PRIMARY STUDY OF SULFATE AND CARBONACEOUS AEROSOLS IN BEIJING

Results of our aerosol study, performed during 1983–1984 in Beijing, demonstrate that ambient carbonaceous aerosols are derived mainly from coal combustion. Different SO₂ oxidation processes have been observed in summer and winter. The winter sulfate appears to be produced locally and associated with products of incomplete combustion.     

吉林省冬季燃煤民居室内CO污染监测分析

利用多功能无线电采集器在吉林省开展了冬季燃煤民居室内CO、CO₂、气温自动观测和室内外对比观测试验,分析了CO和CO₂浓度的变化特征及与用火规律、室内温度的关系。结果表明：吉林省冬季燃煤民居中普遍存在CO污染,60 %的民居出现浓度持续超过125mg·m^-3的高污染;CO浓度的逐月变化与燃煤量有关,日变化与用火过程、燃烧阶段和燃烧状态有关;在不同季节、不同城市、不同民居、不同室温以及不同燃烧过程中,CO在烟气中所占的比例不同;在点火、持续燃烧、压炉子和熄火等不同燃烧阶段及旺火燃烧、急倒烟和慢倒烟等不同燃烧状态下,CO浓度的变化特征有显著差异。     

Characterization of Black Carbon in the Ambient Air of Agra,India:Seasonal Variation and Meteorological Influence

This study characterizes the black carbon in Agra, India home to the Taj Mahal—and situated in the Indo-Gangetic basin.The mean black carbon concentration is 9.5 μg m~(-3)and, owing to excessive biomass/fossil fuel combustion and automobile emissions, the concentration varies considerably. Seasonally, the black carbon mass concentration is highest in winter, probably due to the increased fossil fuel consumption for heating and cooking, apart from a low boundary layer. The nocturnal peak rises prominently in winter, when the use of domestic heating is excessive. Meanwhile, the concentration is lowest during the monsoon season because of the turbulent atmospheric conditions and the process of washout by precipitation. The ratio of black carbon to brown carbon is less than unity during the entire study period, except in winter(December). This may be because that biomass combustion and diesel exhaust are major black carbon contributors in this region, while a higher ratio in winter may be due to the increased consumption of fossil fuel and wood for heating purposes. ANOVA reveals significant monthly variation in the concentration of black carbon; plus, it is negatively correlated with wind speed and temperature. A high black carbon mass concentration is observed at moderate(1–2 m s~(-1)) wind speed, as compared to calm or turbulent atmospheric conditions.     

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.     

中国地区黑碳气溶胶直接辐射效应的数值模拟研究

利用意大利国际理论物理研究中心（ICTP）提供的2000年各月气溶胶资料（包括人类活动和生物质燃烧所产生的气溶胶）,使用并行版本区域气候模式RegCM3,研究了黑碳气溶胶对中国区域气候的影响。结果表明,引入黑碳气溶胶后,冬、夏季中国大部分地区大气顶出现了正辐射强迫,其分布与垂直负荷分布基本相似。在仅考虑黑碳气溶胶的直接辐射效应时,中国大部分地区冬、夏季地面气温呈下降趋势,降温的高值区均位于中国东南部,冬季最大降温幅度约为0．9℃,夏季最大降幅约为2．4℃,夏季降温幅度明显大于冬季。相对于温度变化,黑碳气溶胶引起的降水变化较为复杂,无论是冬季还是夏季,降水量减小的区域均大于增加区。冬季降水量最大减幅约为20mm,夏季降水量最大减幅超过100mm,夏季降水量减幅明显大于冬季。冬、夏季仅西北和华南部分地区降水量有所增加。冬季中国大部分地区痕量降水和弱降水日数呈增加趋势;夏季黄河以北中国北方地区痕量降水和弱降水日数也是以增加为主。     

Distribution and source apportionment of Polycyclic aromatic hydrocarbons from atmospheric particulate matter PM<Subscript>2.5</Subscript> in Beijing

A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city. The PM2.5 concentrations are all above the PM2.5 pollution standard （65 μg m^-3） established by Environmental Protection Agency, USA （USEPA） in 1997 except for the Ming Tombs site. PM2.5 concentrations in winter are much higher than in summer. The 16 Polycyclic aromatic hydrocarbons （PAHs） listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high performance liquid chromatography （HPLC） with variable wavelength detector （VWD） and fluorescence detector （FLD） employed. The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing. The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m^-3. The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs. Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions. The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission. New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city.     

