Controls on mineral dust emissions at four arid locations in the western USA

Dust emission measurements from unique military sources, including tracked and wheeled military vehicles, low flying rotary-winged aircraft, and artillery backblast, were conducted in the course of four field campaigns in 2005–2008, at Yuma Proving Ground (YPG) in Arizona (twice), Yakima Test Center (YTC) in Washington State, and Ft. Carson in Colorado. This paper reports on the observed relationships between levels of dust emission, and the mineralogy, particle size, and chemical composition of the surface sediment and associated airborne mineral dust. We propose a mechanism for the generation of fine particulate matter, providing an explanation for high emissions in certain regions. PM10 (particulate matter with aerodynamic diameter of <10 μm) and PM2.5 (particulate matter with aerodynamic diameter of <2.5 μm) filter as well as bulk samples were collected for laboratory analysis in the course of the field campaigns. Analytical techniques applied include X-ray diffraction, Scanning Electron Microscopy, laser particle size analysis, as well as X-ray fluorescence spectrometry, Ion Chromatography, and Automated Colorimetry. Previous work has shown YTC has higher dust emission factors than YPG and Ft. Carson. The results presented in this paper demonstrate that the high PM10 and PM2.5 emissions measured at YTC can be explained by the high silt and low clay content of the surface sediment, attributed to glacial loess. In the other test areas, the abrasion of microscopic clay and oxide coatings, from and by silicate mineral grains, is considered a factor in the generation of fine particulate matter.