1. Controls on the Emission and Composition of Dust Generated from Ash Meadows – Franklin Lake Playa, Mojave Desert, Southwestern U.S.A. Harland L. Goldstein 1, George N. Breit 1, James King 2, James C. Yount 1, Richard L. Reynolds 1 and Marith C. Reheis 1 1 U.S. Geological Survey Denver, Colorado, USA 2 Desert Research Institute Las Vegas, Nevada, USA

2. Ash Meadows – spring discharge area Franklin Lake playa – wet playa Wet playa Dry playa Mojave Desert Franklin Lake playa (wet) Amargosa River Carson Slough Ash Meadows Setting

3. Sustained aridity suppresses dust emission Wet episodes promote dust emission Dust days Precipitation Drought index Month and Year 20042005200620072008 no data >14400 images examined Emission

4. Collect dust Dust Vacuum cleaner with cyclone impactor Wind Tunnel Dust Collection PI-SWERL I – November 2007 (Fall) PI-SWERL II – April 2008 (Spring) PI-SWERL III – February 2009 (Winter) Wind tunnel experiments conducted at 6 Sites

5. Meteorological Conditions, Surface Moisture and Dust

6. Composition

7. Dust-Crust Compositions (water soluble) Chloride-Carbonate Sites Soluble components: Crust  50 wt.% Dust  50 wt.% ConductivityAlkalinityChlorideSulfateArsenicUranium  S/cm mg/L  g/L

8. ConductivityAlkalinityChlorideSulfateArsenicUranium  S/cm mg/L  g/L Soluble components: Crust  13 wt.% Dust  50 wt.% Dust-Crust Compositions (water soluble) Sulfate Sites

9.  Generally, when surface moisture declines so does the potential for dust generation  Dust generation is greatly reduced when excessive moisture is present  The proportion of soluble components in the dust varies depending on salt composition  Chloride-carbonate dominated crusts and resulting dusts are compositionally similar  Sulfate crusts generate dusts that are preferentially enriched in salts and soluble trace elements relative to the crusts. Conclusions