Updated October 2020
Past and present students (from 1996 -)
Dr Paul Christian Frogner- Kockum (Sweden) from 1999 - 2001.
Dr Domenik Wolff-Boenisch (Germany) from 2001 - 2004.
Dr Domenik Wolff-Boenisch (Germany) from 2007 - 2011.
Dr Morgan Tomas Jones (United Kingdom) from 2011 - 2013.
Dr Iwona Monica Gałeczka (Poland) from 2013 - 2016.
Dr Eydís Salome Eiríksdóttir (Iceland) from 2016 - 2016.
Dr Sandra Ósk Snæbjörnsdóttir (Iceland) from 2017 - 2017.
Dr Martin Voigt 2018 (Germany)- .
Dr Marie-Anne Ancellin (France) 2018-.
Dr Deirdre Elizabeth Clark (USA and Canada) 2019-2020.
Marin Ivanov Kardjilov (Bulgaria) from 2000 - 2008.
Josh Wimpenny (United Kingdom) from 2004 - 2009.
Bergur Sigfússon (Iceland) from 2005 - 2009.
Therese Kaarbø Flaathen (Norway) 2006 - 2009.
Gabrielle Jarvik Stockmann (Denmark) from 2007 - 2012.
Iwona Monica Gałeczka (Poland) from 2009 - 2013.
Snorri Guðbrandsson (Iceland) from 2007 - 2013.
Jonas Olsson (Denmark) from 2010 - 2014.
Helgi Alfreðsson (Iceland) from 2007 - 2015.
Eydís Salome Eiríksdóttir (Iceland) from 2012 - 2016.
Sandra Ósk Snæbjörnsdóttir (Iceland) from 2012-2017.
Rebecca Anna Neely (United Kingdom) from 2012-2017.
Deirdre Elizabeth Clark (USA and Canada) from 2014-2019.
Current PhD students
Tobias Linke, (Germany) from 1. November 2016.
Andri Stefánsson (Iceland) from 1996 - 1998.
Matthildur Bára Stefánsdóttir (Iceland) from 1997 - 1999.
Ingunn María Þorbergsdóttir (Iceland) from 1999 - 2002.
Bergur Sigfússon (Iceland) from 2002 - 2003.
Eydís Salome Eiríksdóttir (Iceland) from 2005 - 2007.
Sigríður Magnea Óskarsdóttir (Iceland) from 2006 - 2007.
Mahnaz Rezvani Khalilabad (Iran) from 2007 - 2008.
Sylviane L. G. Lebon (Belgium) from 2008 - 2009.
Anja Leth (Denmark ) from 2010 - 2012.
Description of postdoctoral students (from 1996 -)
Dr. Paul Christian Frogner- Kockum 1999 -2001.
Paul measured the fertilization and toxic potential of pristine volcanic ash by single flow ambient pressure plug flow reactors.
Frogner P., Gislason S. R. and Oskarsson N. (2001). Fertilizing potential of volcanic ash in ocean surface water. Geology 29, 487-490.
Paul C. Frogner, Kockum, Roger B. Herbert, Sigurdur R. Gislason (2006). A diverse ecosystem response to volcanic aerosols. Chemical Geology 231, 57–66. This work was supported by the Nordic Council of Ministers through Nordvolk, the Nordic Volcanological Institute in Iceland.
Dr. Domenik Wolff-Boenisch 2001 - 2004, 2007-2011.
Domenik measured the dissolution rate of volcanic glasses of different compositions in various water compositions at 25° to 74 °C, and the effect of crystallinity on the dissolution rate of rocks. For these experiment he used mixed flow through reactors. Domenik came back in 2007 to become a project manager of the University of Iceland’s part of CarbFix until 2011. This work was financed by the European Union through a Research Training Network entitled “Quantifying the dissolution and precipitation of solid solutions in natural and industrial processes” within the 5th framework programme (contract number: HPRN-CT-2000-00058).
Wolff-Boenisch, D., Gislason, S.R. and Oelkers, E.H. (2006). The effect of crystallinity on dissolution rates and CO2 consumption capacity of silicates. Geochimica et Cosmochimica Acta, 70, 858-870.
Wolff-Boenisch, D., Gislason, S. R., and Oelkers, E. H. (2004). The effect of fluoride on the dissolution rates of natural glasses at pH 4 and 25°C. Geochim. Cosmochim. Acta 68, 4571-4582.
Wolff-Boenisch, D., Gislason, S. R., Oelkers, E. H., and Putnis, C. V. (2004). The dissolution rates of natural glasses as a function of their composition at pH 4 and 10.6, and temperatures from 25 to 74°C. Geochim. Cosmochim. Acta 68, 4843-4858.
Dr. Morgan Tomas Jones 2011 - 2013.
Morgan studied the reactivity of river suspended matter in the oceans and its role in the various element cycles on the Earth. In the second half of his postdoc he tested the use of osmotic samplers for river monitoring. The research was supported by the European Union through the Funding Scheme: FP7-PEOPLE-2009-IEF, Grant Agreement number: 254495 Project acronym: VOLCANIC WEATHERING and the Seventh Framework Programme “FutureVolc”, EC project number: 308377.
