【作者】 赵彤；

【导师】 王文兴； 杨凌霄；

【作者基本信息】 山东大学 ， 环境科学， 2020， 博士

【摘要】 大气颗粒物是造成气候变化及空气质量变化的重要污染物,且对人体健康有一定的危害。与大气粗颗粒物相比,大气细颗粒物(PM2.5)具有更小的粒径及更大的比表面积,因此,大气细颗粒物可在大气中停留更长的时间且更易吸附大气中的有害物质。有机组分是大气PM2.5的重要组成部分,其含量因地而异,可在PM2.5质量浓度的20～90%范围内变动。有机物中多环芳烃(PAHs)及其衍生物(如NPAHs,OPAHs)作为大气PM2.5中一类重要的有机组分,因其具有较高的毒性而引起越来越多的关注。近年来,随着我国机动车数量的飞速增长,机动车排放成为了 PM2.5中多环芳烃及其衍生物的重要来源之一。对机动车排放PM2.5进行研究,可使某一区域内大气污染的数据更全面,为降低机动车排放污染物防控措施提供科学参考。但当前对机动车排放PM2.5中多环芳烃及其衍生物的研究较少,因此,深入开展机动车排放PM2.5中多环芳烃及其衍生物污染特征的研究,具有较大的学术意义及应用价值。本研究采用整车转鼓(台架)实验、隧道实验和道路实验,对机动车排放的PM2.5进行采集,分析了 PM2.5中多环芳烃、硝基多环芳烃及含氧多环芳烃的浓度水平及分子组成,对机动车排放PM2.5中多环芳烃、硝基多环芳烃(NPAHs)及含氧多环芳烃(OPAHs)的排放因子进行了计算,最后估算了对人体健康产生的风险。本研究通过整车转鼓实验所得实验数据分析,得到了汽油车排放PM2.5中PAHs和NPAHs的排放水平及变化特征。在国I到国V排放标准下,汽油车所排放PM2.5中多环芳烃及硝基多环芳烃的平均排放因子随着排放标准的提高而减小,硝基多环芳烃的排放因子比其对应的多环芳烃的排放因子低2-3个数量级;在不同排放标准下,BghiP、DahA和BkF为汽油车所排放PM2.5中含量最丰富的三种多环芳烃,6N-BaP和6N-CHR为硝基多环芳烃中的主导成分;4环、5环和6环多环芳烃的总和贡献了多环芳烃总量的95%以上,与其它环数多环芳烃相比,汽油车累积行驶里程的变化会对4环多环芳烃产生更大的影响,而在不同排放标准及不同行驶里程下,各种环数硝基多环芳烃的占比无明显差异,4环硝基多环芳烃占主导地位。通过对配备了不同类型发动机的汽油车所排放PM2.5中多环芳烃和硝基多环芳烃的观测分析,发现由进气道喷射(PFI)发动机排放PM2.5中多环芳烃及硝基多环芳烃的排放因子在不同累积行驶里程下均大于缸内直喷(DI)发动机中多环芳烃及硝基多环芳烃的排放因子;发动机类型对汽油车排放PM2.5中不同环数多环芳烃的分布影响较小。与PFI汽油车相比,DI汽油车更利于PM2.5中高环数硝基多环芳烃的累积。此外,研究还发现汽油车排放PM2.5中多环芳烃和硝基多环芳烃的排放量与CO.排放量的相关性较小,多环芳烃的排放总量与HC的排放量呈现强正相关,而硝基多环芳烃的总量与HC相关性较弱,表明汽油车发动机对HC和多环芳烃可能有相似的转化效率;汽油车排放PM2.5中4环硝基多环芳烃与4环多环芳烃之间具有较高的相关性,而5环硝基多环芳烃与5环多环芳烃之间几乎不存在相关性。通过对汽油车所排放PM2.5中多环芳烃和硝基多环芳烃的等效致癌当量浓度(TEQ)计算,发现与国I和国Ⅱ排放标准下的汽油车相比,国Ⅲ、国IV和国V排放标准下汽油车所排放PM2.5中多环芳烃和硝基多环芳烃的TEQ显著降低。通过在青岛市仰口隧道内开展观测实验,本研究获得了该隧道内PM2.5中多环芳烃、硝基多环芳烃及含氧多环芳烃的浓度水平及分子组成,并结合特征比值与主成分分析(PCA)探讨它们的主要来源,最后定量估算隧道内PM2.5中多环芳烃、硝基多环芳烃及含氧多环芳烃的排放因子。结果表明,FLT和PYR为含量最丰富的多环芳烃,1N-PYR和2N-PYR是占主导地位的硝基多环芳烃,9-FO和9,10-ANQ为浓度最高的含氧多环芳烃。特征比值和PCA的分析结果表明,隧道内PM2.5中的多环芳烃及硝基多环芳烃主要来源于汽油和柴油车辆的尾气排放,而非尾气排放源(例如道路扬尘、制动管路、沥青和轮胎磨损等)也对隧道内PM2.5中的多环芳烃及硝基多环芳烃有一定贡献。因此,也有必要制定适当的法规来规范非废气排放并采取适当的控制措施。隧道内PM2.5中总多环芳烃(TPAHs)、总硝基多环芳烃和总含氧多环芳烃的排放因子分别为60.98,9.02和8.47 μg veh-1 km-1。高环数(4-6环)多环芳烃的排放因子明显大于低环数(2-3环)多环芳烃的排放因子。在所有测得的硝基多环芳烃中,1N-PYR的排放因子最高;9-FO和9,10-ANQ为排放因子最高的两种含氧多环芳烃。利用道路实验,本研究探讨了机动车排放PM2.5中多环芳烃及其衍生物在实际大气中的污染特征,获得了青岛市城区和郊区道路PM2.5中多环芳烃、硝基多环芳烃及含氧多环芳烃的浓度水平和分子组成,利用特征比值和PCA分析查明了其来源,利用全生命周期的癌症风险增加量(ILCR)对青岛市城区和郊区道路边PM2.5中多环芳烃以及硝基多环芳烃对不同年龄段人群的人体健康暴露风险进行了评估。结果表明,与污染严重的内陆地区相比,青岛地区多环芳烃及其衍生物的污染较轻。在城区道路点,FLT和PHE为PM2.5中多环芳烃的主要组分;而在郊区道路点,FLT和PYR为多环芳烃中最丰富的组分;在城区和郊区点,9N-ANT和2+3N-FLA均为含量最丰富的硝基多环芳烃;9-FO、1-NALD和9,10-ANQ是所测得的含氧多环芳烃中最主要的三种组分。在城区和郊区道路点,4环多环芳烃均为主导多环芳烃,4环硝基多环芳烃为所观测到的硝基多环芳烃的主导成分。在城区点,早高峰和晚高峰是多环芳烃和硝基多环芳烃浓度最高的两个时段,这与城区点交通繁忙的时间段一致。而在郊区点,多环芳烃及硝基多环芳烃浓度的最高值出现在早高峰时段,而次高值出现在夜间。不同于多环芳烃和硝基多环芳烃的日变化趋势,含氧多环芳烃浓度的峰值没有明确的变化趋势,但在城区和郊区点,含氧多环芳烃浓度的最低值均出现在午间时段。结合特征比值和PCA分析的结果表明城区道路点PM2.5中的多环芳烃主要来源于煤和石油燃烧及机动车尾气排放;郊区点PM2.5中的多环芳烃主要来源于煤和石油燃烧源、机动车排放源及生物质燃烧源的贡献。城区点PM2.5中硝基及含氧多环芳烃主要来源于机动车排放及固体燃料燃烧的排放;郊区点PM2.5中硝基及含氧多环芳烃主要来源于机动车排放、固体燃料燃烧的排放、生物质燃烧排放及二次生成。此外,本研究还发现交通繁忙时段,城区点和郊区点PM2.5中硝基多环芳烃的毒性高于交通空闲时段,即机动车的排放利于PM2.5中硝基多环芳烃毒性的增加。本论文较深入地分析了机动车排放PM2.5中多环芳烃、硝基多环芳烃及含氧多环芳烃的浓度水平、分子组成、排放因子及其所带来的健康风险,能够为研究我国机动车排放污染提供了数据支持,并可为我国制定机动车排放污染控制对策提供理论依据。更多还原

