一种用于SPM分析的大气气溶胶单颗粒样品的制备方法

介绍了一种用于扫描质子微探针分析的大气气溶胶单颗粒样品的制备方法。通过实验摸索出一种适合于支撑颗粒物的材料聚乙烯醇缩丁醛(PVB)。大气颗粒物被直接采集在PVB薄膜上从而制成样品,保持了颗粒物的原始信息。用显微镜观察了采集的颗粒物,颗粒物之间完全分开,颗粒物间距合适。样品的扫描质子微探针试验结果表明,所制成的单颗粒样品能经受住质子束的长久轰击。对PVB薄膜的本底测试表明,这种膜的本底很小,不会对被测颗粒物的元素产生干扰。     

气溶胶样品氢含量的质子弹性散射分析

利用单个标准样品比较法质子弹性散射分析（PESA）对一组采集在核孔膜上的气溶胶样品的氢含量进行定量分析。在质子束能量为2.5MeV、散射角为40°时，PESA测量10μm厚核孔膜上气溶胶中H含量的探测限为0.36μg/cm²。几个样品H含量的测量结果在3.2~37.5μg/cm²之间，显著高于探测限。质子能量在1.0~2.5MeV范围内，3.5μmMylar膜的束流归一化H峰面积随入射质子能量的变化在±3%以内。所以，不同厚度的气溶胶样品可采用同一个标准样品来进行PESA测量。     

质子非卢瑟福背散射测量气溶胶样品中氢、碳、氮和氧的含量

气溶胶样品中Z＞12以上元素含量的质子荧光(PIXE)分析是北京师范大学GIC4117串列加速器的主要应用领域之一。为弥补PIXE无法分析H、C、N和O等轻元素之不足，在PIXE靶室160°散射角安装金硅面垒探测器，用质子非卢瑟福背散射分析（PNBS）方法对核孔膜采集的气溶胶样品中H、C、N和O等轻元素的含量进行测量。测量得到的气溶胶样品中H和Si元素含量与质子前角散射（PESA）和PIXE的分析结果相近，表明PNBS可用于核孔膜采集的气溶胶样品的分析。     

用核分析技术研究上海市空气和水环境污染

用扫描质子微探针对上海市中心区和若干排放大气气溶胶单颗粒的质子激发X射线能谱进行了测量和形貌分析,然后用人工神经网络计算机识别技术追踪市中心区污染的来源,确定各排放源对它的贡献;用穆斯堡尔效应研究了市中心高架桥和隧道内含铁大气气溶胶颗粒的铁化学形态、尺寸和浓度,以及使用低本底放射性测量技术研究了苏州河水的α、β放射性强度。     

北师大串列加速器在气溶胶离子束分析上的新进展

气溶胶样品中Z＞12元素含量的质子X射线荧光分析是北师大GIC4117串列加速器的主要应用领域之一.为弥补该方法不能分析H、C、N和O等轻元素之不足,我们通过在PIXE靶室40°和160°散射角安装金硅面垒探测器,用质子前角弹性散射分析和非卢瑟福背散射方法对核孔膜采集的气溶胶样品中H、C、N和O等轻元素的含量进行了测量.     

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。     

质子X荧光分析在大气气溶胶研究中的应用(英文)

为了确定PIXE(质子X荧光分析)的测量准确性,进行了三个实验室的横向比对分析。比对中使用了30个单元素样品和一个多元素样品。结果显示,对于绝大多数样品,三家的一致性好于10％,三次测量的重复性相对于平均值好于6％。用一个自动的时间顺序步进采样器在北京采集了大气气溶胶样品,用PIXE对这些样品进行元素分析,然后对元素浓度数据用绝对主因子分析(APFA)进行统计分析,求出主成分以及它们解释的百分数。结果表明,PIXE与统计方法相结合可以有效地分解出城市大气气溶胶的主成分,并能将该地的和远地来的成分区别开来。用一个八级撞击式采样器在四个有代表性的地区进行了大气气溶胶采样,从由PIXE分析得到的一些代表性元素浓度的粒径分布特征,推断出大气气溶胶的来源。     

