As the bioengineered creepers grew, they slowly released the oxygen once bound into the soil eons ago.

The R state, with oxygen bound to a heme group, has a different conformation and does not allow this interaction.

Under certain conditions, oxygen bound to the haemoglobin is released into the blood's plasma and absorbed into the tissues.

The strength with which oxygen binds to haemoglobin is affected by several factors.

Carbon monoxide binds to hemoglobin in the site where oxygen normally should bind.

Oxyhemoglobin is formed during physiological respiration when oxygen binds to the heme component of the protein hemoglobin in red blood cells.

This forced low-spin pairing is indeed thought to happen in iron when oxygen binds, but is not enough to explain iron's change in size.

Additionally, dissolved oxygen passively binds to metals and sulfides, further depleting the oxygen in the water column.

In theory the culprit could be something as simple as rust, which forms when oxygen binds to iron or steel.

Molecular oxygen binds covalently to the distal axial coordination position of the heme iron.