ELEMENTAL COMPOSITION OF THE RESPIRABLE FRACTION OF MINERAL DUST FROM THE EXPOSED PLAYA OF THE GREAT SALT LAKE, USA
A systematic soil sampling campaign was conducted between June 2016 and August 2018 using Incremental Sampling Methodology. Surface crust samples were collected at 5246 locations and composited into 122 samples which were then dried and sieved. The silt and clay fractions were then placed in a resuspension chamber. The PM10 fraction was extracted and analyzed by a combination of Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and Synchrotron X-ray Fluorescence (S-XRF). The combination of these two analytical techniques was able to quantify the mass fraction of 53 elements. The PM10 soil from the GSL lakebed is highly enriched in elements associated with evaporite minerals (e.g., Ca, Mg, S, Sr, Cl, Li, and B). Five elements (Co, Cu, Mn, Sb, and V) had some values which exceeded the Residential, but not the Industrial, Regional Screening Levels (RSLs) established by the EPA for soils. Three elements (La, Li, and Zr) had some values which exceeded both the Residential and Industrial RSLs. Arsenic was the only element measured for which all values exceeded both the Residential and Industrial RSLs. Site-specific exposure assessments should be performed for As, Co, Cu, La, Li, Mn, Sb, V, and Zr to determine whether the measured concentrations of these elements pose health risks at the observed exposure frequencies.