Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps: Case study in Peel Plateau, western Canadian Arctic

Maxime Thomas; Arthur Monhonval; Catherine Hirst; Lisa Bröder; Scott Zolkos; Jorien Vonk; Suzanne E. Tank; Kirsi Keskitalo; Sarah Shakil; Steven V. Kokelj; Jurjen van der Sluijs; Sophie Opfergelt

doi:10.1016/j.geoderma.2023.116443

Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps: Case study in Peel Plateau, western Canadian Arctic

Maxime Thomas^*, Arthur Monhonval, Catherine Hirst, Lisa Bröder, Scott Zolkos, Jorien Vonk, Suzanne E. Tank, Kirsi Keskitalo, Sarah Shakil, Steven V. Kokelj, Jurjen van der Sluijs, Sophie Opfergelt

^*Corresponding author for this work

Earth and Climate

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

In northern high latitudes, rapid warming is set to amplify carbon-climate feedbacks by enhancing permafrost thaw and biogeochemical transformation of large amounts of soil organic carbon. However, between 30 % and 80 % of permafrost soil organic carbon is considered to be stabilized by geochemical interactions with the soil mineral pool and thus less susceptible to be emitted as greenhouse gases. Quantification of the nature of and controls on mineral-organic carbon interactions is needed to better constrain permafrost-carbon-climate feedbacks, particularly in ice-rich environments resulting in rapid thaw and development of thermokarst landforms. On sloping terrain, mass wasting features called retrogressive thaw slumps are amongst the most dynamic forms of thermokarst. These multi-decadal disturbances grow due to ablation of an ice-rich headwall, and their enlargement due to warming of the Arctic is mobilizing vast stores of previously frozen materials. Here, we investigate headwall profiles of seven retrogressive thaw slumps and sediments displaced from these mass wasting features from the Peel Plateau, western Canadian Arctic. The disturbances varied in their headwall height (2 to 25 m) and affected land surface area (<1 to > 30 ha). We present total and water extractable mineral element concentrations, mineralogy, and mineral-organic carbon interactions in the headwall layers (active layer, permafrost materials above an early Holocene thaw unconformity, and Pleistocene-aged permafrost tills) and in displaced material (suspended sediments in runoff and material accumulated on the debris tongue). Our data show that the main mechanism of organic carbon stabilization through mineral-organic carbon interactions within the headwall is the complexation with metals (mainly iron), which stabilizes 30 ± 15 % of the total organic carbon pool with higher concentrations in near-surface layers compared to deep permafrost. In the displaced material, this proportion drops to 18 ± 5 %. In addition, we estimate that up to 12 ± 5 % of the total organic carbon is stabilized by associations to poorly crystalline iron oxides, with no significant difference between near-surface layers, deep permafrost and displaced material. Our findings suggest that the organic carbon interacting with the sediment mineral pool in slump headwalls is preserved in the material mobilized by slumping and displaced as debris. Overall, up to 32 ± 6 % of the total organic carbon displaced by retrogressive thaw slumps is stabilized by organo-mineral interactions in this region. This indicates that organo-mineral interactions play a significant role in the preservation of organic carbon in the material displaced from retrogressive thaw slumps over years to decades after their development resulting in decadal to centennial scale sequestration of this retrogressive thaw slump-mobilized organic carbon interacting with the soil mineral pool.

Original language	English
Article number	116443
Pages (from-to)	1-17
Number of pages	17
Journal	Geoderma
Volume	433
Early online date	6 Apr 2023
DOIs	https://doi.org/10.1016/j.geoderma.2023.116443
Publication status	Published - May 2023

Bibliographical note

Funding Information:
Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich’in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, Élodie Devos, and Hélène Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Benoît Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments.

