P sorption in HP1

The HP1 code incorporates modules simulating
(1) transient water flow in variably-saturated media,
(2) transport of multiple components, and
(3) mixed equilibrium/kinetic geochemical reactions.
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P sorption in HP1

Post by phillipsi2 » Mon Nov 27, 2023 9:23 pm

I am simulating P sorption in a sandy soil with surface charge properties dominated by FeOH minerals (goethite and haematite) and amorphous hydrous oxides. I have calculated sorbed P in PHREEQC using the function SURF("P", "Hfo") and the output represented very closely the measured P sorption isotherm based on the contribution of strong and weak Hfo sites (see below)

SURFACE 0 Strong and weak adsorption sites - iron oxides
Hfo_sOH 0.0313 6.85 5.353
Hfo_wOH 0.0788

I am enquiring if this same function is used in HP1 as when I run HP1 values for Sorbed P are not written as output using the following lines:

-headings SorbP
10 PUNCH SURF("P", "Hfo")
thanks for any assistance.

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