Vertical Distribution Characteristics of PM<Subscript>2.5</Subscript> Observed by a Mobile Vehicle Lidar in Tianjin,China in 2016

We present mobile vehicle lidar observations in Tianjin, China during the spring, summer, and winter of 2016. Mobile observations were carried out along the city border road of Tianjin to obtain the vertical distribution characteristics of PM_2.5. Hygroscopic growth was not considered since relative humidity was less than 60% during the observation experiments. PM_2.5 profile was obtained with the linear regression equation between the particle extinction coefficient and PM_2.5 mass concentration. In spring, the vertical distribution of PM_2.5 exhibited a hierarchical structure. In addition to a layer of particles that gathered near the ground, a portion of particles floated at 0.6–2.5-km height. In summer and winter, the fine particles basically gathered below 1 km near the ground. In spring and summer, the concentration of fine particles in the south was higher than that in the north because of the influence of south wind. In winter, the distribution of fine particles was opposite to that measured during spring and summer. High concentrations of PM_2.5 were observed in the rural areas of North Tianjin with a maximum of 350 μg m^–3 on 13 December 2016. It is shown that industrial and ship emissions in spring and summer and coal combustion in winter were the major sources of fine particles that polluted Tianjin. The results provide insights into the mechanisms of haze formation and the effects of meteorological conditions during haze–fog pollution episodes in the Tianjin area.     

Polycyclic aromatic hydrocarbons and their molecular diagnostic ratios in urban atmospheric respirable particulate matter

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) in Santiago de Chile city were evaluated to study particulate PAHs profiles during cold and spring weather periods. Urban atmospheric particulate matter PM10 was collected using High Volume PM10 samplers. Fifteen samples of 24 h during austral winter and 20 samples of 24 h during spring, 2000 were collected at two sampling sites (North–East and Central areas of the city) whose characteristics were representative of the prevailing conditions. Seventeen PAHs were quantified and total PAHs concentration ranged from 1.39 to 59.98 ng m⁻³, with a seasonal variation (winter vs. spring ratio) from 0.5 to 12.6 ng m⁻³. Molecular diagnostic ratios were used to characterize and identify PAHs emission sources such as combustion and biogenic emissions. Results showed that the major sources of respirable organic aerosol PM10 in Santiago are mobile and stationary ones.     

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.     

Variation in black carbon mass concentration over an urban site in the eastern coastal plains of the Indian sub-continent

Black carbon (BC) mass concentration variation has been studied, over a period of 2 years (June 2010–May 2012) at Bhubaneswar. Daily, monthly and seasonal measurements revealed a clear winter maxima (5.6 μg/m³) of BC followed by post-monsoon (4.05 μg/m³), monsoon (3.02 μg/m³) and pre-monsoon (2.46 μg/m³). Nighttime BC mass concentrations have been found to be distinctly higher during winter followed by post-monsoon and monsoon. Investigations reveal that the winter maxima are due to a stable atmospheric condition and long-range transport over the Indo-Gangetic Plain and Western Asia. Local boundary layer dynamics and anthropogenic activities have been assumed to have a pronounced effect on the diurnal cycle seasonally. Statistical analysis suggests significant variation of BC during the months and non-significant during the days. The study also gives an insight into importance of BC study from health angle and suggests an assessment and management framework. Source apportionment study suggests that BC mass concentration observed at Bhubaneswar is generally dominated by fossil fuel combustion.     

武汉市居民区大气VOCs的污染特征和来源解析

于2016年7月-2017年6月在武汉市典型居民区对大气中101种挥发性有机物（VOCs）进行了监测,以便研究武汉市典型居民区周边VOCs的组成特征和变化规律,并探讨了其主要来源.结果表明,武汉市空气中VOCs的体积分数为（46.24±24.57）×10^-9,表现为烷烃>含氧有机物>烯烃>卤代烃>芳香烃.受交通排放影响烷烃的比例上午高于下午,1月机动车尾气为武汉市主要的VOCs排放源,夏季含氧类化合物浓度高于冬季,可能更多地受本地喷涂等溶剂使用行业和光化学反应生成的影响,5-9月表现出明显的生物源排放特征.利用正交矩阵因子分析（PMF）得到武汉市居民区大气VOCs主要有6个来源,分别为燃烧源、机动车尾气、工业排放、溶剂使用、汽油挥发和植物排放.其中,燃烧源、机动车尾气贡献比例最高,是该区域VOCs控制的重要排放源.     

