Contemporary and future dust sources and emission fluxes from gypsum- and quartz-dominated eolian systems, New Mexico and Texas, USA

Mark R Sweeney,Eric V Mcdonald,Steven L Forman

doi:10.1130/g49488.1

Mark R Sweeney, Eric V Mcdonald + Show 1 more

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https://doi.org/10.1130/g49488.1

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Abstract

AbstractRecent research on dust emissions from eolian dunes seeks to improve regional and global emissions estimates and knowledge of dust sources, particularly with a changing climate. Dust emissions from dune fields can be more accurately estimated when considering the whole eolian system composed of active to stabilized dunes, interdunes, sand sheets, and playas. Each landform can emit different concentrations of dust depending on the supply of silt and clay, soil surface characteristics, and the degree to which the landforms are dynamic and interact. We used the Portable In Situ Wind Erosion Laboratory (PI-SWERL) to measure PM10 (particulate matter &lt;10 μm) dust emission potential from landforms in two end-member eolian systems: the White Sands dune field in New Mexico (USA), composed of gypsum, and the Monahans dune field in west Texas, composed of quartz. White Sands is a hotspot of dust emissions where dunes and the adjacent playa yield high dust fluxes up to 8.3 mg/m2/s. In contrast, the active Monahans dunes contain 100% sand and produce low dust fluxes up to 0.5 mg/m2/s, whereas adjacent stabilized sand sheets and dunes that contain silt and clay could produce up to 17.7 mg/m2/s if reactivated by climate change or anthropogenic disturbance. These findings have implications for present and future dust emission potential of eolian systems from the Great Plains to the southwestern United States, with unrealized emissions of &gt;300 t/km2/yr.

Highlights

Field measurements and model-based estimates of dust emissions from dune systems are difficult to characterize (Amit et al, 2014; Adams and Soreghan, 2020; Swet et al, 2020), confounding present and future contributions to atmospheric dust loading (Bullard et al, 2011; Crouvi et al, 2012). This is important to resolve because estimates of total atmospheric dust loading are wide-ranging and contain uncertainties associated with source areas and the processes driving dust emissions, limiting our understanding of the impacts of atmospheric dust on radiative forcing, biogeochemical cycles, extreme climate variability (Kok et al, 2021), and human health (Crooks et al, 2016)
Laboratory and wind tunnel research on abrasion, the process of chipping, spalling, and grain coating removal of quartz sand, suggests that quartz-rich sand dunes are not major dust sources (Bullard et al, 2004; Adams and Soreghan, 2020; Swet et al, 2020), while other field research (Sweeney et al, 2011; Bolles et al, 2019) and remote-sensing analyses (Bullard et al, 2008; Lee et al, 2012) suggest that dunes and sand sheets containing even a few percent silt and clay can potentially produce dust over large areas and wide ranges of concentrations. This may be especially true in eolian systems with diverse landforms where saltation bombardment of sand on finergrained soils, such as playas, results in high dust emissions (Bullard et al, 2011)
Our study provides insight on dust sources and ranges of dust emissivity for two end-member eolian systems: (1) White Sands dune field in New Mexico (USA), composed of gypsum sand (Mohs hardness = 2), and (2) Monahans dune field in west Texas, composed of mature quartz sand (Mohs hardness = 7; Fig. 1)

Summary

Introduction

Field measurements and model-based estimates of dust emissions from dune systems are difficult to characterize (Amit et al, 2014; Adams and Soreghan, 2020; Swet et al, 2020), confounding present and future contributions to atmospheric dust loading (Bullard et al, 2011; Crouvi et al, 2012). This may be especially true in eolian systems with diverse landforms where saltation bombardment of sand on finergrained soils, such as playas, results in high dust emissions (Bullard et al, 2011). These dune fields produce a range of dust emission potentials from active dunes and other associated landforms including vegetated dunes, sand sheets, interdunes, and playas.

Results

Conclusion