Visualization and quantification of carbon “rusty sink” by rice root iron plaque: Mechanisms, functions, and global implications

Liang, Wei; Zhu, Zhenke; Razavi, Bahar S.; Xiao, Mouliang; Dorodnikov, Maxim; Fan, Lichao; Yuan, Hang; Yurtaev, Andrey; Luo, Yu; Cheng, Weiguo; Kuzyakov, Yakov; Wu, Jinshui; Ge, Tida

doi:10.1111/gcb.16372

Cited by 32 publications

(15 citation statements)

References 86 publications

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“…Along with the decrease in DOM concentration, most of the measured soil physicochemical variables exhibited significant relationships with DOM properties and biodegradability possibly due to their complex interactions (Table S5). Similarly, previous researches have also reported DOM properties to be affected by these edaphic variables, including SOM concentration (Camino‐Serrano et al, 2018), nutrient supply (Chen et al, 2014; Guigue et al, 2015), pH (Kang et al, 2018), and minerals (Chen et al, 2022; Wei et al, 2022). However, only DCo, Fe(II), ratios of Fe(II)/Fe(III), and OM‐Fe had significant independent impacts on DOM quality; among which, oxygen availability was the most important (Figure 7a,b).…”

Section: Discussionmentioning

confidence: 62%

Oxygen availability regulates the quality of soil dissolved organic matter by mediating microbial metabolism and iron oxidation

Chen

et al. 2022

Global Change Biology

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Dissolved organic matter (DOM) plays a vital role in biogeochemical processes and in determining the responses of soil organic matter (SOM) to global change. Although the quantity of soil DOM has been inventoried across diverse spatio-temporal scales, the underlying mechanisms accounting for variability in DOM dynamics remain unclear especially in upland ecosystems. Here, a gradient of SOM storage across 12 croplands in northeast China was used to understand links between DOM dynamics, microbial metabolism, and abiotic conditions. We assessed the composition, biodegradability, and key biodegradable components of DOM. In addition, SOM and mineral-associated organic matter (MAOM) composition, soil enzyme activities, oxygen availability, soil texture, and iron (Fe), Fe-bound organic matter, and nutrient concentrations were quantified to clarify the drivers of DOM quality (composition and biodegradability). The proportion of biodegradable DOM increased exponentially with decreasing initial DOM concentration due to larger fractions of depolymerized DOM that was rich in small-molecular phenols and proteinaceous components.Unexpectedly, the composition of DOM was decoupled from that of SOM or MAOM, but significantly related to enzymatic properties. These results indicate that microbial metabolism exhibited a dominant role in DOM generation. As DOM concentration declined, increased soil oxygen availability regulated DOM composition and enhanced its biodegradability mainly through mediating microbial metabolism and Fe oxidation.The oxygen-induced oxidation of Fe(II) to Fe(III) removed complex DOM compounds with large molecular weight. Moreover, increased oxygen availability stimulated oxidase-catalyzed depolymerization of aromatic substances, and promoted production of protein-like DOM components due to lower enzymatic C/N acquisition ratio.As global changes in temperature and moisture will have large impacts on soil oxygen availability, the role of oxygen in regulating DOM dynamics highlights the importance of integrating soil oxygen supply with microbial metabolism and Fe redox status to improve model predictions of soil carbon under climate change.

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Section: Discussionmentioning

confidence: 62%

Oxygen availability regulates the quality of soil dissolved organic matter by mediating microbial metabolism and iron oxidation

Chen

et al. 2022

Global Change Biology

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“…The C-related enzymes (β-glucosidase and xylanase) were measured using zymography imaging, which is based on fluorescent substrates and can acquire the 2D distribution of soil/sediment enzyme activity in situ . , The substrates used in this study were 4-methylumbelliferyl-β- d -glucoside for β-glucosidase and 4-methylumbelliferyl-β- d -xylopyranoside for xylanase . The membrane preparation, calibration, application, and data processing are described in Text S2.…”

