近14年西北地区甲醛柱浓度的时空变化研究

基于臭氧监测仪（OMI）卫星反演数据,对2005~2018年西北4省区域大气甲醛柱浓度数据进行提取及分析,探讨其时空变化特征及影响因素.结果表明：在时间变化上,14a甲醛柱浓度整体呈先上升后下降的波动变化趋势,夏秋季显著高于冬春季,且冬季均值略高于春季.在空间分布上,甲醛柱浓度自西向东、自北向南逐渐升高,高值区集中于陕西和甘肃东南部及青海西南部;低值区集中于宁夏、青海和甘肃的西北部;稳定性呈现出东部分散、西部集聚、差异显著的分布格局.影响甲醛柱浓度变化的因素包括自然和人为因素,自然因素中,甲醛柱浓度受地形影响显著,与风向、气温均呈现显著正相关;人为因素中,甲醛柱浓度与人口密度、地区生产总值、工业废气排放量及建筑房屋竣工面积均表现出正相关关系,与工业废气排放量的相关度最高.大气中甲醛分子与气溶胶粒子二者间呈显著正相关关系,这进一步说明甲醛浓度受到了诸多因素的综合影响,但气溶胶粒子、气温及工业废气的排放是主导因素.     

NOx存在条件下相对湿度对甲苯氧化产物的影响

利用流动管反应器模拟甲苯与氧化剂×OH在NO_x存在条件下的反应,定量测定了不同相对湿度条件下（17.5%、35%、50%、70%）反应生成的部分气相产物和颗粒相产物,计算了不同相中产物产率,测量了不同相对湿度下的颗粒相有机碳（OC）产率,推导了相对湿度对甲苯氧化反应的影响机制.结果表明,相对湿度不仅对甲苯与×OH反应途径比例有影响,还对产物的产率及氧化程度有影响.     

北京地区基于化学组分的夏季气溶胶吸湿特性

利用吸湿增长光散射测量系统、黑碳仪和气相色谱质谱联用仪等仪器,于2019年7月15日~8月4日在北京地区开展了为期21d的大气气溶胶观测实验.观测期间北京市区于7月27日出现短暂的轻度污染,并在7月29日出现强降水天气.结果显示：北京市区夏季大气污染变化剧烈且短暂,大气气溶胶散射吸湿增长因子f（RH）呈现平滑连续的特点,并且降水会对f（RH）造成显著影响.7月27日PM_2.5的平均质量浓度为（92.54±47.05）μg/m³;,表现出较为剧烈的污染变化.7月28~30日平均散射吸湿增长因子f（80%±1%）分别为（1.50±0.35）,（1.43±0.36）和（1.48±0.25）,反映了降水对于大气气溶胶的湿清除作用.最后利用实验数据估算粒径吸湿增长因子gf（RH）,并建模研究f（RH）和gf（RH）的关系,模型精度R²最高可达0.698.     

水库沉积物贫营养型好氧反硝化菌(Pseudomonas sp.)分离及其对微污染水体脱氮效率分析

为探究深水水库沉积物微生物功能特征及利用价值,于2019年在实验室对小湾水库表层沉积物微生物进行了驯化分离,并分析了其中一株细菌的脱氮效率.结果表明,分离出的细菌XW731经鉴定属于假单胞菌属（Pseudomonas sp.）,是一种贫营养型好氧反硝化菌;在分别以NH₄⁺-N、NO₃^--N和NO₂^--N为唯一氮源时,该菌对NH₄⁺-N、NO₃^--N和NO₂^--N去除率分别为33.6%、68.5%和9.1%;以NH₄⁺-N和NO₃^--N为氮源时,对NH₄⁺-N和NO₃^--N去除率分别为66.4%、89.6%,同步硝化反硝化能力更强.将该菌投加到两种城市微污染水体后测试表明,该菌对城市河道水体的NH₄⁺-N和NO₃^--N去除率分别为38.3%和42.4%,对城市降雨水体的NH₄⁺-N和NO₃^--N去除率分别为22.2%和7.7%.     

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.     

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.     

雨水管道沉积物中典型无机氮的干期粒径分布

以南京江北新区分流制雨水管道沉积物为研究对象,考察不同粒径沉积物中铵态氮（NH₃-N）和硝态氮（NO₃^--N）干期分布特征,分析其随干期长度的变化关系,并探讨沉积物理化性质及微生物菌群结构对NH₃-N和NO₃^--N干期分布的影响.结果表明：粒径≤0.075mm的沉积物中NH₃-N占比最高（交通区30.8%,商业区36.7%）;交通区粒径≤0.075mm的沉积物中NO₃^--N占比最高（33.0%）,而商业区粒径0.075~0.15mm沉积物中NO₃^--N占比最高（34.4%）;干期长度与交通区0.075~0.15mm粒径段的沉积物中NO₃^--N含量及商业区粒径≥0.3mm的沉积物中NH₃-N含量之间的相关性均最显著;雨水管道沉积物中NH₃-N和NO₃^--N的干期分布与O-H和N-H等官能团、表面极性和亲水性、微观形貌等有一定关联;交通区雨水管道沉积物中Gemmobacter等反硝化优势菌种（相对丰度总和为20.15%）对NO₃^--N干期分布影响更显著.     

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.