“Implementation of an expert system for the qualitative interpretation of x-ray-fluorescence spectra”. Janssens K, van Espen P, Analytica chimica acta 184, 117 (1986). http://doi.org/10.1016/S0003-2670(00)86475-2
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/S0003-2670(00)86475-2
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“Enhancement effect in X-ray fluorescence analysis of environmental samples of medium thickness”. Van Dyck PM, Török SB, Van Grieken RE, Analytical chemistry 58, 1761 (1986). http://doi.org/10.1021/AC00121A036
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00121A036
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“Internal mixture of sea salt, silicates, and excess sulfate in marine aerosols”. Andreae MO, Charlson RJ, Bruynseels F, Storms H, Van Grieken R, Maenhaut W, Science 232, 1620 (1986). http://doi.org/10.1126/SCIENCE.232.4758.1620
Abstract: Individual aerosol particles from the remote marine atmosphere were investigated by scanning electron microscopy and electron microprobe analysis. A large fraction of the silicate mineral component of the aerosol was found to be internally mixed with sea-salt aerosol particles. This observation explains the unexpected similarity in the size distributions of silicates and sea salt that has been observed in remote marine aerosols. Reentrainment of dust particles previously deposited onto the sea surface and collision between aerosol particles can be excluded as possible source mechanisms for these internally mixed aerosols. The internal mixing could be produced by processes within clouds, including droplet coalescence. Cloud processes may also be responsible for the observed enrichment of excess (nonsea-salt) sulfate on sea-salt particles.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1126/SCIENCE.232.4758.1620
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“Absorption correction in electron probe x-ray microanalysis of thin samples”. Markowicz AA, Storms HM, Van Grieken RE, Analytical chemistry 58, 1282 (1986). http://doi.org/10.1021/AC00298A003
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00298A003
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“Classification of estuarine particles using automated electron-microprobe analysis and multivariate techniques”. Bernard PC, Van Grieken RE, Eisma D, Environmental science and technology 20, 467 (1986). http://doi.org/10.1021/ES00147A005
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/ES00147A005
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“Evaluation of an equation for bremsstrahlung background in electron-probe X-ray microanalysis of composite samples”. Markowicz A, Storms H, Van Grieken R, X-ray spectrometry 15, 131 (1986). http://doi.org/10.1002/XRS.1300150211
Abstract: A new equation for predicting the generated bremsstrahlung background intensity in electron-probe x-ray microanalysis has been verified experimentally. This equation is applicable to all bulk composite specimens and reduces to Kramers' equation for pure elements only. The experimental verification has been carried out for Al2O3, Fe2O3 and ZrO2 with radiation energies from 4.2 to 14.8 keV. The predicted bremsstrahlung intensities are in good agreement with the experimental data.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300150211
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“A simple absorption correction for electron probe X-ray microanalysis of bulk samples”. Markowicz A, Storms H, Van Grieken R, X-ray spectrometry 15, 115 (1986). http://doi.org/10.1002/XRS.1300150209
Abstract: A simple procedure is proposed for the calculation of the absorption correction factor in electron-probe x-ray microanalysis. It is based on the concept of an effective depth of x-ray production, assuming a rectangular depth distribution function for x-ray generation. This effective x-ray production depth is expressed as a fraction of the x-ray excitation depth given by Whelan's expression. Adequate values for this fraction are presented. Two versions are considered. In the first the effective x-ray production is a function of both the characteristic x-ray energy and the atomic numbers of the matrix elements, whereas in the second one, which is indicated for routine use, the energy dependence is neglected. Calculations pointed to satisfactory results, even for low x-ray energies and high overvoltages.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300150209
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“Determination of barium, lanthanum, cerium and neodymium in lateritic materials by various energy-dispersive X-ray fluorescence techniques and neutron activation analysis”. Labrecque JJ, Beusen JM, Van Grieken RE, X-ray spectrometry 15, 13 (1986). http://doi.org/10.1002/XRS.1300150105
