Laboratory simulation of an oxidizing perturbation in a deep granite environment

Overview

Title: 

Laboratory simulation of an oxidizing perturbation in a deep granite environment

Abstract: 

An experiment designed to study oxidizing perturbations in deep crystalline rock, a potential host for nuclear waste disposal, was conducted. This experiment simulated a fracture surface in contact with circulating groundwater, in which dissolved oxygen was injected periodically. Major physicochemical and biological parameters were monitored during this 1-yr experiment. Modeling of the results indicates that the kinetics of oxygen uptake may be represented by a simple steady-state rate law combining enzymatic catalysis (Monod) and a first-order rate law. Combined chemical and biological data demonstrate the coupling of organic/inorganic processes during the uptake of dissolved oxygen and the progressive return to reducing conditions. Timescales for these stages are discussed. Experimental results also suggest that iron-reducing bacteria, which are robust and well-adapted microorganisms, play a key role in these interfacial processes. These results show that an operational definition of the "redox buffering capacity" in a granitic medium cannot ignore the effect of bacteria and therefore the controls on bacterial substrates (organic carbon, H-2, CH4, CO2). Copyright (C) 2002 Elsevier Science Inc.

Authors: 

Laurent Trotignon, Valrie Michaud, Jean-Eric Lartigue, Jean-Paul Ambrosi, Laurent Eisenlohr, Lise Griffault, Michel de Combarieu, Sylvie Daumas

DOI: 

Journal: 

Geochimica Et Cosmochimica Acta

Year: 

2002

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