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Dust emission and deposition—linking geomorphology, hydrology, and ecology

Geomorphic, hydrologic, and ecological processes are commonly linked in the pathways of atmospheric dust-in its generation through wind erosion and its re-deposition across landscapes. The intensity of dust generation from vegetated drylands depends greatly on interannual variability in vegetation density, which is strongly influenced by antecedent precipitation. Dust generation from dry lakebeds, generally lacking vegetation, is controlled primarily by hydrologic factors. Critical hydrologic factors include depth to water table, as well as presence or absence of subsurface impermeable beds. Dust production from dry lakebeds can be prolific where vapor discharge produces salt-rich, soft sediments in the capillary fringe zone, an interval within about 3 m of the surface. The chemistry of salt-rich dusts is determined by rock-water interactions in aquifers and evolution of ground-water solutes. Deposited dust is redistributed across topographically uneven landscapes by geomorphic and biologic (bioturbation) processes. Eolian dust in geologic substrates (soils and surficial deposits) plays a critical role in terrestrial ecosystem dynamics. Most importantly, dust may provide essential nutrients, replenishing ecosystem fertility over centuries to millennia. The atmospheric addition of silt and clay also contributes to soil texture, affecting water-holding capacities of substrates and thus, perhaps, microbial communities. Interdisciplinary studies that recognize eolian dust in substrates, climate variability, and human-related land disturbance help identify regions vulnerable to wind erosion and rapid loss of nutrients, with potentially adverse impacts on ecosystems.

Reynolds, R.L., Forester, R., Neff, J.C., and Reheis, M.C., 2005, Dust emission and deposition-linking geomorphology, hydrology, and ecology: Sixth International Conference on Geomorphology, September 7-11, 2005, Zaragoza (Spain), Abstracts volume, p. 501.