Characteristics and source of black carbon aerosols at Akedala station, Central Asia

Black carbon concentration and weather data were online monitored continuously from March 2008 to February 2009 at the Akedala regional atmosphere station in the arid region of Central Asia. We present the daily, monthly and seasonal variations of BC concentration in the atmosphere and discuss the possible emission sources. Black carbon concentration in this region varies in the range of 43.7–1,559.2?ng/m³. A remarkable seasonal variation of BC in the aerosol was observed in the order of winter?>?spring?>?autumn?>?summer. The peak value of BC appeared at 10:00–13:00 while the lowest one at 7:00–9:00 each day. Air masses backward trajectories show the potential emission sources in the northwest from spring to autumn. Through back trajectory also revealed that BC in winter might be attributed to the emission from the anthropogenic activities, including domestic heating, cooking, combustion of oil and natural gas, and the medium-range transport from those cities in northern slope of Tianshan Mountains and Siberia. Some BC aerosols from the arid region of Central Asia were transported to the Pacific Ocean by the Westerlies.     

Organic composition of atmospheric urban aerosol: Variations and sources of aliphatic and polycyclic aromatic hydrocarbons

The non-polar organic composition of airborne particulate matter was analysed over a two year period in an urban area under oceanic climate conditions (Errenteria, Basque Country, Spain). In addition, the distribution of polycyclic aromatic hydrocarbons (PAH) among different aerosol particle sizes was determined. Clues as to the origin of various particle types were gained by using scanning electron microscopy to view the morphology of the particulates in each size fraction. Samples were collected on glass fibre filters and analysed by means of soxhlet extraction and gas chromatography (either with a flame ionization detector or coupled to a mass spectrometry). In general, total PAH levels were moderate (0.96–50 ng m^− 3) as compared to other studies conducted in Europe, and showed clear seasonal variation with maxima in winter and minima in summer. Vehicular traffic was identified as a major source of PAHs in the study area. Regarding particle size, a bimodal distribution was observed. The large sized particles exhibited an apparent seasonal variation with higher concentrations in winter than in summer. The dependences between particle size, PAH distribution and meteorological variables were studied with multivariate statistics. Three main sources of organic compounds were identified: combustion, vegetation, and atmospheric oxidation.     

北京地区PM2.5的成分特征及来源分析

选用2003—2004年初PM_2.5连续观测资料，统计分析了北京地区PM_2.5的特征、PM_2.5与PM₁₀以及PM_2.5与地面气象要素的相互关系。结果表明:四季中夏季PM_2.5浓度最低，冬、春两季浓度较高。PM_2.5与PM₁₀比值平均为0.55，非采暖期两者比值为0.52，采暖期两者比值为0.62；夏季该比值主要分布在0.3~0.6之间，春、秋两季该比值分布在0.3~0.8之间，冬季采暖期该比值分布在0.4~0.9之间。PM_2.5与PM₁₀比值日变化与气象条件日变化、人们日常生活习惯密切相关，沙尘天气和交通运输高峰期扬起地面粗颗粒物会导致PM_2.5在PM₁₀中的比例下降，而冬季取暖以及夏季光化学反应则会引起PM_2.5的比例升高。PM_2.5的浓度与地面气象要素中本站气压、相对湿度和风速有很好的的相关性，与气温的相关性较差。SO₄2-，NO₃-和NH₄+为北京地区PM_2.5中主要离子。PMF源解析方法确定了北京地区5类细粒子污染源，分别是:土壤尘、煤燃烧、交通运输、海洋气溶胶以及钢铁工业。     

Urban growth effects on low-temperature fog in Edmonton

Visibility observations at rural and urban airports in the Edmonton area during the severe winter of 1968–69 are compared with similar observations described in 1955 by G. W. Robertson for the winter of 1949–50. The new observations tend to confirm Robertson's finding that low-temperature fog in Edmonton is due mainly to saturation of the air by water vapour produced in burning natural gas. Visibilities in such fog are strongly temperature-dependent. The urban population more than doubled between 1950 and 1969, and new large sources of water vapour were added to the city. The effects of both changes are apparent in the visibility data. Computations of excess water content and temperature increases are made assuming that an isothermal layer develops as rural air passes over the city and is modified by the combustion of natural gas and motor vehicle fuel. The results are consistent with local measurements of surface temperature and vertical temperature gradients in the lowest 100 m over the city. Computations of excess water content are presented for fuel consumption rates corresponding to populations of 150000 to 800000. Measurements of the thickness of the fog layer over the city and of the frozen water content of ice fog for various visibilities are needed for additional verification of the calculations.Presented at the 5th Annual Congress of the Canadian Meteorological Society, Ste Anne de Bellevue, Quebec, 1971.     

