Regulation of O2, N2 and CO2 in the atmosphere; thoughts of a laboratory chemist

The real system (air + sea + sediments) is compared with an equilibrium model, an imaginary system containing the same components at equilibrium. In the model, the presence of five aluminosilicate phases (six, if Fe is included) SiO₂ and CaCO₃ will fix the concentrations of the major ions, pH, and p(CO₂), if temperature and [Cl-] are given. It is suggested that the real system behaves similarly to the model. The T-dependence of p(CO₂) may be a more important factor than industrial activity.

The behavior of the equilibrium model system on reduction is described; it may resemble earlier states of our real system. The present p(O₂) is probably regulated by a steady state, even if some data might seem to indicate the equilibrium (3) to be nearly fulfilled.

Nitrogen exists as N₂ instead of the equilibrium form, NO₃^–. There is a nitrate sink close to the surface of the ocean, but the explanation still seems to be unknown.