乌鲁木齐市气溶胶光学厚度时空分布特征及潜在来源分析

依据2009年1月—2019年7月MODIS/AQUA C6.1 MYD04_L2 气溶胶光学厚度（Aerosol Optical Depth, AOD）日数据,在宏观视角下对乌鲁木齐市AOD时空分布特征进行分析,利用后向轨迹模式（Hybrid Single Particle Lagrangian Integrated Trajectory,HYSPLIT）和潜在源贡献作用分析方法（Potential Source Contribution Function, PSCF）讨论气溶胶运输的季节性变化,并揭示研究不同季节对AOD影响较为明显的潜在源空间分布.结果表明：①乌鲁木齐市AOD呈显著的季节性差异,四季均值依次为：春季（0.328） > 夏季（0.310） > 秋季（0.273） > 冬季（0.137）,AOD高值区主要集中在市区.②AOD年内呈双峰分布,峰值分别对应为4月（0.402）和8月（0.346）;10 a间AOD呈弱下降趋势,其中2014年最高（0.316）,2017年最低（0.235）,AOD均值为0. 276.③春季和冬季乌鲁木齐市气团输送主要来自中亚地区,夏季和秋季则来自于天山周边地区;AOD主要潜在源区为乌鲁木齐市及其周边地区,对乌鲁木齐市空气质量具有显著影响.     

色氨酸对生物成因铁硫酸盐次生矿物形成的影响

采用氧化亚铁硫杆菌催化合成铁硫酸盐次生矿物,研究不同L-色氨酸添加浓度对矿物合成体系pH、氧化还原电位（ORP）、Fe²⁺氧化率、总Fe沉淀率,以及次生矿物产量、化学组成及矿物相的影响.结果表明,随着体系色氨酸浓度的增加,pH降低幅度越小,ORP上升越不明显.色氨酸对铁硫酸盐次生矿物合成的影响依赖于其浓度,当色氨酸浓度低于1.67 g·L^-1时,色氨酸对铁硫酸盐次生矿物的形成起促进作用,表现为总Fe沉淀率及矿物产量随着色氨酸浓度升高而增加.而当色氨酸浓度升高至6.67 g·L^-1时,Fe²⁺氧化率、总Fe沉淀率和矿物产量远低于对照组,表明高浓度色氨酸会抑制铁硫酸盐次生矿物的形成.次生矿物内Fe/S比介于施氏矿物和黄钾铁矾的理论值之间,表明不同合成体系所得次生矿物均为黄钾铁矾和施氏矿物的混合物.矿物学特征分析表明,随着色氨酸浓度的升高,矿物的合成表现为黄钾铁矾向施氏矿物转移.     

东南亚生物质燃烧输送影响我国西南气溶胶辐射特性研究

利用2013年地基CE-318太阳光度计观测数据,结合中分辨率成像光谱仪（MODIS）遥感产品和HYSPLIT后向轨迹分析,研究了一次东南亚生物质燃烧污染长距离输送至中国西南昆明站点过程（2013年4月5~8日）中,气溶胶光学特性和辐射特性的变化及其可能来源.结果表明,此次污染过程期间,我国西南地区生物质燃烧活动较少,而中南半岛地区生物质燃烧活动显著.4月5~7日,昆明站点气溶胶光学厚度（AOD）升高,消光波长指数（EAE）和吸收波长指数（AAE）均增大.此外,依据EAE和AAE分类方法,5~6日昆明站点以城市工业气溶胶为主,7~8日以生物质燃烧气溶胶为主,其细模态峰值半径（0.11μm）小于5~6日（0.15μm）,7日细模态粒子体积浓度峰值（约为0.16μm³/μm²）是5日的2倍.气溶胶直接辐射强迫（ARF）日变化结果表明4月7日气溶胶对地表的降温效应达到最大,对大气的加热作用最强.气溶胶直接辐射强迫效率值（ARFE）的变化表明生物质燃烧气溶胶对大气顶的降温作用减弱.MODIS遥感以及HYSPLIT模式后向轨迹表明,此次昆明站点生物质燃烧气溶胶主要来源于东南亚地区（主要是印度北部、印缅北部和不丹地区）.     

