Multiple Effects of Humic Components on Microbially Mediated Iron Redox Processes and Production of Hydroxyl Radicals

Environmental Science & Technology, Год журнала: 2022, Номер 56(22), С. 16419 - 16427

Опубликована: Окт. 12, 2022

Microbially mediated iron redox processes are of great significance in the biogeochemical cycles elements, which often coupled with soil organic matter (SOM) environment. Although influences SOM fractions on individual reduction or oxidation have been studied extensively, a comprehensive understanding is still lacking. Here, using ferrihydrite, Shewanella oneidensis MR-1, and operationally defined components including fulvic acid (FA), humic (HA), humin (HM) extracted from black peat, we explored SOM-mediated microbial hydroxyl radical (•OH) production processes. The results showed that addition inhibited transformation ferrihydrite to highly crystalline oxides. FA HA increased Fe(II) over four times average due complexation their high electron exchange capacities, 30–43% •OH yield, while had no significant influence it. Superoxide (O2•–) was predominant intermediate FA-containing system, one- two-electron transfer were concurrent HA- HM-containing systems. These findings provide deep insights into multiple mechanisms regulating microbially production.

Язык: Английский

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Significant Contribution of Solid Organic Matter for Hydroxyl Radical Production during Oxygenation

Environmental Science & Technology, Год журнала: 2022, Номер 56(16), С. 11878 - 11887

Опубликована: Авг. 8, 2022

Dark formation of hydroxyl radicals (•OH) from soil/sediment oxygenation has been increasingly reported, and solid Fe(II) is considered as the main electron donor for O2 activation. However, role organic matter (SOM) in •OH production not clear, although it represents an important pool subsurface. In this study, reduced humic acid (HAred) was investigated at pH 7.0. linearly correlated with electrons released HAred suspension. Solid transferred rapidly to via surface-reduced moieties (hydroquinone groups), which fueled by slow transfer inside HA. Cycling dissolved HA between oxidized states could mediate enhancement. Modeling results predicted that SOM played or even dominant soils sediments possessing high molar ratios SOC/Fe(II) (e.g., >39). The significant contribution further validated modeling 88 soils/sediments literature. Therefore, should be carefully comprehensively understand SOM-rich subsurface environments.

Язык: Английский

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Insight into the Photodegradation of Microplastics Boosted by Iron (Hydr)oxides

Environmental Science & Technology, Год журнала: 2022, Номер 56(24), С. 17785 - 17794

Опубликована: Дек. 6, 2022

Iron (hydr)oxides as a kind of natural mineral actively participate in the transformation organic pollutants, but there is large knowledge gap their impacts on photochemical processes microplastics (MPs). This study first to examine degradation two ordinary plastic materials, polyethylene (PE) and polypropylene (PP), mediated by iron (goethite hematite) under simulated solar light irradiation. Both significantly promoted MPs (particularly PP) with greater effect goethite than hematite, related hydroxyl radical (•OH) produced (hydr)oxides. Under irradiation, surface Fe(II) phase catalyzed production H2O2 release Fe2+, leading subsequent light-driven Fenton reaction which amount •OH. As were modified NaF at various concentrations, activity well Fe2+ greatly reduced, thus •OH formation MP depressed remarkably. It worth noting that groups (especially ≡FeOH) affected kinetics regulating Fe species. These findings unveil distinct intrinsic mechanisms influencing photodegradation MPs.

Язык: Английский

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Microscale Spatiotemporal Variation and Generation Mechanisms of Reactive Oxygen Species in the Rhizosphere of Ryegrass: Coupled Biotic–Abiotic Processes

Environmental Science & Technology, Год журнала: 2022, Номер 56(22), С. 16483 - 16493

Опубликована: Ноя. 3, 2022

Reactive oxygen species (ROS) play key roles in soil biogeochemical processes, yet the occurrence and accumulation of ROS rhizosphere are poorly documented. Herein, we first developed a ROS-trapping membrane to situ determine ryegrass then quantified temporal spatial variations representative (i.e., O2•─, H2O2, •OH). Fluorescence imaging clearly visualized production rhizosphere. Both O2•─ H2O2 content increased declined throughout life cycle ryegrass, while •OH concentration decreased continuously. Spatially, contents remained at relatively high level 0-5 mm descended with increasing distance. The concentrations different soils followed order black > latosol yellow-brown tier ∼ red soil. Analysis properties suggested that both biotic factors (microbial community) abiotic (Fe(II) water-soluble phenols) played critical production. combined including Fe(II) phenol-mediated electron transfer, microbial community-driven extracellular release, Fe(II)/Fe(III) cycling, may be responsible for These findings provide insights into ROS-associated effects inspiration phytoremediation pollutants element cycling.

