Examining Atmospheric Dust Deposition and its Effects on Alpine Lakes in the Uinta Mountains, Utah

The composition and effects of atmospheric dust on remote alpine lakes were investigated using geological and paleolimnolgical techniques. Short cores (\u3c 50 cm long) were retrieved from five lakes on the eastern side of the Uinta Mountains, Utah. Sediment core chronologies are based on 210 Pb and 14C dates. Dust and lake sediment core samples were analyzed for their particle size distribution, mineralogy, and chemistry. Dust was fine grained (\u3c 10 μm) and was enriched (i.e., 50X greater concentrations) in 31 major, minor and trace elements relative to local bedrock material. In lake sediments, changes in the concentrations of key dust elements were recorded beginning in ~ AD 1900. Elements that increased in all five lakes included metals (Bi, Pb, Sb, Sn) and the nutrient P. The metals Cu and Cd also increased in four lakes. These changes are coincident with European settlement, the onset of mining, and the intensification of agriculture. The findings of this thesis show that atmospheric deposition in the Uinta Mountains is unique in composition relative to the last several hundred years. Percentage organics also increased during this period indicating increased productivity. Cladocera community composition recorded changes potentially caused by variations in atmospheric deposition of Ca in this region, although results were inconclusive