Deposition rates and characteristics of aeolian dust in the semi-arid and sub-humid regions of the Argentinean Pampa

Atmospheric dust inputs were monitored at four sites in the south-western Argentinean Pampa over a 3-year period. Dust traps (open bucket type) were installed at the soil surface and at 2 and 4 m above the surface. Total deposition rate, mineralogy, chemical properties, total element content and particle-size distribution of dust and soil samples of adjacent soil profiles were determined and analysed. Rainwater was also collected and analysed for salt content. Dust input varied between 400 and 800 kg ha(-1) year(-1) averaged over 3 years, and did not follow a clear seasonal pattern. An unexpectedly high fine sand content in the dust samples and higher salt content of dust and rainwater at the coastal site indicate the participation of an important local component in this area. Feldspars and quartz were the principal constituents of the bulk mineralogy. Additional components were volcanic glass, micas, magnetite and calcite. The nun-lent status of the dust was greater than that of the surrounding soil, and therefore may serve as a renewal factor. Nutrient input is a function of dust quantity and distance from the sea. (C)1998 Academic Press Limited.