Morgan T. Jones, Christopher R. Pearce, Catherine Jeandel, Sigurdur R. Gislasona, Eydis S. Eiriksdottir, Vasileios Mavromatis, Eric H. Oelkers (2012). Riverine particulate material dissolution as a signiﬁcant ﬂux of strontium to the oceans. Earth and Planetary Science Letters 355-356, 51–59.
Jones MT, SR Gislason, KW Burton, CR Pearce, V Mavromatis, P AE Pogge von Strandmann, EH Oelkers (2014). Quantifying the impact of riverine particulate dissolution in seawater on ocean chemistry. Earth and Planetary Science Letters 395, 91-100.
Jones MT, IM Gałeczka, A Gkritzalis-Papadopoulos, MR Palmer, MC Mowlem, K Vogfjörð, Þ Jónsson and Gislason (2015). Monitoring of jökulhlaups and element fluxes in proglacial Icelandic rivers using osmotic samplers. Journal of Volcanology and Geothermal Research 291, 112-124
Dr. Iwona Monica Gałeczka 2013 - 2016.
Iwona worked with and modified the high pressure plug flow reactor that she build during her PhD study, continued working on “jökulhlaup”, tested the use of osmotic samplers for river monitoring with Morgan Jones, and applied them successfully for monitoring Jökulsá á Fjöllum river chemistry during and following the Bárðarbunga eruption in 2014-2015 and in collaboration with Eydís S. Eiríksdóttir after the eruption in the direct runoff river Fellsá which catchment is about 100 km east of the eruption site. Furthermore she ran a huge sampling campaign on the Vatnajökull glacier to define the pollution form the Bárðarbunga eruption. These projects have been funded by The European Union through the Collaborative project (generic) FP7-ENERGY-2011-1, Grant Agreement Number 283148, CarbFix creating the technology for safe, long-term carbon storage in the subsurface, Nordic Innovation, through the Top Level Initiative the 11029-NORDICCS – The Nordic CCS Competence Centre and SPI-Cooperation, the Icelandic government by funding through the Civil Protection related to the eruption of the Bárðarbunga volcano 2014-15 and the Icelandic research Fund RANNÍS (Grant # 163531-051 og 163531-052).
Galeczka I. M., D. Wolff-Boenisch, E. H. Oelkers, S. R. Gislason (2014). An experimental study of basaltic glass–H2O-CO2 interaction at 22 and 50° C: Implications for subsurface storage of CO2. Geochimica et Cosmochimica Acta 126, 123-145.
Galeczka IM, ES Eiriksdottir, J Hardardottir, EH Oelkers, P Torssander, and SR Gislason (2015). The effect of the 2002 glacial flood on dissolved and suspended chemical fluxes in the Skaftá river, Iceland. Journal of Volcanology and Geothermal Research 301, 253–276.
Iwona Galeczka, Gunnar Sigurdsson, Eydis Salome Eiriksdottir, Eric H. Oelkers, Sigurdur R. Gislason (2016). The chemical composition of rivers and snow affected by the 2014/2015 Bárðarbunga eruption, Iceland. Journal of Volcanology and Geothermal Research, 316,101-119. http://www.sciencedirect.com/science/article/pii/S0377027316000615
Galeczka, Iwona M., Eydis Salome Eiriksdottir, Finnur Pálsson, Eric Oelkers, Stefanie Lutz, Liane G. Benning, Andri Stefánsson, Ríkey Kjartansdóttir, Jóhann Gunnarsson-Robin, Shuhei Ono, Rósa Ólafsdóttir, Elín Björk Jónasdóttir, Sigurdur R. Gislason (2017). Pollution from the 2014–15 Bárðarbunga eruption monitored by snow cores from the Vatnajökull glacier, Iceland. Journal of Volcanology and Geothermal Research, 347, 371-396.
Iwona Galeczka, Eydís Salome Eiríksdóttir, Finnur Pálsson, Rósa Ólafsdóttir, Elín Björk Jónasdóttir & Sigurður R. Gíslason (2017). Pollution from the 2014/2015 Bárðarbunga eruption monitored by snow cores from Vatnajökull glacier, Iceland. Í; Áhrif Holuhraunsgossins á umhverfi og heilsu. Ritstjórar Bjarni Diðrik Sigurðsson og Gerður Stefánsdóttir bls. 41 –45. Rit LbhÍ nr. 83, Desember 2017. Landbúnaðarháskóli Íslands og Veðurstofa Íslands, ISSN 1670-5785, ISBN 978-9979-881-54-4.
Iwona Galeczka, Gunnar Sigurdsson, Eydís Salome Eiríksdóttir, Eric H. Oelkers & Sigurður R. Gíslason (2017). The chemistry of rivers and snow affected by the 2014/2015 Bárðarbunga eruption, Iceland. Í; Áhrif Holuhraunsgossins á umhverfi og heilsu. Ritstjórar Bjarni Diðrik Sigurðsson og Gerður Stefánsdóttir bls. 46 –56. Rit LbhÍ nr. 83, Desember 2017.
