EVALUATING SOURCES AND TRANSPORT OF ARSENIC IN A SEMIARID ALLUVIAL BASIN AQUIFER, GOSHEN VALLEY, UTAH

Arsenic (As) is a common metalloid in the environment that causes health concerns worldwide. As has a number of natural and anthropogenic sources, including geothermal waters, weathering of arsenic bearing minerals, mining, and agricultural application. In this investigation, we sampled surface water and groundwater in semiarid Goshen Valley, Utah, to evaluate As sources and transport within the surface water and alluvial aquifer. Goshen Valley is projected to be an area of rapid urban development along southwestern shoreline of Utah Lake, the largest freshwater lake in Utah. The groundwater system in Goshen Valley is characterized by over a thousand meters of alluvial material underlain by volcanic rocks and limestone. We sampled groundwater wells in spring of 2013 and surface waters in spring and fall of 2014 to identify major sources of As among the various hydrologic compartments. As concentrations range from <1 µg/L to 20 µg/L in groundwater and from <1 µg/L to 150 µg/L in surface water. Although pathways of As transport between surface water and groundwater are not well understood, it is possible that infiltrating surface water (with high As concentrations) is negatively impacting the groundwater. Another potential source of As to the alluvial aquifer is interactions with geothermal waters along major fault zones. This study will provide a framework for understanding sources and transport of As in semiarid alluvial basins that are common across the western United States.