Publication Date:
2022-10-26
Description:
Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 48(18), (2021): e2021GL092621, https://doi.org/10.1029/2021GL092621.
Description:
In the subsurface ocean, O2 depleted because of organic matter remineralization is generally estimated based on apparent oxygen utilization (AOU). However, AOU is an imperfect measure of oxygen utilization because of O2 air-sea disequilibrium at the site of deepwater formation. Recent methodological and instrumental advances have paved the way to further deconvolve the processes driving the O2 signature. Using numerical model simulations of the global ocean, we show that the measurements of the dissolved O2/Ar ratio, which so far have been confined to the ocean surface, can provide improved estimates of oxygen utilization, especially in regions where the disequilibrium at the site of deepwater formation is associated with physical processes. We discuss applications of this new approach and implications for the current tracers relying on O2 such as remineralization ratios, respiratory quotients, and preformed nutrients. Finally, we propose a new composite geochemical tracer, [O2]bio combining dissolved O2/Ar and phosphate concentration. Being insensitive to photosynthesis and respiration, the change in this new tracer reflects gas exchange at the air-sea interface at the sites of deepwater formation.
Description:
Nicolas Cassar was supported by the “Laboratoire d'Excellence” LabexMER (ANR-10-LABX-19) and cofunded by a grant from the French government under the program “Investissements d'Avenir.” Samar Khatiwala was supported by UK NERC grant NE/T009357/1. Ellen Cliff acknowledges support from the Rhodes Trust.
Description:
2022-03-13
Keywords:
AOU
;
Oxygen
;
O2/Ar
;
Remineralization
Repository Name:
Woods Hole Open Access Server
Type:
Article
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