Detection of non-sea salt sulphate aerosol at a remote coastal site in South Africa: A PIXE study

An aerosol sampling site based on a single-stage streaker sampler with four-hour time resolution was established in 1993 at Brandt-se-Baai, on the north-western coast of South Africa (31.5°S 18°E, 50 m asl). The site was deployed to monitor the generation of dust from the local mining operations and in part to test the hypothesis of large-scale air mass recirculation over Southern Africa. Streaker samples were analysed by PIXE for the usual crustal derived elements and sulphur. Sulphate aerosols over southern Africa are produced in the atmosphere by oxidation of SO₂, from industry, or DMS, from the ocean. Industrial related sulphate plays a key role in tracing long-range transport of anthropogenic pollutants.

We present results from selected monthly samples collected during 1996. Measured particulate sulphur has been apportioned between contributions from sea spray and non-sea salt sulphate (NSS) aerosols. Marine particulate sulphur, present in the regional background, was traced by its correlation with Na and Cl, which were routinely detected. The NSS content of these air masses was enriched with respect to the expected sea salt sulphur by two orders of magnitude. Al, Si, K, Ca, Ti and Fe, the major crustal elements, were measured only episodically with the occurrence of strong south-easterly winds. These winds are associated with wind blown dust from a mine located 4 km from the site.

These results are the first direct aerosol characterisation of the remote region of the western seaboard of southern Africa. Specifically the sulphur measurements at this site provide insights into relative contributions of natural DMS, industrial and sea salt contributions of particulate sulphate.     

Industrial aerosol characterisation at a remote site in South Africa

South Africa is the most industrialised country in southern Africa with approximately 1.1 Tg of sulphur emitted from anthropogenic activities per annum. Complex circulation patterns and highly stable vertical atmospheric conditions promote the accumulation of pollutants below 700 hPa or 3000 m asl. A remote site in the Eastern Cape of South Africa, Ben Macdhui (30.5°S 27.9°E, 3001 m) was selected for testing the hypothesis that industrial emissions, specifically sulphate, are transported over thousands of kilometres in anticyclonic type patterns of flow and exported from the subcontinent towards the Indian Ocean at about 30°S. Time resolved particulate sampling (streaker) was conducted between June 1995 and January 1997. To characterise the industrial aerosol signal, two intensive sampling campaigns (summer and winter) were undertaken in 1996. Aerosol samples were collected by a streaker sampler and an open-faced stacked filter unit (SFU). Samples were PIXE analysed to obtain elemental concentrations. The industrial signature detected at Ben Macdhui was characterised by elevated concentration of sulphur and iron in the fine fraction and fine sulphur detected in the coarse mode. Other sources identified from the elemental data were soil (Al, Si, Ca, Mg, K, S, Mn), biomass burning (fine K) and marine (Cl, Ca, Mg, S and coarse K). These four sources accounted for approximately 70% of the total detected elemental mass. Major individual contributions came from the crustal (53%) and industrial components (21%). Air parcel trajectory analyses confirmed that peak episodes of enhanced aerosol sulphur were related to transport from the industrial Highveld region of South Africa and conversely that clean air masses originated over the southern oceans.     

Aerosol composition and source apportionment in Santiago de Chile

Santiago de Chile, São Paulo and Mexico City are Latin American urban areas that suffer from heavy air pollution. In order to study air pollution in Santiago area, an aerosol source apportionment study was designed to measure ambient aerosol composition and size distribution for two downtown sampling sites in Santiago. The aerosol monitoring stations were operated in Gotuzo and Las Condes during July and August 1996. The study employed stacked filter units (SFU) for aerosol sampling, collecting fine mode aerosol (dp<2 μm) and coarse mode aerosol (210 mass of particles smaller than 10 μm) and black carbon concentration were also measured. Particle-Induced X-ray Emission (PIXE) was used to measure the concentration of 22 trace elements at levels below 0.5 ng m⁻³. Quantitative aerosol source apportionment was performed using Absolute Principal Factor Analysis (APFA). Very high aerosol concentrations were observed (up to 400 μg/m³ PM₁₀). The main aerosol particle sources in Santiago are resuspended soil dust and traffic emissions. Coarse particles account for 63% of PM₁₀ aerosol in Gotuzo and 53% in Las Condes. A major part of this component is resuspended soil dust. In the fine fraction, resuspended soil dust accounts for 15% of fine mass, and the aerosols associated with transportation activities account for a high 64% of the fine particle mass. Sulfate particle is an important component of the aerosol in Santiago, mainly originating from gas-to-particle conversion from SO₂. In the Gotuzo site, sulfates are the highest aerosol component, accounting for 64.5% of fine mass. Direct traffic emissions are generally mixed with resuspended soil dust. It is difficult to separate the two components, because the soil dust in downtown Santiago is contaminated with Pb, Br, Cl, and other heavy metals that are also tracers for traffic emissions. Residual oil combustion is observed, with the presence of V, S and Ni. An aerosol components from industrial emissions is also present, with the presence of several heavy metals such as Zn, Cu and others. A factor with molybdenum, arsenic, copper and sulfur was observed frequently, and it results from emissions of copper smelters.     

