The role of abrasion and resident fines in dust production from aeolian sands as measured by the Portable in situ Wind Erosion Laboratory (PI-SWERL)

Abstract

Aeolian deposits are important sources of atmospheric dust, particularly from extensive dune fields, interdune areas and vast sand sheet deposits across the globe. This study quantified the total suspended particle flux (TSP), particulate matter <10 μm (PM10) and PM2.5 emissions with the Portable in situ Wind Erosion Laboratory (PI-SWERL) for eighteen different types of sand to determine the role of aeolian abrasion in dust production. Aeolian abrasion results in grain coating removal, chipping, and spalling of sand grains during saltation transport, producing dust-sized particles. The studied sands were poorly- to well-sorted, round to angular, coarse to fine sand composed of quartz-rich to gypsum-rich particles. Some sand samples contained up to 14 % silt and clay, referred to as resident fines. Experiments on sand with diverse characteristics elucidated dust production processes. Samples composed of 100 % sand produced dust by aeolian abrasion with fluxes of 0.2–2.5 mg m−2 s−1 indicating aeolian abrasion as a potentially important process contributing to dust storms and desert loess deposits. Sand containing resident fines produced up to 42 mg m−2 s−1, an order of magnitude more dust than clean sand samples, with >60 % of the dust produced by the release of silt and clay and up to 40 % from aeolian abrasion. These high fluxes rival dust storms emanating from playas like Owens Lake in California. Climate change and anthropogenic disturbance of stabilized aeolian sand deposits in arid lands will likely result in increased dust emissions in the future which should be parameterized in climate models.