New evidence for preservation of contemporary marine organic carbon by iron in Arctic shelf sediments

Faust, J. C., Ascough, P. , Hilton, R. G., Stevenson, M., Hendry, K. R. and März, C. (2023) New evidence for preservation of contemporary marine organic carbon by iron in Arctic shelf sediments. Environmental Research Letters, 18(1), 014006. (doi: 10.1088/1748-9326/aca780)

Abstract

The protection of organic carbon through association with iron minerals (FeR) is an important factor in its stabilisation, long-term storage, and burial efficiency in marine sediments. However, large uncertainties still exist concerning the sources, lability, age, and composition of the organic matter associated with FeR in natural sediments. Therefore, the timing and environmental setting of the carbon-iron bonding process remain elusive. Here we use radiocarbon (Δ14C) and stable isotopes (δ13C) of downcore bulk sedimentary organic matter, benthic foraminifera and the organic carbon fraction bound to FeR to interrogate the source and age of the organic carbon pool associated with FeR in Arctic marine sediments. In the Barents Sea, we find that the organic carbon associated with FeR is younger overall than the bulk organic matter and is probably marine derived. The comparison to other investigations of OC-FeR origins reveals that in large parts of Arctic shelf regions FeR associated organic carbon is radiocarbon enriched and has a higher δ13Corg value compared to the bulk sediment, irrespective of sediment depth/age. Our findings suggest a rapid and preferential binding of fresh and marine organic matter with FeR. Hence, labile organic matter prone to decomposition is protected and stabilised, underlining the potential of the organic carbon-iron association as an efficient carbon burial mechanism.

• Item Type: Articles
• Additional Information: This work resulted from the ChAOS project (NE/P006493/1), part of the Changing Arctic Ocean programme, jointly funded by the UKRI Natural Environment Research Council (NERC) and the German Federal Ministry of Education and Research (BMBF). Furthermore, this work was supported by a NERC Environmental Isotope Facility, NEIF, Radiocarbon grant (allocation number 2095.0218) and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through Germany’s Excellence Strategy to the Cluster of Excellence “The Ocean Floor – Earth’s Uncharted Interface” (EXC-2077 (grant no. 390741603).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ascough, Dr Philippa
• Authors: Faust, J. C., Ascough, P., Hilton, R. G., Stevenson, M., Hendry, K. R., and März, C.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Environmental Research Letters
• Publisher: IOP Publishing
• ISSN: 1748-9326
• ISSN (Online): 1748-9326
• Published Online: 30 November 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Environmental Research Letters 18(1): 014006
• Publisher Policy: Reproduced under a Creative Commons License