干旱区生态环境知识资源中心

Particle-size distributions and depositional fluxes were investigated for present-day Asian dust and for the late Quaternary loess/palaeosol sequences from central China. The regional-scale transport of Asian dust during interglacial stages is mainly attributable to non-dust storm processes and is dominated by northwesterly surface winds. Conversely, during glacial stages the impact of dust storms on the accumulation of loess is enhanced. These regional effects are in contrast to the global-dispersal of dust which is associated with transport by upper-level westerly winds and is mainly the result of desert dust storms during both glacial and interglacial conditions. Temporal differences in the dust transport patterns to the Loess Plateau suggest that the variability in the coarse particle fraction (>20 mu m) during interglacial times is not directly attributable to the strong dust storms and dust fall events that have been linked to a strengthening of East Asian winter monsoonal winds. This is in contrast to the dust-deposition rates which are strongly influenced by the monsoonal circulation. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.