Landbúnaðarháskóli Íslands og Veðurstofa Íslands, ISSN 1670-5785, ISBN 978-9979-881-54-4.
Dr. Eydís Salome Eiríksdóttir, post doc in 2016.
Eydís studied the environmental impact of the Holuhraun 2014-2015 eruption on the direct runoff river Fellsá. The catchment is located about 100 km east of the eruption site. The study was done in collaboration with Iwona Galeczka using osmotic samplers which provided continuous daily average river composition monitoring for the entire first snowmelt period following the end of the eruption. The Icelandic government funded the study through the Civil Protection related to the eruption of the Bárðarbunga volcano 2014-15, and the Landsvirkjun Power Company, Iceland, also provided funding.
ES Eiriksdottir, IM Galeczka & SR Gislason (2020). Continuous measurements of riverine chemical constituents reveal the environmental effect of the 2014–2015 Bárðarbunga eruption in Iceland. Journal of Volcanology and Geothermal Research 392, 106766.
Eydís Salome Eiríksdóttir, Iwona M. Gałeczka & Sigurður Reynir Gíslason (2017). Áhrif eldgossins í Bárðarbungu 2014–2015 á efnasamsetningu og framburð Fellsár í Fljótsdal. Í; Áhrif Holuhraunsgossins á umhverfi og heilsu. Ritstjórar Bjarni Diðrik Sigurðsson og Gerður Stefánsdóttir bls. 57 –64. Rit LbhÍ nr. 83, Desember 2017. Landbúnaðarháskóli Íslands og Veðurstofa Íslands, ISSN 1670-5785, ISBN 978-9979-881-54-4.
Dr Sandra Ósk Snæbjörnsdóttir, post doc 2017.
Sandra gathered published and unpublished data, some of it from her own MSc thesis on the stratigraphy, porosity, chemical composition of rock, minerals and glasses at the CarbFix2 injection site at Hellisheidi Iceland. Injection of a CO2-H2S gas mixture started in June 2014. This short project was funded by the Research Fund of University of Iceland.
Snæbjörnsdóttir, Sandra Ó, Sigrún Tómasdóttir, Bergur Sigfússon, Edda Sif Aradóttir, Gunnar Gunnarsson, Auli Niemi, Farzad Basirat, Benoît Dessirier, Sigurdur R Gislason, Eric H Oelkers, Hjalti Franzson (2018). The geology and hydrology of the CarbFix2 site, SW-Iceland, Energy Procedia 146, 146-157.
Dr. Martin Voigt, post-doc from January 2018.
Martins work at University of Iceland will mainly focus on low-temperature (5°-150°C) basalt-seawater interactions, both to look at natural ocean-floor processes and at the fate of added CO2 to such systems.
About Martin: Martin did his BSc in Freiburg Germany, MSc in Victoria Canada, where he studied magmatic processes at oceanic ridges and finally he got his PhD in geochemistry from Paul Sabatier in Toulouse France in 2017. There he used experiments in the laboratory, for example, to study Mg- and Sr-isotope fractionation during seawater-basalt interactions at elevated temperature and pressure to simulate processes at oceanic ridges.
M Voigt, C Marieni, DE Clark, SR Gíslason, EH Oelkers (2018). Evaluation and refinement of thermodynamic databases for mineral, Energy Procedia (2018) 146, 81-91.
This study is a part of the CarbFix2 project: https://www.or.is/carbfix2 and funded by the European Union grant 764760 - CarbFix2- H2020-LCE-2017-RES-CCS-RIA.
Dr. Marie-Anne Ancellin, post-doc from September 2018.
The last IPCC report stressed the importance to use Carbon capture and storage (CCS) to reduce the effects of anthropogenic greenhouse gases. The goal of Marie-Anne’s study is to investigate the utility of metal stable isotopes to monitor geochemical reactions induced by injection of CO2 and H2S in basaltic aquifers. The isotope work is done at Durham University (UK) in collaboration with Kevin Burton. Marie-Anne has analysed Fe, Cu, Zn and St isotopes in water samples from the low temperature (20° - 50°C) CarbFix1 injection site Hellisheiði, Iceland to complement existing Ca and Mg isotope data. And the same isotopes from the high temperature (80°-270°C) Carbfix2 injection site to complement existing Mg isotope data. Here below is her latest abstract from the Goldschmidt 2020 conference, which focused on the low-temperature Carbfix1 site. Tracing CO2 and H2S sequestration in a basaltic aquifer using stable isotopes at CarbFix, Iceland.