Aerosol optical properties under different pollution levels in the Pearl River Delta (PRD) region of China

To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The concentrations and chemical compositions of PM_(2.5),aerosol optical properties and meteorological parameters were measured.The mean value of PM_(2.5) increased from less than 35(excellent) to 35-75 μg/m~3(good) and then to greater than 75 μg/m~3(pollution),corresponding to mean PM_(2.5) values of 24.9,51.2,and 93.3 μg/m~3,respectively.The aerosol scattering hygroscopic growth factor(f(RH = 80%)) values were 2.0,2.12,and 2.18 for the excellent,good,and pollution levels,respectively.The atmospheric extinction coefficient(σext)and the absorption coefficient of aerosols(σ_(ap)) increased,and the single scattering albedo(SSA)decreased from the excellent to the pollution levels.For different air mass sources,under excellent and good levels,the land air mass from northern Heshan had lower f(RH) and σ_(sp) values.In addition,the mixed aerosol from the sea and coastal cities had lower f(RH) and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.     

Characterization of atmospheric aerosol (PM10 and PM2.5) from a medium sized city in São Paulo state, Brazil

Air pollution causes deleterious effects on human health with aerosols being among the most polluting agents.The objective of this work is the characterization of the PM_(2.5) and PM_(10) aerosol mass in the atmosphere.The methods of analysis include WD-XRF and EDS.Data were correlated with meteorological information and air mass trajectories(model HYSPLIT)by multivariate analysis.A morphological structural analysis was also carried out to identify the probable sources of atmospheric aerosols in the city of Sao Jose do Rio Preto,Brazil.The mean mass concentration values obtained were 24.54 μg/m~3 for PM_(10),above the WHO annual standard value of 20 μg/m~3 and 10.88 μg/m~3 for PM_(2.5) whose WHO recommended limit is10 μg/m~3.WD-XRF analysis of the samples revealed Si and Al as major components of the coarse fraction.In the fine fraction,the major elements were Al and S.The SEM-FEG characterization allowed identifying the morphology of the particles in agglomerates,ellipsoids and filaments in the PM_(10),besides spherical in the PM_(2.5).The analysis by EDS corroborated WD-XRF results,identifying the crustal elements,aluminosilicates and elements of anthropogenic origin in the coarse fraction.For the fine fraction crustal elements were also identified;aluminosilicates,black carbon and spherical particles(C and O) originating from combustion processes were predominant.The use of multivariate analysis to correlate air mass trajectories with the results of the morpho-structural characterization of the particulate matter allowed confirmation of the complex composition of the particles resulting from the combination of both local and long-distance sources.     

Effect of NOx and SO2 on the photooxidation of methylglyoxal: Implications in secondary aerosol formation

Methylglyoxal(CH_3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3) K,atmospheric pressure,(18±2)% relative humidity,and under different NOx and SO_2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS) and the results showed that the addition of SO_2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO_2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO_2 and MG/OH/NOx/SO_2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS) and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR) analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO_2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.     

2006-2017年四川盆地MODIS气溶胶光学厚度时空变化特征

四川盆地地形复杂、气候特殊,是我国颗粒物污染高发地.为探究四川盆地气溶胶分布和周期变化特征,深入认识气溶胶污染特性及其气候效应,结合卫星遥感探测方法,利用2006-2017年MODIS C006 3 km AOD（气溶胶光学厚度）产品,分析了四川盆地AOD的时空特征.结果表明:①MODIS AOD（MODIS数据反演的气溶胶光学厚度）与太阳光度计CE318观测的AOD、ρ（PM_2.5）、ρ（PM₁₀）线性相关系数分别为0.78、0.77、0.75,表明MODIS C006 3 km AOD产品适用于四川盆地颗粒物污染研究.②四川盆地AOD平均值范围为0.1~1.3,其中,成都平原和四川盆地东南部地区是AOD高值（AOD值>1.0）中心,四川盆地周边高海拔区AOD均小于0.3.③2006-2017年AOD年均值范围为0~2.5,整体呈"倒N型"曲线下降,其峰值和谷值分别出现在2013年和2017年;2013年AOD大于1.0的区域占四川盆地的34.1%,是12 a中颗粒物污染最重的一年;2017年AOD小于0.3的面积占57.1%.④AOD季节性变化呈春季最大、夏季次之、秋季最小的特征.⑤AOD月变化呈"双峰型"波动特征,AOD月均值范围为0~2.5,其中,2-5月AOD月均值均大于0.7,8月AOD月均值为0.6,11-12月AOD月均值均小于0.5.研究显示,四川盆地颗粒物污染防治应以成都平原城市群和四川省南部城市群为主,应重点控制细颗粒物排放,合理安排工业企业的周期性生产强度.      

