DUST COMPOSITION IN THE URBAN WASATCH FRONT, UTAH, AND COMPARISON TO NEARBY DESERT PLAYAS

Dry lakebeds (playas) are important dust sources globally, with potentially harmful impacts to downwind urban areas. The Wasatch Front (population >2 million) in northern Utah, USA, is located adjacent to multiple playas, including the Great Salt Lake (GSL). As water levels in GSL continue to decline due drought and water diversions, there could be intensified dust emissions from the newly exposed lakebed. The pupose of this study was to quantify dust fluxes from GSL relative to other playas and evalute trace metal inputs from anthropogenic sources. Dust emissions were sampled at GSL and seven playas in western Utah, including Sevier Dry Lake, and dust deposition was sampled at four locations in the Wasatch Front, including Provo, Salt Lake City, Ogden, and Logan. The samples were analyzed for ⁸⁷Sr/⁸⁶Sr ratios and concentrations of 40+ elements. Sr isotope (⁸⁷Sr/⁸⁶Sr) ratios in the carbonate mineral fraction were variable in the playa dust sources, ranging from 0.7100 in Sevier Dry Lake to 0.7150 in GSL. Wasatch Front dust deposition samples fell within these endmember values, ranging from 0.7110 to 0.7130, denoting that GSL contributed 0 to 40% of the urban dust flux during different seasons. Anthropogenic activities are also important for contributing trace metals to the Wasatch Front. Elements such as Cu, Sb, Se, Cd, Ag, Be, and Co were enriched in urban dust deposition relative to playa sources, indicating that local inputs from construction, roads, and mining contribute to the dust flux. Futher, La concentrations were highly enriched in the Salt Lake City samples, suggesting that local refineries are an additional source of anthropogenic aerosols. Our findings signify that urban dust is a complex mixture multiple playas and anthropogenic sources, with implications for better understanding how to mitigate and control dust emissions.