The last IPCC report stressed the importance to use Carbon capture and storage (CCS) to reduce the effects of anthropogenic greenhouse gases. The goal of our study is to investigate the utility of metal stable isotopes to monitor geochemical reactions induced by injection of CO2 and H2S in a basaltic aquifer. We have analysed Fe, Cu, Zn and Sr isotopes in water samples from the CarbFix site (Hellisheiði, Iceland) to complement exisiting Ca and Mg isotope data. Pilot injections of (1) 175 tons of CO2 and (2) 73 tons CO2+H2S gas mixture into a deep aquifer were undertaken in 2012. Previous studies have shown that the mobilisation of cations (Ca, Mg, Fe) related to the arrival of the carbonenriched, low-pH waters, was caused by dissolution of the formation basaltic rock. These element concentrations decreased rapidly after this intitial dissolution, being trapped in carbonates, clays, zeolites and hydroxydes. We observe substantial variations in δ56Fe (>1.8 ‰) and δ66Zn (>1.4 ‰) water compositions through the injections and the following monitoring period. Stable Sr, Mg and Zn do not correlate with any specific mineral saturation index, suggesting a multi-mineral influence on their isotopic compositions. Indeed, these isotopes will be fractionated by zeolite, clay, sulfide and carbonate precipitation, for which individual influence are challenging to disentangle. However, Fe and Ca isotope compositions covary when pure CO2 is injected, along with pH variations. Co-injection with H2S at the second injection decouples Fe and Ca isotope fractionation. Ca isotopes are shown to be controlled by calcite dissolution/precipitation at the CarbFix site. Fe isotope fractionation may then be primarly controlled by carbonate precipitation when pure CO2 is involved while being also affected by other phases, in particular sulfides, when H2S is co-injected with CO2. This study demonstrates that Ca and Fe isotopes are the best candidates to quantify carbon capture in carbonates.
Funding: This post-doc work was financially supported from the European Commission through the projects S4CE (EC Project 764810).
About Marie-Anne: After a 2-years preparatory class in Lycée Henri IV (Paris), Marie-Anne did a 3-years geology engineering school in ENSG, Nancy (France) and obtain her M.Sc in 2014. Her end-of-studies internship was completed for ThermoFischer in INGV (Palermo, Italy) to calibrate and monitore the performance of some ThermoFisher instruments on the field. In parallel, she did a second M.Sc in CRPG (Nancy, France) called “Earth and Planets” and studied the geochemistry of Afar depression lavas for her thesis. Then, she did her PhD (2014-2017) in Laboratoire Magmas et Volcans (Clermont-Ferrand, France) where she was investigating the origin of the geochemical diversity of Ecuadorian magmas at different scales, from the Ecuadorian arc down to single minerals in hand-sized samples.
1Institute of Earth Sciences, University of Iceland, Reykjavik, Iceland – firstname.lastname@example.org 2Reykjavik Energy, Reykjavik, Iceland 3 Department of Earth Sciences, Durham Univ., Durham, UK 4 Department of Earth Sciences, UCL, London, UK 5GET, CNRS, Toulouse, France.
ANCELLIN M.-A.1, GISLASON S. R.1, SNAEBJORNSDOTTIR S.2, SIGFUSSON B. 2, , NOWELL G.3, POGGE VON STRANDMANN P.4, OELKERS E.4,5, ALFREDSSON H.A., ARADOTTIR E.2 , MESFIN K.1 , BURTON K. W.3,1
Deirdre Elizabeth Clark 2019-2020.
Industrial-scale testing of a CO2-H2S gas mixture injection commenced in 2014 at the Hellisheiði geothermal power plant in Iceland. By the end of 2017, 23,200 metric tons of CO2 and 11,800 metric tons of hydrogen sulfide (H2S) had been injected to a depth of 750 m into fractured, hydrothermally altered basalts at > 250 °C. Deirdre and collaborators collected over 80 water and gas samples from monitoring and injection wells, before and during injection up to the end of year 2017. Major, minor, and trace element geochemical data were compiled to assess the magnitude of carbon and sulfur mineralization in the subsurface in relation to relevant primary and secondary minerals in the geothermal reservoir and to evaluate the potential scavenging and mobility of trace metals.
Funding: This post-doc work was financially supported from the European Commission through the projects S4CE (EC Project 764810).
About Deirdre: Deirdre Elizabeth Clark was born on 8 April 1988. Her parents are Deanna Borchers and Paul Chudleigh Clark. She grew up in Calgary, AB, Canada and Scotch Plains, NJ, USA. In 2010 she obtained her BSc in geology and BA in environmental studies from the George Washington University in Washington, D.C., USA. She then completed an MSc degree in geochemistry and hydrology from Utrecht University in the Netherlands in 2013. She finished her doctoral studies at the University of Iceland in 2019.
Description of PhD students (from 1996 -)
Marin Ivanov Kardjilov 2000 - 2008.
Riverine and terrestrial Carbon fluxes in Iceland. Supervisors: Guðrún Gísladóttir Professor at the University of Iceland and Sigurður Reynir Gíslason, research Professor at the University of Iceland. Marin Ivanov Kardjilov defended his doctoral thesis in geography in June 2008 at University of Iceland, in Askja, room 132. Opponents were: Dr. Rattan Lal, School of Environment and Natural Resources, Ohio State University, Columbus, Ohio, USA, and Dr. Bjarni Didrik Sigurdsson, Faculty of Environmental Sciences, Agricultural University of Iceland, Hvanneyri, Iceland. The members of the doctoral committee were the supervisors and Dr. Björn Birnir, Department of Mathematics, University of California, Santa Barbara, USA. The defence was chaired by Guðrún Marteinsdóttir the Head of Faculty of Life and Environmental Sciences, University of Iceland.