Funding Information:
Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich'in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, Élodie Devos, and Hélène Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Benoît Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. MT and SO conceived and planned the experimental work. LB and KK led sampling campaign A under the supervision of JV. SZ led sampling campaign B under the supervision of ST and SK. MT realized the total concentration measurements by pXRF, and bulk elements concentration corrections for trueness with the help of AM. MT realized the selective extractions and mineralogical analysis with the help of SO. LB carried out total organic carbon concentrations measurements. MT performed the data processing. JvdS and SK provided the exported volume data of slumps FM2 and FM3 and expertise in geomorphic processes within the Peel Plateau. LB, SZ, JV, ST, SS, KK and SK contributed with their expertise on the study area. CH and AM contributed with their expertise on Fe in Arctic regions. MT wrote the manuscript under supervision of SO with inputs from all co-authors. This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No.714617 to SO (WeThaw), and SO acknowledges funding from the Fund for Scientific Research FNRS in Belgium (FC69480). Further funding for this work came from European Union's Horizon 2020 research and innovation program under grant agreement No.676982 to JV (Thawsome) for sampling campaign A. General support for the overall field campaign and for campaign B was provided from the Natural Sciences and Engineering Research Council of Canada (NSERC; grants nos. 430696 and 444873), the Polar Continental Shelf Program (grant 617-17) and the Campus Alberta Innovates Program. Campaign B received further support from the University of Alberta Northern Research Award to SZ.

Publisher Copyright:
© 2023 The Author(s)

Funding

Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich’in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, Élodie Devos, and Hélène Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Benoît Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich'in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, Élodie Devos, and Hélène Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Benoît Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. MT and SO conceived and planned the experimental work. LB and KK led sampling campaign A under the supervision of JV. SZ led sampling campaign B under the supervision of ST and SK. MT realized the total concentration measurements by pXRF, and bulk elements concentration corrections for trueness with the help of AM. MT realized the selective extractions and mineralogical analysis with the help of SO. LB carried out total organic carbon concentrations measurements. MT performed the data processing. JvdS and SK provided the exported volume data of slumps FM2 and FM3 and expertise in geomorphic processes within the Peel Plateau. LB, SZ, JV, ST, SS, KK and SK contributed with their expertise on the study area. CH and AM contributed with their expertise on Fe in Arctic regions. MT wrote the manuscript under supervision of SO with inputs from all co-authors. This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No.714617 to SO (WeThaw), and SO acknowledges funding from the Fund for Scientific Research FNRS in Belgium (FC69480). Further funding for this work came from European Union's Horizon 2020 research and innovation program under grant agreement No.676982 to JV (Thawsome) for sampling campaign A. General support for the overall field campaign and for campaign B was provided from the Natural Sciences and Engineering Research Council of Canada (NSERC; grants nos. 430696 and 444873), the Polar Continental Shelf Program (grant 617-17) and the Campus Alberta Innovates Program. Campaign B received further support from the University of Alberta Northern Research Award to SZ.

Keywords

Iron
Mass wasting
Mineral-organic carbon interactions
Peel Plateau
Retrogressive thaw slumps

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10.1016/j.geoderma.2023.116443

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Thomas, M., Monhonval, A., Hirst, C., Bröder, L., Zolkos, S., Vonk, J., Tank, S. E., Keskitalo, K., Shakil, S., Kokelj, S. V., van der Sluijs, J., & Opfergelt, S. (2023). Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps: Case study in Peel Plateau, western Canadian Arctic. Geoderma, 433, 1-17. Article 116443. https://doi.org/10.1016/j.geoderma.2023.116443

@article{e0b08c60b7e5479d8fd6216e449dcabc,

title = "Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps: Case study in Peel Plateau, western Canadian Arctic",

