Open AccessCoupled Hydro-Biogeochemical Processes Controlling Cr Reductive Immobilization in Columbia River Hyporheic Zone
Author(s) -
Yuanyuan Liu,
Fen Xu,
Chongxuan Liu
Publication year - 2017
Publication title -
environmental science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.851
H-Index - 397
eISSN - 1520-5851
pISSN - 0013-936X
DOI - 10.1021/acs.est.6b05099
Subject(s) - biogeochemical cycle , hyporheic zone , redox , groundwater , environmental chemistry , aquifer , sediment , environmental science , chemistry , surface water , hydrology (agriculture) , environmental engineering , geology , geomorphology , inorganic chemistry , geotechnical engineering
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 O 2 carried 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 O 2 , Cr, and OC into the HZ. The results provide important insights into the dynamic redox environments in the HZ that can reductively immobilize contaminants.