PhD granted by: The Department of Geography and Tourism, Faculty of Life and Environmental Sciences, University of Iceland. The research was supported by the Icelandic Research Council; RANNÍS, the Research Fund of the University of Iceland, the Science Institute and later the Institute of Earth Sciences.
Abstract: Carbon, organic and inorganic, is one of the fundamental materials of Earth and is of special interest because of its involvement in continuous and complex exchanges between the atmosphere, the land and the ocean. The effect of increased atmospheric CO2 concentration on global climate change calls upon better understanding and quantification of the different carbon fluxes and analyses of how they interact and how they respond to climate change. The aim of this dissertation was to improve knowledge of carbon fluxes in complex geographical, geological and hydrological settings and under different climate conditions and different measurement scales. The research presents the estimation and comparison of the CO2 sequestration rates of the terrestrial carbon fluxes in vegetation and soil and weathering of rocks represented by riverine fluxes in Iceland, and particularly in the northeast for different periods of time during 1998 to 2006. The Geographic Information Systems (GIS) were used to quantify and analyze satellite data, digitized vegetation, soil, and geological maps, and hundreds of river water and river-suspended matter samples, along with continuous monitoring of climate and water discharge over the study period. Temporal carbon fluxes of vegetation were estimated by using MODIS satellite sensor data. MODIS satellite sensor data were used to measure and quantify the carbon fluxes by area on a catchment scale and for the whole of Iceland. All relations between the studied fluxes were analysed. The largest riverine flux was the dissolved inorganic carbon, stemming from chemical weathering. This flux was larger than those for vegetation for the sparsely vegetated areas dominated by young basaltic rocks. In the more vegetated catchments the vegetation fluxes were significantly larger than the riverine fluxes. The annual average temperature of the river catchments in the northeast during this research rose by 2°C over the first 5 years of the study, and the annual river runoff increased by a factor of ~2 for the same period. The Icelandic vegetation responded with a one year time lag to these climate changes. This research results estimated the total amount of carbon fixed by vegetation, respired and exported out of the environment by the rivers as dissolved and particulate organic carbon. This has been the first attempt to quantify and analyse the relationship between riverine and terrestrial carbon fluxes, and to study their response to climate and climate change.
Josh Wimpenny 2004 - 2009.
Chemical weathering and erosional transport in an ancient shield terrain. Supervisors were Kevin Burton and Rachael James Professors at The Open University, the United Kingdom and Sigurður Reynir Gíslason research Professor at the University of Iceland.
PhD granted by the Department of Earth and Environmental Sciences, Centre for Earth, Planetary, Space and Astronomical Research, The Open University, Walton Hall, Milton Keynes, the United Kingdom.
Research focus was on characterising the behaviour of non-traditional stable isotope systems during weathering. Comparing laboratory experiments to field observations focusing on glacial rivers in Greenland. Josh spent a winter at University of Iceland performing experiments on Mg and Li isotope fractionering during weathering of basaltic glass and olivine.
Bergur Sigfússon 2005 - 2009.
Reactive transport of Arsenic through basaltic media. Supervisors were Andy Meharg, University of Aberdeen, Scotland and Sigurður Reynir Gíslason at the University of Iceland. Majority of the work was carried out at the University of Iceland.
PhD granted by University of Aberdeen, Scotland. This study was supported by the Icelandic Research Council; RANNÍS, the Icelandic Governmental Fund for Graduate Education, Orkuveitu Reykjavíkur and Landsvirkjun.
Abstract: This thesis studied the volcanic and geothermal source of arsenic (As) and its fate in shallow ground waters and upon entering the ocean by means of experimental and field measurements combined with geochemical modelling. Arsenic enters the atmosphere and hydrosphere from degassing magmas and during volcanic eruptions. The November 2004 eruption within the Vatnajökull Glacier, Iceland, provided an opportunity to study elemental fluxes from volcanic eruptions into the environment. According to geochemical modelling, lowering of pH due to magma gases during the eruption led to rapid tephra dissolution with corresponding change in flood water chemistry. Geochemical modelling of floodwater/seawater mixing indicated localised decrease in dissolved arsenic and sulphur due to adsorption on the suspended floodwater materials. As the floodwater was diluted the As desorbed and limited effect of the floodwater was predicted after thousand fold dilution. Laboratory experiments were carried out to generate and validate sorption coefficients for arsenite and arsenate in contact with basaltic glass at pH 3 to 10. The mobility of arsenite decreased with increasing pH. The opposite was true for arsenate, being nearly immobile at pH 3 to being highly mobile at pH 10. A 1D reactive transport model constrained by a long time series of field measurements of chemical composition of geothermal effluent fluids from a power plant was constructed. Thioarsenic species were the dominant form of dissolved As in the waters exiting the power plant but converted to some extent to arsenite and arsenate before feeding into a basaltic lava field. Chloride, moved through the basaltic lava field (4100 m) in less than 10 yrs but arsenate was retarded considerably due to surface reactions and has entered a groundwater well 850 m down the flow path in accordance to prediction by the 1D model, which further predicted a complete breakthrough of arsenate in the year 2100 while arsenite will be retained for about 1000 yrs.
