Reactive iron, not fungal community, drives organic carbon oxidation potential in floodplain soils

Naughton, Hannah R.; Tolar, Bradley B.; Dewey, Christian; Keiluweit, Marco; Nico, Peter; Fendorf, Scott

doi:10.1016/j.soilbio.2023.108962

Cited by 16 publications

(5 citation statements)

References 89 publications

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“…It can stimulate organic carbon decomposition by generating black carbon-like carbon, alicyclic aliphatic compounds, or even CO 2 [ 86 , 87 ]. Based on the studies in floodplain soils, abiotic Fe-mediated radicals can significantly enhance the oxidative depolymerization of SOC, and its impact is higher than the fungal-mediated oxidation process [ 88 ]. It is worth noting that most studies concerning the degradation of organic carbon by ROS in the soil focused on the pollutant degradation process, while its impact on the oxidation/degradation of soil organic matter needs more investigation.…”

Section: Interactions Between Minerals and Socmentioning

confidence: 99%

“…Based on the redox processes between organic carbon and soil minerals, organic carbon has a higher possibility of being degraded into organic molecules with smaller size (fragmentation) and richer O functionality [ 19 , 45 , [63] , [64] , [65] , [66] , [75] , [76] , [77] , [78] , [79] , [80] , [81] , 267 , 268 ], and these organic carbons usually have lower stability in the soil. Mn(IV) oxide and Fe(III) oxide are widely reported to be dominant for SOC degradation with the oxidative generation of CO 2 and/or labile organic carbon through direct or catalytic redox reaction [ [18] , [19] , [20] , [21] , 88 , 238 , [269] , [270] , [271] , [272] ]. Active mineral-mediated processes promote organic carbon mineralization through redox reactions over its protection in the soil environment [ 76 , 273 ].…”

Section: Change Of Organic Carbon Stability During Interactions With ...mentioning

confidence: 99%

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Mineral-mediated stability of organic carbon in soil and relevant interaction mechanisms

Xu,

Tsang

2024

Eco-Environment & Health

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Section: Interactions Between Minerals and Socmentioning

confidence: 99%

Section: Change Of Organic Carbon Stability During Interactions With ...mentioning

confidence: 99%

Mineral-mediated stability of organic carbon in soil and relevant interaction mechanisms

Xu,

Tsang

2024

Eco-Environment & Health

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“…The redox features at Hopland are evidence of a mixture of oxic and anoxic microsites within soil. These microsites have been shown to have a higher diversity of aerobic and anaerobic microbial metabolisms and metabolites are key in soil carbon stabilization (Keiluweit et al, 2017;Lacroix et al, 2023;Naughton et al, 2023), but the connection between  13 C values and reactive microsites is not well characterized. This chemical process could explain the divergence of Hopland in its  13 C values in soil depths greater than 30cm (fig.…”

Section: Variance Of  13 C and  15 N Values Explained By Depth And ...mentioning

confidence: 99%

Regional differences in soil stable isotopes and vibrational features at depth in three California Grasslands

Wahab,

Chacon,

Kim

et al. 2024

Preprint

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There are major gaps in our understanding of how Mediterranean ecosystems will respond to anticipated changes in precipitation. In particular, limited data exists on the response of deep soil carbon dynamics to changes in climate. In this study we wanted to examine carbon and nitrogen dynamics between topsoils and subsoils along a precipitation gradient of California grasslands. We focused on organic matter composition across three California grassland sites, from a dry and hot regime (~300 mm precipitation; MAT: 14.6℃) to a wet, cool regime (~2160 mm precipitation/year; MAT: 11.7℃). We determined changes in total elemental concentrations of soil carbon and nitrogen, stable isotope composition (δ13C, δ15N), and composition of soil organic matter (SOM) as measured through Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS) to 1m soil depth. We measured carbon persistence in soil organic matter (SOM) based on beta (β), a parameter based on the slope of carbon isotope composition across depth and proxy for turnover. Further, we examined the relationship between δ15N and C:N values to infer SOM’s degree of microbial processing. As expected, we measured the greatest carbon stock at the surface of our wettest site, but carbon stocks in subsoils converged at the wet and dry sites. Soils at depth (>30cm) at the wettest site had the lowest C:N and highest δ15N values with the greatest proportion of simple plant-derived organic matter according to DRIFTS. These results suggest differing stabilization mechanisms of organic matter at depth across our study sites. We infer that the greatest stability was conferred by associations with reactive minerals at depth in our wettest site. In contrast, organic matter at our driest site was subject to the most microbial processing. Results from this study demonstrate that precipitation patterns have important implications for deep soil carbon storage and composition, suggesting vulnerability of deep SOM to climate change induced alterations in precipitation patterns.

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“…However, fungi are generally adapted to aerobic conditions, and their oxidative enzymes require oxygen or oxygen-generated hydrogen peroxide to function [ 26 ]. Therefore, fungi exert only weak effects on C mineralization under permanent and periodically flooded conditions [ 27 , 28 ] and thus are unlikely to explain the changes in C mineralization rate between natural and rice-cultivated peatlands. By contrast, bacteria-mediated phenolic degradation of polyphenols under anoxia is highly effective [ 29 , 30 ], with the taxa involved including methanogens, denitrifiers, and iron-reducing and sulfate-reducing bacteria [ 31 , 32 ].…”

Section: Introductionmentioning

confidence: 99%

Changes in bacterial communities during rice cultivation remove phenolic constraints on peatland carbon preservation

Qin,

Tian,

Freeman

et al. 2024

ISME Communications

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Northern peatlands contain approximately 30% of terrestrial carbon (C) stores, but in recent decades, 14% to 20% of the stored C has been lost because of conversion of the peatland to cropland. Microorganisms are widely acknowledged as primary decomposers, but the keystone taxa within the bacterial community regulating C loss from cultivated peatlands remain largely unknown. In this study, we investigated the bacterial taxa driving peat C mineralization during rice cultivation. Cultivation significantly decreased concentrations of soil organic C, dissolved organic C, carbohydrates, and phenolics but increased C mineralization rate (CMR). Consistent with the classic theory that phenolic inhibition creates a “latch” that reduces peat C decomposition, phenolics were highly negatively correlated with CMR in cultivated peatlands, indicating that elimination of inhibitory phenolics can accelerate soil C mineralization. Bacterial communities were significantly different following peatland cultivation, and co-occurrence diagnosis analysis revealed substantial changes in network clusters of closely connected nodes (modules) and bacterial keystone taxa. Specifically, in cultivated peatlands, bacterial modules were significantly negatively correlated with phenolics, carbohydrates and dissolved organic C. While keystone taxa Xanthomonadales, Arthrobacter, and Bacteroidetes_vadinHA17 can regulate bacterial modules and promote carbon mineralization. Those observations indicated that changes in bacterial modules can promote phenolic decomposition and eliminate phenolic inhibition of labile C decomposition, thus accelerating soil organic C loss during rice cultivation. Overall, the study provides deeper insights into microbe-driven peat C loss during rice cultivation and highlights the crucial role of keystone bacterial taxa in the removal of phenolic constraints on peat C preservation.

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Reactive iron, not fungal community, drives organic carbon oxidation potential in floodplain soils

Cited by 16 publications

References 89 publications

Mineral-mediated stability of organic carbon in soil and relevant interaction mechanisms

Mineral-mediated stability of organic carbon in soil and relevant interaction mechanisms

Regional differences in soil stable isotopes and vibrational features at depth in three California Grasslands

Changes in bacterial communities during rice cultivation remove phenolic constraints on peatland carbon preservation

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