title: Coupled Hydro-Biogeochemical Processes Controlling Cr Reductive Immobilization in Columbia River Hyporheic Zone.
abstract: An experiment and modeling study was conducted to investigate coupled hydro-biogeochemical processes controlling reductive immobilization of groundwater Cr in the hyporheic zone (HZ) at the U.S. Department of Energy's Hanford Site, where dynamic surface water-groundwater exchange occurs on a daily basis. Experiments were performed to calibrate kinetic models, and the calibrated models were incorporated into a multicomponent reactive transport model to simulate Cr redox transformation and immobilization under field hydrological conditions. The results revealed that the rates of Cr(VI) reduction, Cr(III) accumulation, and Cr(VI) release to the river are mostly affected by dynamic sediment redox conditions represented by Fe(II) reactivity, which is controlled by its cyclic interaction with O2carried by river water, microbial activities, and the supply and bioavailability of organic carbon (OC) that is present in the HZ and/or carried by transport. In addition, the HZ geophysical properties including hydraulic conductivity and the thickness of the top alluvial layer have a significant influence on Cr reactive transport and immobilization by controlling residence times for reactions and the supply rates of O2, Cr, and OC into the HZ. The results provide important insights into the dynamic redox environments in the HZ that can reductively immobilize contaminants.
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.
authors.forename: Yuanyuan
authors.identifier: 0000-0001-6076-9733
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.|School of Environmental Studies, China University of Geosciences , Wuhan 430074, China.
authors.forename: Fen
authors.initials: F
authors.lastname: Xu
authors.affiliation: Pacific Northwest National Laboratory , Richland, Washington 99354, United States.|School of Environmental Science and Engineering, Southern University of Science and Technology , Shenzhen 518055, China.
authors.forename: Chongxuan
authors.identifier: 0000-0002-7403-6001
authors.initials: C
authors.lastname: Liu
mesh_terms: D005618:Fresh Water; D060587:Groundwater / Q000737:chemistry; D062070:Hydrology; D010084:Oxidation-Reduction; D045483:Rivers / Q000737:chemistry*; D014872:Water Movements