Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

Tournassat, Christophe; Alt-Epping, Peter; Gaucher, Eric C.; Gimmi, Thomas; Leupin, Olivier X.; Wersin, Paul (2011). Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling. Applied geochemistry, 26(6), pp. 1009-1022. Oxford: Pergamon 10.1016/j.apgeochem.2011.03.009

[img] Text
Alt-Epping_Gimmi.pdf - Published Version
Restricted to registered users only
Available under License Publisher holds Copyright.

Download (1MB) | Request a copy

Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C. dissolved inorganic C and SO(4) concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of clay surfaces.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Alt-Epping, Peter; Gimmi, Thomas and Wersin, Paul

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0883-2927

Publisher:

Pergamon

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:29

Last Modified:

05 Dec 2014 20:10

Publisher DOI:

10.1016/j.apgeochem.2011.03.009

Web of Science ID:

000291578400007

BORIS DOI:

10.7892/boris.10601

URI:

https://boris.unibe.ch/id/eprint/10601 (FactScience: 216502)

Actions (login required)

Edit item Edit item
Provide Feedback