Variation in dissolved gases

Some of the properties of seawater affect how much gas can be dissolved in it:

•Cold water holds more gas than warm water. You will have seen this with cans of coke, which are basically carbon dioxide in water. Warm coke cannot hold its gas, so as soon as you open a can of it, the carbon dioxide leaves the water in a big spray of bubbles. It is less messy to open a cold can of coke.

•Seawater with low salinity holds more gas than high salinity water.

•Deep water, which has a high pressure, holds more gas than shallow water.

The use and creation of dissolved gases by living things can over-ride the effect of these properties. For example, warm water with lots of plankton in it can hold more carbon dioxide than cold water with few living things in it.

Dissolved gases demo