Collaborative Research: Investigation of the fate and transport of dust-borne trace metals and solutes during snowmelt

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Collaborative Research: Investigation of the fate of dust-borne trace metals and solutes during snowmeltAbstractWind-blown dust contributes trace metals and soluble salts to mountain snowpack, with potential negative impacts on water quality during snowmelt. Sediment records from mountain lakes in the western U.S. suggest that dust deposition has increased five-fold over the past 150 years due to human disturbance of desert soils, with more dust expected in the future due to climate change. Little is known, however, concerning the impacts of dust on the chemistry of mountain streams. Snowmelt-fed streams are a primary source of drinking water in the western U.S. The Provo River is a prime example of this, supplying water to over 50% of the residents of Utah. This project investigates the effects of dust on water quality during snowmelt in the upper Provo River watershed in the Uinta Mountains. Assessment of dust contributions to mountain snowpack and demonstration of pathways of trace metal and salt transport during snowmelt have the potential to extend across the Intermountain West and beyond the U.S. to other mountainous areas receiving substantial dust input, including the Andes, Himalayas, and European Alps. This project provides K-16 student outreach opportunities during inquiry-based field exercises, fosters cross-campus collaborations for graduate students at Utah's three major research institutions (University of Utah, Utah State University, and Brigham Young University), and broadens participation of underrepresented groups by involving women and minorities. The project investigates the fate and transport of dust-derived trace metals and solutes during snowmelt building from detailed field sampling and comprehensive analyses. Dust contributions to stream solute budgets during snowmelt are quantified with isotopic tracers (e.g., strontium, boron, sulfur, oxygen and hydrogen) and mixing analyses. The role of organic matter-facilitated trace-metal transport from snowpack to streams is examined through application of several novel analytical methods. Spatial heterogeneity in dust deposition is quantified, and the availability of trace metals in dust is characterized via sequential leaching experiments. The Provo River watershed is an ideal location for investigating impacts of dust on water chemistry because it is underlain by relatively simple siliciclastic bedrock that permits clear observations of exogenous dust and is well instrumented with atmospheric and aquatic monitoring stations from the Innovation Urban Transitions and Aridregion Hydro-sustainability (iUTAH) observatory funded by NSF. The geological setting and extensive instrumentation provide an unprecedented opportunity to explore the impacts of dust deposition on stream chemistry during snowmelt.