The effects of electron shuttles (biochar/anthraquinone-2,6-disulphonate (AQDS)) on the process of the Shewanella oneidensis MR-1-induced As(V)-adsorbed ferrihydrite reduction were studied. The results showed that biochar could stimulate Fe(Ⅱ) and As release during the ferrihydrite bioreduction. After the addition of biochar, more dissolved organic matter (DOM) can be consumed as an electron donor to promote the metabolism of microorganisms by the fluorescence excitation-emission matrix spectra analysis. After microbial treatment, cyclic voltammetry (CV) showed that a unique cathodic peak and a distinct anodic peak appeared, which may represent the reduction of Fe(OH) to Fe(OH) and the complexed oxidation of Fe to Fe. No characteristic peak was associated with arsenate reduction or arsenite oxidation. The mineralogical characterization of the final products indicated that AQDS can promote solid-state conversion from ferrihydrite to vivianite (Fe(PO)·8HO). However, the addition of biochar inhibited solid-state conversion of ferrihydrite. It was shown that after 6 d, the secondary mineral vivianite production in the bacteria alone and AQDS treatments was 8.12% and 15.6% respectively by mössbauer spectroscopy analysis. Moreover, the XPS indicated that As(V) has no species transformation. It provided new data for understanding the iron-reducing bacteria induced mineralization process and related biogeochemical cycles of Fe and As.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121391 | DOI Listing |
Water Res
January 2025
Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China. Electronic address:
Anoxygenic photosynthetic bacteria (APB) have been frequently detected as a photoautotrophic Fe-carbon cycling drivers in photic and anoxic environment. However, the potential capacity of these bacteria for photoheterotrophic extracellular reduction of iron-containing minerals and their impact on the transformation of organic pollutants remain currently unknown. This study investigated the capacity of R.
View Article and Find Full Text PDFEnviron Pollut
December 2024
State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
The sulfate-reducing bacteria (SRB)-induced ferrihydrite transformation is an important cause for arsenic (As) contamination in the aquifer near mining area. Calcium carbonate (CaCO) is widespread and has the potential of regulating As fate directly or indirectly. However, the influence of CaCO on ferrihydrite transformation and the associated As mobilization/redistribution in SRB-containing environments remains unclear.
View Article and Find Full Text PDFSci Total Environ
January 2025
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
Despite many studies on the environmental cycling of As, Fe, and S, sulfide (S(-II))-induced hydrous ferric arsenate (HFA) transformation remains to be elucidated. Herein, we investigated the anaerobic reaction of HFA with S(-II) at three environmental concentrations (1, 10, and 50 mM) at pH 48. Changes in solid-phase As, Fe, and S speciation were investigated by XRD, FTIR, Raman, XPS, synchrotron XANES, SEM, and TEM.
View Article and Find Full Text PDFGeobiology
December 2024
Géosciences Montpellier, CNRS, Université de Montpellier, Montpellier, France.
Banded iron formations (BIFs) are chemical sedimentary rocks commonly utilized for exploring the chemistry and redox state of the Precambrian ocean. Despite their significance, many aspects regarding the crystallization pathways of iron oxides in BIFs remain loosely constrained. In this study, we combine magnetic properties characterization with high-resolution optical and electron imaging of finely laminated BIFs from the 2.
View Article and Find Full Text PDFSci Total Environ
January 2025
Department of Biological, Geological and Environmental Sciences - BiGeA, Alma Mater Studiorum University of Bologna, Via Zamboni 67, 40126 Bologna, Italy.
This study investigates the impact of intense rainfall on chromium concentrations in five springs discharging from ultramafic rocks in the Northern Apennines (Italy), which are used for drinking water supply through integration into the local water network. Total chromium concentration increased significantly in response to heavy rain, exceeding the WHO drinking water guideline value (up to 80 μg/L) in one spring and the forthcoming 2036 EU target of 25 μg/L in all the springs. This increase could be attributed to a synergistic combination of factors: i) the reduction of Cr(VI) to Cr(III) by natural organic matter (NOM) in soil and transport as NOM-Cr(III) colloids and/or during the oxidation of magnetite to ferrihydrite in the aquifer; ii) the abundance of detrital ultramafic material in the study area, which may store Cr(III)-bearing colloids too; iii) a triggering effect of first intense rainfall after a 20 dry consecutive days period (wet-dry cycle).
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