BjerrumModell

The Bjerrum model, also known as the Bjerrum correction, is a method used in oceanography and glaciology to account for the non-ideal behavior of carbon dioxide (CO2) in seawater. Specifically, it addresses the fact that the dissolution of CO2 in water is not a simple chemical equilibrium. The model was developed by Niels Bjerrum.

When CO2 dissolves in water, it forms carbonic acid (H2CO3), which then dissociates into bicarbonate ions (HCO3-) and carbonate ions (CO32-). The Bjerrum model recognizes that the presence of these dissolved ions, as well as the formation of undissociated carbonic acid and bis-carbonate, affects the partial pressure of CO2 in the gas phase in equilibrium with the water. Traditional equilibrium calculations often assume that all dissolved inorganic carbon exists as either HCO3- or CO32-, neglecting the contribution of undissociated H2CO3.

The Bjerrum model introduces correction factors that adjust the calculated equilibrium CO2 partial pressure based on temperature and salinity. These corrections are particularly important in understanding the oceanic uptake and release of atmospheric CO2, a critical component of the global carbon cycle. By providing a more accurate representation of CO2 solubility, the Bjerrum model helps improve climate models and predictions of future ocean acidification.