abstract = "In northern high latitudes, rapid warming is set to amplify carbon-climate feedbacks by enhancing permafrost thaw and biogeochemical transformation of large amounts of soil organic carbon. However, between 30 \% and 80 \% of permafrost soil organic carbon is considered to be stabilized by geochemical interactions with the soil mineral pool and thus less susceptible to be emitted as greenhouse gases. Quantification of the nature of and controls on mineral-organic carbon interactions is needed to better constrain permafrost-carbon-climate feedbacks, particularly in ice-rich environments resulting in rapid thaw and development of thermokarst landforms. On sloping terrain, mass wasting features called retrogressive thaw slumps are amongst the most dynamic forms of thermokarst. These multi-decadal disturbances grow due to ablation of an ice-rich headwall, and their enlargement due to warming of the Arctic is mobilizing vast stores of previously frozen materials. Here, we investigate headwall profiles of seven retrogressive thaw slumps and sediments displaced from these mass wasting features from the Peel Plateau, western Canadian Arctic. The disturbances varied in their headwall height (2 to 25 m) and affected land surface area (<1 to > 30 ha). We present total and water extractable mineral element concentrations, mineralogy, and mineral-organic carbon interactions in the headwall layers (active layer, permafrost materials above an early Holocene thaw unconformity, and Pleistocene-aged permafrost tills) and in displaced material (suspended sediments in runoff and material accumulated on the debris tongue). Our data show that the main mechanism of organic carbon stabilization through mineral-organic carbon interactions within the headwall is the complexation with metals (mainly iron), which stabilizes 30 ± 15 \% of the total organic carbon pool with higher concentrations in near-surface layers compared to deep permafrost. In the displaced material, this proportion drops to 18 ± 5 \%. In addition, we estimate that up to 12 ± 5 \% of the total organic carbon is stabilized by associations to poorly crystalline iron oxides, with no significant difference between near-surface layers, deep permafrost and displaced material. Our findings suggest that the organic carbon interacting with the sediment mineral pool in slump headwalls is preserved in the material mobilized by slumping and displaced as debris. Overall, up to 32 ± 6 \% of the total organic carbon displaced by retrogressive thaw slumps is stabilized by organo-mineral interactions in this region. This indicates that organo-mineral interactions play a significant role in the preservation of organic carbon in the material displaced from retrogressive thaw slumps over years to decades after their development resulting in decadal to centennial scale sequestration of this retrogressive thaw slump-mobilized organic carbon interacting with the soil mineral pool.",

keywords = "Iron, Mass wasting, Mineral-organic carbon interactions, Peel Plateau, Retrogressive thaw slumps",

author = "Maxime Thomas and Arthur Monhonval and Catherine Hirst and Lisa Br{\"o}der and Scott Zolkos and Jorien Vonk and Tank, \{Suzanne E.\} and Kirsi Keskitalo and Sarah Shakil and Kokelj, \{Steven V.\} and \{van der Sluijs\}, Jurjen and Sophie Opfergelt",

note = "Funding Information: Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich{\textquoteright}in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, {\'E}lodie Devos, and H{\'e}l{\`e}ne Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Beno{\^i}t Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. Funding Information: Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich'in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, {\'E}lodie Devos, and H{\'e}l{\`e}ne Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Beno{\^i}t Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. MT and SO conceived and planned the experimental work. LB and KK led sampling campaign A under the supervision of JV. SZ led sampling campaign B under the supervision of ST and SK. MT realized the total concentration measurements by pXRF, and bulk elements concentration corrections for trueness with the help of AM. MT realized the selective extractions and mineralogical analysis with the help of SO. LB carried out total organic carbon concentrations measurements. MT performed the data processing. JvdS and SK provided the exported volume data of slumps FM2 and FM3 and expertise in geomorphic processes within the Peel Plateau. LB, SZ, JV, ST, SS, KK and SK contributed with their expertise on the study area. CH and AM contributed with their expertise on Fe in Arctic regions. MT wrote the manuscript under supervision of SO with inputs from all co-authors. This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No.714617 to SO (WeThaw), and SO acknowledges funding from the Fund for Scientific Research FNRS in Belgium (FC69480). Further funding for this work came from European Union's Horizon 2020 research and innovation program under grant agreement No.676982 to JV (Thawsome) for sampling campaign A. General support for the overall field campaign and for campaign B was provided from the Natural Sciences and Engineering Research Council of Canada (NSERC; grants nos. 430696 and 444873), the Polar Continental Shelf Program (grant 617-17) and the Campus Alberta Innovates Program. Campaign B received further support from the University of Alberta Northern Research Award to SZ. Publisher Copyright: {\textcopyright} 2023 The Author(s)",

year = "2023",

month = may,

doi = "10.1016/j.geoderma.2023.116443",

language = "English",

volume = "433",

pages = "1--17",

journal = "Geoderma",

issn = "0016-7061",

publisher = "Elsevier B.V.",

}

Thomas, M, Monhonval, A, Hirst, C, Bröder, L, Zolkos, S, Vonk, J, Tank, SE, Keskitalo, K, Shakil, S, Kokelj, SV, van der Sluijs, J & Opfergelt, S 2023, 'Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps: Case study in Peel Plateau, western Canadian Arctic', Geoderma, vol. 433, 116443, pp. 1-17. https://doi.org/10.1016/j.geoderma.2023.116443

TY - JOUR

T1 - Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps

T2 - Case study in Peel Plateau, western Canadian Arctic

AU - Thomas, Maxime

AU - Monhonval, Arthur

AU - Hirst, Catherine

AU - Bröder, Lisa

AU - Zolkos, Scott

AU - Vonk, Jorien

AU - Tank, Suzanne E.

