Carbon dioxide emissions by rock organic carbon oxidation and the net geochemical carbon budget of the Mackenzie River Basin

Horan, Kate; Hilton, Robert; Dellinger, Mathieu; Tipper, Edward T.; Calmels, Damien; Selby, David; Gaillardet, Jérôme; Ottley, Chris J.; Parsons, D.; Burton, Kevin W.

doi:10.2475/06.2019.02

Cited by 54 publications

(96 citation statements)

References 77 publications

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“…Nevertheless, the similar magnitude of the geological sources and sinks could keep the C cycle in an approximate steady-state balance over million-year timescales ( Taiwanese catchment 41,43, 59,86,93,143 (the Liwu River); and mountain catchments in Guadeloupe 144,145 . We can calculate the net rock-atmosphere CO2 flux (Jnet, tC km -2 yr -1 ) in such regions 142 Environment, 20 th April 2020, https://doi.org/10.1038/s43017-020-0058-6 For the final corrected version of the manuscript, please see the journal link, or contact the authors.…”

Section: Net 'Rock-atmosphere' Carbon Transfersmentioning

confidence: 99%

“…Mountain building could potentially drive such transient C cycle perturbations and associated climatic change.Insights into how C cycle imbalances can arise comes from river catchments where enough data have been collected to quantify each rock-atmosphere C transfer term(Fig. 1B,and Supplementary Information): four catchments in the western Southern Alps of New Zealand69,127,139 (the Haast, Hokitika, Waiho and Whataroa Rivers); three draining the Mackenzie Basin in Canada 42,43,[140][141][142] (the Peel, Arctic Red and Mackenzie Rivers); a…”

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confidence: 99%

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Mountains, erosion and the carbon cycle

Hilton

West

2020

Nat Rev Earth Environ

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Mountain building results in high erosion rates and the interaction of rocks with the atmosphere, water and life. Carbon transfers that result from increased erosion could control the evolution of Earth's long-term climate. For decades, attention has focused on the hypothesised role of mountain building in drawing down atmospheric carbon dioxide (CO2) via silicate weathering. However, it is now recognized that mountain building and erosion affect the carbon cycle in other important ways. For example, erosion mobilises organic carbon (OC) from terrestrial vegetation, transferring it to rivers and sediments and thereby acting to draw down atmospheric CO2 in tandem with silicate weathering. Meanwhile, exhumation of sedimentary rocks can release CO2 through the oxidation of rock OC and sulfide minerals. In this Review we examine the mechanisms of carbon exchange between rocks and the atmosphere and discuss the balance of CO2 sources and sinks. Our Review demonstrates that OC burial and oxidative weathering, not widely considered in most models, control the net CO2 budget associated with erosion. Therefore, lithology strongly influences the impact of mountain building on the global carbon cycle, with an orogeny dominated by sedimentary rocks, and thus abundant rock OC and sulfides, tending towards being a CO2 source.

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Section: Net 'Rock-atmosphere' Carbon Transfersmentioning

confidence: 99%

mentioning

confidence: 99%

Mountains, erosion and the carbon cycle

Hilton

West

2020

Nat Rev Earth Environ

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209

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“…The ∆ 14 C analysis of riverine OC, carried out on samples collected from the mouth of the Arctic Great Rivers (Holmes et al, 2020) has revealed that the MRB exports on average the oldest POC (i.e., 14 C depleted) to the Arctic Ocean out of all Arctic Great Rivers, but also a mixture of aged and modern DOC (Holmes et al, 2020; Raymond et al, 2007). The prevailing hypothesis explaining these age patterns is that POC is mostly derived from petrogenic sources (Hilton et al, 2015; Horan et al, 2019) and thawing permafrost and river bank erosion (Feng et al, 2013; Vonk et al, 2015; Wild et al, 2019), while DOC contains a comparatively larger proportion of recent photosynthates derived from terrestrial vegetation (Guo et al, 2007; Marwick et al, 2015). At present, the range and variability in riverine Δ 14 C‐OC is unknown in large parts of the MRB, partly owing to the remoteness of the region and the limited network of roads allowing access to the rivers.…”

Section: Introductionmentioning

confidence: 99%

Controls on the ¹⁴C Content of Dissolved and Particulate Organic Carbon Mobilized Across the Mackenzie River Basin, Canada

