【作者】 李梅；

【导师】 杨新；

【作者基本信息】 复旦大学 ， 环境科学， 2009， 博士

【摘要】 半挥发性有机化合物（SVOCs）通常是指沸点在70℃～300℃之间，蒸汽压在101×1O^-6～0．101 Pa之间的物质，它们能在气相和空气中的固相颗粒物之间形成一定的平衡。SVOCs是大气气溶胶中的主要组分并对大气化学起重要作用。SVOCs的种类繁多，结构复杂，其分析测试难度大。对大气气溶胶中SVOCs的检测通常有气相色谱—质谱（GC-MS）法、高效液相色谱—质谱（HPLC-MS）法、毛细管电泳法、离子色谱法（IC）等传统方法，这些方法通常都需要经过萃取、预浓缩、预制备等预处理过程。这些过程即费时费力又可能会造成某些组分的丢失。本论文针对SVOCs传统分析方法中存在的问题，将一种直接快速的分析技术-电喷雾解吸电离质谱技术（DESI-MS）应用于大气环境中SVOCs的分析中。本论文主要完成了以下三部分的工作：1)DESI-MS实验条件的优化选择以及标准曲线和检测限的测定。分别以16种U．S．EPA优控PAHs、草酸、油酸作为SVOCs中非极性和极性有机化合物的代表，详细研究了DESI-MS分析以上化合物时的优化条件。首先利用DESI-MS测定上述化合物的标准曲线，对于16种U．S．EPA优控PAHs在四个数量级范围内，R²＞0．97，RSD＜15％，对于草酸和油酸，在五个数量级范围内R²＞0．99，RSD分别小于10％和15％，检测限都达到了1 pg／mm²。2)利用DESI-MS分别对稻草秸秆燃烧气溶胶和大气气溶胶中的16种U．S．EPA优控PAHs、草酸、油酸进行定性和定量分析。在优化条件下，DESI-MS可以将气溶胶中的上述化合物选择性的检测出来，结果与传统方法相比有比较好的可信度。除了上述三类化合物，DESI-MS在气溶胶中还检测到了糖类化合物，丙二酸，丁二酸等有机酸以及无机酸盐的信号，表明DESI-MS可用于气溶胶中半挥发性有机化合物的分析。生物质燃烧气溶胶和大气气溶胶中各种PAHs的组成不同，前者高环PAHs的含量高于低环PAHs的含量，后者利用DESI-MS分析时，除了Ant和Phe信号强度较大外，其它的信号强度都差不多。大气气溶胶采样期间上海大气中PM_2．5的平均浓度为110．0μg／m³，与（US EPA，1997）规定的PM_2．5日均值65μg／m³相比，前者是后者的1．7倍。说明上海冬季大气中颗粒物污染特别是细颗粒物污染非常严重。PM_2．5中草酸和油酸的平均浓度分别为289．0和11．3 ng/m³。其中草酸的浓度与中国其它城市相比，比香港、南京低的多，略低于北京，高于乌鲁木齐，与深圳的差不多。3)利用DESI-MS、IC和GC-MS测得的数据，对稻草秸秆燃烧气溶胶排放的成分进行分析，进行了污染物成分的排放因子实验室测量和排放量估算；并对上海大气气溶胶中的多种无机酸离子和有机酸进行了分析。2006年稻秸用作炊事及采暖燃料燃烧时向大气中排放TSP大约64．52万吨。TSP中各种污染物的含量依次为：Cl^-＞SO_<sup>2-＞NO₂^-＞HCOO^-＞F^-＞H₂C₂O₄＞NO₃^-＞MSA＞PAHs＞OA。上海大气气溶胶中各种污染物的含量依次为：SO₄^2-＞NO₃^-＞Cl^-＞F^-＞NO₂^-＞C₂＞C₃＞C₄＞MSA＞HCOOH＞OA。NO₃^-／SO₄^2-的比值为0．65，表明随着上海经济的高速发展，机动车数量增加，由移动源引起的污染正越来越严重。而NO₃^-／SO₄^2-的比值小于1，说明在上海大气中固定源对大气颗粒物的贡献仍然非常重要。C₃／C₄的比值为1．15，说明上海大气中的光化学氧化作用产生二次源对气溶胶有显著的贡献。更多还原