AU - Keskitalo, Kirsi

AU - Shakil, Sarah

AU - Kokelj, Steven V.

AU - van der Sluijs, Jurjen

AU - Opfergelt, Sophie

N1 - Funding Information: Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich’in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, Élodie Devos, and Hélène Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Benoît Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. Funding Information: Research was conducted under Northwest Territories Scientific Research License 15887 within the Gwich'in Settlement Region. The authors acknowledge fieldwork support from Rosemin Nathoo, Erin MacDonald, Christine Firth, Dempster Colin, Abraham Snowshoe, Keith Colin and Andrew Koe. The authors further acknowledge Laurence Monin, Claudine Givron, Élodie Devos, and Hélène Dailly from the Mineral and Organic Chemical Analysis (MOCA) platform at UCLouvain for conducting chemical analysis, Benoît Pereira and Aubry Vandeuren for their expertise on portable X-Ray Fluorescence measurements, and the members of the WeThaw project for useful discussions. MT thanks the members of the ELIE-SOIL lab for useful critical comments. We finally acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. MT and SO conceived and planned the experimental work. LB and KK led sampling campaign A under the supervision of JV. SZ led sampling campaign B under the supervision of ST and SK. MT realized the total concentration measurements by pXRF, and bulk elements concentration corrections for trueness with the help of AM. MT realized the selective extractions and mineralogical analysis with the help of SO. LB carried out total organic carbon concentrations measurements. MT performed the data processing. JvdS and SK provided the exported volume data of slumps FM2 and FM3 and expertise in geomorphic processes within the Peel Plateau. LB, SZ, JV, ST, SS, KK and SK contributed with their expertise on the study area. CH and AM contributed with their expertise on Fe in Arctic regions. MT wrote the manuscript under supervision of SO with inputs from all co-authors. This project received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No.714617 to SO (WeThaw), and SO acknowledges funding from the Fund for Scientific Research FNRS in Belgium (FC69480). Further funding for this work came from European Union's Horizon 2020 research and innovation program under grant agreement No.676982 to JV (Thawsome) for sampling campaign A. General support for the overall field campaign and for campaign B was provided from the Natural Sciences and Engineering Research Council of Canada (NSERC; grants nos. 430696 and 444873), the Polar Continental Shelf Program (grant 617-17) and the Campus Alberta Innovates Program. Campaign B received further support from the University of Alberta Northern Research Award to SZ. Publisher Copyright: © 2023 The Author(s)