Abstract: A comparison of four methods for the determination of barium, lanthanum, cerium and neodymium in lateritic materials from Brazil is presented. Three of the methods were based on x-ray fluorescence (XRF) spectroscopy: two by radioisotope excitation (Co-57 and Am-241) and one by secondary target XRF (a molybdenum target with a tungsten anode). The other method was based on neutron activation analysis employing both a Ge(Li) coaxial detector and a high-purity germanium detector. The results from these four methods were similar for lanthanum, cerium and neodymium, but for barium at low concentrations (<500 ppm) the neutron activation and the secondary target XRF methods were not suitable. Data on the precision and accuracy of these methods using a series of standard reference rocks are given. The advantages and limitations of each of these methods with respect to the analysis of lateritic materials are discussed.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300150105
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“Heterogeneity effects in direct XRF analysis of traces of heavy metals preconcentrated on polyurethane foam sorbents”. Török S, Braun T, Van Dyck P, Van Grieken R, X-ray spectrometry 15, 7 (1986). http://doi.org/10.1002/XRS.1300150104
Abstract: Trace amounts of heavy metals were preconcentrated on discs of polyurethane (PU) foam loaded with ammonium diethyldithiocarbamate (DDTC), to increase the sensitivity of XRF. Since the diameter of the cavities in the open-cell PU foams reaches 30300 μm, considerable heterogeneity effects might occur, which could reduce the accuracy of the method. The possible systematic error introduced by considering the sample to be homogeneous is calculated using the Berry et al. model. The calculations show that the underestimation of the absorption correction factor when considering the sample as being homogeneous is less than 2% for high-Z elements when the sample thickness is at least 2 mm. The detection limits are also around the minima for this thickness.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300150104
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“Analysis of lateritic material from Cerro impacto by instrumental neutron activation employing a low-energy photon semiconductor and a high-energy Ge(Li) detector”. LaBrecque JJ, Beusen JM, Van Grieken RE, Applied spectroscopy 40, 140 (1986). http://doi.org/10.1366/0003702864509600
Abstract: Nineteen elements were determined in four different grain size fractions of a bulk geological material from Cerro Impacto for a study of the physical (mechanical) concentration process of different elements based upon the hardness of the different minerals. The analysis was performed by excitation of the sample with a high, slow neutron flux followed by gamma-ray spectroscopy with both a conventional Ge(Li) high-energy detector and a low-energy photon detector (LEPD). The accuracy of this method was studied with the use of two standard reference materials, SY-2 and SY-3, which are similar to the real samples. The values determined were also compared with a secondary target x-ray fluorescence method for all the elements that were suitable to both methods. Actually, the x-ray fluorescence method was found to be more complementary than competitive.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1366/0003702864509600
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“Investigation of heterogeneous reactions of PAH's on particle surfaces using laser microprobe mass analysis”. Niessner R, Klockow D, Bruynseels F, Van Grieken R, International journal of environmental analytical chemistry 22, 281 (1985). http://doi.org/10.1080/03067318508076427
Abstract: Artificially generated NaCl particles were coated with PAH's by using a condensation technique. These particles were exposed to reactive gases like ozone, bromine and nitrogen dioxide. The original as well as the exposed particles were investigated by fluorimetric analysis and by LAMMA (Laser Microprobe Mass Analysis) in the desorption mode, which allows the evaporation and characterization of surfaces of single particles. The results are interpreted in terms of possible heterogeneous atmospheric reactions. The reactivity of the considered PAH's towards nitrogen dioxide was found to be negligible. The structure of the reaction products formed with ozone was partially elucidated.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1080/03067318508076427
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“Characterization of individual particle types in coastal air by laser microprobe mass analysis”. Bruynseels F, Storms H, Tavares T, Van Grieken R, International journal of environmental analytical chemistry 23, 1 (1985). http://doi.org/10.1080/03067318508076430
