Geomorphic and hydrologic controls of dust emissions during drought from Yellow Lake playa, West Texas, USA

Abstract

a b s t r a c tNumerous complex geomorphic and hydrologic factors have been identified that control dust emissions from playas, yet there are few measurements of dust emissions from playas during drought, which is assumed to enhance emissions, or during low-emission seasons. We used the PI-SWERL (Portable in situ Wind Erosion Laboratory) to measure dust emission potential at Yellow Lake, a saline playa in West Texas, USA, during the drought of 2011. Direct aeolian entrainment of dust occurred primarily on supplylimited surfaces consisting of mud-cracked surfaces as well as crusts containing halite, thenardite, and gypsum. High-magnitude, low duration peaks in dust emissions occurred over parts of the playa underlain by shallow groundwater (<1 m) where conditions encouraged the crystallization of efflorescent salts. In contrast, surfaces characterized by loose sand-sized aggregates produced sustained dust emissions two to three orders of magnitude higher than the playa surface because aggregates broke apart during saltation. Prolonged drought at Yellow Lake will significantly change the frequency and type of dust emissions. We propose that a similar scenario characterizes dust production at many hydrologically similar playas. More research is needed to assess the impacts of changing groundwater levels on dust emissions in the context of extended drought and anthropogenic climate change.

Assessing Landscape Dust Emission Potential Using Combined Ground‐Based Measurements and Remote Sensing Data

“…Of further critical importance here are the environmental conditions at the time of surface testing. The longterm Landsat record established that the ephemeral lakes are highly emissive (Figure 2), in accordance with many dust sources (e.g., Gill, 1996;Bullard et al, 2008;Ginoux et al, 2012;Reynolds et al, 2009), but their emissivity was relatively low during the PI-SWERL testing due to the prevailing elevated humid conditions in proximity to the coast at the time of PI-SWERL testing, as well as the hygroscopic saline surfaces and periodic shallow water nature that can create wet playas (Reynolds et al, 2009;Sweeney et al, 2016). This also raises an important issue regarding dust emission not captured with remote sensing.…”

“…Modeling of dust emission must account for factors that affect the threshold friction velocity (u *t ) and, as a result, the variable erodibility of the surface (Marticorena & Bergametti, 1995;Shao et al, 1996). Some of the major drivers influencing the variability of the surface erosion thresholds include soil moisture (influenced by relative humidity), particle size, degree of crusting (including physical, saline, and biological soil crusts), and mineralogy of surface sediments (e.g., Belnap & Gillette, 1998;Buck et al, 2011;Cornelis et al, 2004;Gillette et al, 1982;King et al, 2011;Marticorena & Bergametti, 1995;McKenna Neuman & Nickling, 1989;McKenna Neuman & Maxwell, 2002;Munkhtsetseg et al, 2016;Sweeney et al, 2016), as well as surface roughness (characterized by the aerodynamic roughness length, z o ; Raupach et al, 1993), with vegetative and topographic (micro to macro) roughness having significant influences (e.g., Gillies et al, 2006;Okin & Gillette, 2001;Sankey et al, 2010). Incorporating the influence of these surface characteristics into soil erodibility and dust emission predictions is one of the biggest challenges for dust simulation, especially given that global data sets of these input variables are not always available or are not at a spatial scale appropriate for model input.…”

Fine dust emissions from active sands at coastal Oceano Dunes, California

“…3. rupturing of clay and oxide coatings attached to the surfaces of sand grains (Bullard et al, 2004(Bullard et al, , 2007; and 4. chipping or spalling of sand grains, for instance of sharp corners, which is also known as aeolian abrasion (Kuenen, 1960;Whalley et al, 1987;Jerolmack and Brzinski, 2010;Sweeney et al, 2016).…”

“…Considering these limitations of satellite observations, field measurements of dust emission from active sands are needed to inform whether active sands are indeed important contributors to the global dust cycle and, if so, what the physics of the emission process and the dust emission pro-ductivity of active sands are. Unfortunately, there are few measurements of dust emissions from active sands, especially under natural field conditions (Bullard et al, 2004;Sweeney et al, 2016;Swet et al, 2019). To improve our understanding of dust emission from active sands, we present the first (to our knowledge) in situ field measurements of dust emission under natural aeolian saltation from active sands at the coastal Oceano Dunes in California.…”

Fine dust emissions from active sands at coastal Oceano Dunes, California

“…After saltation starts, saltator impacts on the soil surface cause the release of dust into the air; this process is typically referred to as "sandblasting" or "saltation bombardment" (Shao, 2008). Sandblasting can emit dust in four primary ways: (1) fragmentation of aggregates of clay-sized (<2 μm in diameter) and silt-sized (2-63 μm in diameter) 20 particles in the soil (Kok, 2011a), (2) release of single fine particles trapped between the sand particles (referred to as "resident fines") (Bullard et al 2004), (3) rupturing of clay-and oxide-coatings attached to the surfaces of sand grains (Bullard et al, 2004;2007), and (4) chipping or spalling of sand grains, for instance of sharp corners, which is also known as aeolian abrasion (Kuenen, 1960;Whalley et al, 1987;Jerolmack and Brzinski, 2010;Sweeney et al, 2016;Bristow and Moller, 2018). The relative importance of each physical process depends largely on soil texture and composition: aggregate 25 breakage is likely most important for soils with a large fraction of fine (clay-and silt-sized) grains (Shao, 2008;Kok et al, 2012), whereas removal of mineral coatings and aeolian abrasion might be more important for predominantly sandy soils (Kuenen, 1960;Bullard et al, 2004;2007;Jerolmack et al, 2011).…”