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

Faust, Johan C; Ascough, Philippa; Hilton, Robert G; Stevenson, Mark A; Hendry, Katharine R; Marz, Christian

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.

Citation

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

• Journal Article Type: Article
• Acceptance Date: Nov 30, 2022
• Online Publication Date: Dec 15, 2022
• Publication Date: 2023-01
• Deposit Date: Mar 15, 2023
• Publicly Available Date: May 30, 2023
• Journal: Environmental Research Letters
• Electronic ISSN: 1748-9326
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 18
• Issue: 1
• Article Number: 014006
• DOI: https://doi.org/10.1088/1748-9326/aca780
• Public URL: https://durham-repository.worktribe.com/output/1179570