Identification of redox and buffering processes during injection of oxic water into a deep pyritic aquifer: Experiments and kinetic reaction model

C. Descourvieres, H. Prommer, N. Hartog, C. Oldham

Research output: Chapter in Book/Conference paperConference paper

Abstract

Laboratory experiments were used to study the geochemical controls on sediment reactivity and buffering processes during the injection of oxygen (O 2) saturated waters into a deep anoxic heterogeneous siliclastic sedimentary aquifer. Detailed geochemical characterisation and sediment incubation experiments identified pyrite (20-100%), sedimentary organic matter (SOM; 3-56%), siderite (3-28%) and Fe(II)-aluminosilicates (8-55%) as the main O 2 reductants. Trace-levels of carbonate acted as a pH buffer, while a lower boundary pH of 3 indicated acid buffering by K-feldspar dissolution. The processes identified were used to formulate a kinetic reaction modelling framework that was able to reproduce (i) the observed, transient O 2 consumption and CO 2 production (ii) the major ion composition at completion, and (iii) the observed trace metal releases in each of the treatments. The experiments showed that the approach was useful for identifying and quantifying key geochemical reactions that affect the water quality evolution in artificially recharged anoxic aquifers.

Original languageEnglish
Title of host publicationWater-Rock Interaction - Proceedings of the 13th International Conference on Water-Rock Interaction, WRI-13
Pages375-378
Number of pages4
Publication statusPublished - 1 Dec 2010
Event13th International Conference on Water-Rock Interaction, WRI-13 - Guanajuato, Mexico
Duration: 16 Aug 201020 Aug 2010

Publication series

NameWater-Rock Interaction - Proceedings of the 13th International Conference on Water-Rock Interaction, WRI-13

Conference

Conference13th International Conference on Water-Rock Interaction, WRI-13
CountryMexico
CityGuanajuato
Period16/08/1020/08/10

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