加入SOA示踪的深圳大气PM2.5受体模型源解析

为厘清包括二次有机气溶胶（SOA）在内的深圳市区PM_2.5各种一次和二次来源贡献,本文于2017年9月2日~2018年8月29日在深圳市大学城点位开展PM_2.5样品采集,并进行化学组分和水溶性有机物（WSOM）质谱测量,共获得162组有效数据.观测期间深圳市大气PM_2.5平均质量浓度为26μg/m³,在传统PMF源解析的基础上加入羧基离子碎片（CO₂⁺）作为SOA的示踪物,加入水溶性有机氧（WSOO）用于计算各因子O/C,验证有机物解析效果.结果表明,SOA可以被独立解析出,其O/C明显高于其他一次污染源中有机物;机动车、二次硫酸盐、二次硝酸盐、SOA为最主要的4个源,对PM_2.5质量浓度的贡献分别为25%、23%、17%和10%,船舶、地面扬尘、老化海盐、建筑尘、生物质燃烧、燃煤和工业贡献均在5%以内.各个源的变化特征表明,机动车、二次硫酸盐、二次硝酸盐、SOA等源贡献呈现冬高夏低的季节特征,与冬季季风条件下源自内陆的污染传输密切相关.污染天气时,二次硝酸盐和SOA的贡献增加相对最显著,因此NOx和挥发性有机物是减排的关键.     

利用HYSPLIT模型研究珠三角地区VOCs时空分布特征

于2016年在中国广东大气超级监测站,开展4个季节的VOCs长时间观测,共获得2142组有效数据,并利用HYSPLIT模型分析珠三角地区VOCs时空分布特征.结果表明,各类VOCs混合比和化学反应活性具有明显的季节变化特点.观测期间,VOCs平均浓度为（18.523±20.978）×10^-9,其中,低碳烯烃和苯系物二者混合比之和仅占46%,但贡献了85%的·OH消耗速率（L_OH）、82%的臭氧生成潜势（OFP）和97%的二次气溶胶生成潜势（SOAFP）.观测站点主要受来自北部内陆地区气团（1#）、西部内陆地区气团（2#）、台湾海峡南端气团（3#）以及南部海洋地区气团（4#）的影响.1#气团中炔烃和苯系物的混合比占比最高,分别达到10%、37%,而3#气团中低碳烷烃的浓度水平最高,达到（8.437±5.561）×10^-9.通过估算气团中VOCs的化学反应活性,可以发现,1#气团的VOCs化学反应活性最强,其对O₃和SOA的生成贡献最高.1#、2#、3#和4#气团中VOCs的化学反应活性主要由苯系物和低碳烯烃贡献.     

华北地区沙尘天气垂直气溶胶直接辐射强迫

利用CALIOP数据和SBDART（Santa Barbara DISORT Atmospheric Radiative Transfer）辐射传输模式研究了2013~2016年华北地区8d沙尘天气气溶胶及其直接辐射强迫垂直分布特征,分析了气溶胶垂直分布和光学特性对直接辐射强迫的影响.结果表明,气溶胶集中分布在地表及以上3km范围,其中纯净沙尘型和污染沙尘型气溶胶位于上层,污染大陆型气溶胶和烟雾位于下层.大气层顶、地表和大气层的日均气溶胶直接辐射强迫分别是-38.41~-88.44,-74.03~-225.86,9.06~137.42W/m².0~8km高度范围气溶胶直接辐射强迫是负值,且随着高度的增加绝对值逐渐减小.气溶胶垂直分布对大气层顶、地表和大气层的直接辐射强迫影响较小,但对直接辐射强迫垂直分布影响较大,由气溶胶廓线差异造成的同一高度层气溶胶直接辐射强迫最大差值能达到31.18W/m².气溶胶光学厚度和单次散射反照率对直接辐射强迫影响明显.消光能力相同时,吸收性气溶胶对短波太阳光的衰减作用大于散射性气溶胶,后向散射比例大的气溶胶大于后向散射比例小的气溶胶.