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This content will become publicly available on March 4, 2017

Title: River stage influences on uranium transport in a hydrologically dynamic groundwater-surface water transition zone

A well-field within a uranium (U) plume in the groundwater-surface water transition zone was monitored for a 3 year period for water table elevation and dissolved solutes. The plume discharges to the Columbia River, which displays a dramatic spring stage surge resulting from snowmelt. Groundwater exhibits a low hydrologic gradient and chemical differences with river water. River water intrudes the site in spring. Specific aims were to assess the impacts of river intrusion on dissolved uranium (Uaq), specific conductance (SpC), and other solutes, and to discriminate between transport, geochemical, and source term heterogeneity effects. As a result of water table elevation fluctuations, river water intrusion, and changes in groundwater flow directions, time series trends for Uaq and SpC were found to be complex and displayed large temporal and well-to-well variability. The wells were clustered into subsets exhibiting common behaviors resulting from the intrusion dynamics of river water and the location of source terms. Hot-spots in Uaq varied in location with increasing water table elevation through the combined effects of advection and source term location. Heuristic reactive transport modeling with PFLOTRAN demonstrated that mobilized Uaq was transported between wells and source terms in complex trajectories, and was diluted as river watermore » entered and exited the groundwater system. Moreover, while Uaq time-series concentration trends varied significantly from year-to-year as a result of climate-caused differences in the spring hydrograph, common and partly predictable response patterns were observed that were driven by water table elevation, and the extent and duration of river water intrusion.« less
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  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0043-1397; 641378
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Water Resources Research
Additional Journal Information:
Journal Volume: 52; Journal Issue: 3; Journal ID: ISSN 0043-1397
American Geophysical Union (AGU)
Research Org:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States