Tephra Deposition and Bonding With Reactive Oxides Enhances Burial of Organic Carbon in the Bering Sea

Longman, Jack, Gernon, Thomas M., Palmer, Martin R. and Manners, Hayley R. (2021) Tephra Deposition and Bonding With Reactive Oxides Enhances Burial of Organic Carbon in the Bering Sea. Global Biogeochemical Cycles, 35 (11). e2021GB007140. ISSN 0886-6236

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Official URL: https://doi.org/10.1029/2021GB007140


Preservation of organic carbon (OC) in marine sediments exerts a major control on the cycling of carbon in the Earth system. In these marine environments, OC preservation may be enhanced by diagenetic reactions in locations where deposition of fragmental volcanic material called tephra occurs. While the mechanisms by which this process occurs are well understood, site-specific studies of this process are limited. Here, we report a study of sediments from the Bering Sea (IODP Site U1339D) to investigate the effects of marine tephra deposition on carbon cycling during the Pleistocene and Holocene. Our results suggest that tephra layers are loci of OC burial with distinct δ13C values, and that this process is primarily linked to bonding of OC with reactive metals, accounting for ∼80% of all OC within tephra layers. In addition, distribution of reactive metals from the tephra into non-volcanic sediments above and below the tephra layers enhances OC preservation in these sediments, with ∼33% of OC bound to reactive phases. Importantly, OC-Fe coupling is evident in sediments >700,000 years old. Thus, these interactions may help explain the observed preservation of OC in ancient marine sediments.

Item Type: Article
Additional Information: Funding Information: This work was funded by a Natural Environment Research Council (NERC) grant, NE/K00543X/1, “The role of marine diagenesis of tephra in the carbon cycle.” T. M. Gernon acknowledges support from NERC grant, NE/R004978/1. We are grateful for the comments of Johan Faust and two anonymous reviewers, and those of the associate editor which greatly improved the manuscript. Open access funding enabled and organized by Projekt DEAL.
Uncontrolled Keywords: tephra, carbon burial, reactive Fe, volcanism, carbon preservation, organic carbon
Subjects: F800 Physical and Terrestrial Geographical and Environmental Sciences
Department: Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User: Rachel Branson
Date Deposited: 17 Feb 2023 15:32
Last Modified: 17 Feb 2023 15:45
URI: https://nrl.northumbria.ac.uk/id/eprint/51435

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