M.H. Tabacniks

Characteristics of fine and coarse particles of natural and urban aerosols of Brazil

Abstract Fine and coarse particles have been sampled from 1982 to 1985 in one natural forest seacoast site (Jureia) and five urban-industrial cities (Vitoria, Salvador, Porto Alegre, Sao Paulo and Belo Horizonte). The time variations of concentrations in air and the relative elemental compositions of fine and coarse particle fractions, sampled by Nuclepore stacked filter units (SFU), have been determined gravimetrically and by PIXE analysis, respectively. Enrichment factors and correlation coefficients of the trace elements measured led to unambiguous characterization of soil dust and sea salt, both major aerosol sources that emit coarse particles, and soil dust is also a significant source of fine particles.

Preliminary data on atmospheric aerosol of the Amazon Basin

Abstract Preliminary distributions of the trace-elements Al, Si, P, S, Cl, K, Ca, Ti, V and Fe in the atmospheric aerosol of the Amazon Basin have been determined through samples collected from 23 August to 2 September 1980, at a remote place located in the Amazon Forest, about 30km NE of the city of Manaus. In all, 10 complete cascade impactor samples of 6-stage, Battelle model, have been exposed but only 8 with success, thus generating 48 samples. From these, 33 samples have been successfully analyzed by the PIXE method (Particle Induced X-Ray Emission), using particle beam of the Pelletron Accelerator of the University of Sao Paulo, and the results revealed that the trace-elements S and K have a noticeable predominance, mainly in the fine particle size range relative to the others. The high correlation factor found between the fine particle concentrations of S and K (0.96) support the assumption of their common airborne transport on the same particulates, originated from the gas-to-particle conversion of gases exuded by the trees of the forest, their only existing sources. Coarse airborne particles, of a probable soil origin, are also present but in unusally small amounts, as it was revealed by the Al, Si, Ca, Ti and Fe size distribution curves.

Analysis and discussion of trace elements in teeth of different animal species

Human, bovine and swine teeth were analyzed by Proton Induced X-ray Emission (PIXE). The aim of this work was to determine the concentration of trace elements in enamel and dentine of different animal species. PIXE analysis was carried out at the Laboratrio de Anlise de Materiais por Feixes Inicos da USP (LAMFI) using a 2.4 MeV proton beam to probe the samples. Healthy teeth from So Paulo region were analyzed. Thirteen elements were measured and quantified in the samples: P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Ba. The measured ratio of Ca:P in dentine and enamel teeth is the same expected for hydroxyapatite: 2.13, for all three types. Trace element concentrations were found to be very similar between the three species, except for S, Cl, Fe, Cu and Sr. Ni and Cu concentrations were found to be close to 1 ppm, which is also close to the detection limits of the SP-PIXE system.

MultiSIMNRA: A computational tool for self-consistent ion beam analysis using SIMNRA

Abstract SIMNRA is widely adopted by the scientific community of ion beam analysis for the simulation and interpretation of nuclear scattering techniques for material characterization. Taking advantage of its recognized reliability and quality of the simulations, we developed a computer program that uses multiple parallel sessions of SIMNRA to perform self-consistent analysis of data obtained by different ion beam techniques or in different experimental conditions of a given sample. In this paper, we present a result using MultiSIMNRA for a self-consistent multi-elemental analysis of a thin film produced by magnetron sputtering. The results demonstrate the potentialities of the self-consistent analysis and its feasibility using MultiSIMNRA.

Correlation between heavy metal ions (copper, zinc, lead) concentrations and root length of Allium cepa L. in polluted river water

O presente trabalho foi realizado utilizando a cebola comum (Allium cepa L.) como bioindicador da toxicidade de metais pesados em agua de rio. As aguas de teste foram coletadas em dois locais: na nascente e na foz do rio Toledo. Os bulbos de A. cepa L. foram cultivados em agua de teste com nove niveis de concentracao de cobre, zinco e chumbo de 0,1 a 50 ppm. Em laboratorio a influencia destes liquidos de teste em crescimento de raiz foi examinada durante cinco dias. Em todos os liquidos de teste o metal dissolvido contido foi medido pela tecnica TXRF. Para liquidos de teste contendo 0,1-ppm de Cu dissolvido o crescimento da raiz foi reduzido em 50%. Entretanto, ocorreu a mesma reducao para 1-ppm de Zn dissolvido. Para Pb dissolvido, o metodo do Allium teste revela toxidade acima de 0,1 e 0,5 ppm para a nascente e a foz do rio Toledo, respectivamente.

