airsaturated

Airsaturated describes a state in which a material, typically a liquid, contains dissolved gases at their equilibrium concentration with the surrounding air. In liquids, air saturation refers to the maximum amount of gases such as oxygen, nitrogen, and carbon dioxide that can dissolve under the prevailing temperature and pressure.

Formation and maintenance of an air-saturated condition occur when the liquid is exposed to air or subjected to aeration. The dissolved-gas concentration rises until it matches the partial pressures of gases in the atmosphere, after which no further net dissolution occurs. Temperature, pressure, and salinity influence the level of saturation: increasing temperature generally lowers gas solubility, while higher pressure increases it.

Measurement and theory are often described using Henry’s law, which states that the concentration of a dissolved gas is proportional to its partial pressure in the air. In practice, air-saturated water is a common reference state in environmental science, aquaculture, brewing, and water treatment. For example, water at room temperature (around 20°C) in contact with air contains nearly saturated dissolved oxygen, typically on the order of about 8–9 mg/L, though exact values vary with temperature and salinity. Atmosphere composition—roughly 21% oxygen, 78% nitrogen, and trace carbon dioxide—drives the types and amounts of gases that can dissolve.

Applications and considerations: maintaining air saturation can be important for aquatic life and fermentation; conversely, supersaturation can lead to bubble formation, while undersaturation can stress organisms or affect chemical processes.

See also: Henry’s law; dissolved gases; aeration.