Non-linear coupling of geochemical reservoirs

A different weathering reaction proposed by Berner et al. (1983) involves HC03 instead, but is entirely equivalent to the present equation when HC03 dissociation is taken into account. 

Carbonic acid is diprotic and its dissociation may be written with the two equations 

Combining the last three equations gives the C02 pressure as a function of the speciation of carbonates 

Writing for short p=pCo2 =Ca2+, y=Z(C02), and label with the subscript r the riverine values. The alkalinity A of a solution (Stumm and Morgan, 1981) is defined as its neutralizing capacity 

Subtracting (7.4.14 ) from (7.4.15) and turning to the short notation results in 

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