Elemental analysis of limestone samples from Ewekoro limestone deposit in southwest Nigeria

Limestone samples of different colours from Ewekoro limestone deposit in Ogun State, Nigeria were subjected to elemental analysis by proton-induced X-ray emission (PIXE) and proton-induced gamma-ray emission (PIGME) techniques. The irradiation was by 2.5 MeV proton beams from the ion beam analysis (IBA) facility of the 3 MV Van de Graaff accelerator at the Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights. Elemental composition and concentrations of 22 major, minor and trace elements were determined. The NIST geological standard, NBS278, was analysed for quality assurance. The concentrations of the major elements (Ca, Fe, K and Al) are similar in the samples while the other major elements differed. Calcium accounts for about 38%, giving 86.8% CaCO₃ content in the limestones. The major elements (Al, Ca, Fe, Si, S and K), present in the limestones, were also found to be enriched in airborne particulate matter studied by earlier workers, thus confirming cement dust as the major contributor to the particulate matter within and around cement factories.     

Roadside dust contamination with toxic metals along industrial area in Islamabad,Pakistan

An investigation has been carried out to understand the contamination characteristics of roadside dust in the industrial area of Islamabad, Pakistan. The amounts of Si, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Pb, Zn, Ga, As, Se and Cd were determined from 95 roadside dust samples collected along the Islamabad industrial area using Proton Induced X-ray Emission （PIXE）. The results indicated that concentrations of all elements, except Cd, in the roadside dust were significant. The results of the enrichment factor show that the elementary composition of the roadside dust could be categorized as soil elements from the crust of the earth and elements from anthropogenic pollution. The high enrichment factors imply that elements such Cr, Cu, Pb, Zn, As, Se, Cd, Ni, Co and S came from anthropogenic activities. The source of metal contamination was identified using multivariate statistical analysis. It has been concluded that Ca, Sc, Ti, V, Mn and Fe mainly originate from crustal sources; Cr, Cu, Ni, Pb, Zn and Ga are associated with point-sources from industrial pollution/traffic; and S, Cl, K, As and Se are mainly related to oil/coal combustion.     

A high sensitivity elemental analysis methodology for upper tropospheric aerosol

In this study, a sampling and analysis tool for aerosol particles has been developed. Its purpose is to characterize upper tropospheric aerosols, where concentrations are low. Since measurements will be made from an airplane, a time resolution of one hour is desirable. These conditions require efficient sampling and analysis with low detection limits. To accomplish this, our sampler uses impaction, concentrating the aerosol deposit on a small area. The impactor has 14 parallel sampling lines which are used sequentially to achieve the time resolution. The elemental analysis is done with Particle-Induced X-ray Emission (PIXE), profiting from its high absolute sensitivity. The aerosol is expected to contain primarily sulphur (S) and emphasis is placed on this element, however the multi-elemental nature of PIXE is of course used. Several substrates have been investigated regarding minimum detection limits. Scanning Transmission Ion Microscopy (STIM) analysis has been conducted on two outdoor aerosol samples, rendering three-dimensional images and mass distribution profiles. The setup was tested at ground level with high time resolution (5 min). Results show that the detection capabilities are excellent.     

Trace elements in lake sediments measured by the PIXE technique

Lakes are ecosystems where there is a great potential of metal accumulation in sediments due to their depositional characteristics. Total concentration of trace elements was measured on a 50 cm long sediment core from the Infernão Lake, that is an oxbow lake of the Moji-Guaçu River basin, in the state of São Paulo, Brazil. Dating of the core shows up to 180 yrs old sediment layers. The use of the PIXE technique for elemental analysis avoids the traditional acid digestion procedure common in other techniques. The multielemental characteristic of PIXE allows a simultaneous determination of about 20 elements in the sediment samples, such as, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr, Ba, and Pb. Average values for the elemental composition were found to be similar to the bulk crustal composition. The lake flooding pattern strongly influences the time series of the elemental profiles. Factor analysis of the elemental variability shows five factors. Two of the factors represent the mineralogical matrix, and others represent the organic component, a factor with lead, and another loaded with chromium. The mineralogical component consists of elements such as, Fe, Al, V, Ti, Mn, Ni, K, Zr, Sr, Cu and Zn. The variability of Si is explained by two distinct factors, because it is influenced by two different sources, aluminum-silicates and quartz, and the effect of inundation are different for each other. The organic matter is strongly associated with calcium, and also bounded with S, Zn, Cu and P. Lead and chromium appears as separated factors, although it is not clear the evidences for their anthropogenic origin. The techniques developed for sample preparation and PIXE analysis was proven as advantageous and provided very good reproducibility and accuracy.     

