基于同步辐射技术研究上海大气细颗粒物分布特征

用同步辐射X射线荧光分析(SRXRF)测定了上海市大气中粒径0.03-10 μm的13级颗粒物的元素组分,用X射线吸收近边谱(XANES)研究了颗粒物中S的化学价态.结果发现,在生活区和郊区,超细颗粒(<0.4 μm)对粒子质量浓度贡献较大,而工业区则细颗粒(1-10μm)对质量浓度贡献较大.元素浓度测定表明,吴淞工业区大气颗粒物中S、Ca、Ti、V、Cr、Fe、Ni、Cu、Zn和Pb元素浓度最高,且Ni、Mn、As和Pb等污染元素在细颗粒尤其是超细颗粒中有明显富集.化学价态测定显示,钢研所采样点不同粒径颗粒物中的S主要以硫酸盐形态存在,而在粒径<0.1μm 超细颗粒中还存在着一些还原态的低价态S.     

同步辐射中能X射线近边吸收谱方法研究不同施肥制度对土壤中硫形态的影响

土壤中硫是继氮、磷、钾之后的第四位重要的营养元素,它的形态转化对农作物生长等有很大的影响。本文利用同步辐射中能X射线近边吸收谱(XANES)方法研究用于长期定位试验的不同施肥制度的潮土,利用实验谱拟合出土壤中硫的不同价态的百分含量。结果表明,还原态,中间价态和高氧化态的硫在土壤中都存在,但主要以高氧化态的形式存在;不同的施肥制度对土壤全硫的含量也有不同的影响,不同氧化态的硫的比例和含量也都发生了变化。     

Eu,Dy共掺杂长余辉发光材料中稀土离子价态的研究

利用同步辐射X射线吸收近边结构(XANES)对Eu,Dy共掺杂硅酸盐体系长余辉发光材料中的稀土离子的价态进行分析，结果表明有 2价和 3价的Eu离子存在，但未发现 1价的Eu离子，而Dy离子则始终以 3价形式存在，未发现 4价Dy离子存在。这说明空穴传输模型还存在许多值得商榷的问题。该研究为进一步研究长余辉材料的发光机理提供了实验依据。     

质子激发X射线分析——生物医学中痕量元素分析的新技术

本文讨论了质子激发X射线分析对于生物体内各种元素的分析能力,并结合人体和动物的组织、血清、尿、头发中痕量元素分析的实例讨论了质子激发X射线分析的灵敏度、准确度和多元素分析能力,阐明了它在生物医学领域的痕量元素分析中的优点。     

质子激发X射线分析——生物医学中痕量元素分析的新技术

本文讨论了质子激发X射线分析对于生物体内各种元素的分析能力,并结合人体和动物的组织、血清、尿、头发中痕量元素分析的实例讨论了质子激发X射线分析的灵敏度、准确度和多元素分析能力,阐明了它在生物医学领域的痕量元素分析中的优点。     

杭州市区夏季大气飘尘中元素成分的测定

飘尘是主要的大气污染物,它不仅危害人体健康,而且是其他有害物的运载体。测定杭州市区大气飘尘的元素成分,有利于这个风景城市的三废治理及工业、交通等的合理布局,为城市规划提供环境保护方面资料。 1.采样 我们在杭州市区选择了有代表性的三个采样点:以128医院为清洁区;浙江旅馆为居民生活区;望江门车辆段为工业、交通区。采用滤膜抽滤空气的方法得到飘尘样品。选用杂质含量低的微孔滤膜,其采样有效面积为1.13cm~3。使用2XZ-4型真空泵作为采样动力,转子流量计的流速为50 1/min。每次采样持续4小时,总采大     

手持式XRF分析仪快速检测大气颗粒物中Cu、Zn、Pb含量

介绍了用手持式X射线荧光光谱(XRF)分析仪对大气颗粒物PM2.5中的Cu、Zn和Pb含量进行快速检测的方法。该方法用ICP-MS对滤膜样品的分析结果作为标样,建立XRF法被测元素含量——特征谱线强度工作曲线,利用此工作曲线测定大气颗粒物PM2.5中Cu、Zn和Pb的含量。该方法对大气颗粒物中Cu、Zn和Pb含量测量结果的相对标准偏差依次为5.50%、1.56%、4.71%。通过实验比对,该方法测试结果能与成都地区3月上旬浮尘天气现象相吻合。     