质子X荧光分析在大气气溶胶研究中的应用

了确定PIXE(质子X荧光分析)的测量准确性,进行了三个实验室的横向比对分析。比对中使用了30个单元素样品和一个多元素样品。结果显示,对于绝大多数样品,三家的致性好于10％,三次测量的重复性相对于平均值好于6％。用一个自动的时间顺序步进采样器在北京采集了大气气溶胶样品,用PIXE对这些样品进行元素分析,然后对元素浓     

大气气溶胶含碳组分的来源研究：加速器质谱法

使用加速器质谱技术进行了大气中气溶胶含碳组分的来源分析。对于北京近效区采集的总悬浮颗粒物样品，多元统计模式计算结果表明，ＴＳＰ的最主要来源是土壤扬尘，对大气气溶胶的贡献超过了５０％，     

扫描质子微探针对IAEA城市飞灰参考物质的微区均匀性研究

使用扫描质子微探针技术测定了由国际原子机构提供的两种不同颗粒度的城市飞灰参考物质。得到了样品压片的１００μｍ×２００μｍ微小区域内的微量元素分布均匀性水平。介绍了实验技术，并以分析结果进行了讨论。     

核分析技术在大气环境研究中的重要作用

核分析技术（尤其是中子活化分析）以其检测限低、精密度高、不破坏样品等优点成为气溶胶元素分析的最有效手段之一。核分析方法所产生的大量可靠数据对气溶胶领域研究近一二十年来的重大发现起到了不可取代的作用。以中国气溶胶对太平洋生产力乃至全球环境变化的影响为例，评述了近20看来气溶胶研究的重大成果和发展，并阐明了该分析技术在大气环境研究中的重要作用。     

Analysis of atmospheric aerosols by PIXE: the importance of real time and complementary measurements

Particle-Induced X-ray Emission (PIXE) has been used for more than 30 yr in many urban and background air pollution studies. The technique has certainly contributed to the understanding of source-receptor relationship for aerosol particles as well as to aerosol physics and chemistry. In the last few years, where aerosol issues were strongly linked to global climate change through the relationship between aerosol and atmospheric radiation points to new challenges in atmospheric sciences, where PIXE could play an important role. Also the recognition for the inter-relationship between aerosol and liquid and gas phases in the atmosphere makes important to integrate PIXE aerosol analysis with other complementary measurements. The use of Nephelometers and Aethalometers to measure scattering and absorption of radiation by aerosol particles can be done in parallel with particle filter collection for PIXE analysis. Parallel measurements of trace gases using traditional monitors as well as with new techniques such as Differential Optical Absorption Spectroscopy (DOAS) that can provide concentration of O₃, SO₂, NO₃, NO₂, HCHO, HNO₃, Benzene, Toluene, and Xylene, is also important for both urban and remote aerosol studies. They provide information that allows a much richer interpretation of PIXE data. Recently developed instruments that provide real time aerosol data such as the Tapered Element Oscillating Microbalance (TEOM) PM₁₀ monitor and automatic real time organic and elemental carbon analyzers provide extremely useful data to complement PIXE aerosol analysis. The concentrations of trace elements measured by PIXE comprise only 10–30% of the aerosol mass, leaving the organic aerosol characterization and measurement with an important role. The aerosol source apportionment provided by PIXE analysis can be extended with other aerosol measurements such as scattering and absorption, estimating for example, the radiative impact of each discriminated aerosol source. The aerosol bulk PIXE measurements can be complemented with soluble concentrations provided by Ion Chromatography (IC) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Recent developments in remote sensing techniques and products also enhance significantly regional aerosol studies. Three-dimensional air mass trajectories should be integrated in aerosol studies for urban and remote areas. The applications of these techniques to study urban aerosols from São Paulo and Santiago de Chile have broadened extensively the scientific scope of these studies.     

PIXE and XRF analysis of particulate matter samples: an inter-laboratory comparison

PIXE and XRF are very effective techniques in atmospheric aerosol investigation, therefore they are extensively used by the authors. In this work an inter-laboratory comparison of the results obtained analysing several samples (collected on different substrata) with both techniques is presented: the samples were analysed by PIXE (in Florence, at the 3 MV Tandetron accelerator of LABEC laboratory) and by XRF (in Genoa and Milan, where two Oxford XRF instruments are operational). The results of the three sets of measurements are in good agreement for all the analysed samples.The aim of this work was also to compare PIXE and XRF performance in atmospheric aerosol analysis with the routine set-up currently in use at the three laboratories, to determine the best technique to be applied depending on the substratum used for aerosol sampling and the main elements of interest for each specific research project. Results of the comparison between the minimum detection limits of both techniques will be shown for all the measured elements, for different substrata (Teflon, polycarbonate and cellulose mixed esters).     