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.     

Quantitative analysis of cascade impactor samples – revisited

Concentrations of aerosols collected in Singapore during the three months long haze period that affected the whole South-East Asian region in 1997 are reported. Aerosol samples were continuously collected by using a fine aerosol sampler (PM2.5) and occasionally with a single orifice cascade impactor (CI) sampler. Our results show that in the fine fraction (<2.5 μm) the concentrations of two well-known biomass burning products, i.e. K and S were generally increased by a factor 2–3 compared to the non-hazy periods. However, a discrepancy was noticed, at least for elements with lower atomic number (Ti and below) between the results obtained by the fine aerosol sampler and the cascade impactor. Careful analysis by means of Nuclear Microscopy, in particular by the Scanning Transmission Ion Microscopy (STIM) technique, revealed that thicknesses of the lower CI stages exceeded thick target limits for 2 MeV protons. Detailed depth profiles of all CI stages were therefore measured using the STIM technique and concentrations corrected for absorption and proton energy loss. After correcting results for the actual sample thickness, concentrations of all major elements (S, Cl, K, Ca) agreed much better with the PM2.5 results. The importance of implementing thick target corrections in analysis of CI samples, especially those collected in the urban environments, is emphasized. Broad beam PIXE analysis approach is certainly not adequate in these cases.     

Elemental and topographic characterization of LDPE based copolymeric films obtained by gamma irradiation

The preparation of PE-g-HEMA (polyethylene-grafted-hydroxyethyl methacrylate) films by ⁶⁰Co gamma irradiation has been optimized to produce a new material suitable for bioapplications.This paper reports the elemental and topographic analysis of PE-g-HEMA films with different grafting degrees, obtained under optimized experimental conditions, with the purpose to appraise their possible toxicological risk and their surface roughness properties.In this way a Nuclear Microprobe using PIXE (Proton Induced X-ray Emission) technique was used to assess the elemental analysis of the film samples prepared. Trace contaminations of elements heavier than Si (Ca, Cl, Fe, K, P, S, Si and Zn) were found, but their concentrations do not pose toxicological risk.Atomic Force Microscopy (AFM) and Scanning Electronic Microscopy (SEM) techniques were used to assess the morphological characterization of the films, revealing the roughness and 3D porous structure of their surface, which are ones of essential characteristics for bio-interaction or cell adhesion.     

用地层元素测井(ECS)资料研究沉积环境

沉积物中某些元素的富集和贫化与沉积时的沉积环境密切相关。通过分析地层中原始沉积的元素含量与变化规律,建立与环境变化的相互关系,可以为研究沉积环境提供重要线索。地层元素测井(ECS)能够利用测井方法探测地层中Si、Ca、S、Fe、Cl、Ti、Cr和Gd等元素的含量,对各元素在地层单元中的含量及组合关系进行了分析．为沉积环境特征研究提供了依据．而各单元之间的元素变化与组合特征反映了沉积环境的变迁。     

Study of emission episodes of urban aerosols by ion beam analytical techniques

The quantitative elemental composition and morphology of over 500 atmospheric aerosol particles were determined by nuclear microscopy and scanning electron microscopy (SEM). The samples originated from eight sampling campaigns, when hourly variation and sources of the urban aerosol elemental components were studied in Debrecen between 2007 and 2010. Aerosol which could be connected to heavy metal pollution episodes and high aerosol pollution levels deposits were selected for the nuclear microprobe study.Ion beam analytical methods (micro-PIXE and STIM) provided the elemental composition of coarse (particles with aerodynamic diameter between 2.5 and 10 μm) aerosols while the morphology of the different particle types was determined by SEM.Through the elemental composition, elemental correlations and morphology different particle types were identified and attributed to different anthropogenic sources like biomass burning, oil combustion, traffic or industry.     

Ion beam methods to determine trace heavy metals concentrations and sources in urban airsheds

Unique data for Australia on the concentration of selected metals in fine particle ambient air pollution is presented for urban, industrial and rural sites along 300 km section of the eastern coast line of Australia around Sydney. IBA techniques were used to determine over 25 different chemical species in the air including, H, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Se and Pb. This included many trace metals at concentrations around 1 ng/m³ of air sampled.     

