strengthens the energy exchange of the atmosphere-earth system, increasing the surface sensible heat flux. After the dust storm event, the atmosphere was dominated by higher pressures and was relatively wet and cold. Net radiation and latent heat flux show an evident increase, while the surface sensible heat flux shows a clear decrease.     

Chemical characterization of fine particulate matter during peak PM10 episodes in Apulia (South Italy)

Some peak PM10 episodes, occurred during PM monitoring campaigns performed on October 2005 and February and June 2006 in Bari town, have been characterized. Moreover back trajectories of air masses and Principal Component Analyses were applied. Three of the peak PM10 episodes investigated were related to local emissions of primary pollutants during poor atmospheric dispersion conditions. The other two peak PM10 episodes considered are related with long range transport air masses toward Apulia region: in one case the chemical characterization and the back trajectories analysis indicate that high PM10 value detected is due to the Saharan dust advection in the Apulia region; in the other case air masses with different origin give rise to high PM10 value.Moreover PM10 daily mean concentrations, presented in this paper collected from January 2005 to August 2007 and obtained by automatic device in six stations of air quality monitoring networks in Bari territory, do not show a seasonal trend for PM10 concentrations, contrary to the PM10 trend shown in the towns of North Italy. This can be explained mostly considering that our region presents generally meteo-climatic conditions that favour pollutants dispersion.     

Chemical characterization of fine particulate matter during peak PM10 episodes in Apulia (South Italy)

Some peak PM10 episodes, occurred during PM monitoring campaigns performed on October 2005 and February and June 2006 in Bari town, have been characterized. Moreover back trajectories of air masses and Principal Component Analyses were applied. Three of the peak PM10 episodes investigated were related to local emissions of primary pollutants during poor atmospheric dispersion conditions. The other two peak PM10 episodes considered are related with long range transport air masses toward Apulia region: in one case the chemical characterization and the back trajectories analysis indicate that high PM10 value detected is due to the Saharan dust advection in the Apulia region; in the other case air masses with different origin give rise to high PM10 value.Moreover PM10 daily mean concentrations, presented in this paper collected from January 2005 to August 2007 and obtained by automatic device in six stations of air quality monitoring networks in Bari territory, do not show a seasonal trend for PM10 concentrations, contrary to the PM10 trend shown in the towns of North Italy. This can be explained mostly considering that our region presents generally meteo-climatic conditions that favour pollutants dispersion.     

Climate forcing by carbonaceous and sulfate aerosols

 An atmospheric general circulation model is coupled to an atmospheric chemistry model to calculate the radiative forcing by anthropogenic sulfate and carbonaceous aerosols. The latter aerosols result from biomass burning as well as fossil fuel burning. The black carbon associated with carbonaceous aerosols is absorbant and can decrease the amount of reflected radiation at the top-of-the-atmosphere. In contrast, sulfate aerosols are reflectant and the amount of reflected radiation depends nonlinearly on the relative humidity. We examine the importance of treating the range of optical properties associated with sulfate aerosol at high relative humidities and find that the direct forcing by anthropogenic sulfate aerosols can decrease from −0.81 W m^-2 to −0.55 Wm^-2 if grid box average relative humidity is not allowed to increase above 90%. The climate forcing associated with fossil fuel emissions of carbonaceous aerosols is calculated to range from +0.16 to +0.20 Wm^-2, depending on how much organic carbon is associated with the black carbon from fossil fuel burning. The direct forcing of carbonaceous aerosols associated with biomass burning is calculated to range from −0.23 to −0.16 Wm^-2. The pattern of forcing by carbonaceous aerosols depends on both the surface albedo and the presence of clouds. Multiple scattering associated with clouds and high surface albedos can change the forcing from negative to positive. Received: 29 September 1997 / Accepted: 10 June 1998     

A Global Inventory of Burned Areas at 1 Km Resolution for the Year 2000 Derived from Spot Vegetation Data

