September 1, 2016.
More than 35 million people in the western United States depend on the Colorado River as a resource for drinking water, irrigation systems, and hydropower. Recent climate change reports predict average water levels within the Colorado River Basin will continue to decrease throughout the next century due to decreased precipitation, warming temperatures, and increased usage. Decreased river flow may have major impacts within the subsurface that are two-fold: 1) decreased water flowing may result in greater issues of water quality-due to accumulation and concentration of some elements within the subsurface, and 2) a decreased water stage may significantly alter the redox cycling within the subsurface and affect major biogeochemical elemental cycles. Therefore, a greater understanding of current subsurface elemental distributions throughout the Upper Colorado River Basin is needed.
To examine the elemental distributions throughout the Upper Colorado River Basin, a total of 321 contaminated sediment samples were collected from five Department of Energy-Legacy Management (DOE-LM) sites: Riverton, WY, Shiprock, NM, Naturita, CO, Grand Junction, CO and Rifle, CO to a depth of 5-10m. Sediment samples were characterized for elemental composition by x-ray fluorescence (XRF) and elemental analysis (EA) for their carbon/nitrogen (C:N) content. Sediments were water extracted and measured by pH probe, refractometer, and by spectrophotometry for approximated, in situ values of pH, salinity, and nitrogen species (NO3-, NO2-, NH4+). Overall, this study enhances greater knowledge of elemental distributions throughout the Upper Colorado River Basin, and may help DOE-LM develop regional and site-specific management strategies for future climate scenarios.
Emily L. Cardarelli
SLAC National Accelerator Laboratory (SLAC)
This project was supported by a grant to the CSU STEM Teacher Researcher (STAR) Program from the Howard Hughes Medical Institute and by the SLAC Science Focus Area program, “Coupled Cycling of Organic Matter, Uranium, and Biogeochemical Critical Elements in the Subsurface Systems”, funded by the Department of Energy. Special thanks to the Francis Lab, ArcGIS staff of Branner Earth Sciences Library, and the STAR Bay Area Cohort 2016.