title: Reactive transport in the complex heterogeneous alluvial aquifer of Fortymile Wash, Nevada.
abstract: Yucca Mountain, Nevada, had been extensively investigated as a potential deep geologic repository for storing high-level nuclear wastes. Previous field investigations of stratified alluvial aquifer downstream of the site revealed that there is a hierarchy of sedimentary facies types. There is a corresponding log conductivity and reactive surface area subpopulations within each facies at each scale of sedimentary architecture. Here we use a Lagrangian-based transport model in order to analyze radionuclide dispersion in the saturated alluvium of Fortymile Wash, Nevada. First, we validate the Lagrangian model using high-resolution flow and reactive transport simulations. Then, we used the validated model to investigate how each scale of sedimentary architecture may affect long-term radionuclide transport at Yucca Mountain. Results show that the reactive solute dispersion developed by the Lagrangian model matches the ensemble average of numerical simulations well. The link between the alluvium spatial variability and reactive solute dispersion at different spatiotemporal scales is demonstrated using the Lagrangian model. The longitudinal dispersivity of the reactive plume can be on the order of hundreds to thousands of meters, and it may not reach its asymptotic value even after 10,000 years of travel time and 2-3 km of travel distance.
authors.affiliation: School of Earth Sciences, The Ohio State University, Columbus, OH, USA. Electronic address: m.rezasoltanian@gmail.com.
authors.forename: Mohamad Reza
authors.initials: MR
authors.lastname: Soltanian
authors.affiliation: Jackson School of Geosciences, Bureau of Economic Geology, University of Texas at Austin, Austin, TX, USA. Electronic address: alex.sun@beg.utexas.edu.
authors.forename: Alexander
authors.initials: A
authors.lastname: Sun
authors.affiliation: EES-16, Earth and Environmental Sciences Division, Los Alamos National Laboratory, Mailstop T003, Los Alamos, NM 87545, USA; College of Construction Engineering, Jilin University, Changchun, China. Electronic address: daiz@lanl.gov.
authors.forename: Zhenxue
authors.initials: Z
authors.lastname: Dai
mesh_terms: D005844:Geology; D060587:Groundwater / Q000737:chemistry*; D008962:Models, Theoretical; D009505:Nevada; D011850:Radioactive Waste / Q000032:analysis*; D011868:Radioisotopes; D014872:Water Movements
chemical_list: D011850:Radioactive Waste; D011868:Radioisotopes
keywords: Alluvial aquifer; Fortymile Wash Nevada; Hierarchical porous media; Lagrangian theory; Numerical simulation; Reactive transport