The São Paulo PIXE system and its use on a national monitoring air quality program

Abstract The SP-PIXE has been installed on the 8 MV pelletron accelerator of the IFUSP. Its characteristics and calibration procedure are presented below. The SP-PIXE is being used as the reference analytical method on a national monitoring air quality program performed by the Group for Air Pollution Studies (GEPA) of the IFUSP. As part of the program eight sites around Brazil, seven having critical air pollution problems and one with a natural atmosphere, have been selected for sampling. Each aerosol is sampled continuously for one year using stacked filter units and, for period of 3 to 5 days, by ten stage cascade impactors. Partial results from the two first sites investigated are presented here by element size distribution curves and histograms of relative concentrations.

External PIGE-PIXE measurements at the São Paulo 8UD tandem accelerator

Abstract An external PIGE–PIXE setup was installed on a beam line of the 8 MV tandem Pelletron accelerator of the Open Nuclear Physics Laboratory (LAFN). Proton beam energy was chosen in the 8–12 MeV range, sufficient to get an acceptable gamma ray yield but not so high as to prevent us from measuring X-rays. This also allowed the use of a thick aluminum exit window (0.5 mm) instead of the usual thin and sometimes fragile plastic windows. This external PIXE–PIGE system was used to analyze trace element concentrations in the enamel of human and animal teeth. The main interest was to find compatible human teeth substitutes for dentistry laboratory practice and chemical tests. In spite of their morpho-histological similarity, trace element concentrations in human and animal teeth have not yet been compared. Teeth from humans, cattle and swine collected primary at Sao Paulo region were analyzed. The elements Cu, K, Zn, Fe, Ti, Sr, V, Mn and Zr were detected by high energy external beam PIXE technique. Though preliminary, the results showed that the trace element concentrations observed in the enamel of human and swine are more similar to each other than to cattle teeth.

PIXE ANALYSIS FOR AIR POLLUTION SOURCE APPORTIONMENT IN URBAN AREAS OF BRAZIL

PIXE analysis has been applied to an air quality monitoring and assessment program in south-eastern Brazil. Fine and coarse particle size fractions were sampled selectively, using Nuclepore in stacked filter units, once a week for one year in one background and five urban sites. The procedures used for sampling and analysis have been developed and refined in close conjunction with the application to aerosol studies, and 138 pairs of filters have been analyzed by PIXE. Once a national source signatures library for particulate matter has been created, the data are suitable for receptor modeling and source apportionment for anthropogenic and natural particulate constituents by chemical mass balance models.

RBS AS A TOOL FOR TOPOGRAPHIC MODELLING OF POLYCRYSTALLINE THIN FILM INTERACTIONS

Abstract Thermal interdiffusion between polycrystalline metal films may involve a variety of concurrent processes, such as grain boundary or pipe penetration, solution of one metal in the other, grain growth and aggregation, and interface roughening. A detailed analysis of a series of RBS profile shapes obtained as such interactions proceed can provide information about the individual constituent processes and their kinetics. Examples are shown for the interactions of TaNiFe, TaNi, TaFe, AuNi and AgNiFe, in which extended time-temperature annealing matrices have allowed us to obtain new information, in particular on the role of grain boundary diffusion at relatively low temperatures, and the microscopic thermal stability of these interfaces.

SR-TXRF detection limit reduction using thin polymer film substrates

Three different substrates for the analysis of liquid samples by Total Reflection X-Ray Fluorescence with Synchrotron Radiation (SR-TXRF) were investigated and compared: Lucite (Perspex), Kimfoil and Mylar. Dry targets were prepared by pipetting 5 „l aliquotes of the liquid samples (synthetic standards and fresh water samples) on the different substrates. A five fold reduction of the continuous background and a corresponding reduction of the elementary detection limits were observed when thin polymer film substrates were used instead of the common thick Perspex substrate.