Heavy Metals in Dust From the Shrinking Great Salt Lake: Where Do They Come From and Where Do They Go?

Increased human water use and severe drought have drained the Great Salt Lake (GSL) to a new historic low. Since a high stage in the mid 1980s, the lake area has been reduced by 50 percent, exposing over 1900 square kilometers of former lakebed to potential erosion and entrainment in the atmosphere. As a terminal lake, the GSL and its sediments are polluted with contaminants from anthropogenic activities across the entire watershed, including mining, smelting, agriculture, wastewater, and urban runoff. Polluted dust from the lakebed may blow across northern Utahs Wasatch Front where two million people already suffer from some of the worst air quality in the United States. Although particulate concentrations are monitored at multiple locations in northern Utah, little is known about the chemical composition of GSL dust and the risks it might pose to humans or ecosystems. For the past three years, which have included a wet year (2019) and two record-setting drought years (2020 and 2021), we collected airborne dust from five remote locations on the GSL playa. We detected heavy metals such as arsenic, lead, and zinc in dust collected less than five kilometers from existing neighborhoods and ongoing residential construction projects. In this presentation we discuss temporal and spatial variations in GSL dust composition and production rates and present a novel, multi-isotope tracer technique for attributing heavy metal enrichments in polluted dust to culpable industrial sources.