Dust originating from dry lakes contributes harmful and toxic elements to downwind urban areas and mountain snowpack that is compounded by local contaminant inputs from anthropogenic sources. To evaluate dust contributions to an urban area from regional playas, we sampled playa dust sources, urban dust deposition, and snow dust deposition in central Utah, USA. Samples were analyzed for grain size, mineralogy, and chemistry. Bulk mineralogy between playa, urban, and snow dust samples was similar, with silicate, carbonate, and evaporite minerals. Grain size distribution between fine playa, urban, and snow dust particles was also similar. Elements found at high concentrations in playas include Li, Na, Mg, Ca, Sr, and U, and most other elements were found at higher concentrations in urban and snow deposition samples. Particularly enriched elements in dust deposition include Cu, Se, Ag, Cd, Sb, and La, which are sourced from industrial activity, mining, and vehicular emissions and wear. Based on results from mass balance modeling, a large majority of the dust mass deposited on the Wasatch Front is from playa sources. Urban and playa dust sources largely remain constant seasonally, although spikes in playa-associated element concentrations during a particular seasonal sample may indicate frequent and/or more intense dust events. Among the highly environmentally available elements B, Ca, Sr, and U, are Cd and Se, both of which present toxicity concerns for humans and environments. This is the first study describing heavy metal contamination and sources in Utah, USA.

The frequency of dust storms is increasing globally yet it is often difficult to determine dust sources in mixed events. Dust events may negatively impact human health, but the composition of major dust sources is not well characterized in arid regions globally. In the western US, the National Wind Erosion Research Network (NWERN) has various sites evaluating seasonal dust emissions to quantify dust fluxes. We used existing dust samples to characterize the isotopic, chemical, and mineralogical composition of dust over multiple seasons from ten representative NWERN sites and compared with land use, vegetation, and surficial geology. Our results show variability in dust chemistry across the ten sites primarily related to differences in surficial geology (local bedrock and sediment) with other factors playing a minor role. In some cases, seasonal vegetation and wind direction played a role in controlling dust composition. For example, the El Reno site showed seasonal differences in mineralogy related to carbonate precipitation and dissolution in the soil during wet summers and dry winters. The Holloman Air Force Base (HAFB) site had distinct seasonal changes in dust chemistry with spikes in Na, Mg, Ca, Ni, and Sr during the spring months possibly related to changes in wind direction and inputs from neighboring White Sands National Park. The Lordsburg Playa site had distinct chemistry relative to other sites with high concentrations of Li, Na, Ca, and Sr due to the prevalence of evaporite minerals. Mineralogy results show the presence of quartz, phyllosilicates, and feldspar minerals at each of the NWERN sites with HAFB also containing calcium sulfate and iron oxide minerals. The 87Sr/86Sr results showed lower ratios correlating with younger bedrock (e.g., ~0.7075 at the Red Hills site surrounded by Miocene volcanic rocks), but some of the sites with recent surficial sediments had higher ratios (e.g., ~0.714 at the CPER site with Tertiary sediments). By creating a library of isotopic, chemical, and mineralogical data for dust sources across the western US, our dataset has implications for identifying characteristics that may be used for tracking dust sources.