TESTING THE PREFERENTIAL DUST SOURCE SCHEME USING THE PI-SWERL IN THE NORTHERN CHIHUAHUAN DESERT, NEW MEXICO AND TEXAS

Verifying dust sources identified by remote sensing with field testing is essential to accurately assess sources of dust and to improve dust emission modeling. The Preferential Dust Source (PDS) scheme is one method that identifies dust sources through landform mapping, emphasizing sediment supply and availability. The PDS was applied to the Chihuahuan Desert (Baddock et al., 2011, J. of Maps) and tested by dust plume mapping, where 48% of satellite observed dust plumes were sourced from ephemeral lakes. To test the PDS with field data, the Portable In-Situ Wind Erosion Lab (PI-SWERL) was used to measure dust emission potential from six landform types in the northern Chihuahuan Desert, New Mexico and Texas, U.S.A.: ephemeral lake, dry lake, high relief alluvial, low relief alluvial, aeolian sand sheet and sand dunes. PM10 (particulate matter <10 μm) dust was measured for each site at different shear velocities to detect seasonal differences in potential emissivity. At a shear velocity of 0.6 m/s, average fluxes from sand sheets were the highest (0.69 mg/m²/s), followed by alluvial, dry lake, dune, and ephemeral lake (0.1 mg/m²/s). Sand sheets and alluvial landforms with the highest potential emissivity are currently stabilized by varying degrees of vegetation densities and do not presently emit dust regularly. When ranked by maximum flux, ephemeral and dry lakes are highest (up to 21 mg/m²/s) and dunes are the lowest (1.0 mg/m²/s). To be emissive, ephemeral and dry lakes require low soil moisture, relatively low crustal strength and surface sand, pointing to a strong seasonal influence in their emission potential. This finding supports previous works that ephemeral and dry lakes are prominent dust sources in the Chihuahuan Desert. Aeolian and alluvial landforms also have the potential to release large amounts of dust that has been trapped by vegetation. The PDS is a viable method to predict dust prone surfaces but is limited by lack of information pertaining to surface characteristics such as soil crusting and moisture content. With future landscape destabilization by anthropogenic activity and climate change, soil and air quality in the northern Chihuahuan Desert may severely deteriorate.