A Field Wind Tunnel Study of Fine Dust Emissions in Sandy Soils.

A portable field wind tunnel has been developed to allow measurements of dust emissions from soil surfaces to test the premise that dust concentration and properties are highly correlated with surface soil properties, as modified by crop management system.  In this study, we report on the effect of soil properties on fine dust emissions for three sandy soils when using the field wind tunnel.  In addition, we compare dust emissions using the field wind tunnel with those measured using a laboratory dust generator. The wind profile of the field wind tunnel was conditioned to simulate the wind above a level, smooth fine sandy loam surface.  Dust samples were gathered through an isokinetic vertical slot sampler, with PM₁₀ and dust less than 25 microns measured using a GRIMM particle size analyzer and collected on glass fiber filters.  Larger saltating particles and some dust settled into a tray at the bottom of the vertical slot sampler while smaller suspended particles were pulled through a vacuum tube attached to the sampler.  Dust emissions were also tested on 5 g samples of each soil using the laboratory dust generator.  All sites had similar amounts of airborne dust emissions measured gravimetrically in the field wind tunnel. The soil with the highest dry and wet aggregate stability had the lowest total sediment and PM₁₀ captured in the saltation trap.  The soil with the lowest organic matter content and soil stability had a high amount of soil captured in the saltation sampler but the lowest sustained PM₁₀ dust emissions in the field wind tunnel and lowest amount of PM₁₀ measured gravimetrically in the dust generator.