某核电厂大气气溶胶总α、总β监测

介绍了某核电厂大气中气溶胶放射性监测情况。对监测结果进行分析统计,得到某核电厂大气气溶胶总α、总β水平季节变化规律,衰变规律,以及应用K值法快速判断核电厂放射性的排放异常。     

Response Surface Modeling of Aerosol Release Fraction in Sodium Pool Combustion

A response surface model has been proposed to evaluate an aerosol release fraction during sodium pool fire in a liquid metal fast reactor (LMFR). Air containing aerosols are radiative and they influence the allocation of combustion heat from the flame to atmospheric gas or sodium pool. Hence, the aerosol release fraction needs to be quantified based on the behavior of the aerosols and physics of mass and heat transfer. However, the aerosol release fraction is one of user-specified parameters of computer codes for the sodium fire safety analysis of the LMFR. In the present study, a response surface model of the aerosol release fraction has been developed based on numerical experiments of aerosol dynamics. For developing the model, aerosol dynamic equation has been solved coupled with thermal-hydraulics and chemical reaction. The authors obtained good agreement of the aerosol release fraction between the numerical experiments and the past experiments. Therefore, the aerosol behavior model has been validated with regard to the pool combustion phenomena and is reasonably applicable to the numerical experiment. Three influential variables on the release fraction are identified as pool temperature, gas temperature and oxygen molar fraction in the air. The proposed response surface model is a quadratic expression of the influential variables and can be easily employed in the sodium fire analysis code.     

大气气溶胶滞留时间计算和分析

基于放射性核素的衰变平衡条件,使用氡衰变链核素^210Pb、^210Bi和^210Po的参数对大气颗粒物的滞留时间做了理论推导。测量了我国20个城市近地面大气气溶胶的^210Pb和^210Po的活度浓度,得到^210Po／^210Pb活度浓度比值范围为0．28-0．86,对计算结果进行分析。     

Analysis of sulphur with external beam proton induced gamma-ray emission analysis

Applicability of the ³²S(p, p′ γ)³²S reaction for sulphur analysis as a complementary method to PIXE has been investigated. The optimum energy region for the bombarding protons has been determined for both thick samples and for thin atmospheric aerosol samples. By optimizing the external beam method, sulphur concentrations at the 100 ppm level for thick organic samples and at the 100 ng/cm² level for aerosol samples are detectable.     

Composition of urban and rural aerosol samples collected in the Great Hungarian Plain

Urban and rural atmospheric aerosol samples have been collected simultaneously during 1997 in the Great Hungarian Plain. The elemental composition of the coarse and fine mode aerosol have been determined by the Proton-Induced X-ray Emission method. From the observed elemental concentrations, seasonal variations and variations with the wind sector distributions were found for separate elements. Principal component analyses gave four factors in urban aerosol, and three factors in the rural one. The order of the factors in the coarse mode aerosol is different from the order, found in the fine mode.     

Atmospheric radionuclides from Fukushima Dai-ichi nuclear accident detected in Lanzhou,China

After the Fukushima Dai-ichi nuclear power plant accident on March 11,2011,the radioactivity released from the accident was transported around the globe by atmospheric processes.The radioactivity monitoring program on atmospheric particulate in Lanzhou,China was activated by GSCDC to detect the input radionuclides through atmospheric transport.Several artificial radionuclides were detected and measured in aerosol samples from March 26 to May 2,2011.The peaked activity concentrations(in m Bq/m3)were:1.194(131I),0.231(137Cs),0.173(134Cs)and 0.008(136Cs),detected on April 6,2011.The average activity ratio of131I/137Cs and134Cs/137Cs in air were 13.5 and 0.78.The significant increase of137Cs activity concentration,one order of magnitude higher than pre-Fukushima accident levels,in ground level aerosol was observed in 2013,as its resuspension from soil.The back-trajectory analysis simulated by NOAA-ARL HYSPLIT shows a direct transfer of the air masses released from Fukushima to Lanzhou across the Pacific Ocean,North America and Europe at the height close to 9000 m AGL.The value of effective dose for inhalation is close to one millionth of the annual limit for the general public.