【Abstract】 Usually,semi-volatile organic compounds are the kinds of compounds whichboiling points and vapor tensions are between 70℃and 300℃,101×10^-6 and 0.101respectively.They can make the balance between the gas and particles phase inatmosphere.SVOCs comprise major components in aerosols and play important rolesin atmospheric chemistry.Their species are various,the structure is complex andanalysis method is difficult.The traditional methods for the analysis of SVOCs in aerosol samples,such asGC-MS,HPLC,capillary electrophoresis and IC usually involve pretreatmentprocedures such as extraction,preconcentration and preseparation.These proceduresare labor intensive and time consuming.Moreover,they may cause the change or lossof certain components during analysis （for example,due to low extractionefficiency）.This paper aims at resolving the problems of traditional methods for theanalysis of SVOCs,applied a direct,rapid traditional technology-desorptionelectrospray ionization mass spectrometry （ DESI-MS ） to the analysis of SVOCs inaerosol samples.This paper mainly accomplished three parts of work below:The optimization of experimental conditions of DESI,the determination ofcalibration and the limit of detection were achieved.Experimental parameters forDESI-MS were carefully optimized to enhance the signal intensity by using thestandard PAHs,oxalic acid and oleic acid solution.First we used the standardsolutions of PAHs,oxalic acid and oleic acid with different concentrations depositedon the quartz filter to calibrate the intensities of ion signals.A dynamic range of 4orders of magnitude was observed for PAHs with good linearity （R²＞0.97）.TheRSD was less than 15% for PAHs.A dynamic range of 5orders of magnitude wasobserved for both oxalic acid and oleic acid with excellent linearity （R²＞0.99）.TheRSD was less than 10% for oxalic acid and within 15% for oleic acid.The LOD forthe above compounds was estimated as 1 pg/mm² respectively with 5～10 s samplingtime using this particular mass spectrometer.DESI-MS was applied in the qualitative and quantitative analysis of PAlls.oxalic acid and oleic acid in rice straw burning aerosol and ambient aerosol.Under theoptimized condition,DESI-MS can selectively detect the above target compounds from the aerosol samples with reliable results comparing with the traditionalmethods.Besides the above compounds,DESI-MS also detected the signals of organicacids,sugars and inorganic salts in aerosols.Which indicates DESI-MS can beapplied in the analysis of SVOCs and some inorganic components in aerosol.Thecompositions of PAHs in biomass burning and ambient aerosol are different.Weconclude that the mass concentrations of large PAHs are higher than those of smallPAHs in aerosols from rice straw burning.In ambient sample,the ion signalintensities for the observed PAHs are close to one another except for the strong 179（Ant and Phe） ion.During the sampling period,the average concentration of PM_2.5 inshanghai was 110.0μg/m³,which was 1.7 times of the standard values 65μg/m³ forPM_2.5（US EPA,1997）.This indicates the particle pollution especially fine particlepollution in winter of shanghai is very serious.The average concentrations of oxalicacid and oleic acid are 289.0 and 11.3 ng/m³ respectively.Compared with other citiesin China,the concentration of oxalic acid in Shanghai is much lower than Hongkongand Nanjing,little lower than Beijing,higher than Urumqi,and close to Shenzhen.Based on the data of DESI-MS and IC,analysed the composition constitute inrice burning aerosol,measured their emission factors through laboratory methods andestimated their emission mass.A kinds of inorganic acids ions and organic acids werealso analyzed.In 2006,the TSP emitted from rice straw burning for domestic fuel usewas about 64.52 million tons.The content of contamination in TSP is in the order ofCl^-＞SO₄²-＞NO₂^-＞HCOO^-＞F^-＞H₂C₂O₄＞NO₃^-＞MSA＞PAHs＞OA.In PM2.5,the concentrations of the most abundant species followed the order of SO₄^2-＞NO₃^-＞Cl^-＞F^-＞NO₂^-＞C₂＞C₃＞C₄＞MSA＞HCOOH＞OA.The mass ratio of NO₃^-/SO₄^2-was 0.65,which indicated that with the rapid modernization and motorization ofShanghai,the pollutants from vehicle emissions （mobile source） became severercompared with that of a few years ago.However,NO₃^-/SO_<sup>4（2-） was lower than 1 inShanghai,revealing that stationary source emissions are still the important contributorto atmospheric particles.The C₃/C₄ ratio was 1.15,which indicated the secondaryproduction from photochemical oxidation should be more important in Shanghai.更多还原