On Friday 30th of March a doctoral defense will take place at the Faculty of Earth Sciences at the University of Iceland. At that occasion Hanna S. Kaasalainen will defend her doctoral thesis: "Chemistry of metals and sulfur in geothermal fluids, Iceland"
Opponents are Dr. D. Kirk Nordstom, scientist at the U.S. Geological Survey, Boulder, USA, and Dr. Anthony E. Williams-Jones, professor at Earth & Planetary Sciences, McGill University, Montreal, Canada
Hanna's supervisor is Dr. Andri Stefánsson, professor at Faculty of Earth Sciences, University of Iceland
The PhD committee comprises of professor Stefán Arnórsson and professor Jón Ólafsson. The head of the Faculty of Earth Sciences, professor Magnús Tumi Guðmundsson, will conduct the ceremony which takes place in Main Lecture Hall of the Main building, University of Iceland, and will begin at 16:00.
Hanna S Kaasalainen was born in Riihimäki, Finland, 4th January 1980. She earned her Master degree in Geology in 2005 from the University of Helsinki. In 2008 she started her PhD. study at the Faculty of Eearth Sciences at the University of Iceland. The project was supported by the Nordic Volcanic Center, Icelandic Research Fund, and the Research Fund of the University of Iceland.
Hanna‘s Ph.D. thesis deals with the chemistry of sulfur and metals in geothermal fluids in Iceland. Sampling and analytical methods were developed to studying the concentration of various sulfur species present in geothermal waters including sulfide (H2S), sulfate (SO4), sulfite (SO3), thiosulfate (S2O3) and polythionates (SnO6). Moreover, samples of natural geothermal waters were collected and analyzed for the various sulfur species. The results demonstrate that H2S and SO4 are the dominant sulfur species in geothermal well discharges and that has not been in contact with atmospheric oxygen. Upon oxidation and mixing with oxygenated surface- and shallow ground waters other sulfur species form with thiosulfate being the most common together with H2S and SO4. To better constrain the chemical behavior sets of experiments were conducted on H2S oxidation kinetics in pure water. The results indicate a complex reaction mechanism that is very pH dependent. The results have been published in international scientific journals. In addition to sulfur, the chemistry of trace elements was studied in geothermal fluids in Iceland. Samples of surface geothermal fluids were collected and analyzed for major and trace elements. The fluids sampled included waters from hot springs, mud pots, carbonate springs, steam from steam vents and single phase liquid and two-phase liquid and steam discharges. Based on the results and using geochemical modeling the processes influencing the chemical behavior of various elements were quantified as possible. The processes of importance include fluid-rock interaction, boiling, steam condensation, oxidation, and mixing of geothermal water, condensed steam non-thermal waters. The results have been submitted for publication in international journals.