Abstract by Michael Goodman
Using 87Sr/86Sr Ratios of Carbonate Minerals in Dust to Quantify Contributions from Desert Playas to the Urban Wasatch Front, Utah, USA
Desert playas are important dust sources to downwind communities such as those of us living along the Wasatch Front. Another dust source contributing to the poor air quality during dust events is the exposed lakebed of the nearby Great Salt Lake (GSL). To investigate dust source contributions to the Wasatch Front, we sampled dust emissions from the exposed GSL lakebed and seven playas in western Utah, and dust deposition at four locations along the Wasatch Front, including Provo, Salt Lake City (SLC), Ogden, and Logan. The dust samples were analyzed for mineralogy, chemical composition, and strontium isotope (87Sr/86Sr) ratios for source apportionment. What we found is that the 87Sr/86Sr of the carbonate fraction of dust source samples varies significantly, from ~0.7105 in Sevier Dry Lake to ~0.7150 in Great Salt Lake. In fall 2015, we estimated that the GSL contributed ~45% of the dust flux at Ogden and Logan, but only 20% at SLC and 0% at Provo. In spring 2016, the GSL contributed ~20% of the dust flux at SLC and Logan, and 0% in Provo. We are looking into other ways of quantifying dust source contributions as we collect seasonal dust deposition samples.