We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The Fate of Oxygen in the Ocean and Its Sensitivity to Local Changes in Biological Production.
- Abstract
We investigate the sensitivity of the oxygen content and true oxygen utilization of key low‐oxygen regions Ω to pointwise changes in biological production. To understand how the combined water and biogenic particle transport controls the sensitivity patterns and the fate of oxygen in the ocean, we develop new relationships that link the steady‐state oxygen content and deficit of Ω to the downstream and upstream oxygen utilization rate (OUR), respectively. We find that the amount of oxygen from Ω that will be lost per unit volume at point r is linked to OUR(r) through the mean oxygen age accumulated in Ω. The geographic sensitivity pattern of the Ω‐integrated oxygen deficit is shaped by where the utilization occurs that causes this deficit. The contribution to the oxygen deficit of Ω from utilization at r is controlled by the mean time that water at r spends in Ω before next ventilation at the surface. We illustrate these relationships and the new transport timescales using a simple steady‐state data‐constrained carbon and oxygen model. We focus on Ω being the global ocean, the Pacific Hypoxic Zone (PHZ, [O2] < 62.5 µM), and the North Pacific oxygen minimum zone. The oxygen deficit of the PHZ is most sensitive where mode and intermediate waters form and where increased organic‐matter production directly increases the PHZ's oxygen demand. The fraction of the local oxygen concentration that will be utilized in respiration is as high as 90% in the PHZ and up to 70% in the water column beneath it. Plain Language Summary: Dissolved oxygen is vital for marine animals. Oxygen in the ocean comes primarily from the atmosphere and is consumed throughout the water column by microbes that break down organic matter produced by photosynthesis near the surface. In certain parts of the ocean interior, where oxygen consumption is high and the supply of freshly oxygenated waters is low, the oxygen concentration is lethally low for many animals. As the surface production of organic matter changes due to environmental factors, so does the oxygen demand in the ocean interior. Here we develop new relationships for understanding the fate of oxygen in the ocean and illustrate them with an ocean model. By tracing the oxygen deficit of a given subsurface region back in time to where the oxygen was consumed, we show that the sensitivity of the region's oxygen content to changes in biological productivity is controlled mainly by the time water spends in the region before getting re‐oxygenated at the surface. By tracing oxygen forward in time to where it gets utilized, we show that 70%–90% of the oxygen in the North Pacific below a few hundred meters depth gets utilized in the breakdown of organic matter. Key Points: We map out where the oxygen deficit of low‐oxygen regions originates and link deficit and utilization rates with a new mean transport timeThe sensitivity pattern of low‐oxygen regions to production changes is shaped by the time to next ventilation spent in the regionsIn and below the hypoxic North Pacific 70%–90% of the oxygen concentration will get utilized before next ventilation
- Subjects
OXYGEN carriers; BIOCHEMICAL oxygen demand; BIOLOGICAL productivity; OXYGEN; OCEAN; MINE ventilation; OXYGEN consumption; MARINE animals
- Publication
Journal of Geophysical Research. Oceans, 2022, Vol 127, Issue 8, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2022JC018802