Section: Methodsmentioning

confidence: 99%

“…19−21 Overall, the carbon pool of the rhizosphere is strongly affected by Fe oxidation−carbon sequestration and Fe reduction−carbon mineralization, and the influencing factors include radial oxygen loss (ROL), root exudates, the microbial community, manganese, etc. 14,22 Although the closely coupled cycling of Fe and C in the rhizosphere of wetland plants has been studied, [9][10][11]19 our understanding in the context of submerged plants is lacking. The ROL of submerged plants strongly influences the surrounding sediments, which may lead to the particularity of the C cycling.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Although the closely coupled cycling of Fe and C in the rhizosphere of wetland plants has been studied, − , our understanding in the context of submerged plants is lacking. The ROL of submerged plants strongly influences the surrounding sediments, which may lead to the particularity of the C cycling. ,, Previous studies have tended to focus on the rusty sink rather than observing carbon mineralization processes, such as the release of CO 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Iron (Fe) oxides serve as an rusty sink that can protect organic carbon (OC) from decomposition through the formation of Fe–OC complexes. − However, Fe oxides can serve as terminal electron acceptors in microbially mediated dissimilatory Fe(III) reduction in anaerobic or alternating redox environments, leading to the release of Fe-bound OC. − Additionally, Fe(II) can react with H 2 O 2 to generate the reactive oxygen species that can enhance the oxidation of OC. , The rhizosphere of plants under short-term or long-term flooding is a typical environment in which these dual roles of Fe oxides may coexist. − Plants growing under flooding conditions can deliver O 2 from the shoot to the root and soil/sediment, thereby promoting the formation of Fe oxides and Fe–OC complexes in the rhizosphere. , The Fe oxides commonly precipitate on the root surface, which are termed Fe plaques. , In addition, the input of labile root exudates and other less decomposable rhizodeposits creates microbial hot spots in the rhizosphere. − As a result of accumulation of Fe oxide in the rhizosphere, the abundance of the microbial community and the dissimilatory Fe(III) reduction rates in the rhizosphere are relatively greater than in the bulk soil/sediment. − Overall, the carbon pool of the rhizosphere is strongly affected by Fe oxidation–carbon sequestration and Fe reduction–carbon mineralization, and the influencing factors include radial oxygen loss (ROL), root exudates, the microbial community, manganese, etc. , …”

Section: Introductionmentioning

confidence: 99%

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The Root Tip of Submerged Plants: An Efficient Engine for Carbon Mineralization

Zhong

Cai

Chen

et al. 2023

Environ. Sci. Technol. Lett.

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The cycling of iron (Fe) and carbon in the rhizosphere of submerged plants and the associated impact on organic carbon (OC) sequestration are poorly understood. We detected the spatiotemporal distribution of CO2 using a planar optode in the rhizosphere of a common submerged plant as an indicator of OC mineralization. We found that the rhizosphere was a hot spot of CO2 and that the CO2 concentration decreased rapidly from the root tip zone (maximum of 19.68 ± 0.60 matm) to the root base zone (maximum of 12.10 ± 0.29 matm), with the trend of change being the opposite of that of O2. The Fe plaques in the root tip zone had the highest concentration of amorphous Fe. However, the concentration of Fe-bound OC was not significantly different among the different root parts. Because the relative abundances of ferrobacteria decreased in the order tip (8.45%) > base (4.05%) ≈ bulk sediment (3.05%), the enrichment of CO2 in the rhizosphere was attributed to dissimilatory Fe(III) reduction, O2-induced microbial respiration, and root respiration. Our conclusion was that the root tip of submerged plants is an efficient engine for Fe oxidation–carbon sequestration and Fe reduction–carbon mineralization processes, which may affect the stability of sediment carbon pools.

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Falling water tables reduce peatland semiconductor minerals' capacity for preserving carbon

Zeng,

Cao,

Bai

et al. 2023

Land Degrad Dev

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Semiconductor minerals in peatland play a significant role in the stability of the soil carbon pool. Nevertheless, the ecosystem‐scale importance of semiconductor minerals distribution and their influence on carbon stability in peatlands is still to be determined. Therefore, this study investigated the spatial distribution of semiconductor minerals and their photoelectrochemical activity (PA) in three peatlands with distinct water tables (Equisetum‐swamp [−2.0 cm], Caltha‐meadow [−8.0 cm], and Carex‐meadow [−13.8 cm]). The results indicate that the peatlands of the Qinghai‐Tibet Plateau mainly contain hematite (4.64 wt%), brookite (0.71 wt%), baddeleyite (0.23 wt‰), and zincite (0.10 wt‰); hematite content is the main mineral in peatland. And significantly increased with the decrease of the water table; the photoelectrochemical examination showed that the band gap of semiconductor minerals displayed Caltha‐meadow > Equisetum‐swamp > Carex‐meadow, and the carrier concentration displayed Carex‐meadow > Equisetum‐swamp > Caltha‐meadow, and Carex‐meadow exhibits a steady photocurrent density (0.3 μA/cm2) under light. This suggests that peat soils exhibit an improved photoelectric response with water table drawdown, which would promote the potential for soil carbon mineralization; structural equation model analysis showed that hematite had a significant positive effect on soil organic carbon (SOC), while the PA of semiconductor minerals had a significant negative effect on SOC. That is, semiconductor minerals can not only protect SOC by adsorption but also accelerate organic carbon mineralization by photo‐catalytic generation of reactive oxygen species. Therefore, the decrease in the water table increases the PA of semiconductor minerals, which will weaken the protective effect of semiconductor minerals on soil carbon through adsorption and other means.

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Visualization and quantification of carbon “rusty sink” by rice root iron plaque: Mechanisms, functions, and global implications

Cited by 32 publications

References 86 publications

Oxygen availability regulates the quality of soil dissolved organic matter by mediating microbial metabolism and iron oxidation

Oxygen availability regulates the quality of soil dissolved organic matter by mediating microbial metabolism and iron oxidation

The Root Tip of Submerged Plants: An Efficient Engine for Carbon Mineralization

Falling water tables reduce peatland semiconductor minerals' capacity for preserving carbon

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