Chemical and mineralogical analysis of individual mineral dust particles

Individual mineral dust particles collected in a dust storm over Israel wer e analyzed by a scanning electron microscopy and energy-dispersed system (S EM-EDS). The analysis shows that the particles were mostly aggregates of va rying mineralogical composition rather than pure minerals. It is also shown that sulfur (not associated with gypsum) and, to a lesser extent, iron ten ded to reside on the particles' surface, while Ca, Mg, K, Al, and Si were a ll an integral part of the particles. The lack of NaCl and sulfuric acid ae rosols in the sample indicates that the air mass did not interact with mari ne air or with clouds. This conclusion is further supported by back traject ory calculations. These findings suggest that the sulfur in the aerosols di d not result from atmospheric processes but rather originated from processe s in the source region. Black residue, surrounding some of the particles, s uggests the possible existence of organic matter in the sample, probably or iginating from biological activity in the soil at the source of the particl es. The method of individual particle analysis provides important informati on about the composition and morphology of the particles, information that otherwise cannot be obtained by bulk analysis methods.