同步辐射微区X射线荧光和吸收谱技术在大气、土壤和动植物分析中的应用

同步辐射微区X射线荧光(Synchrotron micro-X-ray fluorescence spectroscopy,μ-SXRF)能够对物质进行元素分布分析和微区原位测定,具有高灵敏度、低检出限的特点。同步辐射X射线吸收谱技术(X-ray absorption fine spectroscopy,XAFS)能够提供原子周围的配位环境和化学形态,适用于进行元素形态分析。大气飘尘、土壤和动植物等是环境中元素迁移转化的重要载体,获取具有生物学意义的元素分布和形态,以及准确的定性或定量信息对研究这些元素在环境和生物体中的作用至关重要。随着研究的发展,同步辐射微区分析技术在此领域中得到越来越多的应用。本文介绍了同步辐射技术的基本原理和发展历程,回顾了近几年μ-SRXRF和XAFS技术在大气飘尘、土壤、植物和蚯蚓中元素的分布与形态研究领域的应用进展,对目前应用于此领域遇到的一些挑战进行了概括,并对其未来发展趋势提出了展望。     

冬季上海吴淞地区大气颗粒物PM10的元素主成分分析

从2002年12月到2003年2月,利用8通道采样器对上海吴淞地区进行3个月的大气气溶胶PM10(空气动力学直径小于10μm的颗粒)的采样。使用质子激发X射线荧光(PIXE)分析方法进行了多元素质量浓度测定,然后对获取数据进行主成分分析,讨论了吴淞地区8个风向采集的PM10中含有的主要化学元素成分和可能的来源。     

PIXE analysis of airborne particulate matter from Monterrey, Mexico. A first survey

A first survey of elemental contents in airborne particulate matter from Monterrey, Nuevo León, Mexico, was performed using PIXE. This second largest industrial city is located 715 km north of Mexico City, and counts with a population of nearly three million inhabitants in its conurbation. Air pollution in the place comes from a great variety of industries ranging from iron smelters to furniture manufacturing, as well as from fuel combustion in vehicles and industries. This study presents results of elemental contents in airborne particulate matter in two particle size fractions: PM_2.5 and PM₁₅. The samples were collected during five weeks on working days, Monday–Friday, from 9 December 1996 to 14 January 1997. Two samples a day were collected, 12 h each, night-time and day-time. These first results show local pollution as typical from a large urban area in conjunction with an active industry. Thirteen elements were consistently detected in most of the samples and some episodes due to both industrial and human activities were identified. A general discussion about the results obtained is presented.     

PIXE analysis of airborne particulate matter from Xalostoc, Mexico: winter to summer comparison

A study of elemental contents in airborne particulate matter from the industrial city of Xalostoc, Estado de México, was performed using PIXE. The place has a great variety of industries, it is a heavily populated, and it is a part of Mexico City's conurbation, thus contributing significantly to its atmospheric pollution. At present, there is few information available about elemental contents in airborne particulate matter from that region. In this study, two sets of samples of airborne particulate matter were collected daily during periods of four weeks in summer 1996 and winter 1997; two samples a day, 12 h each, night-time and day-time. Results revealed important information about elemental contents in airborne particulate matter from that area, especially in the respirable fraction PM_2.5. Comparison of night and day figures showed the presence of some elements such as Cu, Zn, and Pb, attributed, as it was expected, to uninterrupted industrial processes. Appearance of some other elements was more consistent only in either day-time or night-time due to diurnal or nocturnal industrial activities, or produced by human activities such as fuel combustion of automotive vehicles. Comparison of winter to summer results showed some other important features such as higher concentrations of pollutants in winter, because of the dry and cold weather, while summer samples exhibited lower concentrations mainly due to the presence of rain showers.     

Chemical speciation of chlorine in particulate matter by wavelength-dispersive PIXE technique

Chemical speciation of chlorine (Cl) in atmospheric particulate matter (APM) was performed by using a wavelength-dispersive PIXE spectrograph based on high-resolution measurement of Cl-Kβ emission. Samples of atmospheric particles were size-fractioned and collected by a cascade impactor at an urban area in Tokyo. The target position with respect to the spectrograph was precisely adjusted by a 2D laser displacement sensor to achieve high detection efficiency. The samples were irradiated with 2 MeV protons from a tandem electrostatic accelerator. The beam current was 300-500 nA. During the irradiation, the target was cooled by liquid nitrogen to avoid the evaporation of volatile Cl compounds. The measured spectra for the NaCl standard samples clearly showed the Cl-Kβ series composed of the Kβ₁ and the satellite Kβ_x, Kβ₅ lines. From the measured X-ray yields, it was found that the chemical speciation of samples with Cl concentrations as low as ≈1% is possible by this method. The Cl-Kβ series were also successfully observed in the case of APM samples with particle sizes of 11.0-2.1 μm. The spectra shapes of the NaCl standard samples and an APM sample were slightly different from each other, because of some possible mixing of non-sea salt component in the APM sample.     

