Dissolved Organic Radiocarbon in the West Indian Ocean

Creators: Druffel, Ellen R. M.; Lewis, Christian B.; Griffin, Sheila; Flaherty, Alessandra^{1, 2}; Rudresh, Megha; Hauksson, Niels E.; Key, Robert M.; McNichol, Ann P.; Hwang, Jeomshik; Walker, Brett D.

1. University of California, Irvine
2. California Institute of Technology

Abstract

We report marine dissolved organic carbon (DOC) concentrations, and DOC Δ¹⁴C and δ¹³C in seawater collected from the West Indian Ocean during the GO-SHIP I07N cruise in 2018. We find bomb ¹⁴C in DOC from the upper 1,000 m of the water column. There is no significant change in ∆¹⁴C of DOC in deep water northward, unlike that of dissolved inorganic carbon (DIC), suggesting that transport of deep water northward is not controlling the ¹⁴C age of DOC. Variability of DOC ∆¹⁴C, including high values in the deep waters, is more pronounced than in other oceans, suggesting that dissolution of surface derived particulate organic carbon is a source of modern carbon to deep DOC in the West Indian Ocean. Low δ¹³C are present at two of the five stations studied, suggesting a source of low δ¹³C DOC, or additional microbial utilization of deep DOC.

Copyright and License

© 2023. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

We thank Jennifer Walker, Xiaomei Xu, and Hector Martinez De La Torre for the stable carbon isotope measurements, John Southon and staff for their assistance and advice, chief scientists Denis Volkov and Viviane Menezes, and Jim Swift for shared ship time.

Funding

This work was supported by NSF (OCE-1458941 and OCE-1951073 to E.R.M.D.), Fred Kavli Foundation, Keck Carbon Cycle AMS Laboratory, NSF/NOAA funded GO-SHIP Program, and Canada Research Chairs program (to B. D. W.).

Contributions

Conceptualization: Ellen R. M. Druffel, Brett D. Walker.

Data curation: Ellen R. M. Druffel, Sheila Griffin, Robert M. Key, Brett D.Walker.

Formal analysis: Ellen R. M. Druffel, Sheila Griffin, Niels E. Hauksson, RobertM. Key, Jeomshik Hwang, Brett D.Walker.

Funding acquisition: Ellen R. M. Druffel.

Investigation: Robert M. Key, Brett D.Walker.

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