太原市气溶胶中细粒子污染特征及多环芳烃两相分配研究

【作者】 闫雨龙；

【导师】 何秋生；

【作者基本信息】 太原科技大学 ， 材料物理与化学， 2011， 硕士

【摘要】 本研究选择太原科技大学科技楼顶为采样点,从2009年8月至2010年4月开展环境空气中的细粒子(PM_2.5)和气相污染物采样,研究了太原市环境空气中细粒子和多环芳烃（PAHs）的污染状况。细颗粒上的PAHs采用超声波萃取方法进行提取,PUF上的气相PAHs采用索氏抽提法进行提取,然后分离纯化并由气相-色谱质谱联用仪测定。结合采样期间气象资料,本研究报道了PM_2.5和PAHs的浓度水平、时间和季节变化特征,阐述了PAHS在气相-颗粒相上的分配平衡,评价了PAHs的健康风险,最后分析了PAHs的来源。主要结论如下:1、太原全年的PM_2.5日均浓度为222.60μg/m³,超过EPA的环境空气标准（EPA-NAAQS, 2006）6.36倍。太原市冬季环境空气中的PM_2.5的日均浓度为260.82μg/m³;春季和秋季PM_2.5的日均浓度为254.89μg/m³和182.24μg/m³;浓度最低的是夏季,为135.78μg/m³。季节变化过程综合分析后可知季节之间的变化主要是受到典型污染源和气候等因素影响。日间的PM_2.5浓度基本上都大于夜间的浓度。PM_2.5与温度、湿度、风速之间的相关性呈现一定的相关性;PM_2.5的浓度与风速的负相关显示了本地源是造成太原大气中PM_2.5污染的主要因素;湿沉降和迁移是目前太原空气中的PM_2.5去除的主要过程。2、15种PAHs在全年的浓度平均为744.48 ng/m³。其中,气相中的PAHs平均为452.31 ng/m³;颗粒相中的PAHs平均为297.17 ng/m³。不同环数的PAHs在空气中的含量不同,3环PAHs最多,占ΣPAHs的51.2%;在颗粒相上的PAHs最多的是四环PAHs,占ΣPAHs的47.7%。冬季环境空气中的PAHs浓度高达1710.97 ng/m³;其次为秋季和春季,夏季空气中的∑PAHs最低,为310.10 ng/m³。全年空气中的ΣPAHs与温度的正相关性很强,与湿度和风速的相关性都一般;但是在冬季,湿度和风速与ΣPAHs分别呈正相关和负相关,相关性较强。全年空气中的PAHs在气相和颗粒相上的分配较为平衡,尤其是秋季和冬季。全年Benzo（a）pyrene等效浓度（BEQ）,均值为14.04 ng/m³,尤其是冬季达到41.74 ng/m³。太原环境空气中的PAHs的BEQ远远高于许多城市,显示了空气中的PAHs的毒性很大。3、由比值分析判断出PAHs的来源复杂,主要包括煤燃烧排放和移动源的排放。利用定量的主成分分析可以看出,太原各个季节环境空气中PAHs主要的来源为液体化石燃料的燃烧、煤的燃烧、生物质燃烧、炼焦等。每个季节的来源不同,但液体化石燃料的燃烧（含机动车排放和重油燃烧排放）已经成为主要的来源。尤其是在夏季,空气中的PAHs来源中液体石油燃料的燃烧排放的贡献达到54.92%,冬季取暖等因素的影响,导致煤燃烧排放的贡献上升,达到32.94%。更多还原

【Abstract】 In order to study the pollution of the fine particles and polycyclic aromatic hydrocarbons （PAHs） in ambient air in Taiyuan, the samples of PM_2.5 and gas pollutants were collected in Taiyuan university of Science and Technology, during the period from August 2009 to April 2010. The compounds of PAHs were extracted by ultrasonic extraction method from aerosol samples, by Soxhlet extraction method from gas samples. The compounds of PAHs were analyzed by gas-chromatography mass spectrometry determination. Combined with meteorological data during the sampling period, this study reported levels of PM_2.5 and PAHs concentrations, time and seasonal variations, described distribution balance of PAHs in the gas-particle phase, assessed the health risks of PAHs, and analysised the source of PAHs finally. Some results are listed below:1. The daily average concentration of PM_2.5 was 222.60μg/m³ during the sampling time, and exceeded ambient air standards of EPA （EPA-NAAQS, 2006） 6.36 times.The highest seasonal average concentration of PM_2.5 was 260.82μg/m³, in winter; and the lowest was 135.78μg/m³, in summer.The seasonal variation mainly should due to the emission of typical pollution sources and climate change. The concentration of PM_2.5 in the day was higher than the night mostly. The correlations between PM_2.5 and temperature, humidity, wind speed were ordinary. And the concentration between PM_2.5 and wind speed was negative showed that the main source of PM_2.5 pollution in Taiyuan was local source, not from other places. The main way of PM_2.5 removal is wet deposition and air mass migration.2. The daily average concentration of PAHs was 744.48 ng/m³ during the sampling time. The average concentration PAHs in gas phase and particulate phase was 452.31 ng/m³ and 297.17 ng/m³, respectively. Compared to other cities, the pollution of PAHs in Taiyuan was very serious. The concentration of different rings number of PAHs was different: the highest was 3 rings PAHs （51.2% ofΣPAHs）.But in particle phase, the highest concentration was 4 rings. The concentration ofΣPAHs in winter was 1710.97 ng/m³, the highest of four seasons; the next was the autumn and spring; the lowest ofΣPAHs was 310.10 ng/m³, in summer.The correlation betweenΣPAHs and temperature was strong positive. And other correlations, like betweenΣPAHs and humidity and wind speed, were generally ordinary in the all year. But in the winter, the correlations betweenΣPAHs and humidity, wind speed were strong positively and negatively, respectively. The state of gas-article distribution was balance all year, especially in autumn and winter. The seasonal sequence of Benzo （a） pyrene equivalent concentration （BEQ） was: winter> autumn> spring> summer. The annual average value of BEQ was 14.04 ng/m³ during the sampling time. That showed toxicity of PAHs in Taiyuan ambient air is serious.3. The qualitative source analysis of PAHs by ratios determines method showed that the sources of PAHs ware complex, including coal combustion emission and mobile sources emission. The quantitative source analysis of PAHs by principal component analysis method showed that the major sources of PAHs in Taiyuan ambience air were liquid fossil fuels combustion （including automobile emission ）, coal combustion, biomass burning, coke emissions, et al. the combustion of liquid fossil fuels （including automobile emission and fuel oil combustion emission） has become a major source in different seasons.Especially in the summer, the contribution of liquid fossil fuel combustion emission has reached 54.92%.And in winter, due to heating and other reasons, the contribution of coal combustion emission increased, reached 32.94%.更多还原