Oxidation and reduction of redox-sensitive elements in the presence of humic substances in subsurface environments: A review

Lee, Seyong; Roh, Young-Hee; Koh, Dong‐Chan

doi:10.1016/j.chemosphere.2018.11.143

Cited by 47 publications

(19 citation statements)

References 167 publications

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“…Our study does not indicate a rate‐limiting step for the native HA at the concentrations tested, though there was an apparent rate‐limiting step involving the transfer of electrons from reduced AQDS (i.e., AHDS) to Fe(III) in the soil. We speculate that our native HA treatment overcame such reduction‐rate limitations by having a higher aromatic C content compared to the Elliott soil HA standard tested in the previous study (Ratasuk and Nanny, 2007; Lee et al, 2018, 2019), and by being more effective than AQDS at undergoing exchange and/or complexation with Fe(II) adsorbed to partially reduced Fe(III) minerals (Rakshit et al, 2009). By comparison, AQDS has not been shown to have such an affinity for adsorbed Fe(II) (Lovley et al, 1996; Lee et al, 2019).…”

Section: Resultsmentioning

confidence: 94%

“…We speculate that our native HA treatment overcame such reduction‐rate limitations by having a higher aromatic C content compared to the Elliott soil HA standard tested in the previous study (Ratasuk and Nanny, 2007; Lee et al, 2018, 2019), and by being more effective than AQDS at undergoing exchange and/or complexation with Fe(II) adsorbed to partially reduced Fe(III) minerals (Rakshit et al, 2009). By comparison, AQDS has not been shown to have such an affinity for adsorbed Fe(II) (Lovley et al, 1996; Lee et al, 2019). In our experiment, removal of Fe(II) from mineral surfaces by exchange and/or complexation with native HA during Fe(III) reduction would have allowed more continuous electron transfer without a rate‐limiting step, because HA‐catalyzed Fe(III) reduction could have proceeded as long as accumulating Fe(II) (which impedes addition of electrons to Fe[III] minerals) was simultaneously removed from Fe(III)‐mineral surfaces by native HA.…”

Section: Resultsmentioning

confidence: 94%

“…Taken together, our data imply that native HA (or, more generally, soil‐derived humic substances) can outcompete more soluble, lower‐molecular‐weight electron‐shuttling compounds that lack carboxyl groups (e.g., AQDS) in systems that contain heterogeneous solid electron acceptors (e.g., Fe[III] minerals) like those found in natural soils and sediments. Further, considering that the specific bonding environment near redox‐sensitive functional groups (e.g., quinones and condensed aromatics) can alter the electron‐shuttling properties of HA (Ratasuk and Nanny, 2007; Lee et al, 2019), our data suggest that a combination of higher proportions of aromatic C (with more H‐bonds than O‐bonds) and amino acid C may increase both the electron‐shuttling capacity and efficiency of native humic substances during microbial Fe(III) reduction in the environment. These combined properties of native HA compared with AQDS likely contributed to the higher rates of CO 2 emission, microbial Fe(III) reduction, and P solubilization observed in our study.…”

Section: Resultsmentioning

confidence: 99%

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Humic Acid Buildup Increases Carbon Dioxide Emissions from Redox‐Oscillating Upland Soils while Catalyzing Iron(III) Reduction and Phosphorus Desorption

2019

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Humic substances comprise chemically and physically complex forms of organic C that are recognized to be involved in the catalytic cycling of electrons in diverse biogeochemical reactions. Recent investigations have indicated that humic substances existing in redox-dynamic terrestrial environments, such as intermittently wet soils, may be uniquely important for regulating greenhouse gas emissions. However, many relevant studies have relied on the use of commercially available humic substances and/or synthetic humic analogs. In the present study, during a 42-d anoxic incubation, we investigated the regulatory and catalytic effects of increasing concentrations of site-specific (i.e., native) humic acid (HA) in an Appalachian upland soil known to experience redox-oscillating conditions in the field. Extracted native HA was characterized using 13 C nuclear magnetic resonance ( 13 C-NMR), Fourier transformed infrared (FT-IR), and total CHNS elemental analyses. We found that native HA was relatively enriched in aromatic and amino acid C. Increasing concentrations of native HA added at the start of soil incubations led to higher rates of CO 2 emission and microbial Fe(III) reduction, indicating that a buildup of soil HA allows for a greater number of electrons to shuttle between Fe(III) reducers and Fe(III) electron acceptors during microbial oxidation of organic C. Treatments with native HA were also compared against a synthetic HAanalog treatment containing 0.2 g anthraquinone-2,6-disulfonic acid (AQDS) kg −1 dry soil to investigate catalytic electron cycling by native HA and AQDS. Our data suggest that the buildup of native humic substances, which are relatively rich in aromatic and amino acid C, leads to globally relevant increases in CO 2 emissions, the redox cycling of Fe, and the availability of organic P after transition to anaerobic conditions in upland soils.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

