Fluvial organic carbon cycling regulated by sediment transit time and mineral protection

Repasch, Marisa; Scheingross, Joel S.; Hovius, Niels; Lupker, Maarten; Wittmann, Hella; Haghipour, Negar; Gröcke, Darren R.; Orfeo, Oscar; Eglinton, T. I.; Sachse, Dirk

doi:10.1038/s41561-021-00845-7

Cited by 68 publications

(41 citation statements)

References 58 publications

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“…Therefore, iron minerals could generate a considerable amount of ROS in the long term and play a role in accelerating biogeochemical processes as well as pollutant dynamics. For instance, previous studies on interactions between pollutants and iron minerals typically focus on interfacial hydrolysis, adsorption, − and immobilization processes; − this study suggests that pollutant transformation processes should be considered with ROS photochemically produced on the iron mineral surface. In other words, the iron mineral surface may act as a hotspot for pollutant transformation.…”

Section: Environmental Implicationsmentioning

confidence: 95%

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Zheng

Zhou

et al. 2022

Environ. Sci. Technol.

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Photochemically generated reactive oxygen species (ROS) play numerous key roles in earth's surface biogeochemical processes and pollutant dynamics. ROS production has historically been linked to the photosensitization of natural organic matter. Here, we report the photochemical ROS production from three naturally abundant iron minerals. All investigated iron minerals are photoactive toward sunlight irradiation, with photogenerated currents linearly correlated with incident light intensity. Hydroxyl radicals ( • OH) and hydrogen peroxide (H 2 O 2 ) are identified as the major ROS species, with apparent quantum yields ranging from 1.4 × 10 −8 to 3.9 × 10 −8 and 5.8 × 10 −8 to 2.5 × 10 −6 , respectively. Photochemical ROS production exhibits high wavelength dependence, for instance, the • OH quantum yield decreases with the increase of light wavelength from 375 to 425 nm, and above 425 nm it sharply decreases to zero. The temperature shows a positive impact on • OH production, with apparent activation energies ranging from 8.0 to 17.8 kJ/mol. Interestingly, natural iron minerals with impurities exhibit higher ROS production than their pure crystal counterparts. Compared with organic photosensitizers, iron minerals exhibit higher wavelength dependence, higher selectivity, lower efficiency, and long-term stability in photochemical ROS production. Our study highlights natural inorganic iron mineral photochemistry as a ubiquitous yet previously overlooked source of ROS.

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Section: Environmental Implicationsmentioning

confidence: 95%

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Zheng

Zhou

et al. 2022

Environ. Sci. Technol.

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“…For instance, lateral erosion of rivers cutting through floodplains releases additional organic carbon fluxes to downstream depositional sinks (e.g., tidal flats and deltas). Hence, rivers with high channel mobility can enhance CO 2 drawdown (Repasch et al., 2021).…”

Section: Feedbacks Between Bank Retreat and Morphodynamicsmentioning

confidence: 99%

A Review on Bank Retreat: Mechanisms, Observations, and Modeling

Zhao

Coco

Gong

et al. 2022

Reviews of Geophysics

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Bank retreat plays a fundamental role in fluvial and estuarine dynamics. It affects the cross‐sectional evolution of channels, provides a source of sediment, and modulates the diversity of habitats. Understanding and predicting the geomorphological response of fluvial/tidal channels to external driving forces underpins the robust management of water courses and the protection of wetlands. Here, we review bank retreat with respect to mechanisms, observations, and modeling, covering both rivers and (previously neglected) tidal channels. Our review encompasses both experimental and in situ observations of failure mechanisms and bank retreat rates, modeling approaches and numerical methods to simulate bank erosion. We identify that external forces, despite their distinct characteristics, may have similar effects on bank stability in both river and tidal channels, leading to the same failure mode. We review existing data and empirical functions for bank retreat rate across a range of spatial and temporal scales, and highlight the necessity to account for both hydraulic and geotechnical controls. Based on time scale considerations, we propose a new hierarchy of modeling styles that accounts for bank retreat, leading to clear recommendations for enhancing existing modeling approaches. Finally, we discuss systematically the feedbacks between bank retreat and morphodynamics, and suggest that to move this agenda forward will require a better understanding of multifactor‐driven bank retreat across a range of temporal scales, with particular attention to the differences (and similarities) between riverine and estuarine environments, and the role of feedbacks exerted by the collapsed bank soil.

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“…Sample material was oven dried at 40°C for ∼48 hr and suspended sediment was weighed to calculate suspended sediment concentrations. Total organic carbon (TOC) content was measured on acid‐treated samples using an elemental analyzer and grain size distributions were measured with a laser diffraction particle size analyzer (Repasch et al., 2021).…”

Section: Study Area and Methodsmentioning

confidence: 99%

River Organic Carbon Fluxes Modulated by Hydrodynamic Sorting of Particulate Organic Matter

Repasch

Scheingross

Hovius

et al. 2022

Geophysical Research Letters

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Cycling of organic carbon (OC) between the lithosphere, biosphere, and atmosphere regulates Earth's climate. Rivers modulate this cycle by redistributing OC from vegetated uplands to sedimentary basins. If fluvially transported OC is preserved during source-to-sink transit, its long-term burial sequesters atmospheric CO 2 over geologic timescales (Berner, 1990;Burdige, 2005;France-Lanord & Derry, 1997). To estimate OC burial fluxes and assess the influence of fluvial transport on the geologic carbon cycle, we need mechanistic explanations of the complex links between the geomorphic and biogeochemical processes driving the sourcing, transport, oxidation, and burial of OC in river systems.Fluvial particulate organic carbon (POC) comprises a mixture of petrogenic POC from organic-rich bedrock (e.g., shale) and biospheric POC from plants and soils (Galy et al., 2015;Rosenheim & Galy, 2012). While petrogenic POC decomposes slowly and can be preserved and recycled through the lithosphere over million-year cycles (Galy, et al., 2008;Scheingross et al., 2019;Sparkes et al., 2020), biospheric POC is physically and chemically unstable at Earth's surface and can be oxidized to CO 2 if not rapidly buried. Biospheric POC can bind

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Fluvial organic carbon cycling regulated by sediment transit time and mineral protection

Cited by 68 publications

References 58 publications

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

Sunlight-Driven Production of Reactive Oxygen Species from Natural Iron Minerals: Quantum Yield and Wavelength Dependence

A Review on Bank Retreat: Mechanisms, Observations, and Modeling

River Organic Carbon Fluxes Modulated by Hydrodynamic Sorting of Particulate Organic Matter

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