Microscopic Mass Transfer on U(VI) and Tc(VIII) in Subsurface sediments
EMSL Project ID
31295
Abstract
This project will investigate microscopic mass transfer process and its influence on and coupling with geochemical and biogeochemical reactions in subsurface sediments. The research will focus on the reactive diffusion at pore and sub-pore scales that are relevant to U/Tc residence in Hanford sediment microenvironments. These include intragrain fractures, aggregates, cements, and coating materials with mass flux dominated by abiotic processes, and intra-aggregates and biofilms of microbial agents and minerals with activity/concentration gradients dictated by biological reactions. Molecular dynamic simulations of ions with different size and charge will be performed to determine self-diffusion coefficients in porous media with variable pore sizes and pore surface charges, and provide insights into charge- and species- coupled ion diffusion. Percolation-based analysis will be performed to investigate the influence of intragrain pore or fracture connectivity on the apparent diffusion coefficients by integrating molecular self-diffusion coefficients and statistical percolation threshold. Microscopic and spectroscopic measurements of diffusion systems that are representative of Hanford U/Tc microenvironments will be performed to measure diffusion properties and validate theoretical calculations. Batch, stirred-flow cell, and short column experiments will be used to evaluate the influence of coupled diffusion and geochemical/biogeochemical reactions in controlling the reactive diffusion rates at pore-scale (Fendorf). Multi-component, pore-scale reactive diffusion models will be developed to integrate self-diffusion coefficients, charge and species coupling, and pore connectivity effect; and to describe and be validated by the results from the wet-lab experiments. The project will collaborate with the Fredrickson pore scale and Zachara reactive transport projects. The geochemical and biogeochemical reactions from these projects will be used for experimental design and data interpretation of microscopic reactive diffusion. This project will benefit pore-scale modeling efforts (Scheibe) by providing sub-pore reactive diffusion models. The pore-scale simulations will in turn benefit this project by providing insights for developing scaling approaches to model pore-scale reactive diffusion processes in the mineralogically complex Hanford sediments. The research will incrementally increase the number of controlling factors and will focus on the following three scenarios: 1) saturated, microporous environments dominated by abiotic processes, 2) saturated microenvironments with mass flux dictated by biological reactions, and 3) unsaturated microenvironments with mass flux affected by water content and percolation.
Project Details
Project type
Limited Scope
Start Date
2008-08-08
End Date
2008-10-08
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Ewing R, Q Hu, and C Liu. 2010. "Scale dependence of intragranular porosity, tortuosity, and tortuosity." Water Resources Research 46:Art. No. W06513. doi:10.1029/2009WR008183
Greskowiak J, H Prommer, C Liu, V Post, R Ma, C Zheng, and JM Zachara. 2010. "Comparison of parameter sensitivities between a laboratory and field scale model of uranium transport in a dual domain, distributed-rate reactive system." Water Resources Research 46:Article No. W09509. doi:10.1029/2009WR008781
Kerisit SN, and C Liu. 2010. "Molecular Simulation of the Diffusion of Uranyl Carbonate Species in Aqueous Solution." Geochimica et Cosmochimica Acta 74(17):4937-4952. doi:10.1016/j.gca.2010.06.007
Keristi S, Liu C, Ilton E, 2008, Molecular Dynamic Simulations of Orthoclase (001) and (010) Water Interface, Geochim. Cosmochim Acta, 72, 1481-1497
Liu C, Jeon BH, Zachara JM, Wang Z, 2007, Influence of Calcium on Microbial Reduction of Solid Phase Uranium(VI), Biotech. Bioeng. Vol 97, 1415-1422
Liu C, Jeon BH, Zachara JM, Wang Z, Dohnalkova A, Fredrickson JK, 2006, Kinetics of Microbial Reduction of Solid Phase U(VI), Environ. Sci. Technol., Vol 40, 6290-6296
Liu C, JM Zachara, L Zhong, SM Heald, Z Wang, BH Jeon, and JK Fredrickson. 2009. "Microbial Reduction of Intragrain U(VI) in Contaminated Sediment." Environmental Science & Technology 43(13):4928-4933. doi:10.1021/es8029208
Liu C, Zachara, JM, Qafoku NP, Wang Z, (2008) "Scale-dependent desorption of uranium from contaminated subsurface sediments. Water Resources Resarch, Vol 44, W08413, doi: 10.1029/2007WR006478, 2008