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Transformation of organic matter in a Barents Sea sediment profile: coupled geochemical and microbiological processes

Stevenson, Mark A.; Faust, Johan C.; Andrade, Luiza L.; Freitas, Felipe S.; Gray, Neil D.; Tait, Karen; Hendry, Katharine R.; Hilton, Robert G.; Henley, Sian F.; Tessin, Allyson; Leary, Peter; Papadaki, Sonia; Ford, Ailbe; März, Christian; Abbott, Geoffrey D.

Authors

Johan C. Faust

Luiza L. Andrade

Felipe S. Freitas

Neil D. Gray

Karen Tait

Katharine R. Hendry

Robert G. Hilton

Sian F. Henley

Allyson Tessin

Peter Leary

Sonia Papadaki

Ailbe Ford

Christian März

Geoffrey D. Abbott



Abstract

Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment–water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic–pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0–4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5–10.5 cm depth). Sulfate reducers dominate in the deeper (approx. 10.5–33 cm) anoxic sediments which is consistent with the modelled reactive transport framework. Importantly, organic matter reactivity as tracked by organic geochemical parameters (n-alkanes, n-alkanoic acids, n-alkanols and sterols) changes most dramatically at and directly below the SWI together with sedimentology and biological activity but remained relatively unchanged across deeper changes in sedimentology.

This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning’.

Citation

Stevenson, M. A., Faust, J. C., Andrade, L. L., Freitas, F. S., Gray, N. D., Tait, K., …Abbott, G. D. (2020). Transformation of organic matter in a Barents Sea sediment profile: coupled geochemical and microbiological processes. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 378(2181), https://doi.org/10.1098/rsta.2020.0223

Journal Article Type Article
Acceptance Date Jul 15, 2019
Online Publication Date Aug 31, 2020
Publication Date Oct 2, 2020
Deposit Date Nov 16, 2020
Journal Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences.
Print ISSN 1364-503X
Electronic ISSN 1471-2962
Publisher The Royal Society
Volume 378
Issue 2181
DOI https://doi.org/10.1098/rsta.2020.0223
Public URL https://durham-repository.worktribe.com/output/1251028
Related Public URLs https://research-information.bris.ac.uk/en/publications/transformation-of-organic-matter-in-a-barents-sea-sediment-profil