【Abstract】 Atmospheric particulate matter is an important pollutant that causes climate change and changes in air quality,and it is harmful to human health.Compared with coarse particles,fine particles(PM2.5)have a smaller particle size and a larger specific surface area.Therefore,PM2.5 can stay in the atmosphere for a longer time and are more likely to adsorb harmful substances in the atmosphere.Organic components are an important part of PM2.5,which contributes 20 to 90%of the PM2.5 mass concentration.Polycyclic aromatic hydrocarbons(PAHs)and their derivatives(NPAHs and OPAHs),as an important organic component in PM2.5,have attracted more and more attention due to their higher toxicity.In recent years,with the rapid growth of the number of motor vehicles,motor vehicle emissions have become one of the important sources of PAHs,NPAHs and OPAHs in PM2.5.The study of PM2.5 emissions from motor vehicles can make the air pollution data in a certain area more comprehensive,and provide scientific reference for prevention and control measures to reduce pollutants emitted by motor vehicles.However,there are few studies on PAHs.NPAHs and OPAHs in PM2.5 emitted from motor vehicles.Therefore,further studies on the pollution characteristics of PAHs,NPAHs and OPAHs in PM2.5 emitted by motor vehicles has great academic and application value.In this study,the vehicle drum(bench)experiment,tunnel experiment,and road experiment were used to collect PM2.5 emitted from motor vehicles,and the PAHs,NPAHs and OPAHs in PM2.5 were analyzed.The concentration level and molecular composition of aromatic hydrocarbons were analyzed.The emission factors of PAHs,NPAHs and OPAHs in PM2.5 emitted by motor vehicles were calculated,and their health risks were estimated.Based on the experimental data obtained from the vehicle drum experiment,this research systematically grasped the emission levels and change characteristics of PAHs and NPAHs in PM2.5 emitted by gasoline vehicles.Under the China I to China V emission standards,the average emission factors of PAHs and NPAHs in PM2.5 emitted by gasoline vehicles decrease with the increase of emission standards.The emission factors of NPAHs are 2-3 orders of magnitude lower than their corresponding PAHs.Under different emission standards,BghiP,DahA and BkF are the most abundant PAHs in PM2.5 emitted from gasoline vehicles,BaP and 6N-CHR are the dominant components in NPAHs;the sum of 4-rings,5-rings,and 6-rings PAHs contributed more than 95%of the total PAHs.The change in mileage of gasoline vehicles may have a greater impact on 4-ring PAHs.Under different emission standards and mileage,there was no significant difference in the proportion of NPAHs by number of rings.Based on the observation and analysis of PAHs and NPAHs in PM2.5 emitted by gasoline vehicles equipped with different types of engines,it was found that the emission factors of PAHs and NPAHs in PM2.5 