DOI: 10.1016/j.watres.2018.12.040
Scopus记录号: 2-s2.0-85060254955
论文题名: Uranium storage mechanisms in wet-dry redox cycled sediments
作者: Noël V. ; Boye K. ; Kukkadapu R.K. ; Li Q. ; Bargar J.R.
刊名: Water Research
ISSN: 431354
出版年: 2019
起始页码: 251
结束页码: 263
语种: 英语
英文关键词: Contaminant release-trapping cycling
; Groundwater quality
; Sediment-water interaction
; U mobility
; Wet-dry redox cycling
Scopus关键词: Biogeochemistry
; Digital storage
; Groundwater
; Groundwater pollution
; Organic carbon
; Organic minerals
; Oxidants
; Oxidation
; Sols
; Water quality
; Contaminant release
; Hydrological condition
; Hydrological variability
; Microbial activities
; Redox cycling
; Seasonal fluctuations
; Water interactions
; Water table fluctuations
; Oxic sediments
; ground water
; iron
; sulfur
; surface water
; uranium
; evapotranspiration
; fine grained sediment
; hydrological cycle
; moisture content
; oxidation
; pollutant transport
; radionuclide
; seasonal variation
; sediment-water interface
; uranium
; water quality
; water table
; Article
; controlled study
; evapotranspiration
; moisture
; oscillation
; oxidation
; oxidation reduction reaction
; priority journal
; recycling
; sediment
; solubility
; water table
; Colorado Basin [North America]
英文摘要: Biogeochemical redox processes that govern radionuclide mobility in sediments are highly sensitive to forcing by the water cycle. For example, episodic draining and intrusion of oxidants into reduced zones during dry seasons can create biogeochemical seasonal hotspots of enhanced and changed microbial activity, affect the redox status of minerals, initiate changes in sediment gas and water transport, and stimulate the release of organic carbon, iron, and sulfur by oxidation of solid reduced species to aqueous oxic species. In the Upper Colorado River Basin, water-saturation of organic-enriched sediments locally promotes reducing conditions, denoted ‘Naturally Reduced Zones’ (NRZs), that accumulate strongly U(IV)sol. Subsequently, fluctuating hydrological conditions introduce oxidants, which may reach internal portions of these sediments and reverse their role to become secondary sources of Uaq. Knowledge of the impact of hydrological variability on the alternating import and export of contaminants, including U, is required to predict contaminant mobility and short- and long-term impacts on water quality. In this study, we tracked U, Fe, and S oxidation states and speciation to characterize the variability in redox processes and related Usol solubility within shallow fine-grained NRZs at the legacy U ore processing site at Shiprock, NM. Previous studies have reported U speciation and behavior in permanently saturated fine-grained NRZ sediments. This is the first report of U behavior in fine-grained NRZ-like sediments that experience repeated redox cycling due to seasonal fluctuations in moisture content. Our results support previous observations that reducing conditions are needed to accumulate Usol in sediments, but they counter the expectation that Usol predominantly accumulates as U(IV)sol; our data reveal that Usol may accumulate as U(VI)sol in roughly equal proportion to U(IV)sol. Surprisingly high abundances of U(VI)sol confined in transiently saturated fine-grained NRZ-like sediments suggest that redox cycling is needed to promote its accumulation. We propose a new process model, where redox oscillations driven by annual water table fluctuations, accompanied by strong evapotranspiration in low-permeability sediments, promote conversion of U(IV)sol to relatively immobile U(VI)sol, which suggests that Usol is accumulating in a form that is resistant to redox perturbations. This observation contradicts the common idea that U(IV)sol accumulated in reducing conditions is systematically re-oxidized, solubilized and transported away in groundwater. © 2019 Elsevier Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/122002
Appears in Collections: 气候变化事实与影响
There are no files associated with this item.
作者单位: Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, United States; Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, United States; Department of Environmental Earth System Science, Stanford University, Stanford, CA 94305, United States
Recommended Citation:
Noël V.,Boye K.,Kukkadapu R.K.,et al. Uranium storage mechanisms in wet-dry redox cycled sediments[J]. Water Research,2019-01-01