Therese Kaarbø Flaathen 2006 - 2009.
Water rock interaction during CO2 sequestration in basalt The supervisors were Sigurður Reynir Gíslason, University of Iceland and Eric Oelkers, CNRS Toulouse France. Therese Kaarbø Flaathen defended her thesis Thursday, September 3, 2009 in the University Aula in Reykjavík. The Opponents were Dr. Yousif Kharaka, US Geological Survey, USA and Dr. Luigi Marini, University of Genova, Italy and representing Université de Toulouse III; Dr. Halldór Ármannsson, Icelandic GeoSurvey, Dr. Kevin Burton, Université de Toulouse III – Paul Sabatier, France and Dr. Pierre Agrinier, Institue de Physique de Globe de Paris, France. The defence was chaired by Magnús Tumi Guðmundsson, Head of the Faculty of Earth Sciences. Joint degree from: Faculty of Earth Science, School of Engineering and Natural Sciences, University of Iceland & Université de Toulouse, Universitée III Toulouse – Paul Sabatier, Géosciences Environment Toulouse, France, September 2009
This research was funded by the Nordic Council of Ministers through NORDVULK and The European Union through The MIN-GRO Research and Training Network (MRTN-CT-2006-035488).
Abstract: The potential dangers with increased concentration of CO2 in the atmosphere, such as climate changes and sea level rise, have led to an interest in CO2 sequestration in geological formations. The thermodynamically most stable way to store carbon is as carbonate minerals. Carbonate mineral formation, however, requires divalent cations originating from a noncarbonated source. One such source is basaltic rocks which contain high concentrations of Ca2+, Mg2+ and Fe2+. The aim of this thesis was to help optimize carbonate mineral precipitation in basalts during CO2 injection through a series of related field and laboratory studies. A detailed study of the chemical composition of the groundwater surrounding the Mt.
Hekla volcano in south Iceland was performed to assess fluid evolution and toxic metal mobility during CO2-rich fluid basalt interaction. These fluids provide a natural analogue for evaluating the consequences of CO2 sequestration in basalt. The concentration of dissolved inorganic carbon in these groundwaters decreases from 3.88 to 0.746 mmol/kg with increasing basalt dissolution while the pH increases from 6.9 to 9.2. This observation provides direct evidence of the potential for basalt dissolution to sequester CO2. The concentrations of toxic metals in these waters are low and reaction path modelling suggests that calcite and Fe(III) (oxy)hydroxides scavenges these metals as the fluid phase is neutralized by further basalt dissolution. The rate limiting step of mineralization of CO2 in basalt is thought to be the release of divalent cations to solution through basaltic glass dissolution. The dissolution rate of basaltic glass can be enhanced by adding ligands which complex aqueous Al3+. Aqueous SO42- can complex Al3+ and the effect of SO42- on the dissolution rate of basaltic glass where performed using mixed flow reactors at 3 < pH < 10 at 50 °C. Moreover, sulphur is often present in the flue gases of power plants and their disposal also poses an environmental challenge. If possible, co-injection of sulphur with CO2 could provide a novel cost effective disposal method for industrial generated sulphur. Consistent with current models describing basaltic glass dissolution with aqueous solution composition, results show that SO42- enhances the dissolution rate of the glass in acidic conditions, while no effect was found in alkaline solutions. These results suggest both that 1) co-injection of sulphate may accelerate CO2 mineralization in basalts, and 2) existing kinetic models provide an accurate description of basaltic glass dissolution.
To further assess the potential effect of SO42- on the precipitation rate of carbonates, steady-state rates of calcite precipitation were measured in mixed flow reactors at 25 °C and pH ~9.1. The results show that 0.005 M Na2SO4 decreases the precipitation rate of calcite with ~40%. This result suggests that co-injected sulphate could slow calcite precipitation at the pH conditions typical of calcite precipitation in the subsurface. Further experiments are planned to completely define these effects at conditions expected at subsurface CO2 injection sites.
Gabrielle Jarvik Stockmann 2007 - 2012.
Experimental Study of Basalt Carbonisation. The supervisors were Dr. Sigurður Reynir Gíslason at the University of Iceland‘s Institute of Earth Sciences and Eric Oelkers, CNRS Toulouse France.
Gabrielle Jarvik Stockmann defended her thesis Wednesday, May 16, 2012 in the University Aula, Reykjavík. The Opponents were Prof. Benedicte Menez, Institut de Physique du Globe de Paris, and Prof. Liane G. Benning, University of Leeds. The defence was chaired by Magnús Tumi Guðmundsson, Head of the Faculty of Earth Sciences. Joint degree from: Faculty of Earth Science, School of Engineering and Natural Sciences, University of Iceland & Université de Toulouse, Universitée III Toulouse – Paul Sabatier, Géosciences Environment Toulouse, France, May 2012.
The Ph.D. project was supported by Reykjavik Energy, the Research Fund of the University of Iceland, the Nordic Council of Ministers through NORDVULK, and the European Community through the MIN-GRO Research and Training Network (MRTN-CT-2006-035488) and the ERASMUS student mobility program.
