Disputas: Julien Declercq

Prøveforelesning

Bedømmelseskomité

Professor Sigurður R Gíslason, Institute of Earth Sciences, University of Iceland
Dr Irina Gaus, Nagra - National Cooperative for the Disposal of Radioactive Waste, Switzerland
Professor Håkon Austrheim, Department of Geosciences, University of Oslo

Leder av disputas:  Professor Nils Roar Sælthun

Veileder:  Per Aagaard, Eric Oelkers and Jens Jahren

Sammendrag

The aim of this study was to improve our understanding of water-rock interaction. In particular the dissolution/precipitation of minerals and glasses in aqueous media and their respective mechanisms. These kinetic studies yielded results applicable in several different fields. The most important is the updating of kinetic databases used in geochemical software like PHREEQC. But the knowledge gained can also be used, together with a careful application of geochemical models to address issues related to carbon storage and remediation, such as defining the phases forming when CO2 is injected into the aquifer and reservoirs and the timeframe of such reactions.

The updated kinetic models can also be used outside of CO2 sequestration, for example the alteration of glass and the secondary products generated during these processes. The dissolution of volcanic glass has a major role in natural processes. There is about one cubic kilometer produced every year, mostly along volcanic ridges. The weathering of the ocean floor mostly formed of basalts influences the global amount of CO2 in the atmosphere and thus the climate on the long term. The dissolution mechanism of volcanic glass as been studied extensively but until now a unique dissolution mechanism has not been defined, for those different processes. Being able to generate one reaction mechanism, represented by one equation for all natural glasses extend the models to all glasses. We were then able to use that equation in the case of the alteration of impact glasses. In the case of impact craters most of the deposit are heavily weathered and are mostly composed of clay deposits. Being able to define and quantify the alteration production and rates allows us to define several key parameters of the impact.

Kontaktperson

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