Abstract: Laser Microprobe Mass Analysis (LAMMA) was used in a preliminary study to characterize aerosol particles from a beach and inland sites and from a heavily industrialized area. As many as six types of both positive and negative mass spectra with different inorganic and organic signals could be distinguished in the different particle size ranges. Information about the elemental composition and the speciation of S and N was obtained. With increasing distance from sea, progressive uptake of nitrate in seasalt particles was found. Complex particles, containing soot and organic ammonium sulfate, were also detected.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1080/03067318508076430
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“Bremsstrahlung background in electron-probe X-ray-microanalysis of thin films”. Markowicz AA, Storms HM, Van Grieken RE, Analytical chemistry 57, 2885 (1985). http://doi.org/10.1021/AC00291A032
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00291A032
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“Influence of sample thickness, excitation energy and geometry on particle size effects in XRF”. Van Dyck P, Markowicz A, Van Grieken R, X-ray spectrometry 14, 183 (1985). http://doi.org/10.1002/XRS.1300140409
Abstract: Expressions are presented for calculating the matrix effect and the pure particle size effect in the XRF analysis of particulate samples with a discrete particle size. The equations are based on the absorption-weighted radiometric diameter concept. Two excitationdetection geometries are considered, with the angles between the sample plane and both the incident and emerging radiation being either 90° (π geometry) or 45° (π/2 geometry). Calculations were made for different sample loadings and exciting radiation energies. The influence of these parameters on the matrix and pure particle size effects is shown. From the results, it is possible to predict the performances of alternative experimental correction procedures for the particle size effect, involving dual measurements at different excitation energies or in different excitationdetection geometries.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300140409
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“Preliminary studies on the geochemistry of the Cauvery river basin”. Subramanian V, Van 't dack L, Van Grieken R, Proceedings of the Indian Academy of Sciences: earth and planetary sciences 94, 99 (1985). http://doi.org/10.1007/BF02871942
Abstract: Samples of water and sediments were collected over a three year period from the entire region of Cauvery river basin excluding the estuary. On the basis of our observations, we have calculated the average composition of the Cauvery river at several locations from the catchment to the river mouth, the downstream profile of sediment load, annual erosion rates, solute and sediment fluxes and have predicted on long term changes. The sediment chemistry was determined by x-ray fluorescence (xrf) technique, and calculated mean compositions of the Cauvery and its tributary bed and the suspended sediment were compared to those of world average river sediments. Downstream profiles of some of the elements appear to be controlled by size and mineralogical characteristics besides local factors specific to the location of the samples. Interelemental relationships indicated good correlation among the transition elements indicating their co-genetic behaviour within the drainage basin.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1007/BF02871942
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“Chemical composition of river sediments from the Indian sub-continent”. Subramanian V, Van 't dack L, Van Grieken R, Chemical geology 48, 271 (1985). http://doi.org/10.1016/0009-2541(85)90052-X
Abstract: River sediments from all of the major drainage basins (except the Indus) in the Indian sub-continent were collected and analysed by thin-film X-ray fluorescence technique (XRF) to determine their chemical composition. On the basis of analysis of more than 120 samples, average chemical compositions of river-borne sediments from the Indian sub-continent have been calculated. Also, average concentration values for sediments from each of the river basins, and the sub-continent average and the inter-basin differences are discussed in relation to weathering processes in the drainage basins. Comparisons have been made with the chemistry of sediments from the Bay of Bengal (which receives the bulk of sediments delivered by Indian rivers). Our observations are discussed in the light of average chemical composition of world-river sediments and the world surface rock exposed for continental weathering.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0009-2541(85)90052-X
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“Kinetics of iron(II) oxidation in seawater of various pH : reply”. Roekens EJ, Van Grieken RE, Marine chemistry 15, 281 (1984). http://doi.org/10.1016/0304-4203(84)90025-2