Abstract: The increasing levels of CO2 in the atmosphere and the potential dangers this pose to the Earth through climate change, ocean acidification and sea-level rise has lead to a substantial number of projects attempting to find a safe and benign way to capture and store CO2 in geological formations, also referred to as the CCS (Carbon Capture and Storage) technology. One of these CCS attempts is currently taking place in Iceland at the geothermal power plant Hellisheidi, located close to the capital Reykjavik (the CarbFix project). CO2 and other gasses (H2S, N2, H2, CH4) are waste products of the geothermal energy exploitation and the aim is with time to store all of this anthropogenic-made CO2 in the basaltic formations underlying Hellisheidi. The CO2 is dissolved in groundwater as it is pumped down to 350 meters depth and then injected into mixed horizons of basaltic glass and crystalline basalt. The basaltic rocks are characterized by high contents of divalent cations like Mg2+, Fe2+ and Ca2+ and relatively fast dissolution rates. The acidic CO2-loaded water will dissolve the basalt thereby releasing cations, which can react with the aqueous carbonate ions to form carbonate minerals (magnesite, siderite, calcite, ankerite and Ca-Mg-Fe solid solutions). The rate-limiting step of this carbon sequestration process is thought to be the dissolution of basaltic rocks, thus any effect that could potentially limit basalt dissolution would be detrimental to the overall CO2 sequestration process. My part of the CarbFix project has been to look at the effects the formation of calcium carbonate coatings would have on the dissolution of the primary phase, in this case basaltic glass and the clinopyroxene diopside, so there would be a glass phase to compare with the results of a mineral phase. Furthermore, a series of experiments were conducted where we tested the primary mineral structure’s effect on calcite nucleation. This was done in order to test if different silicate structures would lead to different extent of calcite nucleation and growth. Finally, extensive series were conducted on the dissolution of basaltic glass in the presence of dead and live heterotrophic bacteria, Pseudomonas reactans in order to determine the potential effect of bacteria on the carbon storage effort at the Hellisheidi site.
The basaltic glass and diopside dissolution experiments were run at 25 and 70 °C and pH 7-8 in mixed-flow reactors connected to solutions containing CaCl2 ± NaHCO3 with ionic strengths > 0.03 mol/kg. Two sets of experimental series were run simultaneously, one series called the “precipitation” experiments in which the solution inside the reactor was supersaturated with respect to calcite, and the other series called the “control” experiments, where PHREEQC modeling foretold no major secondary mineral formation. By this, it was possible to compare dissolution rates of basaltic glass and diopside at 25 ºC with and without calcium carbonate and other secondary mineral formation in order to deduce the effect on their dissolution rates. Scanning electron microscope images showed substantial amounts of calcium carbonate had precipitated in the ”precipitation” experiments, but in the case of basaltic glass the primary growth appeared as big, discrete cluster of calcite and aragonite with no growth on the glass itself. Opposed to this, several of the diopside crystals were extensively overgrown by calcite coatings and no aragonite was found. In neither cases did the presence of calcite/aragonite have an effect on the dissolution rates of basaltic glass and diopside when compared to the “control’ dissolution rates. It appears the discontinuous cover of the carbonate allows the ions of the primary phases to continue to diffuse through the secondary layer unhindered.
To further assess the effect of silicate surface on the nucleation of calcite, the dissolution rates of six selected silicate minerals and rocks were measured in mixedflow reactors in solutions supersaturated with respect to calcite at 25 ºC and pH ~9.1. The silicate phases were: Mg-rich olivine, enstatite, augite, labradorite, basaltic glass and peridotite. The results show different onset time of calcite nucleation and thus different extent of carbonate coverage with elapsed time depending on silicate phase. Within the same timeframe olivine, enstatite and peridotite (mainly composed of Mgrich olivine) were the most covered by calcite precipitations, followed by augite, labradorite and finally basaltic glass. All calcite growth took place on the silicate surface including on the basaltic glass. Kinetics favor calcite nucleation growth on the orthorhombic minerals (enstatite and olivine) over the monoclinic and triclinic minerals. Least calcite was found on the glass, which has no ordered silicate structure.
Heterotrophic bacteria, Pseudomonas reactans was extracted from one of the monitoring wells at Hellisheidi, and then separated, purified and cultured in the laboratory. Its optimal growth conditions were found to be 5-37 ºC and pH 7.0-8.2 on Brain Heart Broth nutrient. Being a common water- and soil bacteria it offered a good candidacy to test what could be expected of heterotrophic bacteria in general when storing CO2 in a natural aquifers like the one at the Hellisheidi site, in Iceland. Basaltic glass dissolution rates were measured at 25 °C in newly developed Bacterial Mixed-Flow reactors (BMFR) in buffer solutions carrying 0.1–0.4 g/L of dead bacteria and 0.9–19 g/L of live bacteria at 4 ≤ pH ≤10. The results show that the presence had either no or a slightly rate-limiting effect. The overall conclusion is that neither the carbonate coatings nor the bacteria had major impact on the measured dissolution rates of the primary silicate phases, thus their effect are expected to be negligible on the CO2 sequestration process in basalt. Crystalline basalt might be faster covered by calcium carbonate, but also basaltic glass can act as a nucleation platform for calcite nucleation.
