Total suspended particulate matter emissions at high friction velocities from desert landforms

Most wind erosion studies that characterize dust emission potential measure particulate matter smaller than 10 m (PM₁₀) for air quality purposes or atmospheric modeling. Because the PM₁₀ size fraction is only a portion of the total range of fine-grained particles potentially emitted from desert landforms, we modified the miniature Portable In Situ Wind Erosion Lab (PI-SWERL) by adding a new instrument to measure total suspended particulate matter (TSP). The modified PI-SWERL is capable of measuring TSP with diameters <500 μm emitted from highly erodible surfaces at friction velocities up to 1.28 m s^-1. Undisturbed and artificially disturbed surfaces of six common landforms in the Negev Desert of Israel were studied to evaluate the utility of TSP measurements. These landforms include alluvial fans and plains armored by desert pavements, loessial soils with silt-rich surficial crusts, fluvial loess with biological crusts, and active sand dunes. The landforms differ in character and surface age, thereby exhibiting a wide range of surface covers, soil properties, and soil strengths. Our results indicate that the magnitude of TSP emission is primarily controlled by geomorphic setting and surface characteristics. TSP and PM₁₀ concentrations measured from dust-rich loessial soils were significantly correlated, and TSP emission was best predicted at all sites using PM₁₀ content and bearing capacity. Our results demonstrate that further research is needed to determine correction factors for friction velocities related to erodible, anisotropic surface roughness elements and that the modified PI-SWERL is a promising tool to quantify total potential emission flux from desert landforms.