Redox transformation and reductive immobilization of Cr(VI) in the Columbia River hyporheic zone sediments

Journal Article · Fri Dec 01 04:00:00 EST 2017 · Journal of Hydrology

DOI:https://doi.org/10.1016/j.jhydrol.2017.10.016· OSTI ID:1427927

Xu, Fen; Liu, Yuanyuan; Zachara, John; Bowden, Mark; Kennedy, David; Plymale, Andrew E.; Liu, Chongxuan

An experimental and modeling study was conducted to investigate the redox transformation and reductive immobilization of groundwater contaminant Cr in hyporheic zone (HZ) sediments from U.S. Department of Energy’s Hanford site, where groundwater Cr(VI) is migrating and discharging to the nearby Columbia River. Experimental results revealed that Cr(VI) can be reduced to immobile reduced Cr by the HZ sediments in the presence/absence of O2. Anaerobic pre-incubation of the sediments increased the effective rate of Cr reduction that was correlated with the increase in HCl-extractable Fe(II) content in the sediments. The reduced Cr was stable in exposure to O2 under field-relevant pH (~7.5) and Mn-containing (~0.02% w/w) conditions. The Cr(VI) reduction rate showed a multi-rate behavior, apparently reflecting the presence of reductants with different reactivity in the sediments. The results from this study indicated that the HZ sediments can reductively immobilize Cr and the sediment redox capacity can be recharged through microbial activities. The results implied that HZ can play a role as a natural permeable redox barrier for removing groundwater Cr before it discharges into a river system.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1427927
• Report Number(s): PNNL-SA-130775; 49160; KP1702030
• Journal Information: Journal of Hydrology, Journal Name: Journal of Hydrology Journal Issue: C Vol. 555; ISSN 0022-1694
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

Environmental Molecular Sciences Laboratory