emitted by the port injection(PFI)engines were larger than that in direct-injection(DI)engines under different cumulative mileage.The engine type has little effect on the distribution of PAHs and NPAHs in PM2.5 emited from gasoline vehicles.Compared with PFI gasoline vehicles,DI gasoline vehicles are more conducive to the accumulation of high-rings NPAHs in PM2.5.In addition,the study also found that the emission of PAHs and NPAHs in PM2.5 emitted from gasoline vehicles has a small correlation with CO emissions,and the total amount of PAHs has a strong positive correlation with HC emissions.However,the correlation between the total amount of PAHs and HC was weak,indicating that gasoline vehicle engines may have similar conversion efficiency to HC and PAHs;The correlation coefficients between individual NPAHs and their corresponding parent PAHs were significantly different.4-rings NPAHs(1N-PYR,2-PYR,7N-BaA and 6N-CHR)and their parent PAHs(PYR,BaA and CHR)had highly correlations,while 5-rings NPAH(6N-BaP)and its parent PAH(BaP)showed no correlation.By calculating the equivalent carcinogenic equivalent concentration(TEQ)of PAHs and NPAHs in PM2.5 emitted by gasoline vehicles,it was found that the TEQs of total PAHs and NPAHs from China 3,China 4 and China 5 vehicles were significantly reduced compared to that from China 1 and China 2 vehicles,which may be related to exhaust technology improvements.By carrying out observation experiments in the Yangkou Tunnel of Qingdao,this study obtained the concentration levels and molecular composition of PAHs,NPAHs and OPAHs in PM2.5 in the tunnel,and combined with the characteristic ratio the principal component analysis(PCA)to explore their main sources,and finally the emission factors of PAHs,NPAHs,and OPAHs in PM2.5 in the tunnel were quantitatively estimated.The results showed that FLT and PYR are the most abundant PAHs,1N-PYR and 2N-PYR are the dominant NPAHs,and 9-FO and 9,10-ANQ has the highest concentrations of OPAHs.The characteristic ratio and PCA analysis results showed that the PAHs and NPAHs in PM2.5 in the tunnel were mainly derived from exhaust emissions from gasoline and diesel vehicles,rather than exhaust emission sources(such as road dust,brake pipes,asphalt,tire wear,etc.)also contribute to the PAHs and NPAHs in PM2.5 in the tunnel.Therefore,it is also necessary to formulate appropriate regulations to regulate non-exhaust gas emissions and take appropriate control measures.The emission factors of total PAHs,total NPAHs and total OPAHs in PM2.5 in the tunnel were 60.98,9.02,and 8.47 μg veh-1 km-1,respectively.The emission factor of PAHs with high ring numbers(4-6 rings)was significantly greater than that of PAHs with low ring numbers(2-3 rings).Among all the measured NPAHs,1N-PYR has the highest emission factor;9-FO and 9,10-ANQ were the two OPAHs with the highest emission factors.Using road experiments,this study explored the