Particle size/composition relationships of wind‐eroding sediments, Owens (dry) Lake, California, USA

Abstract

AbstractMajor, minor, and trace element concentrations were determined by particle‐induced x‐ray emission (PIXE) in 118 aeolian sediment samples collected at six heights in seven locations along a 1.2 km transect during three sequential dust storms at Owens (dry) Lake, California, USA. Na and S concentrations covaried with each other (and inversely with Si and Ca), increased with height, and decreased with distance downwind and time. Mg, Al, Si, K, Mn, Fe, and Sr concentrations at northerly sites varied with height and location as opposed to nearly constant concentrations at southerly locations. Volumetric particle‐size distribution (PSD) for each sample was determined via laser diffraction. PSDs of the collected sediment reflected a trimodal distribution:63% of samples peaked at 20–50 µm (silt), 11% at 50–100 µm (very fine sand) and 26% at 100–250 µm (fine sand). Most silty samples occurred during the first two events. Significant differences in element concentrations existed in relation to the PSDs. Na and S concentrations were proportional to the submicron to silt particle fraction during each event. Al, Ti, Mn, K, Fe, and Rb concentrations correlated with 100–500 µm (fine/medium sand) particles in the first two events and a wider PSD range 250–1000 µm (coarse sand) in the third event. The results suggest sodium sulfate aerosol emission during the first windstorm, while subsequent saltation‐dominated events released more aluminosilicate minerals containing higher trace metal concentrations. These combined techniques reveal particle size/chemical fractionation and spatial variability of sediment properties during resuspension at aeolian ‘hotspots,’ with implications to geochemical cycling and aerosol source/receptor relationships. Copyright © 2008 John Wiley & Sons, Ltd.