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Kansas State University (1996)

Suspension component of wind erosion

Mirzamostafa, Naser

Titre : Suspension component of wind erosion

Auteur : Mirzamostafa, Naser

Université de soutenance : Kansas State University

Grade : Doctor of Philosophy (PhD) 1996

Many detrimental impacts from wind erosion are caused by the suspension-size particles (SSP). Adverse effects include depletion of soil fertility, air pollution, visibility reduction, and contamination of food and drinking water. The SSP with an aerodynamic diameter of less than 10 microns (PM-10) are regulated as a human health hazard in the United States. The objectives of this study were : (1) to identify and quantify the sources of suspension component and (2) to develop prediction parameters for the suspension component. The SSP produced during wind erosion come from three possible sources. These sources are : emission of soil aggregates that are smaller than 0.1 mm, abrasion of surface clods and crust by impacting saltating abraders, and breakdown of soil abraders as they move in saltation. The fraction of SSP available for emission was estimated by sampling 11 Kansas soils and it ranged from 0.007 to 0.80. Maximum, loose, PM-10 fraction was 0.0056. Production of SSP from clod abrasion was investigated by abrading soil clods in the wind tunnel. The suspension fraction of clod abrasion ranged from 0.14 to 0.27. The SSP decreased with an initial increase of aggregate stability (sandy loam to silt loam), then increased with further increase of aggregate stability (silt loam to silty clay loam). The PM-10 fraction of suspension from clod abrasion ranged from 0.0071 to 0.1469, and was directly proportional to the clay content and inversely proportional to the abrasion coefficient. Production of SSP from abrader breakdown was studied by saltating soil abraders in the wind tunnel for 300 m. Breakage coefficients were directly proportional to abrasion coefficients and inversely proportional to the clay content. Abrasion coefficients were about nine times greater than breakage coefficients. The PM-10 fraction of suspension created during abrader breakdown was directly proportional to clay content. On simulated fields, as saltation discharge approached transport capacity, the contribution of emission to total suspension decreased and the contribution of abrasion and breakage to total suspension increased. Therefore, the relative contribution from each source to the total suspension depends on total field length.

Mots clés : Agronomy, Soil sciences, soil erosion, Biological sciences

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