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0304-4203(84)90025-2
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“Atomic number correction in electron probe X-ray microanalysis of curved samples and particles”. Markowicz AA, Van Grieken RE, Analytical chemistry 56, 2798 (1984). http://doi.org/10.1021/AC00278A036
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00278A036
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“Composition dependence of Bremsstrahlung background in electron-probe x-ray microanalysis”. Markowicz AA, Van Grieken RE, Analytical chemistry 56, 2049 (1984). http://doi.org/10.1021/AC00276A016
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00276A016
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“Influence of ion-source geometry in spark source-mass spectrometric analysis”. Vos L, Van Grieken R, International journal of mass spectrometry and ion processes 59, 221 (1984). http://doi.org/10.1016/0168-1176(84)85098-3
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0168-1176(84)85098-3
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van de Vijver FL, Verbueken AH, Visser WJ, Van Grieken RE, de Broe ME (1984) Localisation of aluminium and iron by histochemical and laster microprobe mass analytical techniques in bone marrow cells of chronic hemodialysis patients. 837–838
Keywords: L1 Letter to the editor; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
DOI: 10.1136/JCP.37.7.837-B
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“Embedded ion exchange beads as standards for laser microprobe mass analysis of biological specimens”. Verbueken AH, Van Grieken RE, Paulus GJ, De Bruijn WC, Analytical chemistry 56, 1362 (1984). http://doi.org/10.1021/AC00272A036
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00272A036
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“Ultrastructural localization of aluminum in patients with dialysis-associated osteomalacia”. Verbueken AH, van de Vijver FL, Van Grieken RE, Paulus GJ, Visser WJ, d'Haese P, de Broe ME, Clinical chemistry : international journal of laboratory medicine and molecular diagnostics 30, 763 (1984)
Abstract: Using laser microprobe mass analysis, we studied the ultrastructural localization of aluminum in liver and bone tissue of chronic-hemodialysis patients with proven aluminum-induced osteomalacia. In the liver, aluminum was observed to be almost exclusively associated with iron. Detectable aluminum and large amounts of iron were found in lysosomes of both hepatocytes and Kupffer cells. In bone, aluminum was localized at the osteoid/calcified-bone interface and also was associated with iron in some cases.
Keywords: A1 Journal article; Pharmacology. Therapy; Pathophysiology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Laboratory Experimental Medicine and Pediatrics (LEMP)
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“LAMMA and electron-microprobe analysis of atmospheric aerosols”. Bruynseels F, Storms H, Van Grieken R, Journal de physique 45, 785 (1984). http://doi.org/10.1051/JPHYSCOL:19842180
Abstract: A laser microprobe mass analyser and a highly automated electron probe X-ray microanalysis unit have been used to study the elemental composition, inorganic speciation and morphology of atmospheric aerosols collected at various remote to polluted and marine to continental locations.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1051/JPHYSCOL:19842180
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“Automated quantitative electron-microprobe analysis of particulate material”. Van Dyck P, Storms H, Van Grieken R, Journal de physique 45, 781 (1984). http://doi.org/10.1051/JPHYSCOL:19842179
Abstract: An automated electron microprobe, equipped with an energy-dispersive X-ray spectrometer and an additional backscattered electron signal digitalization system, can allow rapid sizing and major element analysis on numerous particles. A software package has been developed to exploit the particle size and shape information to achieve quantitative analysis of single particles, and to compare the performance of the different matrix correction procedures.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1051/JPHYSCOL:19842179
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“Laser microprobe mass spectrometric identification of sulfur species in single micrometer-size particles”. Bruynseels FJ, Van Grieken RE, Analytical chemistry 56, 871 (1984). http://doi.org/10.1021/AC00270A004
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1021/AC00270A004
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“Heterogeneity effects in direct X-ray fluorescence analysis of hair”. Török S, Van Dyck P, Van Grieken R, X-ray spectrometry 13, 27 (1984). http://doi.org/10.1002/XRS.1300130106
