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16-Year Record of Eolian Dust in Southern Nevada and California, U.S.A.: Controls on Dust Generation and Accumulation

The 16-year records of 35 dust-trap sites in the eastern Mojave Desert and southern Great Basin reveal how generation and accumulation of dust and its components are affected by the amount and seasonal distribution of rainfall and the behavior of different source types (alluvium, dry playas, and wet playas). A major factor is the hydrologic condition of surface sediments. The silt-clay and soluble-salt fluxes increased during the El Nino events of 1987-1988 and 1997-1998 at sites close to "wet" playas with shallow depths to groundwater because active evaporative concentration of salts disrupts surface crusts and increases the susceptibility of surface sediment to deflation. The silt-clay flux also increased during drought periods at sites downwind of alluvial sources and "dry" playas with deeper groundwater. These increases are probably related to the die-off of drought-stressed vegetation on alluvial sediments, and in some cases to local runoff events that deliver fresh sediment to playa margins and distal portions of alluvial fans. Wet playas appear to be the most volatile dust sources and produce the most dust following a wet year preceded by a moderate to strong summer event (PSE in plots) and the least dust during dry years, in contrast to dry playas and alluvial fans.