A STUDY OF ATMOSPHERIC DUST

This report discusses the techniques used in and the results of an investigation of the mineral constituency of the dust component of the atmospheric aerosol over White Sands Missile Range, New Mexico, conducted from November 1964 to August 1965. The eighty-one atmospheric dust samples, taken near the surface during this period, were analyzed by the light microscope technique of dispersion staining and by infrared absorption spectroscopy. Dispersion staining was used to determine the concentrations of quartz, kaolinite, illite, gypsum, and the carbonate family when the particle diameters were greater than four microns. Cases of exceptionally high concentrations of gypsum, quartz, and kaolinite, the month-by-month variation of the composite concentration, the seasonal variation of the gypsum concentration, and the lowest single-sample composite concentration are discussed in relation to the mineral content of area soils and meteorological conditions. Comments are made relative to the possible influence of extraterrestrial and sea-salt particles on the observed concentrations. By extending infrared absorption spectra to 40 microns wavelength, it has been possible to identify the minerals gypsum, mirabilite, quartz, kaolinite, illite, calcite, and dolomite in microgram samples of atmospheric dust, although any particular sample might reveal only a few of these constituents.