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Humic Acid Buildup Increases Carbon Dioxide Emissions from Redox‐Oscillating Upland Soils while Catalyzing Iron(III) Reduction and Phosphorus Desorption

2019

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“…This uptake varied significantly according to the type of the organic treatment, with a trend similar to that recorded in P-availability. Humic substances are reported to increase apoplast acidification [56] and act as effective redox mediators [57,58] that decrease P-precipitation via changing phosphate species into diprotonated monodentate mononuclear complexes [25]. Though, plants might not be efficient enough to extract P from their organic complexes, probably because P existed in esaphosphate inositol (high-molecular fractions) in soil [55].…”

Section: Availability and Uptake Of Pmentioning

confidence: 99%

Organic Materials and Their Chemically Extracted Humic and Fulvic Acids as Potential Soil Amendments for Faba Bean Cultivation in Soils with Varying CaCO3 Contents

et al. 2021

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Organic amendments are important sources of nutrients that release upon organic matter degradation, yet the stability of these organics in arid and semi-arid regions is relatively low. In contrast, humic substances (HS) are resistant to biodegradation and can keep nutrients in the soil available for the plant over a long time. Combinations between humic substances (HS) and mineral-N fertilizers are assumed to retain higher available nutrients in soils than those recorded for the sole application of either mineral or organic applications. We anticipate, however, that humic substances might not be as efficient as the organics from which they were extracted in increasing NP uptake by plants. To test these assumptions, faba bean was planted in a pot experiment under greenhouse conditions following a complete randomized design while considering three factors: two soils (calcareous and non-calcareous, Factor A), two organics (biogas and compost, Factor B) and combinations of the organics and their extracts (HA or FA) together with complementary doses of mineral-N ((NH4)2SO4) to attain a total rate of 50 kg N ha−1 (the recommended dose for faba bean plants) (Factor C). Results indicated that nitrogenase activity increased significantly due to the application of the used organics. In this respect, compost manure caused higher nitrogenase activity than biogas manure did. Humic substances raised NP-availability and the uptake by plants significantly; however, the values of increase were lower than those that occurred due to the compost or biogas manure. Moreover, the sole application of the used organics recorded the highest increases in plant biomass. Significant correlations were also detected between NP-availability, uptake and plant biomass. This means that HS could probably retain nutrients in available forms for long time periods, yet nutrients released continuously but slowly upon decomposition of organics seemed more important for plant nutrition.

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“…[10][11][12][13] HA consists of a skeleton of aliphatic or aromatic units cross-linked primarily via all sorts of oxygencontaining functional groups, allures to consider it as a new type of charring agent due to its carbon-enriched chemical composition. [14] For example, Yin et al synthesized high-quality activated carbons (ACs) from HA with a well-pleasing carbonaceous precursor to apply them in supercapacitors. [ 10] Xing et al synthesized graphene nanosheets with interconnected mesoporous structure and oxygen-containing functional groups from HA.…”

Section: Introductionmentioning

confidence: 99%

Preparation of novel biomass humate flame retardants and their flame retardancy in epoxy resin

Liu

Shi

Kundu

et al. 2020

J of Applied Polymer Sci

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Humic acid (HA), a biomass material with plentiful oxygen‐containing functional groups, showed huge potential to be considered as a promising charring agent in flame retardancy. In this study, this HA was modified with four different metal ions like Fe2+, Mn2+, Al3+, and Cu2+ and finally, introduced into the epoxy resin (EP) to enhance the flame retardancy of the EP and the dispersion of these flame retardants into the EP matrix. When 10 wt% of HA‐Fe and HA‐Mn were incorporated into EP matrix, the limiting oxygen index (LOI) was increased from 21.2% for EP to 26.6 and 25.3% for the EP composites and the peak heat release rate (pHRR) was reduced by 36 and 35.5%, respectively. Such a significant improvement in flame retardancy was attributed to the catalytic charring of HA in the presence of metal ions, which ultimately increased the residual char formation and produced compact char layers during the combustion process to retard the transfer of heat and combustible gases between the EP composites and the flame zone. Finally, this kind of application provided a feasible way for the development of an environmentally friendly flame retardant with high efficiency, which improved the fire safety of EP matrix.

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Oxidation and reduction of redox-sensitive elements in the presence of humic substances in subsurface environments: A review

Cited by 47 publications

References 167 publications

Humic Acid Buildup Increases Carbon Dioxide Emissions from Redox‐Oscillating Upland Soils while Catalyzing Iron(III) Reduction and Phosphorus Desorption

Humic Acid Buildup Increases Carbon Dioxide Emissions from Redox‐Oscillating Upland Soils while Catalyzing Iron(III) Reduction and Phosphorus Desorption

Organic Materials and Their Chemically Extracted Humic and Fulvic Acids as Potential Soil Amendments for Faba Bean Cultivation in Soils with Varying CaCO3 Contents

Preparation of novel biomass humate flame retardants and their flame retardancy in epoxy resin

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