Premium
Decomposing the Oxygen Signal in the Ocean Interior: Beyond Decomposing Organic Matter
Author(s) -
Cassar Nicolas,
Nicholson David,
Khatiwala Samar,
Cliff Ellen
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl092621
Subject(s) - organic matter , tracer , oxygen , oceanography , environmental science , disequilibrium , oxygen minimum zone , environmental chemistry , dissolved organic carbon , oxygen evolution , photosynthesis , remineralisation , deep sea , geology , chemistry , upwelling , inorganic chemistry , medicine , biochemistry , physics , fluoride , organic chemistry , electrode , nuclear physics , electrochemistry , ophthalmology
In the subsurface ocean, O 2 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 O 2 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 O 2 signature. Using numerical model simulations of the global ocean, we show that the measurements of the dissolved O 2 /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 O 2 such as remineralization ratios, respiratory quotients, and preformed nutrients. Finally, we propose a new composite geochemical tracer,[ O 2 ] bio *combining dissolved O 2 /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.