Manganese survey in airborne particulate matter from a mining area at Hidalgo State, Mexico

A manganese (Mn) survey in airborne particulate matter from a mining area located in Hidalgo State (Mexico) was performed using PIXE. Deposits of Mn ore, first discovered in 1959 and under continuous exploitation since 1962, are nowadays considered as one of the most important of their kind in the American Continent. Afterwards, local inhabitants have been under continuous overexposure to dusts and water highly enriched with Mn. Since no information was available about Mn content in airborne particulate matter in that area, especially in the respirable fraction PM_2.5, airborne particles were collected simultaneously at two sites located on opposite sides of the rim of the mining valley, and along the line of prevailing local winds. The sample collection was performed on eight alternate days, taking two samples per day (day-time and night-time) at each sampling site, using Stacked Filter Units (SFUs) of the Davis design to separate particles into fine (PM_2.5) and coarse (PM₁₅) sizes. The samples were PIXE analyzed and the results of this study revealed that Mn content, in both fine and coarse fractions, were in excess of the general urban background level of 40 ng/m³ (US Environmental Protection Agency, 1990) in more than 50% of the samples, which indicate severe environmental deterioration in the place under study.     

上海地区PM10和PM2.5中铁元素的种态研究

本工作采集了上海市吴淞、南汇和人民广场三个典型地区的PM10、PM2.5样品,对这些颗粒物样品进行穆斯堡尔光谱测量,研究了PM10、PM2.5样品中铁元素的化学种态.研究结果表明,在大气颗粒物中铁元素主要以α-Fe2O3、Fe3O4、铁的硫酸盐以及少量的α-FeOOH的形式存在.     

Effect of the amount of trapped particulate matter on diesel particulate filter regeneration performance using non-thermal plasma assisted by exhaust waste heat

An experimental system of diesel particulate filter(DPF) regeneration using non-thermal plasma(NTP) technology assisted by exhaust waste heat was conducted and regeneration experiments of DPFs with different amounts of trapped particulate matter(PM) were conducted. The concentrations of the PM decomposition products(COx) and the internal temperature of the DPF were monitored to determine the performance of DPF regeneration and thermal safety of the NTP technology. The results showed that the concentrations of CO and CO_2 and the mass of PM decomposition increased with the increase in the amount of captured PM, whereas the concentration of the NTP active substance(O_3) escaping from the DPF decreased under the same working conditions of the NTP injection system. A higher amount of captured PM promoted the oxidative decomposition reaction between NTP and PM and improved the utilization rate of the NTP active substances. The peak temperature at the same measuring point inside the DPF generally increased and the phases of the peak temperature were delayed as the amount of captured PM increased. The temperature peaks and temperature gradients during the DPF regeneration process were far lower than the failure limit value, which indicates that NTP regeneration technology has good thermal durability and increases the service life of the DPF.     

Ion beam analyses of particulate matter in exhaust gas of a ship diesel engine

There is an urgent need to reduce emission of the particulate matter (PM) in the exhaust gas from ship diesel engines causing various health hazards and serious environmental pollution. Usually the heavy fuel oil (HFO) for ships is of low quality, and contains various kinds of impurities. Therefore, the emission of PM along with exhaust gas from ship diesel engines is one of the most serious environmental issues. However, the PM fundamental properties are not well known. Therefore, it is important to perform elemental analysis of the PM. The HFO contains sulfur with a relatively high concentration of a few percent. It is important to make quantitative measurements of sulfur in the PM, because this element is poisonous for the human body. In the present work, PM samples were collected from exhaust gas of a test engine, and RBS and PIXE analyses were applied successfully to quantitative analysis of the PM samples. The RBS analysis enabled quantitative analysis of sulfur and carbon in the collected PM, while heavier elements such as vanadium and iron were analyzed quantitatively with the PIXE analysis. It has been found that the concentration ratio of sulfur to carbon was between 0.007 and 0.012, and did not strongly depend on the output power of the engine. The S/C ratio is approximately equal to the original composition of the HFO used in the present work, 0.01. From the known conversion ratio 0.015 of sulfur in the HFO to sulfates, the conversion ratio of carbon in the HFO to the PM is found to be 0.01-0.02 by the RBS measurements. On the other hand, the PIXE analysis revealed a vanadium enrichment of one order of magnitude in the PM.     

上海市吴淞工业区大气PM2.5水溶成分的元素分析及细胞毒性研究

通过ICP-MS测定了上海市吴淞地区大气PM2.5水溶成分金属元素含量,通过四唑盐(MTT)测定细胞存活率,通过超氧化歧化酶(SOD)和丙二醛(MDA)两个指标测定细胞氧化损伤,琼脂糖凝胶电泳测定细胞内DNA损伤,流式细胞仪(Flow cytometry)检测细胞凋亡和周期等实验研究了大气PM2.5水溶成分的细胞毒性.实验结果表明:PM2.5可溶成分中Zn元素含量最高,PM2.5在一定浓度范围内能导致细胞死亡,引起细胞的氧化损伤,影响DNA的复制,阻碍细胞增殖,但没有诱导细胞凋亡.PM2.5中可溶金属离子对细胞毒性表现为联合作用.