SURFACE parameters for soil humic acids normalised to pore water volume

[peterwadeuk]

Greetings esteemed colleagues.

I need to formulate the organic carbon component of an agricultural soil and I am hoping someone can confirm or deny my logic.

I am following the formulation in Example 19 of the phreeqc manual (Parkhurst and Appelo, 2013).

I wish to use the WHAM model of Tipping and Hurley for humic materials, as coded in the T&H database (https://www.hydrochemistry.eu/a&p/7/T_H.DAT).

I am using inorganic exchangers and the transport and kinetics functions to model reactive transport through the soil.

The implication of the latter model components is that all references to solid phases are normalised to litres of pore waters in the soil.

I have captured all my calculations, ultimately normalised to litres of soil pore waters, in formulas in the attached Excel file. I would be grateful for someone to comment on my derivation of the SURFACE parameters.

If looking at my Excel file proves onerous please tell me, and I will make a Word file with the equations presented in "longhand".

All the best to you,
Peter