Carbonyls and nonmethane hydrocarbons at rural European sites from the mediterranean to the arctic

Results of regular measurements during 1992–1995 of hydrocarbons and carbonyl compounds for a number of rural European monitoring sites are presented. The measurements are part of the EMEP programme for VOC measurements in Europe. In addition, several years of regular measurements are included from the Norwegian stations Birkenes at the south coast, and Zeppelin Mountain on Spitsbergen in the Arctic. The sampling frequency has been about twice per week throughout the years, implying that a substantial amount of measurement data are available. Almost all the chemical analyses have been performed by one laboratory, the EMEP Chemical Co-ordinating Centre located at NILU, which avoids problems of intercomparison and intercalibration among different laboratories. For the measured concentrations both seasonal and geographical variations are shown and discussed. The diurnal cycles of the hydrocarbon concentrations were studied in detail at one site, where the grab samples by EMEP where compared with a parallel continuous sampler, operated by EMPA, Switzerland. Hydrocarbons linked to natural gas and fuel evaporation become well mixed into the Arctic in the winter, whereas combustion products show a latitudinal gradient. The sum of oxygenated species constitutes about 5–15% of the sum of C₂–C₅ hydrocarbons in winter. In summer they are almost equal in magnitude, consistent with an increasing oxidation of hydrocarbons.     

太原冬季PM2.5中有机碳和元素碳的变化特征

2005年12月—2006年2月在太原市区持续观测了气溶胶细粒子PM_2.5, 并应用Sunset碳分析仪进行了有机碳 (organic carbon, OC) 和元素碳 (elemental carbon, EC) 的测定。结果表明:太原冬季PM_2.5, OC和EC浓度均较高, 其中PM_2.5日平均浓度变化范围为25.4~419.0 μg/m3, 日平均浓度为193.4±102.3 μg/m3, OC平均浓度为28.9±14.8 μg/m3, EC平均浓度为4.8±2.2 μg/m3, OC/EC平均比值是7.0±3.9, 即太原市冬季PM_2.5和碳气溶胶污染严重。OC在PM _2.5中占18.6%, EC占2.9%, 这表明碳气溶胶是太原大气细粒子污染控制的关键组分。在太原市冬季, 采暖燃烧的煤是OC和EC的主要贡献源, 造成OC大大高于EC, 从而使OC/EC比值增大。各种气象条件对PM_2.5, OC, EC和OC/EC比值的变化都有不同程度的影响, 特别是大雾天气、相对湿度、风速和降雪是影响碳气溶胶浓度变化的重要因素。     

辽宁冬季城市空气质量分布状况综合研究

利用2006年12月辽宁14个城市的大气环境现状监测资料和沈阳、鞍山、抚顺、本溪4城市可吸收入颗粒物(PM10,PM2.5和PM1)的监测资料,对辽宁冬季各城市的空气质量分布状况进行了综合研究。结果表明:辽宁14个城市的冬季空气质量分布状况为优、良和轻微污染3个等级,其中铁岭、营口和辽阳的空气质量有28 d为良及以上等级;空气质量级别为轻微污染日数最多的城市是本溪,共计12 d;其次是葫芦岛、沈阳、鞍山、抚顺、盘锦、阜新,共计7—10 d。各城市的首要污染物是PM10。由于冬季燃煤量的增加,沈阳、鞍山、抚顺和本溪4城市PM2.5日平均浓度值的超标率为77.4%—90.3%。     

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.     

Seasonal variation of particulate polycyclic aromatic hydrocarbons associated with PM10 in Guangzhou, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in the urban atmosphere. An investigation on seasonal variation of PAHs in the urban atmosphere of Guangzhou, China was conducted in this study. 112 PM10 (particulate matter with aerodynamic diameter < 10 μm) samples were collected at two sites between June 2002 and June 2003. PAHs were analyzed with GC–MS (gas chromatography–mass spectrometry). The result showed that PAHs exhibit distinct seasonal variation. The seasonal concentration for the ∑PAHs ranged from 8.11 to 106.26 ng m^− 3. The average ∑PAHs measured were highest in winter and lowest in summer. The PAHs distribution patterns were similar within each season at two sites. 5–6 ring PAHs were the abundant compounds, which accounted for 65–90% of ∑PAHs and benzo [b + k] fluoranthene dominated in four seasons. The PAHs concentration and distribution pattern fluctuated greatly in winter for the cold air current. Based on the different temperature in winter, the samples were split into two groups. PM10 and the abundance of the PAHs in winter-1 (temperature, 12–22 °C) were much greater than in winter-2 (temperature, 8–12 °C). In winter-1 benzo [b + k] fluoranthene and Indeno [1, 2, 3] pyrene dominated while chrysene and benzo [b + k] fluoranthene dominated in winter-2. Meteorological conditions such as wind speed and temperature had a strong influence on the seasonal variation. Potential sources of PAHs were identified using the molecular diagnostic ratios between PAHs. Results showed fossil fuel combustion may be the major source of PAHs at the two sites.