期刊
JOURNAL OF HYDROLOGY
卷 555, 期 -, 页码 278-287出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhydrol.2017.10.016
关键词
Hyporheic zone; Toxic metals; Cr(VI) retardation; Redox barrier; Biogeochemical reaction model
资金
- U.S. DOE, Office of Science, Biological and Environmental Research (BER) as part of the Subsurface Biogeochemical Research (SBR) Program through Pacific Northwest National Laboratory (PNNL) SBR Science Focus Area (SFA) Research Project
- National Natural Science Foundation of China [41502233, 41572228, 41521001]
- China Postdoctoral Science Foundation [2015 M582305]
- Southern University of Science and Technology [G01296001]
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. DOE'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 and immobilized by the HZ sediments in the presence/absence of O-2. 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 when exposed to O-2 under field-relevant pH (7.5) with and without dissolved Mn(II), which might be oxidized to form Mn(III/IV) oxides that may oxidize reduced Cr. 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. (C) 2017 Elsevier B.V. All rights reserved.
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