O2(g) diffusion inhibiting SOM mineralization in Richards Mode

[Bisesh Joshi]

Hi all,

I'm trying to equilibrate the top surface layers with atmospheric O2, and I have a water level close to the surface. I'm using the Millington Quirk Tortuosity model for diffusion with a diffusion constant of 2d-5. I'm testing without a reaction network with SOM-ammonium mineralization from the database.

However, I'm unable to get ammonium mineralization with O2(g) in the system, while I get it when the O2(g) fluid property is turned off. I'm wondering what is causing this inhibition. I have tested scenarios by taking off CO2 and H+ suspecting if they are causing the issue, but I did not help. Shouldn't O2(g) diffusion in the saturated zone be near to zero

Please let me know if you have any ideas on this.

In input file I'm using: this for surface cells.

In the database, I have the following reactions of interest:

for O2 :

'O2(g)' 0.0000 1 1.0000 'O2(aq)' -2.6567 -2.8983 -3.0633 -3.1076 -3.0354 -2.8742 -2.6488 -2.3537 31.9988

for SOM

'SOM02' 125.52 7 -0.5 'H2O' 5.0 'Ac-'   0.441  'NH4+'  0.5 'DOM1' 0.5 'CO2(aq)*' 4.559 'H+' 0.441 'Tracer6' -24.32 -25.01 -25.73 -26.27 -26.81 -27.24 -27.60 -27.89 373.31

Thank you.

--

Bisesh Joshi

PhD student

Water Science and Policy

Graduate College

University of Delaware

901-297-6761

[Bisesh Joshi]

Hi all,

Just a gentle reminder.

Anybody have any thoughts on this?

Thank you.

Bisesh

[Hammond, Glenn E]

Bisesh,

Please send you input deck.

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of Bisesh Joshi <bjo...@udel.edu>
Date: Monday, February 23, 2026 at 7:36 AM
To: pflotra...@googlegroups.com <pflotra...@googlegroups.com>
Subject: [pflotran-users: 8675] Re: O2(g) diffusion inhibiting SOM mineralization in Richards Mode

Check twice before you click! This email originated from outside PNNL.

--
You received this message because you are subscribed to the Google Groups "pflotran-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to pflotran-user...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/pflotran-users/CAEvi1yQC0S0RQbfTu1Kw%3DqNgY8jZmWGR0m8D_fvbE8DO9%3DYiRw%40mail.gmail.com.

[Bisesh Joshi]

Hi Glenn,

Thanks for your reply.

Here, I have attached my input file and its dependencies for you review.

Thank you.

Best regards,

Bisesh

To view this discussion visit https://groups.google.com/d/msgid/pflotran-users/BY3PR09MB755593E6F202428D26B4A1779A77A%40BY3PR09MB7555.namprd09.prod.outlook.com.