Natural attenuation mechanism of hexavalent chromium in a wetland: Zoning characteristics of abiotic and biotic effects

Jiang, Kaidi; Zhang, Jia; Deng, Zongquan; Barnie, Samuel; Chang, Jingjie; Zou, Yawen; Guan, Xiangyu; Liu, Fei; Chen, Honghan

doi:10.1016/j.envpol.2021.117639

Cited by 22 publications

(8 citation statements)

References 45 publications

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“…Previous studies found that about 0–3 m thick LPZ (hydraulic conductivity, K , of ∼4 m/day) along the river bank has the redox potential to reduce Cr(VI) to Cr(III) naturally. , The oxidation–reduction potential (ORP) values in such a LPZ was reported between −300 and −600 mV . The natural attenuation mechanism of Cr(VI) in LPZ included biotic and abiotic processes coordinated by microorganisms, organic carbon, and organic or inorganic reducing agents. ,, For example, in a southern Switzerland field, Cr(VI) in the LPZ was reduced undergoing natural reduction in the presence of 1–2% organic carbon, while in another chromate production site in China, Cr(VI) in the LPZ was reduced incompletely as a result of the deficiency of organic carbon (only 0.4–0.6%) . Reduced Cr(III) is stable in natural sediments under circumneutral pH conditions, unless oxidized by strong oxidants, like manganese oxide or KMnO 4 . , However, residual unreduced Cr(VI) in the LPZ can back diffuse to the adjacent zone, still posing as a potential long-term risk.…”

Section: Introductionmentioning

confidence: 99%

“…33 The natural attenuation mechanism of Cr(VI) in LPZ included biotic and abiotic processes coordinated by microorganisms, organic carbon, and organic or inorganic reducing agents. 4,21,34 For example, in a southern Switzerland field, Cr(VI) in the LPZ was reduced undergoing natural reduction in the presence of 1−2% organic carbon, 22 while in another chromate production site in China, Cr(VI) in the LPZ was reduced incompletely as a result of the deficiency of organic carbon (only 0.4−0.6%). 5 Reduced Cr(III) is stable in natural sediments under circumneutral pH conditions, unless oxidized by strong oxidants, like manganese oxide or KMnO 4 .…”

Section: Introductionmentioning

confidence: 99%

“…It is a primary component of chromite ore and is used in textile, tanning, and metal-finishing industries . As a result of mismanagement and/or accidents, Cr has been released in soils, sediment, groundwater, and surface water at many hazardous waste sites. − Dependent upon the redox and pH conditions, Cr(III) and Cr(VI) are the predominant oxidation states of Cr. For these two valence states, Cr(VI) is more toxic and more mobile than Cr(III) .…”

Section: Introductionmentioning

confidence: 99%

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Hydrologic and Biochemical Processes Controlling Chromium Immobilization in a Low-Permeability Groundwater Zone

Gong,

Liu,

et al. 2023

ACS Earth Space Chem.

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Experiments and modeling were performed to investigate the coupled hydrologic and biochemical processes that control chromium (Cr) immobilization in a low-permeability groundwater zone. Bench-top flow cells were packed with a watersaturated high-permeability zone (HPZ) overlying a low-permeability zone (LPZ). Cr(VI) was initially flushed into the LPZ to establish a reservoir of this contaminant. Next, the electron donor acetate and the bacterium Geobacter sulfurreducens were flushed into the HPZ; they mixed with Cr(VI) in the LPZ and promoted its reduction. Experimental depth profiles show that approximately 80% of Cr(VI) introduced to the flow cell was immobilized as Cr(III) over 180 h within a small region on either side of the HPZ−LPZ interface. Groundwater flow and reactive transport in the flow cell were simulated using MODFLOW and RT3D, respectively, with dual-Monod kinetics defined in the custom reaction module of RT3D. Modeling results adequately matched experimental data and were extended to simulate Cr(VI) fate in a numerical flow cell with the same dimensions but with the LPZ replaced by a diffusion-controlled lower permeability clay matrix. For this scenario, approximately 99% of Cr(VI) in the LPZ could eventually be immobilized as Cr(III); this primarily occurred in the LPZ and mitigated Cr(VI) back diffusion to the HPZ. Overall, results from this work support acetate amendment to HPZs as an effective strategy to trap Cr(III) in LPZs and mitigate back diffusion of Cr(VI) into adjacent HPZs of a groundwater aquifer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrologic and Biochemical Processes Controlling Chromium Immobilization in a Low-Permeability Groundwater Zone

Gong,

Liu,

et al. 2023

ACS Earth Space Chem.

