Towards an online ramped oxidation approach for thermal dissection and serial radiocarbon measurement of complex organic matter
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Autor(in)
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Datum
2024-04-19Typ
- Conference Poster
ETH Bibliographie
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Abstract
Radiocarbon (14C) measurements provide a powerful tool to deconvolute sources and dynamics of organic matter in the environment. However, interpretation of conventional bulk-level 14C data is challenging due to the myriad components comprising organic matter in soils and sediments. Thermally ramped oxidation provides one approach for overcoming this limitation, and involves subjecting a sample to gradually increasing temperatures, serially oxidizing the OC to CO2. Collected over prescribed temperature ranges (' thermal fractions'), this CO2 is then analyzed for 14C content using accelerator mass spectrometry (AMS). While effective, current ramped oxidation methods are mostly 'offline', involving manual collection and subsequent AMS analysis of evolved CO2, hindering sample throughput and reproducibility.
Here, we introduce a compact, online ramped oxidation (ORO) setup in which CO2 from discrete thermal fractions is directly collected and measured for 14C by AMS equipped with a gas ion source. The setup comprises two modules: (i) an ORO unit with two sequential furnaces - the first, ramped from room temperature to 900 °C, holds the sample; the second, maintained at 900 °C, includes a catalyst ensuring complete oxidation to CO2; and (ii) a dual-trap interface (DTI) collection unit with two parallel molecular sieve traps alternately collecting and releasing CO2 from a given fraction for direct injection into the AMS.
Preliminary results indicate reproducible data, evident in both thermograms and F14C results. Analysis of natural reference samples reveals that measured 14C values and their associated uncertainties align with those reported in the literature using conventional “off-line” ramped oxidation methods, affirming the utility of the new ORO-DTI-AMS setup.
Our goal is to apply this new method for comprehensive investigation of a range of natural samples, with a particular focus on the improved understanding of the fate of OC held in permafrost soils in the context of on-going climate and carbon cycle change in high latitude ecosystems. Mehr anzeigen
Persistenter Link
https://doi.org/10.3929/ethz-b-000697929Publikationsstatus
publishedVerlag
ETH ZurichKonferenz
Thema
Radiocarbon AMS; ramped pyrolysis-oxidationOrganisationseinheit
03868 - Eglinton, Timothy I. / Eglinton, Timothy I.08619 - Labor für Ionenstrahlphysik (LIP) / Laboratory of Ion Beam Physics (LIP)
Förderung
204093 - Mineralogical Control on Permafrost Carbon Dynamics in Arctic Ecosystems (SNF)
Zugehörige Publikationen und Daten
Documents: https://doi.org/10.5194/egusphere-egu24-7593
Anmerkungen
Poster presented on April 19, 2024.ETH Bibliographie
yes
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