Campeau

Soerensen

Martma

et al. 2020

Global Biogeochemical Cycles

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The Mackenzie River Basin (MRB) delivers large quantities of organic carbon (OC) into the Arctic Ocean, with significant implications for the global C budgets and ocean biogeochemistry. The amount and properties of OC in the Mackenzie River's delta have been well monitored in the last decade, but the spatial variability in OC sources transported by its different tributaries is still unclear. Here we present new data on the radiocarbon (14 C) content of dissolved and particulate OC (Δ 14 C-DOC and Δ 14 C-POC) across the mainstem and major tributaries of the MRB, comprising 19 different locations, to identify factors controlling spatial patterns in riverine OC sources. The Δ 14 C-DOC and Δ 14 C-POC varied across a large range, from −179.9‰ to 62.9‰, and −728.8‰ to −9.0‰, respectively. Our data reveal a positive spatial coupling between the Δ 14 C of DOC and POC across the MRB, whereby the most 14 C-depleted waters were issued from the mountainous west bank of the MRB. This 14 C-depleted DOC and POC likely originates from a combination of petrogenic sources, connected with the presence of kerogens in the bedrock, and biogenic sources, mobilized by thawing permafrost. Our analysis also reveals intriguing relationships between Δ 14 C of DOC and POC with turbidity, water stable isotope ratio and catchment elevation, indicating that hydrology and geomorphology are key to understanding riverine OC sources in this landscape. A closer examination of the specific mechanisms giving rise to these relationships is recommended. For now, this study provides a road map of the key OC sources in this rapidly changing river basin.

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“…For M diss_Re , we excluded an initial rapid period of change of ion concentrations (Re, SO 4 2-, and Ca 2+ ), which is inconsistent with the lowland river processes we sought to model (see the Data Repository). The value of f Re provides a maximum constraint on POC petro loss due to contributions of dissolved rhenium from non-POC petro phases (Horan et al, 2019).…”

Section: Evaluating Poc Oxidationmentioning

confidence: 99%

Preservation of organic carbon during active fluvial transport and particle abrasion

Scheingross

Hovius

Dellinger

et al. 2019

Geology

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Citation for published item:heingrossD tFF nd roviusD xF nd hellingerD wF nd riltonD FqF nd epshD wF nd hseD hF nd qr¤ okeD hFF nd iethErillerndD eF nd urowskiD tFwF @PHIWA 9reservtion of orgni ron during tive )uvil trnsport nd prtile rsionF9D qeologyFD RU @IHAF ppF WSVEWTPF The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. CITATION: Scheingross, J.S., et al., 2019, Preservation of organic carbon during active fluvial transport and particle abrasion: Geology, v. 47, p. 958-962, https:// ABSTRACT Oxidation of particulate organic carbon (POC) during fluvial transit releases CO 2 to the atmosphere and can influence global climate. Field data show large POC oxidation fluxes in lowland rivers; however, it is unclear if POC losses occur predominantly during in-river transport, where POC is in continual motion within an aerated environment, or during transient storage in floodplains, which may be anoxic. Determination of the locus of POC oxidation in lowland rivers is needed to develop process-based models to predict POC losses, constrain carbon budgets, and unravel links between climate and erosion. However, sediment exchange between rivers and floodplains makes differentiating POC oxidation duringin-river transport from oxidation during floodplain storage difficult. Here, we isolated inriver POC oxidation using flume experiments transporting petrogenic and biospheric POC without floodplain storage. Our experiments showed solid phase POC losses of 0%-10% over ∼10 3 km of fluvial transport, compared to ∼7% to >50% losses observed in rivers over similar distances. The production of dissolved organic carbon (DOC) and dissolved rhenium (a proxy for petrogenic POC oxidation) was consistent with small POC losses, and replicate experiments in static water tanks gave similar results. Our results show that fluvial sediment transport, particle abrasion, and turbulent mixing have a minimal role on POC oxidation, and they suggest that POC losses may accrue primarily in floodplain storage.

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Carbon dioxide emissions by rock organic carbon oxidation and the net geochemical carbon budget of the Mackenzie River Basin

Cited by 54 publications

References 77 publications

Mountains, erosion and the carbon cycle

Mountains, erosion and the carbon cycle

Controls on the ¹⁴C Content of Dissolved and Particulate Organic Carbon Mobilized Across the Mackenzie River Basin, Canada

Preservation of organic carbon during active fluvial transport and particle abrasion

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Carbon dioxide emissions by rock organic carbon oxidation and the net geochemical carbon budget of the Mackenzie River Basin

Cited by 54 publications

References 77 publications

Mountains, erosion and the carbon cycle

Mountains, erosion and the carbon cycle

Controls on the 14C Content of Dissolved and Particulate Organic Carbon Mobilized Across the Mackenzie River Basin, Canada

Preservation of organic carbon during active fluvial transport and particle abrasion

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Product

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Controls on the ¹⁴C Content of Dissolved and Particulate Organic Carbon Mobilized Across the Mackenzie River Basin, Canada