Organic matter dynamics in thaw slumps: insights from online ramped oxidation-14C analysis


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Date

2024-09-23

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Abstract

Understanding the origins and cycling of organic matter (OM) in the environment is crucial for tackling issues such as climate change and soil degradation. Permafrost soils in arctic regions are garnering particular attention due to their large carbon stocks and potential vulnerability to ongoing warming and hydrological changes. Radiocarbon (14C) is a powerful tool to understand carbon sources and dynamics, however, traditional bulk 14C analysis offers limited insights due to the complex composition of OM in soils and sediments. Thermally ramped oxidation, which segregates OM based on its decomposition under gradually increasing temperatures (thermal fractions) and 14C analysis of evolved CO2 by accelerator mass spectrometry (AMS), provides a means to overcome this limitation. Here, we present preliminary results from the application of a recently developed compact, online ramped oxidation (ORO) system to permafrost soils from the Canadian arctic. The ORO system allows for the direct collection and 14C measurement of CO2 from discrete thermal fractions using an AMS system equipped with a gas ion source. In this proof-of-concept study, we focused on Retrogressive Thaw Slumps (RTS) on the Peel Plateau, Canada. We examined different samples including those from the seasonally thawed active layer, Holocene and Pleistocene permafrost layers, recently thawed debris, and exported particulate material (runoff). In this presentation, we will elaborate on the technical specifications of the ORO unit coupled with a low-energy AMS (LEA), and present initial results obtained from the analysis of RTS in this rapidly changing permafrost region of the Canadian arctic.

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published

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ETH Zurich

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4th International Radiocarbon in the Environment Conference (RE-IV 2024)

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03868 - Eglinton, Timothy I. (emeritus) / Eglinton, Timothy I. (emeritus) check_circle
08619 - Labor für Ionenstrahlphysik (LIP) / Laboratory of Ion Beam Physics (LIP)

Notes

Conference lecture held on September 23, 2024.

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