The application of mineral magnetic methods to atmospheric aerosol discrimination

Abstract

The magnetic mineral and grain size compositions of atmospheric dust samples collected from the marine aerosols of the North Atlantic Ocean, and the Arabian Sea and from a sampling station on the island of Barbados have been defined using a range of mineral magnetic measurements. The magnetic mineral content or magnetic signature of the soil-sized (predominantly > 5 μm) dust material has been obtained by measuring each sample's response to a number of laboratory-imparted low field and remanent magnetisations. Variations in magnetic signature between groups of dusts have been established using the statistical procedure discriminant analysis. Dissimilarities in magnetic signature suggest that atmospheric dust samples derived from different source areas vary significantly in terms of mineral magnetic composition. In addition it appears that magnetic signatures are often strongly influenced by components that are urban/industrial in origin. The influence of anthropogenic particles on magnetic signatures being confirmed by an examination of the strongly magnetic phases of selected samples under the scanning electron microscope. The existence of differences in the magnetic mineral composition of atmospheric dust samples would suggest that the analysis of magnetic signatures could be applied to such research areas as the study of the long range transport of natural and polluting aerosols.