Why is there less dissolved oxygen in higher water temperatures and more in lower temperatures?

Question

Please cite a source.

Answer 1

Because a gas dissolves better in a liquid if both are cold. Heat up the liquid, and gas becomes so energetic that it cannot stay suspended in the liquid any more, so it rises to the top and escapes.

The opposite is true for solids. think about it for a minute, and you should understand why.

Answer 2

the solute and solvent actually affect the solubility curve but for water and oxygen as you've asked:

the dissolved oxygen molecules are surrounded by the liquid water mollecules thus trapping them. But if you raise the temperature or decrease the pressure, the ability of the water molecules to surround the O2 molecules decreases. The water molecules are either too excited by the increase of energy (for increased temp) or too far apart (for decreased pressure) to effectively surround and trap the O2.

Once again though this isn't true for just any solvent and solute.