Sediment accumulation and carbon burial in four hadal trench systems

Oguri, K., Masqué, P., Zabel, M., Stewart, H. A., MacKinnon, G. , Rowden, A. A., Berg, P., Wenzhöfer, F. and Glud, R. N. (2022) Sediment accumulation and carbon burial in four hadal trench systems. Journal of Geophysical Research: Biogeosciences, 127(10), e2022JG006. (doi: 10.1029/2022JG006814)

Abstract

Hadal trenches are considered to act as depocenters for organic material, although pathways for the material transport and deposition rates are poorly constrained. Here we assess focusing, deposition and accumulation of material and organic carbon in four hadal trench systems underlying different surface ocean productivities; the eutrophic Atacama and Kuril-Kamchatka trenches, the mesotrophic Kermadec trench and the oligotrophic Mariana Trench. The study is based on the distributions of naturally occurring 210Pbex, 137Cs and total organic carbon from recovered sediment cores and by applying previously quantified benthic mineralization rates. Periods of steady deposition and discreet mass-wasting deposits were identified from the profiles and the latter were associated with historic recorded seismic events in the respective regions. During periods without mass wasting, the estimated focusing factors along trench axes were elevated, suggesting more or less continuous downslope focusing of material towards the interior of the trenches. The estimated organic carbon deposition rates during these periods exhibited extensive site-specific variability, but were generally similar to values encountered at much shallower settings such as continental slopes and margins. Organic carbon deposition rates during periods of steady deposition were not mirrored by surface ocean productivity, but appeared confounded by local bathymetry. The inclusion of deposition mediated by mass-wasting events enhanced the sediment and organic carbon accumulations for the past ∼150 years by up to a factor of ∼4. Thus, due to intensified downslope material focusing and infrequent mass-wasting events, hadal trenches are important sites for deposition and sequestration of organic carbon in the deep sea.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacKinnon, Dr Gillian
• Authors: Oguri, K., Masqué, P., Zabel, M., Stewart, H. A., MacKinnon, G., Rowden, A. A., Berg, P., Wenzhöfer, F., and Glud, R. N.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Journal of Geophysical Research: Biogeosciences
• Publisher: American Geophysical Union
• ISSN: 2169-8953
• ISSN (Online): 2169-8961
• Published Online: 26 September 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Journal of Geophysical Research: Biogeosciences 127(10): e2022JG006
• Publisher Policy: Reproduced under a Creative Commons License
• Data DOI: 10.1594/PANGAEA.947927