Doublets correspond to ferrous present in silicate phases such as olivine and orthopiroxene.
Dissolution of pyroxenes that contains ferrous iron will contribute to the hydrogen formation, but to a much less extent than olivine.
Oxidation of ferrous iron by nitrate might prevent the lowest oxygen levels and thus inhibit hydrogen formation.
Oxidation of released ferrous iron may consume oxygen to such an extent that water decomposes and form molecular hydrogen.
In patients with gastrointestinal disturbances, iron may be given with food or an alternative oral iron medication may be substituted (ferrous fumarate, ferrous gluconate).
After a sharp transition into a reduced solution, the hydrogen production becomes proportional to the amount of ferrous iron released.
The first region is characterized by oxygen consumption by the oxidation of ferrous iron without producing hydrogen.
This may lead to a reduced activity of the ferrous iron and less consumption of oxygen by reaction (2).
