H. Storms

Characterization of North-Sea aerosols by individual particle analyses

Abstract On aerosol and rain water samples, collected in the Southern Bight of the North Sea, single particle analyses were performed using both laser microprobe mass analysis and electron-probe X-ray microanalysis in combination with an automated image analysis system. In the aerosols collected from an air mass that had travelled from the Atlantic Ocean along the coast of North France, pure seasalt constituted the most abundant particle type, while aluminosilicates (mostly spherical fly-ash particles) amounted to about 20% and mixed seasalt/aluminosilicate, carbonaceous particles, CaSO 4 and spherical iron oxides contributed each 5–10 %. In air masses that had a longer residence time over the continent, spherical iron oxides, carbonaceous particles and ammonium sulfates together made up 70 % of the total particle load. Seasalt particles were nearly all enriched in sulfate or nitrate, but they were seen to be washed out efficiently after a rain shower. In rain water, some 40 % of the particles appeared to be spherical or irregularly shaped aluminosilicates, from fly-ash and dust dispersal, but more than 50 % consisted of SiO 2 . The high relative abundance of these particles in rain water may be the result of Al leaching from fly-ash, or of more efficient scavenging by rain droplets.

Classification of suspended particles in deposition samples and run-off water samples from a limestone cathedral

Abstract In a study on the mechanism of the air-pollution induced deterioration of the limestone St. Rombouts cathedral in Mechelen, Belgium, automated electron-probe X-ray micro-analysis combined with multivariate analysis was used to characterize the suspension particles in run-off water and in local wet and dry deposition samples. Altogether about 10,000 individual particles were sized, analyzed and classified, according to their chemical composition. It was found that the run-off water samples were highly enriched in CaCO 3 particles, resulting from the stone-erosion by overflowing rainwater, while the Si-rich group was the most abundant one in the deposition samples. Several other particle types were found. Ion chromatography analysis of the run-off water showed 200–1700mg l −1 of sulphate and 20–110mg l −1 of nitrate.

Characterization of Individual Particle Types in Coastal Air by Laser Microprobe Mass Analysis

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.

Characterization of Individual Environmental Particles

Abstract Recently, several micro-analysis techniques have been developed which can advantageously be applied to particulate environmental samples to complement measurements made by traditional bulk analysis methods. Automated electron probe X-ray microanalysis in combination with multivariate numerical analysis can, in a relatively short time, provide information about the major and minor elemental chemical composition of large numbers of aerosol and aqueous suspension particles. Relevant particle types can thus be identified and their behaviour can be followed as a function of time, location, wind direction or depth. In addition, laser microprobe mass analysis can yield complementary knowledge about the trace element distribution over the various particle types and, in some cases, about the particle surface layer characteristics. The potential and limitations of these methods are illustrated in applications to aerosol particles from the North Sea and the Amazon Basin, to particles from the sea surface microlayer, and to aqueous suspension particles from the Baltic Sea.

Composition and size of individual particles from a gold mine atmosphere

Abstract Airborne dust particles were collected in a return airway of a South African gold mine using a 7-stage, single-orifice cascade impactor. Between 70 and 130 individual particles were analysed on each stage using automated electron-probe x-ray microanalysis (EPXMA). Particle size and shape parameters are given for different classes of particles sorted by elemental composition. Silicon-rich particles are the most abundant overall, while chlorine-rich particles dominate (up to 80%) in the range 0.2–1.0 μm. It is shown that EPXMA characterisation of particles can be used to infer relative contributions of various particle sources and dust generating processes to the total dust concentrations in mine atmospheres. An understanding of the nature and source of particles is essential for any source control strategy. We conclude that the EPXMA technique merits inclusion in the repertoire of techniques used for characterising underground dust.

Automated quantitative electron-microprobe analysis of particulate material

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.

LAMMA and electron-microprobe analysis of atmospheric aerosols

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