ELEMENTAL COMPOSITION AND PARTICLE-SIZE DISTRIBUTION OF MINERAL DUST: FIELD AND LABORATORY STUDIES (NEUTRON ACTIVATION, ATMOSPHERIC, TRACE ELEMENTS, SOILS)

The contribution of crustal dust to the atmosphere was studied from two major aspects: field studies to collect mid-tropospheric dust in the ambient air at the Mauna Loa Observatory (MLO), Hawaii, and resuspension of bulk soils to investigate elemental fractionation in the small-particle fraction (16-(mu)m diameter. Most elements did not show strong fractionation with particle size except in an agricultural soil, where many were enriched in the clay mineral (<4 (mu)m) fraction. This suggests that soil contributions to ambient air are highly variable and must be carefully evaluated in atmospheric receptor-model studies.