Язык: Английский

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Hydroxyl radical formation during oxygen-mediated oxidation of ferrous iron on mineral surface: Dependence on mineral identity

Journal of Hazardous Materials, Год журнала: 2022, Номер 434, С. 128861 - 128861

Опубликована: Апрель 5, 2022

Язык: Английский

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Dynamic Production of Hydroxyl Radicals during the Flooding–Drainage Process of Paddy Soil: An In Situ Column Study

Environmental Science & Technology, Год журнала: 2023, Номер 57(43), С. 16340 - 16347

Опубликована: Окт. 19, 2023

Frequent cycles of flooding and drainage in paddy soils lead to the reductive dissolution iron (Fe) minerals reoxidation Fe(II) species, all while generating a robust consistent output reactive oxygen species (ROS). In this study, we present comprehensive assessment temporal spatial variations Fe ROS during flooding-drainage process representative soil. Our laboratory column experiments showed that decrease dissolved O2 concentration led rapid reduction below water-soil interface, aqueous was transformed into solid phases over an extended time. As result, •OH production capacity liquid reduced improved. The increased from 227-271 μmol kg-1 (within 1-11 cm depth) 500-577 499-902 after 50 day, 3 month, 1 year incubation, respectively. During drainage, dynamic triggered by consumption oxidation. ROS-trapping film situ capture revealed soil surface active zone for intense H2O2 production, limited observed deeper layers (>5 cm) due penetration. These findings provide more insights complex interplay between cycling redox transition zones fields.

Язык: Английский

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Kinetic models for hydroxyl radical production and contaminant removal during soil/sediment oxygenation

Water Research, Год журнала: 2023, Номер 240, С. 120071 - 120071

Опубликована: Май 15, 2023

Язык: Английский

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Amendment of organic acids significantly enhanced hydroxyl radical production during oxygenation of paddy soils

Journal of Hazardous Materials, Год журнала: 2023, Номер 457, С. 131799 - 131799

Опубликована: Июнь 8, 2023

Язык: Английский

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Electron transfer processes associated with structural Fe in clay minerals

Critical Reviews in Environmental Science and Technology, Год журнала: 2023, Номер 54(1), С. 13 - 38

Опубликована: Июнь 16, 2023

Fe-bearing clay minerals are widely distributed in soils, sediments, and rocks, representing a significant Fe pool the Earth's crust. The electron transfer (ET) from/to structural is crucial energy flux natural environment, which drives numerous biogeochemical processes contaminant transformation. Depending on types properties of both exogenous reactants as well aqueous chemistry, ET could involve interfacial through edge/basal planes interior inside minerals. This paper reviews important reactions between various reactants, including Fe-cycling microbes, redox-active organic compounds, heavy metals. Moreover, we discuss physical-chemical mechanisms develop models to illustrate thermodynamic kinetic constraints rate extent. On this basis, emphasize environmental implications associated with minerals, such their roles serving biogeobatteries for transformation, coevolution regulation greenhouse gas formation. Finally, research needs proposed advance our molecular-scale understanding utilize them mitigation human health.

Язык: Английский

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Critical Role of Mineral Fe(IV) Formation in Low Hydroxyl Radical Yields during Fe(II)-Bearing Clay Mineral Oxygenation

Environmental Science & Technology, Год журнала: 2024, Номер 58(22), С. 9669 - 9678

Опубликована: Май 21, 2024

In subsurface environments, Fe(II)-bearing clay minerals can serve as crucial electron sources for O2 activation, leading to the sequential production of O2•–, H2O2, and •OH. However, observed •OH yields are notably low, underlying mechanism remains unclear. this study, we investigated oxidants from oxygenation reduced Fe-rich nontronite NAu-2 Fe-poor montmorillonite SWy-3. Our results indicated that dependent on mineral Fe(II) species, with edge-surface exhibiting significantly lower compared those interior Fe(II). Evidence in situ Raman Mössbauer spectra chemical probe experiments substantiated formation structural Fe(IV). Modeling elucidate pathways Fe(IV) respectively consume 85.9–97.0 14.1–3.0% electrons H2O2 decomposition during oxygenation, Fe(II)edge/Fe(II)total ratio varying 10 90%. Consequently, these findings provide novel insights into low different minerals. Since selectively degrade contaminants (e.g., phenol), generation should be taken consideration carefully when assessing natural attenuation redox-fluctuating environments.

Язык: Английский

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