pollution characteristics of PAHs,NPAHs and OPAHs in PM2.5 emitted by motor vehicles in the actual atmosphere,and obtained the concentration levels and molecular composition of PAHs,NPAHs and OPAHs in urban and suburban roadside sites in Qingdao,and their sources were identified using characteristic ratios and PCA analysis.The life-cycle cancer risk increase(ILCR)was used to assess the risk of exposure to human health in different age groups of PAHs and NPAHs in PM2.5 in the urban and suburban roadsides of Qingdao.The results showed that compared with the heavily polluted inland regions,the pollution of PAHs and their derivatives in Qingdao was lighter.At urban roadside site,FLT and PHE were the dominant components of PAHs in PM2.5,while at suburban road roadside site,FLT and PYR were the most abundant components of PAHs,at urban and suburban roadside sites,9N-ANT and 2+3N-FLA were the most abundant NPAHs;9-FO,1-NALD and 9,10-ANQ were the three main components of the OPAHs.In urban and suburban roadside sites,4-rings PAHs were the dominant PAHs,and 4-rings NPAHs were the dominant components of the observed NPAHs.In urban areas,the morning and evening peaks were the two periods when PAHs and nitro polycyclic aromatic hydrocarbons have the highest concentration,which is consistent with the time period of heavy traffic in urban areas.In the suburbs,the highest PAHs and NPAHs appeared during the early peak hours,and the second highest values occurred at night.Unlike the daily variation trend of PAHs andNPAHs,there is no clear trend of the peak value of the concentration of OPAHs.However,in urban and suburban areas,the lowest values of PAHs appeared at noon.The characteristic ratio and PCA analysis results showed that the PAHs in the PM2.5 of the urban roadside site were mainly derived from coal and oil combustion and vehicle exhaust emissions,the PAHs in the PM2.5 of the suburban roadside site were mainly derived from coal and petroleum combustion sources,motor vehicle emissions sources,and biomass combustion sources.NPAHs and OPAHs in PM2.5 in urban areas mainly come from motor vehicle emissions and solid fuel emissions,NPAHs and OPAHs in PM2.5 in urban areas mainly come from vehicle emissions,solid fuel combustion,biomass combustion,and secondary production.In addition,this study also found that the toxicity of NPAHs in PM2.5 in urban and suburban roadside sites during heavy traffic periods was higher than that in idle periods,the emission of motor vehicles was conducive to increase in the toxicity of NPAHs in PM2.5.In this study,the concentration levels,molecular composition,emission factors and health risks of PAHs,NPAHs and OPAHs in PM2.5 emitted by motor vehicles were analyzed in depth.It provides data support for the study of motor vehicle emission pollution in China,and provides a theoretical basis for the development of motor vehicle emission pollution control measures in China.更多还原