SPM analysis on groups of single aerosol particles around steel plant

Several methods for preparing samples of dispersed single aeroslo particles used in scanning proton microprobe(SPM) analysis were tested.Many elements such as Al,Si,S,Cl,Ca,Ti,Cr,Mn,Fe,Ni,Cu and Zn in the groups of different single aerosol particles from the Capital Steel Plant area were analyzed by SPM,The distributions of elemental contents in the group of single particles were mapped with three dimensional contour and the isometric.A new approach to study the group of different single aerosol particles for air pollution is developed in the present work.The results are significant to assessing the environmental impact of the dispersed single aerosol particles.     

Analysis of lichen thin sections by PIXE and STIM using a proton microprobe

In order to better understand the distribution pattern of mineral elements in lichen tissues, thin sections (15 μm) of the foliose, vagrant soil lichen Xanthoparmelia chlorochroa were examined using proton microprobe Particle induced X-ray emission (PIXE). This technique was used to make two-dimensional scans, with 5 μm resolution, across tissue cross sections of the test species. Element maps for Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and As have been prepared. Several elements are strongly localized in the element maps. PIXE data are complimented with STIM, light micrographs, and SEM images. Preliminary data suggest that nuclear microprobe techniques may be useful in elucidating element absorption and transport mechanisms in lichens.     

股骨头松质骨中无机元素的PIXE分析

使用质子激发Ｘ射线荧光分析技术测定了５例正常人和７例股骨颈骨折患者股骨头松质骨中无机元素谱的分布。详细介绍了骨样品处理技术，建立了正确测定骨骼微量元素的定量方法。结果表明在对照组中元素Ｐ、Ｃａ、Ｆｅ、Ｃｕ、Ｓｒ的含量高于病变组，统计检验表明有显著意义，而元素Ｓ、Ｋ、Ｍｎ、Ｚｎ在两组间无显著差异。对Ｃａ、Ｐ、Ｓｒ、Ｃｕ等无机元素的生理功能进行了初步的讨论。     

Elemental analysis of edible grains by micro-PIXE: Common buckwheat case study

The aim of this study was the adaptation of the micro-PIXE method for analysis of nutritionally relevant heavy elements in different tissues of the grain of common buckwheat (Fagopyrum esculentum), as a representative nutritionally interesting grain food source. At 57% of the buckwheat grain biomass, the endosperm was a modest nutrient source when compared to the cotyledons, at 17% of the biomass. These latter contained high concentrations of trace elements, representing 91% of the total grain Zn, 87% for P, 70% for S, 62% for Mg, 60% for K, 54% for Cu, 53% for Mn and 35% for Fe. The husk provided storage for 85% of the total Ca, 84% for Al, 83% for Si, 76% for Cl, 69% for Ti and 46% for Fe. Knowledge on these preferential elemental constitutions of the different grain tissues makes the possibility of designing target products with nutritionally optimal constitution more feasible. These data represent a basis for a more targeted approach to nutritional improvement of grains intended for human consumption.     

X-ray microfluorescence analysis of pigments in decorative paintings from the sarcophagus cartonnage of an Egyptian mummy

This work characterized the elemental composition of the pigments used in decorative paintings from the sarcophagus cartonnage fragments of an Egyptian mummy, using μXRF with Synchrotron Radiation. This female mummy (n.158) is considered one of the most important pieces of the National Museum (Rio de Janeiro, Brazil) because of its unconventional embalming with legs and arms swathed separately. The measurements were performed at the XRF beamline D09B of the Brazilian Synchrotron Light Laboratory (LNLS), using white beam and a Si(Li) detector with resolution of 165 eV at 5.9 keV. The elements found in the samples were: Si, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Sr, Hg and Pb.     

Nuclear microscopy of single whole cultured cells: Beam damage studies

Elemental analysis of individual whole cultured cells using Particle Induced X-ray Emission (PIXE), Scanning Transmission Ion Microscopy (STIM) and Rutherford Backscattering Spectrometry (RBS) can yield quantitative results at the parts per million level. During a continuous scan over a single cell using 2 MeV protons (with a beam current of 100 pA, spot size of 1 μm), elemental loss was monitored and a 60% reduction in hydrogen and oxygen was observed. Concentrations of C, Na, Mg, P, S, Cl, K, Ca, Fe, Cu, and Zn remained constant. The elemental analysis, at the parts per million level, of single whole cultured cells is therefore not limited by beam damage. However, during the irradiation, the size of the cell was observed to shrink by 20%, placing severe restrictions on the imaging and analysis of subcellular structures such as organelles.