Physiology of Finfish and Shellfish (2+1)

2.1.3. Solubility of gases

Solubility of gases plays important role in physiological process. Most of the gases are soluble in water. The amount dissolved in water varies based on.

1. The nature of gas
2. The pressure of gas in the gas phase
3. The temperature
4. Presence of other solutes

The solubility co-efficient is defined as the volume of gas (in milliliters standard temperature and pressure dry (STPD)) dissolved in, one liter of water when the pressure of the gas itself, without the water vapour, is 1 atm. The amount of gas is expressed as volume this gas would occupy if the dry gas were at 0ºC and 1 atm pressure: this is designated as standard temperature and pressure dry (STPD).

Solubility of gases in water at 15ºC and 1 atm pressure

So nitrogen is only half soluble as oxygen but CO₂ is roughly 30times soluble as oxygen or 60 times as soluble as N₂.

Component	%
Oxygen	34.1 ml O2/litre
Carbondioxide	1019.0 ml CO2/litre
Nitrogen	16.9 ml N2/litre