√Polar gas molecules (ammonia, carbon dioxide) have high solubility in water, while non-polar gas molecules (oxygen) have low solubility in water; √The solubility of gases that can chemically react with water is large, and the solubility of gases that cannot chemically react with water is small.

- Generally, as the temperature increases, the solubility of gas in water decreases.

That is: under the same temperature and partial pressure, the solubility of oxygen in seawater is only about 80% to 82% of that in fresh water.

Saturation content: When the speed of O2 dissolving into water is equal to the speed of O2 escaping from water, that is, the concentration of dissolved O2 in water when the dissolution reaches equilibrium.

Apparent Oxygen Consumption (AOU): The difference between the oxygen saturation concentration of a water body and the dissolved oxygen concentration of the water body measured on-site under the conditions of standard atmospheric pressure and air humidity of 100%.