Abstract: The methodology of direct hair analysis by energy-dispersive x-ray fluorescence was studied. The effect on the XRF result of having a non-homogeneous radial distribution of the analyte in a single hair strand and the macroscopic effects in a bundle of hairs were calculated to evaluate possible systematic errors. The detection limits were mapped as a function of the target thickness and surface fraction. It appeared that a 10 mg cm−2 sample thickness, i. e. a target with about four layers of hair strands, is recommended. The standard deviation of this simple direct analytical method is 619% for some important elements. Discrepancies with neutron activation analysis had a mean value of around 15%. About twelve elements can be determined simultaneously on a routine basis.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1002/XRS.1300130106
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“Influence of spark generator parameters in the analysis of graphite-electrodes by spark source-mass spectrometry”. Vos L, Van Grieken R, International journal of mass spectrometry and ion processes 55, 233 (1984). http://doi.org/10.1016/0168-1176(84)87087-1
Abstract: Spark source mass spectrometric analyses of doped carbon samples were performed at different pulse lengths, pulse frequencies and breakdown voltages. The pulse length and pulse frequencies had no influence on the analysis. The relation between breakdown voltage, spark gap and sample matrix was determined. With increasing breakdown voltage, the abundance of the multiply charged ions was found to decrease, whereas the abundance of the cluster ions increased. The breakdown voltage was also found to affect the absolute and relative intensities of different elements in different manners. Interpretation of these results led to some new considerations on the phenomena in a spark discharge.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0168-1176(84)87087-1
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“Preparation of conducting electrodes from biological samples for multi-element trace analysis by spark-source mass spectrometry or emission spectrometry”. Vos L, Van Grieken R, Analytica chimica acta 164, 83 (1984). http://doi.org/10.1016/S0003-2670(00)85619-6
Abstract: Four decomposition procedures frequently used for biological material (dry ashing, open wet digestion, wet digestion in a teflon bomb and low-temperature ashing) are optimized for the conversion of biological samples to conducting electrodes suitable for multi-element trace determinations by spark-source mass spectrometry or emission spectrometry. The optimized procedures are evaluated with respect to contamination, retention and preconcentration of the trace elements, homogeneity of the electrodes and precision of the final results. Both dry-ashing methods are prone to losses by volatilization; simple dry ashing suffers from contamination problems during electrode preparation. Wet digestion gives better precision; digestion with nitric/sulfuric acids in an open flask is the method of choice for most elements being simpler and giving lower blanks than the bomb method.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/S0003-2670(00)85619-6
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“Background aerosol composition in the Namib Desert, South West-Africa (Namibia)”. Annegarn HJ, Van Grieken RE, Dibby DM, Von Blottnitz F, Atmospheric environment : an international journal 17, 2045 (1983). http://doi.org/10.1016/0004-6981(83)90361-X
Abstract: A remote site in the Namib Desert was selected for sampling background aerosols in southern Africa, as one of a wide network of stations spanning the Southern Hemisphere in a programme designed to measure the background concentrations of trace elements in the atmosphere. A series of samples was collected over a 6-month period using a single-orifice cascade impactor, which fractionated the particles into six size groups. Analysis was performed using particle-induced X-ray emission (PIXE), yielding results for S, Cl, K, Ca, Ti, Mn, Fe, Br and Sr, and occasionally also for V, Cr, Ni, Cu, Zn and Pb. No direct correlations with wind direction were observed excluding strong local or regional sources of particles. K, Ca, Ti, Mn and Fe can be identified with a dust dispersion source. Cl, large particle S and Br, and part of the K and Sr are derived from sea spray. Relative to the soil components small particle K is not enriched as it normally is in regions with less scarce vegetation. Cr, V, Ni, Cu, Zn and Pb concentrations and enrichments in the aerosol are lower than practically all values measured at any other location hitherto. The concentration of the small particle sulphur, 200 ng m−3, is believed to be related to anaerobic conditions and plankton blooms in the ocean upwelling zones off Namibia.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/0004-6981(83)90361-X
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