Volatile Organic Compounds: Sampling Methods and Their Worldwide Profile in Ambient Air

The atmosphere is a particularly difficult analytical system because of the very low levels of substances to be analysed, sharp variations in pollutant levels with time and location, differences in wind, temperature and humidity. This makes the selection of an efficient sampling technique for air analysis a key step to reliable results. Generally, methods for volatile organic compounds sampling include collection of the whole air or preconcentration of samples on adsorbents. All the methods vary from each other according to the sampling technique, type of sorbent, method of extraction and identification technique. In this review paper we discuss various important aspects for sampling of volatile organic compounds by the widely used and advanced sampling methods. Characteristics of various adsorbents used for VOCs sampling are also described. Furthermore, this paper makes an effort to comprehensively review the concentration levels of volatile organic compounds along with the methodology used for analysis, in major cities of the world.     

DOAS环境空气质量自动化监测系统运行维护

介绍了DOAS环境空气质量自动化监测系统的性能和特征,指出该系统在日常运行时,需要进行预防性定期例行维护和现场故障排除,总结分析了该系统运行维护的方法,并对常见故障作了剖析.     

Observation of atmospheric nitrous acid with DOAS in Beijing, China

Measurements of nitrous acid （HONO） and nitrogen dioxide （NO2） in Beijing City have been performed by means of a developed differential optical absorption spectroscopy （DOAS） system based on photodiode array （PDA）, during the autumn of 2004. HONO and NO2 were simultaneously identified by their characteristic absorption bands in the spectral region between 337 nm and 372 nm with high sensibility and time resolution. The concentrations of HONO exhibit obviously diurnal variation with a nocturnal maximum and a daytime minimum. The highest HONO value up to 11.8 μg/m^3 was observed during the night of 2/3 September. Possible sources of the observed HONO were discussed. Good correlation to NO2 indicates that NO2 is a main source component. The measurement also shows direct emission of HONO is an imnortant source in strongly polluted urban area.     

紫外大气甲醛卫星遥感反演方法和研究现状

在我国长期稳定的甲醛观测站点十分缺失,卫星平台高时频、大面积覆盖等优势使得通过卫星遥感探测大气甲醛成为了一种重要的研究手段.本文讨论了现有载荷的反演理论和方法,分析了我国大气甲醛的研究现状及不足.简述了从20世纪至今可用于甲醛探测的主要载荷：GOME/ERS-2,SCIAMACHY/ENVISAT,OMI/Aura,GOME-2/MetOp-A（B）,OMPS/Suomi-NPP,总结归纳了各个卫星载荷仪器的轨道信息、时间空间分辨率等相关参数,以及各个传感器在大气甲醛遥感反演中的可行性.由于卫星自上而下的观测方式与地基平台不同,其反演方法也有不同之处,因此本文针对卫星平台综合论述了两种甲醛反演算法：传统的差分吸收光谱法（DOAS）和针对于甲醛反演的一系列改进算法以及近几年提出的主成分分析法（PCA）;另外,本文针对现有反演算法和时空分布在我国中东部地区的研究现状和不足进行了综合讨论,并给出了一定的改进策略.     

差分吸收光谱法(DOAS)与紫外荧光法自动测量空气中SO2的对比

DOAS自动监测系统越来越广泛用于环境空气质量监测中SO2、NO2的监测,将差分吸收光谱法与紫外荧光法自动测量空气中SO2进行对比实验,并对监测结果进行讨论和统计检验,得出两种方法测定空气中的SO2,其监测结果具有较好的相关性、一致性、两者无显著性差异,在今后的监测工作中可用DOAS自动监测系统代替传统的干法点式自动监测系统监测SO2,以降低运行成本,减少仪器维护量,节约经费。     

差分光学吸收光谱法测量大气污染气体的研究

介绍了差分光学吸收光谱(DOAS)法测量大气污染气体的基本原理,描述了收发一体的DOAS系统的设计以及在同一波段对多种被测气体浓度同时进行反演的数据处理方法,并且对周围环境中的SO₂,O₃和NO₂进行了长期监测,得到的结果与实际情况相符合.      

DOAS大气环境质量监测系统与传统点式采样监测法可比性研究

系统比较了DOAS大气监测系统与传统点式采样设备在测定环境空气中二氧化硫的性能。     

Comparison of Open-Path and Point Measurements of a Gaseous Pollutant in the Vicinity of a Model Building

Field experiments were carried out in the vicinity of anisolated building using open-path and point monitoring airpollution detectors to measure concentrations of a tracer gasreleased from a source located either on the building or at thedownwind face of the building. Experiments were conducted underneutral or slightly unstable weather conditions. Either threeor five fast-response point monitors were located along thebeam path of an open-path instrument, in the wake of thebuilding. Experiments were performed with different sourcelocations, detector locations and building orientations to thewind. Visual comparison of data time series showed that datafrom the two types of instruments followed similar trends. Thebest degree of correlation occurred for an averaging timesimilar to the response time of the open-path monitor. Meanconcentrations detected by the open-path instrument weregenerally in very good agreement with the path averaged meanconcentrations from the point monitors. The point monitors werealso capable of providing time-resolved data needed to describedetailed concentration fluctuation statistics.     

多轴差分吸收光谱仪对大气污染物SO2、NO2、O3的立体监测

多轴差分吸收光谱仪（MAX—DOAS）是用来监测大气中痕量气体成分的专用仪器,它能同时自动监测SO2、NO2和03三种污染气体,得到的垂直柱浓度对研究污染物的时空分布特点具有重要意义。分析了2011年5月下旬至2012年4月中旬期间MAX—DOAS在重庆市的测量数据,结果表明：夏季SO2的柱浓度高于其它季节,并在每个季节都出现了峰值：SO2与NO2之间浓度变化趋势相同,且最大小时浓度值都集中在上午;O3垂直柱浓度受气象条件和臭氧前体物的影响呈夏季高、秋冬低的季节性变化;通过多元回归建立了O3柱浓度与气象因素、前体物的关系式。     

利用差分吸收光谱系统对O3，SO2和NO2的监测分析

结合我国对空气质量自动监测系统质量保证的要求及差分吸收光谱(DOAS)技术自身的技术特点,重点讨论了对南京江北地区的大气污染物的DOAS监测数据的质量控制, 并对2007年12月—2008年8月ρ(O₃),ρ(SO₂)和ρ(NO₂)的日、季节变化特征进行了分析. 结果表明:ρ(O₃),ρ(SO₂)和ρ(NO₂)小时均值的频率分布峰值分别出现在30～40,20～30和30～40 μg/m3;三者超过《环境空气质量标准》(GB3095—1996)一、二级标准的频率分别为4.37%和1.02%(O₃),21.78%和0.89%(SO₂),5.65%和0 (NO₂);ρ(O₃)季节变化十分明显,春季最高;ρ(SO₂)和ρ(NO₂)的日变化与局地排放源、大气扩散能力和人类活动密切相关;ρ(O₃)和ρ(NO₂)日变化呈负相关.