CAS OpenIR  > 中科院上海应用物理研究所2004-2010年
Alternative TitleInvestigation of Light Elements in Airborne Particles by XANES and SPM
Thesis Advisor李燕
Degree Grantor中国科学院上海应用物理研究所
Place of Conferral上海应用物理研究所
Keyword大气颗粒物 轻元素 X射线吸收近边结构谱 扫描质子微探针 形态
Abstract大气颗粒物因对环境、气候和人体健康产生影响而备受关注。颗粒物中的持久性有机污染物、酸根等,均由轻元素(如C、N、O、S、Cl等)组成,轻元素的分析是当前大气环境科学研究中的热点及难点。同步辐射技术和核分析技术以其检测限低、精度高、不破坏样品等优点成为颗粒物元素分析的最有效手段之一。本论文利用同步辐射X射线吸收近边结构谱(X-ray absorption near-edge structure,XANES)和扫描质子微探针(scanning proton microprobe,SPM)等技术研究了上海市大气颗粒物中的轻元素。 论文首先建立了基于XANES谱分析大气颗粒物中硫、氯等的形态方法,以及使用扫描质子微探针分析单颗粒中C、N、O等轻元素含量的方法。用所建立的方法对上海典型地区大气颗粒物中轻元素的污染特征进行了研究,评估了燃煤无组织排放污染对环境的影响。上海宝山工业区和嘉定郊区不同粒径的大气颗粒物的研究结果表明:硫的质量浓度粒径分布谱呈多模态,质量主要分布在细粒子中。粗颗粒和细颗粒中硫以硫酸盐为主;超细颗粒物中,除硫酸盐外,还存在低价的金属硫化物、噻吩类有机硫化物。氯的质量主要分布在粗颗粒物中;粗颗粒物中的氯以无机氯为主,细颗粒中的氯以有机氯为主。污染来源、颗粒物形成和转换机制及气象条件差异决定了两个地区颗粒物中元素分布特征。上海地铁站和超市室内的大气颗粒物的研究结果表明:地铁粗颗粒物中部分硫以金属硫化物形态存在,推测来自于地铁中铁轨摩擦产生颗粒物。地铁的超细颗粒物中存在有机硫化物,推测来自于室外汽车尾气的排放。 无组织排放污染是上海市大气污染治理的一个难点。论文对燃煤小锅炉排放颗粒物污染做了研究。结果表明:原煤中有机硫含量70%,硫铁矿硫含量17%,硫酸盐硫含量13%。在底灰、飞灰和细颗粒中,硫酸盐含量分别为80%、79%、94%。使用XANES和PIXE研究了锅炉排放SO2和颗粒物的复合污染对植物的影响,研究发现这种复合污染导致了香樟树叶子中总硫和硫酸盐硫的积累。为了减少燃煤污染,有必要采取措施控制燃煤小锅炉的污染。 用扫描质子微探针技术对上海宝山工业区和中心城区的大气PM10及污染源进行了单颗粒研究。利用质子非卢瑟福弹性背散射谱,得到了单颗粒物中轻元素含量。结果表明中心城区颗粒物碳质成分较高,工业区颗粒物中矿物成分较高。单颗粒的Fe、S、Ca元素的分布表明,工业区的矿物颗粒物存在硫化现象,SO2和颗粒物中的矿物成分反应导致颗粒物中硫含量的升高。
Other AbstractAirborne particulate matter is of great concern due to the adverse effects on human health, their role in climate change, and the environmental issues caused by particulate air pollution. The light elements in aerosol (such as C, N, O, S, Cl, etc.) are related to persistent organic pollutants, acid rain issues which are current hot topics in environmental research. However, analysis of light elements in particles is still a challenge. Synchrotron-based X-ray techniques and nuclear microprobes are very powerful technology in analysis of aerosol with its low detection limit, high accuracy, and the unique advantage of non-destruction of the samples. In this thesis, synchrotron radiation X-ray absorption near-edge structure (XANES) and scanning proton microprobe (SPM) were used to study light elements in airborne particulate matter of Shanghai. Firstly, the methods for speciation of S and Cl in particles by XANES spectra, and the methods for determination of the concentration of light elements like carbon, nitrogen and oxygen in individual particles by SPM were established. Using these methods, the characteristics of light elements in particles in Shanghai air were studied, and the impacts of coal combustion emission on environment were also preliminary evaluated. The results from analysis the size-fractionated airborne particles collected at industrial district and suburban area show that sulfur in particles from industrial district is mainly distributed in the fine fractions with multimode mass concentration size distributions. Sulfate is the dominant form of sulfur in both coarse and fine particles. In addition, a small amount of sulfur also is present as metal sulfide and thiophenic forms in ultrafine particles. Chlorine is mainly existed in the coarse fractions. Organochlorine and inorganic chlorine are the main forms of chlorine in fine and coarse particles, respetively. It is revealed that the differences in sulfur mass distribution of particles between industrial district and suburban area can be attributed to local and regional sources, weather conditions, formation and conversion mechanisms of particles. The results on characterization of the indoor airborne particles at an underground metro station and a supermarket situated in central Shanghai show that metal sulfide exists in coarse particles collected at underground station, which may be related to inorganic metallic dust generated by the friction between the subway train and the railway during motion. Organic sulfur is present in ultrafine particles in the subway’s internal space. It is assumed that it derived from outdoor car exhaust. Unorganized emission sources are widely distributed in suburb of Shanghai and it is difficult to control. The results of studying particles from a small coal-burning boiler show that about 70% of the sulfur in raw coal is present in organic form and a minor fraction of the sulfur occurs as other forms, i.e. 17% of pyrite and 13% of sulfate. In bottom ash, fly ash, and PM2.5, the dominant form of sulfur is sulfate, with the percentage of 80, 79 and 94, respectively. The results in evaluating the impact of coal-burning emission on camphor leaves suggest that synergistic interactions of SO2 and particulate matter pollution resulted in an enhanced content of total sulfur and sulfate in the leaves. The research shows that it is needed to control air pollution caused by small coal-burning boiler. The PM10 single particles from the city center and the industrial area of Shanghai, and the individual particles of pollution sources were analyzed using SPM. The light elemental concentrations in a individual particle were quantitatively determined by proton non-Rutherford elastic backscattering spectrometry (EBS). The results show that carbonaceous matter is enriched in particles from the city center, while mineral matter is the main component of airborne particles in the industrial area. The maps of S, Ca and Fe of individual particles show that sulfuration reaction occurres between SO2 and mineral particles, which increases sulfur content of particles.
Document Type学位论文
Recommended Citation
GB/T 7714
包良满. 大气颗粒物中的轻元素XANES和SPM研究[D]. 上海应用物理研究所. 中国科学院上海应用物理研究所,2009.
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