THE IMPACT OF AEOLIAN DUST ON THE TRACE ELEMENT CHEMISTRY OF SNOWPACK AND SNOWMELT RUNOFF IN HIGH ALPINE WATERSHEDS OF NEVADA AND UTAH

Aeolian dust plays an important role in the transport and deposition of nutrients and trace elements to ecosystems. Over the past 150 years, the Intermountain West has seen a 5-7 fold increase in dust deposition to high alpine lakes, resulting in a 400% increase in trace metal loading. Climate change is expected to increase dust storm frequency and intensity. Little is known about the impact of dust on water quality in high alpine watersheds. The purpose of this research is to evaluate the relationship between the chemistry of snowpack, dust and snowmelt runoff in high alpine watersheds.

During spring 2014, snow, and dust samples were collected from four watersheds in Utah and Nevada at peak snowpack. During 2013 those same samples were collected in one of the Utah watersheds. Water samples were collected from rivers in those watersheds throughout the year in order to report time series data for the measured analytes. Samples were analyzed for trace and major elements, stable water isotopes, and ⁸⁷Sr/⁸⁶Sr. These data were used to evaluate dust fluxes and pathways from the snowpack to rivers and lakes during snowmelt runoff.

Preliminary results from snow and dust samples indicate concentrations of Ca, Rb, Mn, Sm, Gd, Ho, Tl were larger in 2014 than 2013 by a factor of 2 for the same area in the Uinta Mountains in Utah. In 2014 concentrations of Mn, Pb, U, Li, Eu, Ti, Nd, Rb, and Ni in snow and dust ranged by factors of 2-8 across all watersheds. In 2014 particulate matter (>0.45µm) dominated the snowpack chemistry suggesting dust as a primary contributor of trace elements.

During 2014 the Provo river became enriched in many trace elements (Be, Al, Ti, V, Cr, Fe, Ni, As, Y, Cs, La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Lu, U) as discharge increased from base to peak flow. During the same time period other elements (Na, Mg, Sr, Ba) became diluted.