【作者】 许忠扬；

【导师】 肖德涛； 刘卫；

【作者基本信息】 南华大学 ， 辐射防护与环境保护， 2008， 硕士

【摘要】 大气颗粒物作为大气污染的重要组成形式,对环境、气候、人类健康造成了巨大的危害。颗粒物的粒径不同,进入人体的部位不同,从而对人体产生的危害也就不同。细颗粒PM_2.5（空气动力学直径（Da）, Da≤2.5微米）与粗颗粒物（2.5微米≤Da≤10微米）相比,更易沉积到肺叶、呼吸细支气管及肺泡,更易造成呼吸道和肺部疾病。大气颗粒物中绝大多数有机物是三致（致癌、致畸、致变）物质,且81.9%的有机物集中于PM_2.5中。为了保护人的身体健康,必须减少或消除PM_2.5中的有机污染物。为此,首先必要定量估算PM_2.5中有机污染物的来源。大气颗粒物中有机污染物的成分复杂,目前常规的元素含量分析法、发展中的扫描质子微探针（SPM）和同步X荧光（SXRF）都难以实现对它来源的定量估算。本研究将同位素技术应用于环境科学,用放射性碳及稳定碳同位素比定量估算大气颗粒物中有机污染物的来源。大气颗粒物中有机污染物的主要来源有:非石化产物（植物燃烧产物,土壤扬尘）和石化产物（煤燃烧产物和机动车尾气排放物）。碳三种同位素: 12C、¹³C和¹⁴C.其中¹⁴C是半衰期为5730年的放射性β核素。石化燃料（煤,石油等）的形成时间长达百万、千万年甚至更久,石化燃料中不存在¹⁴C。这就给我们提供了用¹⁴C区分大气颗粒物中有机污染物来源的非常简便、有效的方法。有机物污染物中的碳以有机碳（OC）的形式存在。当OC中的¹⁴C被测定,并用现代碳百分比（pMC）表示时,它直接反映大气颗粒物中有机污染物中非石化燃料的分担率（fnon-fossil）。这样OC中的石化燃料分担率（ffossil）可确定为1-fnon-fossil。通过比较OC、植物燃烧产物、土壤颗粒和建筑材料中的¹⁴C,由¹⁴C的质量守恒,可区分大气颗粒物中有机污染物来自土壤粉尘和植物燃烧产物的分担率。石化燃料起因的大气颗粒物中不存在¹⁴C,但有¹³C的存在.比较OC、非石化燃料、煤燃烧产物以及机动车尾气排放物中的δ¹³C,根据δ¹³C的质量守恒,可区分大气颗粒物中有机污染物中来自燃煤排放物和机动车尾气的分担率。现有测量¹⁴C的仪器方法有液体闪烁室法（LSC）和加速器质谱仪法（AMS）。使用LSC和AMS测量¹⁴C时,所需样品碳量分别为1000mg和1mg。大气颗粒物中碳的含量相对1000 mg较少。因此对大气颗粒物中¹⁴C的测定只能是AMS的方法。为此,AMS前处理系统是有必要的。此系统的目的是将样品中不同形态的碳转变成石墨。在本研究中,一套完整的环境和生物样品石墨化系统被研发。此系统中真空度高达8 - 2.5Pa,能处理各种形态（固态,气态）样品,工作效率高达10个/天。此外,本研究对上海市宝山区的大气颗粒物中有机污染物进行分析,结果表明,宝山区冬季大气颗粒物中有机污染物的来源主要来自石化产物,占到了总量的64.74%,而非石化产物只有35.26%,而且,表层土壤（0– 5cm）以降尘为主。更多还原

【Abstract】 Atmospheric particles as an important component of air pollution have caused immense harm to human health, environment, and climate. Particles with different sizes can access to different parts of the body, so that the harm is also different. Compared with coarse particles （aerodynamic diameter （Da）, 2.5 microns≤Da≤10 microns）, fine particles, PM_2.5 （Da≤2.5 microns） are more easily deposited in lung, bronchia, and alveolus. They cause more respiratory and lung disease. Most of particles existed as organic matters are carcinogenic, teratogenic, and mutagenic material, and 81.9 percent of the organic matters focus in PM_2.5. In order to protect people’s health, we have to reduce and eliminate the organic pollutants in PM_2.5. For that, it is necessary to quantitatively estimate sources of the organic pollutants.The ingredients of organic pollutants are complex. The general methods such as the conventional element content analytic method, scanning proton microprobe （SPM） and simultaneous X-ray fluorescence （SXRF） are difficult to quantify the originations of the organic pollutants. In present study, an isotope technology was used in environmental science. Specific activities of ¹⁴C and carbon isotopic compositions were used to quantify the originations of organic pollutants in atmospheric particles. Organic pollutants in atmospheric particles originate from: non-fossil products （soil dust, plant burning products） and fossil products （vehicle burning and oil burning products）. Carbon is a popular molecule in nature. It has a radiocarbon (¹⁴C) with a half life of 5730y and two kinds of stable carbon isotopes (12C and ¹³C). as well known, there are no ¹⁴C in fossil fuels. This has provided us a very simple and effective way to distinguish atmospheric particle sources of organic pollutants with 14 C.Carbon existed in organic pollutants is as the form of organic carbon （OC）. Since ¹⁴C only exists in non-fossil materials, the ¹⁴C values of OC, indicated by percent modern carbon, reflect a distribution of non-fossil carbon to all OC. The distribution of fossil carbon can then be obtained. Every material has intrinsic carbon stable isotopic composition (δ¹³C), so that using a mass approach balance ofδ¹³C can further separate non-fossil sources as well as fossil materials sources. Based on this thought above, a method was developed to separate the sources of OC in PM_2.5 using specific activities of ¹⁴C and stable carbon isotopic composition in this paper.The current apparatus used to measure the ¹⁴C are liquid scintillation chamber （LSC） and accelerator mass spectrometry （AMS）, and the required amount of carbon is 1000 mg and 1 mg, respectively. 1000 mg of carbon in atmospheric particles is hard to be obtained, so the AMS is the only way to be used for determining the ¹⁴C of particulate matter. Thus, an AMS pre-treatment system, which is used to convert different kinds of carbon into a graphite.In this study, a complete set of AMS pre-treatment system was developed. In this system, the vacuum degree reaches as high as 8 - 2.5Pa, it can handle various forms （solid, gaseous） samples, and the working efficiency reaches as high as for 10/days. In addition, the atmospheric particles of the Baoshan District of Shanghai are studied for analysis of organic pollutants. The results showed that the source of organic pollutants in the Baoshan District in winter is mainly fossil products, accounting for 64.74 percent of the total organic pollutants, The distribution of non-fossil accounting for 35.26 percent. Surface layer soil （0 - 5cm） is mainly falling dust.更多还原