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“…Carbon addition causes an increase in growth rates of indigenous bacteria that are able to directly reduce Cr(VI) biologically, through the production of chromate reductase [29][30][31][32] and the development of anaerobic conditions that result in the production of Fe +2 by iron reducing bacteria, which chemically reduces Cr(VI) to Cr(III) [33][34][35]. Thus by cycling minor amounts of iron, a significant amount of Cr(VI) could potentially be reduced to Cr(III) [36][37][38][39]. Therefore, stimulation of anaerobic processes in situ can be an effective treatment alternative for Cr(VI)-polluted waters and has the potential for widespread application.…”

Section: Introductionmentioning

confidence: 99%

Biotic and Abiotic Biostimulation for the Reduction of Hexavalent Chromium in Contaminated Aquifers

Galani

Mamais

Noutsopoulos

et al. 2022

Water

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Hexavalent chromium is a carcinogenic heavy metal that needs to be removed effectively from polluted aquifers in order to protect public health and the environment. This work aims to evaluate the reduction of Cr(VI) to Cr(III) in a contaminated aquifer through the stimulation of indigenous microbial communities with the addition of reductive agents. Soil-column experiments were conducted in the absence of oxygen and at hexavalent chromium (Cr(VI)) groundwater concentrations in the 1000–2000 μg/L range. Two carbon sources (molasses and EVO) and one iron electron donor (FeSO4·7H2O) were used as ways to stimulate the metabolism and proliferation of Cr(VI) reducing bacteria in-situ. The obtained results indicate that microbial anaerobic respiration and electron transfer can be fundamental to alleviate polluted groundwater from hazardous Cr(VI). The addition of organic electron donors increased significantly Cr(VI) reduction rates in comparison to natural soil attenuation rates. Furthermore, a combination of organic carbon and iron electron donors led to a longer life span of the remediation process and thus increased total Cr(VI) removal. This is the first study to investigate biotic and abiotic Cr(VI) removal by conducting experiments with natural soil and by applying biostimulation to modify the natural existing microbial communities.

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“…Some relatively new approaches using nanotechniques and bioremediation have been considered more effective, low cost and eco-friendly(Younan et al 2016;Chen et al 2018). VI) by dissimilar iron-reducing bacteria was also found in some zones of those wetlands(Jiang et al 2021). The evidence for the natural attenuation of Cr(VI) in bedrock was reported in previous studies(Zhao et al 2015(Zhao et al , 2017, which reveals that Cr(VI) in porewater could be reduced by natural occurring reductants and form fresh Cr(III) precipitates in contaminated sandstone bedrock matrix.The transport of Cr(VI) is of importance for the Cr(VI) remediation.…”

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confidence: 99%

The changes of chromium speciation in limestone samples during simulated natural attenuation processes

Zhao

Zhang

Liu

et al. 2022

Preprint

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To study the Cr(VI) natural attenuation processes, Cr(VI) diffusion-reaction experiments for limestone samples were conducted. After experiments, synchrotron radiation µ-XRF maps showed that for organic-rich limestone samples, most of Cr distributed close to the surface, and some high Cr spots were found to be associated with organic matters; whereas, Cr distributed evenly in the samples containing low organic matter. These results indicate that Cr(VI) reacts with organic matter in the fractures and pore space of organic-rich limestone samples, and the reducing products (Cr(III) precipitates) might aggregate and block the pore throats, which might retard the further diffusion of Cr(VI) into the rock matrix. The distributions of Cr chemical forms, which were obtained by X-ray absorption near-edge structure (XANES) spectroscopy, showed that for organic-rich limestone samples, the Cr(OH)3 fraction in the center was higher than that on the surface, whereas, for the samples containing low organic matter, no such significant difference was found. One possible explanation for these findings is that in organic-rich limestone samples, the Cr(III) hydroxides, which aggregate in the zones close to the surface, might age and transform from crystalline to the stable chemical forms of Cr(III) oxyhydroxide or even Cr(III) oxides, which could enhance the effect of Cr(VI) natural attenuation. By using synchrotron radiation based techniques, this work provides a feasible way to investigate the changes of chromium chemical forms during its diffusion-reaction processes in rock samples and can be used to study the mechanism of Cr(VI) natural attenuation.

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Natural attenuation mechanism of hexavalent chromium in a wetland: Zoning characteristics of abiotic and biotic effects

Cited by 22 publications

References 45 publications

Hydrologic and Biochemical Processes Controlling Chromium Immobilization in a Low-Permeability Groundwater Zone

Hydrologic and Biochemical Processes Controlling Chromium Immobilization in a Low-Permeability Groundwater Zone

Biotic and Abiotic Biostimulation for the Reduction of Hexavalent Chromium in Contaminated Aquifers

The changes of chromium speciation in limestone samples during simulated natural attenuation processes

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