【作者】 刘光亚；

【导师】 凌球；

【作者基本信息】 南华大学 ， 核技术及应用， 2011， 博士

【摘要】 大气颗粒污染物分析,特别是对人体健康危害最大、小于2.5μm的颗粒(PM2.5)的大气颗粒污染物进行有效分析,并非一般非核分析技术能够胜任,必须采用现代核分析技术,由于TXRF是一种快速多元素分析方法,可以进行ng量级的痕量分析,且分析样品时所需样品量很少,所以对于大气飘尘来说,TXRF为一理想的分析工具。在城市中,对于高浓度的样品采集时间可以极短。为此,本文对全反射X射线荧光分析技术及其应用于大气颗粒物定量测定和分析方法、武汉市城市布局特点、采样点选择、样品制备与分析、以及大气颗粒物污染浓度分布格局和来源进行了研究。首先从X荧光分析技术的理论基础、基本原理入手,研究了全反射x射线荧光分析技术原理及分析仪结构特点。全反射x射线荧光分析是一种在特殊几何激发条件下的能量色散技术。全反射X射线荧光分析仪的X射线激发源,目前主要使用精细聚焦的x射线管、高功率旋转阳极x射线管等;与常规X射线荧光分析技术中激发光束照射到样品上的角度为40o左右不同,全反射X荧光分析技术中的入射角只有约0.1o,并且其探测器垂直于样品平面,探测器主要采用能谱探测器,Si(Li)探测器常被使用。本研究使用北京大学科技园微构分析研究中心所有、烟台大学田宇宏教授等研制的TXRF-1全反射X射线荧光分析仪就是这种分析仪。在全反射荧光分析中,荧光强度成倍增加和本底强度的大大减少,大大地降低了样品中背景辐射的干扰,使得TXRF的探测能力得到了很大提高。然后从对于区域存在的成因从武汉市地形和气象因素对大气污染污染影响进行了调查和分析,确定出适当采样点和采样方法,并进行采样和样品制备。武汉市地形属残丘性河湖冲积平原,城市主要布局为“钢铁城”、“汽车城”、“文化城”、“商业城”,能源结构是以煤炭为主。武汉市年平均气温都较为稳定、冬季气温低、大气稳定度高、逆温出现频繁,夏季气温高、大气稳定度弱、逆温出现频率低,全年风速不大、小风和静风的情况占了绝大多数时间,污染物扩散程度较弱,武汉市的大气污染应以本地源为主等特点。因此,所选花桥、高新、青山、东湖、紫阳采样点比较得当,采集大气样品42个,基本能够反映城区污染情况和近郊工业区污染情况。接着在所选定的TXRF-1全反射X射线荧光分析仪进行样品分析与数据处理,得出武汉市大气污染元素浓度分布格局。无论是武汉市城区花桥区域,还是武汉市近郊工业区高新区域,PM2.5浓度数有随气温升减低趋势,即夏低冬高趋势;砷元素(As)浓度城区(花桥)明显高于近郊(高新);最高砷元素(As)浓度区域为青山厂前区域。无论是PM10颗粒物中的As、Pb浓度,还是PM10(K、Ca、Fe)总浓度,青山厂前区域明显高于东湖区域,并且在夜深人静的时候东湖区域降底很多,“文化城”紫阳区域的PM10污染元素平均浓度最低。最后采用富集因子法进行污染源的解析,并提出了污染防治措施建议。武汉市城市大气颗粒物污染主要来源燃煤尘、机动车尾气尘、建筑尘源和土壤尘等,城市大气颗粒物为燃煤尘、机动车尾气尘、建筑尘和土壤尘等混合型的颗粒物。这种颗粒物污染已在部分城区上升为大气污染物的首要污染物。大气颗粒物上富集的有毒和有害的组分,不仅对环境空气质量,而且对生态环境和人体健康会造成很大的威胁,需要采取措施防治。更多还原

