Oxygen Solubility

Oxygen solubility is the dissolved O2 concentration seawater holds at saturation in equilibrium with the atmosphere, a function of temperature, salinity, and pressure. It falls with warming and with rising salinity: cold polar surface water saturates near 350 micromoles per kg, warm tropical water near 200. The Garcia and Gordon fit to Benson and Krause data is the standard solubility function. Saturation sets the reference against which apparent oxygen utilization measures the O2 consumed by respiration since a water mass left the surface. Warming-driven solubility loss plus weaker ventilation drives ocean deoxygenation.