KICKING UP DUST ON UTAH’S OFF-ROAD VEHICLE TRAILS: PI-SWERL ASSESSMENT OF ANTHROPOGENIC DUST EMISSIONS

Upward trends in the use of off-road vehicles (ORV) and the creation of new ORV trails facilitates an increase in soil disturbance and dust emissions in Utah. Anthropogenic destruction of biological and physical soil crusts and the removal of vegetation by ORVs exposes and destroys soil structure, making the soil easier to erode. We used the PI-SWERL (Portable In Situ Wind Erosion Laboratory) to measure dust concentrations and the threshold shear velocity of disturbed and undisturbed soil. We tested soils at several popular ORV areas including- Bonneville Salt Flats, Knolls, Lone Rock, and Little Sahara recreation areas composed of sand dunes, playas, and Lake Bonneville sediments with soil textures ranging from sand to silty clay loam. Soil shear strength was also measured on undisturbed and disturbed soils. Dust emissions from undisturbed surfaces are low (~0.001 mg/m²/s) in soils with high shear strength, vegetation, crust, or high moisture content and have a higher threshold shear velocity than those disturbed by ORVs. Disturbed ORV trails produced 1 to 8 orders of magnitude higher concentrations of dust (as high as 200 mg/m²/s) and had lower threshold shear velocities than their undisturbed counterparts. Disturbed soils on Lake Bonneville terraces produce the highest dust concentrations compared to other soils. Vegetation and crusted surfaces protect soils from wind erosion. The generation of dust in Utah is multifaceted, likely owing a significant part of its production to the destruction of natural and crusted surfaces by anthropogenic activity.