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Published March 2011 | public
Journal Article

Physical, Chemical, and Mineralogical Characteristics of a Reservoir Sediment Delta (Lake Powell, USA) and Implications for Water Quality during Low Water Level


Lake Powell is a large reservoir in Utah and Arizona that has experienced large changes in water level during a recent drought. As a first step in assessing the connection between hydrologic and chemical changes at Lake Powell, we characterized the particle size and solid-phase bulk concentrations for 31 elements and 25 minerals in sediment from the inflow region and some shoreline locations by using laser diffractometry, X-ray fluorescence, elemental analysis, and X-ray diffraction. Our results are consistent with previous results that show a negative correlation between particle size and concentrations of most elements and most minerals other than quartz and some feldspars. In our samples, however, solid-phase iron, rather than particle size or organic carbon, is the best predictor variable for the solid-phase concentrations of elements and minerals. Sediment characteristics vary on a scale of tens of kilometers, with fine sediment that is enriched in trace elements nearer to the dam. These trends allow formulation of an algorithm for determining a water-level threshold below which sediment resuspension may alter water chemistry in a generic reservoir with a long and narrow sediment delta.

Additional Information

© 2011 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Received 18 July 2010. Posted online 18 Jan. 2011. The authors are grateful to Jerry Miller, Robert Radkte, Nick Williams (USBR), Andrew Kositsky, Nathan Chan, Claire Farnsworth (Caltech), and Mark Anderson (Glen Canyon NRA) for assistance with sample collection; Nathan Dalleska, Ashley Jones (Caltech), Andreas Papritz, René Saladin, Andreas Müller (ETHZ), Jo Raber (Ametek), Manuel Kunz, Matteo Bonalumi (Eawag), and Zena Harris for assistance with data collection; and NSF SGER grant EAR-0621371, the Alice Tyler Foundation, and USBR grant 06PG400222. The help of Mike Easler (Caltech) was invaluable during sample processing and particle size measurements. Mineralogical analyses would not have been possible without Dennis Eberl of the USGS, Boulder, CO. Arthur Horowitz (USGS) and two anonymous scientists provided valuable reviews. The USBR, Upper Colorado Region, and Glen Canyon NRA provided sampling support.

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