【Abstract】 Analysis of atmospheric particulate pollutant, especially effective analysis of atmospheric particulate pollutants of the most harmful to human health and less than 2.5μm (PM2.5), cannot be completed with an ordinary non-nuclear analytical technique. Instead, it must be performed with modern nuclear analytical techniques. TXRF, as a fast multi-element analysis method, can be used in the trace analysis of pg magnitude. Besides, the required number of samples is small in analysis of samples, so for air particulate, TXRF is an ideal analytical tool. In cities, collecting samples of high concentration can completed within a very short time. In this paper, total reflection X-ray fluorescence analysis technology and its application in the quantitative measurement and analysis of atmospheric particulate matter, Wuhan City layout characteristics, sampling sites selection, sample preparation and analysis, as well as the distribution pattern of atmospheric particulate pollution concentration and the sources were studied.With the theoretical basis and basic principle of X-fluorescence analysis technology as a starting point, the principles of the total reflection x-ray fluorescence analysis technology and the structural characteristics of the analyzer are studied. Total reflection x-ray fluorescence analysis is an energy dispersive technique in special geometric activation cases. At present, x-ray activation source of the total reflection X-ray fluorescence analyzer mainly uses x-ray tubes with sophisticated focus and anode x-ray tubes with high-power rotation, etc. Different from the angle 40°, formed by the activation beam irradiating the sample in conventional X-ray fluorescence analysis, the angle of incidence in total reflection X fluorescence analysis is only about 0.1°and the detector is perpendicular to the sample plane. The detector mainly used is energy spectrum detector, in addition, Si (Li) detector is often used. The TXRF-1 total reflection X-ray fluorescence analyzer owned by micro structure analytical lab in Peking University Science Park and developed by professor Tian Yuhong and other professors in Yantai University is of this kind. In total reflection fluorescence analysis, the fluorescence intensity doubled and background intensity greatly reduced, considerablly decreasing interference from background radiation in the samples, resulting in great improvement in TXRF detection capability.And then from the point of the causes for the regional presence, the impact of Wuhan terrain and meteorological factors on air pollution was surveyed and analyzed to determine appropriate sampling sites and methods for sampling and sample preparing. Characterized by residual hills, river and lakes, the main layout of Wuhan is the "Steel City", "Motor City", "Culture City" and "Commercial City". As far as energy structure is concerned, coal is mainly used. The annual average temperature in Wuhan is relatively stable, with low temperature, high atmospheric stability, and frequent temperature inversion in winter as well as high temperature, weak atmospheric stability, low frequency temperature inversion in summer. The wind speed throughout the year is high and light wind and calm wind blow during most of the time. With weaker degree of dispersion of pollutants, Wuhan air pollution is mainly caused by regional source. Therefore, the selected sampling sites of Huaqiao, Gaoxin, Qingshan, East Lake, Ziyang are appropriate. 42 air samples are collected, fundamentally reflecting pollution in urban and suburban industrial areas.Then, sample analysis and data processing were performed with the selected TXRF-1 total reflection X-ray fluorescence analyzer and the concentration distribution pattern of Wuhan air pollution elements was obtained. Whether in urban Huaqiao region, or suburban industrial region in Gaoxin, Wuhan, PM2.5 concentrations tend to reduce as temperatures rise. That means the concentration tends to be low in summer and high in winter. The concentration of Arsenic (As) in urban regions (Huaqiao) was significantly higher than in suburbs (Gaoxin); Changqian region in Qingshan is the place with the highest arsenic (As) concentration. Whether the concentration of As and Pb in PM10 particles or PM10 (K, Ca, Fe) total concentration is higher in Changqian region, Qingshan than in the East Lake region. Besides, in the quiet of night the concentration in the East Lake region decreases a lot. "Cultural city" Ziyang region bears the lowest average concentration of PM10 pollution elements.Finally enrichment factor method is used for analysis of pollution sources and suggestions on preventing pollution are put forward. Atmospheric particulates pollution in Wuhan urban areas mainly comes from coal dust, vehicle exhaust dust, construction dust, soil dust and so on. Atmospheric particulates in urban areas are mixed particulates of coal dust, vehicle exhaust dust, construction dust, soil dust and so on. The pollution of particulates has evolved to be primary atmospheric pollution. The toxic and harmful components rich in atmospheric particulates pose a serious threat to environment and air quality, the ecological environment and human health, so it is necessary to take measures for prevention.更多还原