北京市大气中PM1.0的季节性分布及其健康效应研究

The air pollution was serious in China in the past few years, and the continuous higher concentration of fine particulate matters pose a great threat to human health. As we know, the toxic effect of particulate matters is closely related to the size, concentration, chemical composition and its sources. It is reported that the particles with the aerodynamic diameter less than 1 μm dominate a big proportion in the number of inhaled particulate matters in Beijing, so it is significant to study the concentration and composition, as well as the bioeffect of PM1.0 for a comprehensive interpretation of China's fine particles pollution and its harm to human health. In this project, the concentration distribution of PM1.0 in different seasons in Beijing is to be studied; also the content and chemical speciation of transition metal and heavy metal element in PM1.0 will be analyzed with inductively coupled plasma mass spectrometry, neutron activation analysis and synchrotron radiation X-ray absorption spectroscopy. Combined with ion chromatography and high performance liquid chromatography, the concentration of organic pollutants and inorganic ions in PM1.0 will be also measured. Thus, the main components and its composition proportion in PM1.0 sampled from different seasons can be used to appoint the pollutants source; meanwhile, the cytotoxicity of PM1.0 and PM2.5 in different seasons will be compared with cell biology and molecular biology methods to elucidate the potential harm of PM1.0 to human health and its mechanism, which will enlarge the research of fine particulate matters in China and provide scientific data for the environmental protection departments as well.

我国细颗粒物污染浓度持续偏高，对人体健康造成了巨大威胁。据报道，北京市10 nm-10 μm粒径范围的颗粒物数目中以粒径小于1微米的颗粒物为主，而颗粒物的毒性与其粒径、浓度、化学组成等紧密相关，因此开展PM1.0颗粒物的分析与研究对于全面诠释我国细颗粒物的污染及其健康危害有很重要的意义。本项目拟采用ICP-MS、同步辐射、中子活化等核分析技术，结合离子色谱与HPLC分析，研究北京市大气中PM1.0在不同季节的浓度分布，检测PM1.0中过渡金属和重金属元素的含量及其化学种态，分析有机污染物组成和无机离子浓度，从而探讨不同季节PM1.0的主要成分及其组成比例，解析PM1.0的污染物来源；利用细胞生物学与分子生物学的方法，对比不同季节PM1.0与PM2.5的细胞毒性作用，阐明PM1.0对人体健康的潜在危害及其作用机制，从而完善我国大气污染研究领域中的相关数据，为环保部门制定相关政策提供科学指导。

大气颗粒物浓度的增加严重威胁着人类的健康，而颗粒物的毒理学作用不仅与颗粒物浓度有关，还受颗粒物的粒径、粒子数、化学组成、污染物来源等影响。由于不同大小的颗粒物随呼吸进入人体的程度不同，因此，粒径更小的PM1.0对于人体的危害可能比PM2.5更为严重。研究PM1.0的空气污染状况及其对人体的潜在危害，对于环保部门制定相关政策，预防颗粒物污染有着前瞻性指导作用。.我们首先通过对北京城区大气颗粒物PM1.0与PM2.5进行采集分析，对比了两种颗粒物的季节分布与污染特征。结果显示，PM1.0年平均浓度为64.04 μg/m3，PM2.5为85.9 μg/m3，PM1.0约占PM2.5的75%（重量比）。两种颗粒物的主要化学成分均为Ca、Al、Fe、K、Mg、Na与NO3-、SO42-、NH4+、Cl-，微量元素以V、Cr、Mn、Ni、Cu、Zn、As、Sr、Ba、Pb等为主。其中PM1.0中的NO3-、SO42-、NH4+与水溶性无机离子Ca2+、K+、Mg2+的含量明显低于PM2.5，而PM1.0中的Fe、Mn及有机碳含量、OC/EC值高于PM2.5，说明PM1.0主要为机动车尾气或内燃机燃烧产生的一次颗粒物。.我们通过体外实验进一步研究了PM1.0对呼吸系统与心血管系统的毒性损伤作用。研究结果显示，PM1.0可以诱导BEAS-2B细胞发生氧化应激与炎症反应，其中，PM1.0可以激活NF-κB信号通路，促使p65入核调控细胞因子IL-6与IL-8的转录。同时，PM1.0显著上调BEAS-2B细胞中miR-146a表达，miR-146a通过影响IRAK1和TRAF6的mRNA表达而调控下游NF-κB信号通路。此外，我们利用细胞共培养技术，将 BEAS-2B细胞与巨噬细胞接种于Transwell的上室中，下室接种血管内皮细胞（EA.hy926）。PM1.0暴露后培养液中炎症因子TNF-α与IL-6的水平呈剂量依赖性升高，且内皮细胞中ICAM-1表达明显增加；培养液经TNF-α与IL-6的中和抗体处理后，内皮细胞中NF-κB信号通路被抑制，ICAM-1的表达水平下降。因此，PM1.0暴露不仅诱导了呼吸系统炎症，产生的TNF-α等炎症因子可以通过循环系统激活血管内皮细胞中NF-κB通路，上调ICAM-1的表达，从而影响内皮细胞的生物功能。