Biomass burning constitutes a major contribution to global emissions of carbon dioxide, carbon monoxide, methane, greenhouse gases and aerosols. Furthermore, biomass burning has an impact on health, transport, the environment and land use. Vegetation fires are certainly not recent phenomena and the impacts are not always negative. However, evidence suggests that fires are becoming more frequent and there is a large increase in the number of fires being set by humans for a variety of reasons. Knowledge of the interactions and feedbacks between biomass burning, climate and carbon cycling is needed to help the prediction of climate change scenarios. To obtain this knowledge, the scientific community requires, in the first instance, information on the spatial and temporal distribution of biomass burning at the global scale. This paper presents an inventory of burned areas at monthly time periods for the year 2000 at a resolution of 1 kilometer (km) and is available to the scientific community at no cost. The burned area products have been derived from a single source of satellite-derived images, the SPOT VEGETATION S1 1 km product, using algorithms developed and calibrated at regional scales by a network of partners. In this paper, estimates of burned area, number of burn scars and average size of the burn scar are described for each month of the year 2000. The information is reported at the country level. This paper makes a significant contribution to understanding the effect of biomass burning on atmospheric chemistry and the storage and cycling of carbon by constraining one of the main parameters used in the calculation of gas emissions.     

南京地区冬季大气冰核特征及其与气溶胶关系的研究

2011年11月15日～12月2日期间对南京地区近地面大气气溶胶和冰核进行了同步观测,综合分析了 冰核浓度的特征及其与气溶胶粒子浓度的关系。结果表明:活化温度T_a为-20℃,水面过饱和度为1%时,南京地区冰核浓度N_IN为0.352 L-1,与0.01～10 μm气溶胶数浓度比值仅为4×10-8。冰核活化温度越低,湿度越大,冰核浓度越高。雾和降雨对冰核都有明显的清除作用。对比不同气团对南京地区冰核的影响发现,偏东方向的污染气团中冰核以及气溶胶的浓度最高,但是来自西北地区的气团中冰核占气溶胶的比例最高,这可能是由于冰相核化能力较强的沙尘气溶胶导致的。分析冰核与不同粒径段气溶胶的相关性发现,较大粒径气溶胶的表面积浓度与冰核相关性更高,本文也得到了由活化温度T_a和粒径大于0.5 μm气溶胶数浓度N_{0.5～10 μm}共同计算冰核浓度的经验公式。     

Source identification of PM2.5 particles measured in Gwangju, Korea

The UNMIX and Chemical Mass Balance (CMB) receptor models were used to investigate sources of PM_2.5 aerosols measured between March 2001 and February 2002 in Gwangju, Korea. Measurements of PM_2.5 particles were used for the analysis of carbonaceous species (organic (OC) and elemental carbon (EC)) using the thermal manganese dioxide oxidation (TMO) method, the investigation of seven ionic species using ion chromatography (IC), and the analysis of twenty-four metal species using Inductively Coupled Plasma (ICP)-Atomic Emission Spectrometry (AES)/ICP-Mass Spectrometry (MS). According to annual average PM_2.5 source apportionment results obtained from CMB calculations, diesel vehicle exhaust was the major contributor, accounting for 33.4% of the measured PM_2.5 mass (21.5 μg m^− 3), followed by secondary sulfate (14.6%), meat cooking (11.7%), secondary organic carbon (8.9%), secondary nitrate (7.6%), urban dust (5.5%), Asian dust (4.4%), biomass burning (2.8%), sea salt (2.7%), residual oil combustion (2.6%), gasoline vehicle exhaust (1.9%), automobile lead (0.5%), and components of unknown sources (3.4%). Seven PM_2.5 sources including diesel vehicles (29.6%), secondary sulfate (17.4%), biomass burning (14.7%), secondary nitrate (12.6%), gasoline vehicles (12.4%), secondary organic carbon (5.8%) and Asian dust (1.9%) were identified from the UNMIX analysis. The annual average source apportionment results from the two models are compared and the reasons for differences are qualitatively discussed for better understanding of PM_2.5 sources.Additionally, the impact of air mass pathways on the PM_2.5 mass was evaluated using air mass trajectories calculated with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) backward trajectory model. Source contributions to PM_2.5 collected during the four air mass patterns and two event periods were calculated with the CMB model and analyzed. Results of source apportionment revealed that the contribution of diesel traffic exhaust (47.0%) in stagnant conditions (S) was much higher than the average contribution of diesel vehicle exhaust (33.4%) during the sampling period. During Asian dust (AD) periods when the air mass passed over the Korean peninsula, Asian dust and secondary organic carbon accounted for 25.2 and 23.0% of the PM_2.5 mass, respectively, whereas Asian dust contributed only 10.8% to the PM_2.5 mass during the AD event when the air mass passed over the Yellow Sea. The contribution of biomass burning to the PM_2.5 mass during the biomass burning (BB) event equaled 63.8%.