Atmospheric Gases also Dissolve in Seawater
(^) Nitrogen, oxygen, argon, and carbon dioxide all dissolve in seawater, and all of them
obey Henry’s Law: the equilibrium solubility is proportional to the partial pressure (in
suitable units such as atmospheres) in the air above the water surface. The
proportionality constant changes inversely with temperature, and for oxygen is
approximately two-fold greater at −1°C than at 40°C. That is, saturation concentration
decreases not quite linearly with rising temperature from 360 μmol kg−1 at −1°C
down to 165 μmol kg−1 at 40°C. Salinity reduces the saturation concentration; for
example, at 0°C and salinity = 34, saturation is 351 μmol kg−1 vs. 457 μmol kg−1 in
fresh water (the salt effect is slightly less strong at higher temperature). Units used in