Szabina Török

Combined SEM/EDX and micro-Raman spectroscopy analysis of uranium minerals from a former uranium mine

Samples of the secondary uranium minerals collected in the abandoned uranium mine at Pecs (Hungary) were investigated by two micro-techniques: scanning electron microscopy (SEM/EDX) and micro-Raman spectroscopy (MRS). They were applied to locate U-rich particles and identify the chemical form and oxidation state of the uranium compounds. The most abundant mineral was a K and/or Na uranyl sulphate (zippeite group). U(VI) was also present in the form showing intensive Raman scattering at 860 cm(-1) which can be attributed to uranium trioxide. This research has shown the successful application of micro-Raman spectroscopy for the identification of uranyl mineral species on the level of individual particles.

Study of Chemical State of Toxic Metals during the Life Cycle of Fly Ash Using X-Ray Absorption Near-Edge Structure

The non-destructive x-ray absorption near-edge structure (XANES) method was applied to the quantitative determination of chromium and arsenic species in coal fly ash. In order to study the chemical state changes caused by deposition and sedimentation of the particles, land fill and river sediment samples obtained in the neighborhood of power plants were also investigated. The measurements were carried out at the X26 beam line of the BNL National Synchrotron Light Source (USA) in fluorescent mode. For achieving quantitative results on the ratio of close-lying oxidation state forms, a non-linear fitting model was developed to process the XANES spectra obtained. The features of the spectra such as the white line, the multiple scattering resonance peak and the absorption edge were modelled with analytical functions. The results obtained show that chromium is present mostly (>95%) as Cr(III) in fly ash and the chemical state remains the same after deposition and sedimentation. Arsenic is present as As(V) in fly ash and land fill samples, while the possible As(III) content of sediment samples is around 40%.

Reference-free quantification of particle-like surface contaminations by grazing incidence X-ray fluorescence analysis

The analysis of the elemental composition of aerosol particles by non-destructive grazing incidence X-ray fluorescence analysis (GIXRF) is possible if the particles are deposited on a flat substrate. If those particles exhibit surface areas parallel to the substrate surface, under certain experimental conditions, total reflection of incident X-rays might arise also at those sites thereby preventing X-rays from penetrating the particles. For a reliable quantitative analysis, this effect and the interaction with the X-ray standing wave field (XSW) has to be further investigated in detail. To study the effects occurring when nanoscaled objects are probed with GIXRF, artificial nanostructures of known size, shape and composition have been manufactured on flat silicon wafer surfaces, with the intention to simulate deposited nanoscaled aerosol particles. A reference-free quantification of the deposited mass was performed employing a simple model for the propagation of the XSW through the sample material. Depending on the quality of the manufactured structures, good agreement between nominal masses and measured values could be stated. Only moderate agreement was found for samples that were more difficult to manufacture. GIXRF measurements yield information on the physical dimensions of the structures which are well in line with results obtained by a combination of scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM/EDX). The presented quantification model, which is based on existing software for XSW calculations, can be transferred to environmental nanoparticles sampled directly from the aerosol phase. All measurements were performed in the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at BESSY II using well-characterized monochromatic synchrotron radiation and calibrated instrumentation.

Distribution of toxic elements in fly-ash particulates

Abstract The physical properties and the chemical compositions of various lignite and coal fly-ash particulate matters sampled in the four main power plants in Hungary are investigated. The morphology of the particles is studied by optical microscopy and SEM, while for chemical analysis SEM micro-X-ray analysis, INAA and ICP-AES/AAS techniques are used. Analytical results are given for about 30 minor- and micro-components. Distribution coefficients for 16 selected toxic elements are calculated among the various species of fly-ash fractions investigated.

A measurement based analysis of the spatial distribution, temporal variation and chemical composition of particulate matter in Munich and Augsburg

The objective of the studies presented in this paper is to present an analysis of spatial distribution and temporal variation of particulate matter in Munich and Augsburg, Germany, and to identify and discuss the factors determining the aerosol pollution in both areas. Surface-based in-situ and remote sensing measurements of particle mass and particle size distribution have been performed in, around, and above the two cities. Two measurement campaigns were conducted in Munich, one in late spring and one in winter 2003. Another campaign has been on-going in Augsburg since 2004. Spatial and temporal variations are analyzed from this data (PM 10 , PM 2.5 and PM 1 ). There are higher particle mass concentrations at the urban site than at the surrounding rural sites, especially in winter. No significant difference in the major ionic composition of the particles between the urban and the rural site was detected. This is considered to be related to the spatial distribution of secondary inorganic aerosol that is more homogeneous than aerosol resulting from other sources like traffic or urban releases in general. During the measurement campaigns mixing layer heights were determined continuously by remote sensing (SODAR, ceilometer, RASS). Significant dependence of particle size distribution and particle mass concentration on mixing layer height was found. This finding paves the way to new applications of satellite remote sensing products.

Airport air quality and emission studies by remote sensing and inverse dispersion modelling

Airport air quality is influenced by traffic mainly. These are emissions from road traffic and aircraft. A measurement campaign on the airport Budapest was performed to investigate airport air quality and to identify major sources of air pollutants and to assess air quality for this airport. At four different locations, concentration of CO, CO2, NO, NO2 and PM10 as well as meteorological parameters were measured simultaneously. Measurement methodologies were classical in-situ techniques and open-path techniques (DOAS and FTIR). Highest concentrations were found during low wind speed conditions downwind of the airport. To quantify emissions on the airport, inverse dispersion modelling with a Bayesian approach was used on the basis of hourly averaged concentration measurements. Single emissions rates were highest for a car park, while for the whole campaign, aircraft emissions on the taxiway around terminal 2 are most important. Similar levels of emissions are reached for the car park and the freight area. Even though the most important source for NOx on an airport, starting aircrafts, were not considered during this investigation, the results reveal, that dealing with air quality on airports, all sources of NOx are important, and not only aircrafts.

Sources and geographic origin of particulate matter in urban areas of the Danube macro-region: The cases of Zagreb (Croatia), Budapest (Hungary) and Sofia (Bulgaria)

The contribution of main PM pollution sources and their geographic origin in three urban sites of the Danube macro-region (Zagreb, Budapest and Sofia) were determined by combining receptor and Lagrangian models. The source contribution estimates were obtained with the Positive Matrix Factorization (PMF) receptor model and the results were further examined using local wind data and backward trajectories obtained with FLEXPART. Potential Source Contribution Function (PSCF) analysis was applied to identify the geographical source areas for the PM sources subject to long-range transport. Gas-to-particle transformation processes and primary emissions from biomass burning are the most important contributors to PM in the studied sites followed by re-suspension of soil (crustal material) and traffic. These four sources can be considered typical of the Danube macro-region because they were identified in all the studied locations. Long-range transport was observed of: a) sulphate-enriched aged aerosols, deriving from SO2 emissions in combustion processes in the Balkans and Eastern Europe and b) dust from the Saharan and Karakum deserts. The study highlights that PM pollution in the studied urban areas of the Danube macro-region is the result of both local sources and long-range transport from both EU and no-EU areas.