PY - 2023/5

Y1 - 2023/5

N2 - In northern high latitudes, rapid warming is set to amplify carbon-climate feedbacks by enhancing permafrost thaw and biogeochemical transformation of large amounts of soil organic carbon. However, between 30 % and 80 % of permafrost soil organic carbon is considered to be stabilized by geochemical interactions with the soil mineral pool and thus less susceptible to be emitted as greenhouse gases. Quantification of the nature of and controls on mineral-organic carbon interactions is needed to better constrain permafrost-carbon-climate feedbacks, particularly in ice-rich environments resulting in rapid thaw and development of thermokarst landforms. On sloping terrain, mass wasting features called retrogressive thaw slumps are amongst the most dynamic forms of thermokarst. These multi-decadal disturbances grow due to ablation of an ice-rich headwall, and their enlargement due to warming of the Arctic is mobilizing vast stores of previously frozen materials. Here, we investigate headwall profiles of seven retrogressive thaw slumps and sediments displaced from these mass wasting features from the Peel Plateau, western Canadian Arctic. The disturbances varied in their headwall height (2 to 25 m) and affected land surface area (<1 to > 30 ha). We present total and water extractable mineral element concentrations, mineralogy, and mineral-organic carbon interactions in the headwall layers (active layer, permafrost materials above an early Holocene thaw unconformity, and Pleistocene-aged permafrost tills) and in displaced material (suspended sediments in runoff and material accumulated on the debris tongue). Our data show that the main mechanism of organic carbon stabilization through mineral-organic carbon interactions within the headwall is the complexation with metals (mainly iron), which stabilizes 30 ± 15 % of the total organic carbon pool with higher concentrations in near-surface layers compared to deep permafrost. In the displaced material, this proportion drops to 18 ± 5 %. In addition, we estimate that up to 12 ± 5 % of the total organic carbon is stabilized by associations to poorly crystalline iron oxides, with no significant difference between near-surface layers, deep permafrost and displaced material. Our findings suggest that the organic carbon interacting with the sediment mineral pool in slump headwalls is preserved in the material mobilized by slumping and displaced as debris. Overall, up to 32 ± 6 % of the total organic carbon displaced by retrogressive thaw slumps is stabilized by organo-mineral interactions in this region. This indicates that organo-mineral interactions play a significant role in the preservation of organic carbon in the material displaced from retrogressive thaw slumps over years to decades after their development resulting in decadal to centennial scale sequestration of this retrogressive thaw slump-mobilized organic carbon interacting with the soil mineral pool.

AB - In northern high latitudes, rapid warming is set to amplify carbon-climate feedbacks by enhancing permafrost thaw and biogeochemical transformation of large amounts of soil organic carbon. However, between 30 % and 80 % of permafrost soil organic carbon is considered to be stabilized by geochemical interactions with the soil mineral pool and thus less susceptible to be emitted as greenhouse gases. Quantification of the nature of and controls on mineral-organic carbon interactions is needed to better constrain permafrost-carbon-climate feedbacks, particularly in ice-rich environments resulting in rapid thaw and development of thermokarst landforms. On sloping terrain, mass wasting features called retrogressive thaw slumps are amongst the most dynamic forms of thermokarst. These multi-decadal disturbances grow due to ablation of an ice-rich headwall, and their enlargement due to warming of the Arctic is mobilizing vast stores of previously frozen materials. Here, we investigate headwall profiles of seven retrogressive thaw slumps and sediments displaced from these mass wasting features from the Peel Plateau, western Canadian Arctic. The disturbances varied in their headwall height (2 to 25 m) and affected land surface area (<1 to > 30 ha). We present total and water extractable mineral element concentrations, mineralogy, and mineral-organic carbon interactions in the headwall layers (active layer, permafrost materials above an early Holocene thaw unconformity, and Pleistocene-aged permafrost tills) and in displaced material (suspended sediments in runoff and material accumulated on the debris tongue). Our data show that the main mechanism of organic carbon stabilization through mineral-organic carbon interactions within the headwall is the complexation with metals (mainly iron), which stabilizes 30 ± 15 % of the total organic carbon pool with higher concentrations in near-surface layers compared to deep permafrost. In the displaced material, this proportion drops to 18 ± 5 %. In addition, we estimate that up to 12 ± 5 % of the total organic carbon is stabilized by associations to poorly crystalline iron oxides, with no significant difference between near-surface layers, deep permafrost and displaced material. Our findings suggest that the organic carbon interacting with the sediment mineral pool in slump headwalls is preserved in the material mobilized by slumping and displaced as debris. Overall, up to 32 ± 6 % of the total organic carbon displaced by retrogressive thaw slumps is stabilized by organo-mineral interactions in this region. This indicates that organo-mineral interactions play a significant role in the preservation of organic carbon in the material displaced from retrogressive thaw slumps over years to decades after their development resulting in decadal to centennial scale sequestration of this retrogressive thaw slump-mobilized organic carbon interacting with the soil mineral pool.

KW - Iron

KW - Mass wasting

KW - Mineral-organic carbon interactions

KW - Peel Plateau

KW - Retrogressive thaw slumps

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Evidence for preservation of organic carbon interacting with iron in material displaced from retrogressive thaw slumps: Case study in Peel Plateau, western Canadian Arctic

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