About Gabrielle: Gabrielle Jarvik Stockmann was born 1969 in Copenhagen, Denmark and grew up in Denmark and Greenland. She received a B.Sc. degree in Chemistry in 1996 and a M.Sc. degree in Geology in 1998 from the University of Copenhagen, Denmark. Her Master’s study took place in Southern Greenland, where she studied rare submarine tufa columns made of the mineral ikaite (CaCO3x6H2O). Following graduation she worked for four years at the Danish Polar Center as an academic employee, one year as information worker at the Geological Institute, University of Copenhagen and finally two years as Head of Section at Universities Denmark before moving to Iceland in 2007. She wrote a book about the Greenlandic ikaite columns together with another geologist, Uffe Wilken in 2007, and this book is now frequently used for teaching in primary and high schools in Denmark. Gabrielle is married to Erik Sturkell, Professor in Applied Geophysics at the University of Gothenburg, Sweden.
Iwona Monica Gałeczka 2009 - 2013.
Experimental and field studies of basalt-carbon dioxide interaction
The supervisors were Sigurður Reynir Gíslason, University of Iceland, Domenik Wolff-Boenisch Department of Applied Geology, Curtin University, Australia, & Eric Oelkers, CNRS Toulouse France. Iwona Galeczka defended her doctoral thesis in geochemistry Friday, September 27th, 2013 at 15:00, at University of Iceland, in Askja, room 132. Opponents were: Prof. Per Aagaard, Department of Geosciences, University of Oslo, and Prof. Alessandro Aiuppa, Dipartimento di Scienze della Terra e del Mare, Palermo University. The defence was chaired by Magnús Tumi Guðmundsson, Head of the Faculty of Earth Sciences.
PhD degree from: Faculty of Earth Science, School of Engineering and Natural Sciences, University of Iceland, September 2013. This PhD study was funded by the European Union through the European Marie Curie network Delta-Min (Mechanisms of Mineral Replacement Reactions; Grant PITN-GA-2008-215360) and SP1-Cooperation (FP7-ENERGY-2011-1; Grant 283148), The Environmental Fund of Reykjavík Energy, University of Iceland and RANNíS, Icelandic Fund for Research Equipment; Grant 10/0293 and 121071-0061, Hitaveita Suðurnesja and Nordurál.
Abstract: The main aim of this study was to design, build, and test a large scale laboratory high pressure column flow reactor (HPCFR) enabling experimental work on water-rock interactions in the presence of dissolved gases, demonstrated here by CO2. The HPCFR allows sampling of a pressurized gas charged fluid along the flow path within a 2.3 m long titanium column filled with mineral, and/or glass particles. In this study, series of experiments were carried out using a carbonated aqueous solution (0.3-1.2 M CO2(aq)) and basaltic glass grains. The scale of the HPCFR, the possibility to sample a reactive fluid at discrete spatial intervals under pressure, and the possibility to monitor the evolution of the dissolved inorganic carbon and pH in-situ all render the HPCFR unique in comparison with other columns constructed for studies of water-rock interactions. Experimental results at ambient temperature showed that the pH of injected pure water evolved from 6.7 to 9-9.5 and most of the dissolved iron was consumed by secondary minerals, similar to natural meteoric water-basalt systems. As CO2-charged water replaced the alkaline fluid within the column, the fluid became supersaturated with respect to carbonates for a short time, but once the entire column was filled with the CO2-charged water and the pH decreased to 4.5, the fluid remained undersaturated with respect to all carbonates. The mobility and concentration of several metals increased significantly in the CO2-fluid phase and some of the metals, including Mn, Fe, Cr, Al, and As exceeded allowable drinking water limits. Iron became mobile and the aqueous Fe2+/Fe3+ ratio increased along the flow path. Basaltic glass dissolution in the CO2-charged water did not overcome the pH buffer capacity of the reactive fluid. The pH rose from an initial pH of 3.4 to 4.5 during the first 40 minutes of CO2-charged water-basaltic glass interaction along the first 18.5 cm of the column but remained constant during the remaining 2.1 meters of the flow path.
In volcanic terrains at high latitude and/or altitude, sub-glacier reservoirs are formed within glaciers by geothermal activity and perhaps small eruptions at the base of ice caps. The reservoirs are periodically drained in glacier floods, called jökulhlaups. Some of these floods, especially those associated with large volcanic eruptions can be disastrous because of their size which is comparable to that of the Amazon River (>200,000 m3/s). In July 2011 two floods ̴ 2,000 m3/s emerged from Icelandic glaciers (Mýrdalsjökull, Vatnajökull). Sub-glacier reservoirs and the geological basement can be looked upon as a laboratory column flow reactor filled up with rocks of a given chemical composition and surface area, where percolating fluid and external gas source react with each other and with the solid material. The fluid represents melt water and external gas source can represent magmatic gases such as CO2, SO2, HCl and HF.
Water samples collected during both floods had neutral to alkaline pH and conductivity up to 900 µS/cm. Alkalinity present mostly as HCO3- was ~9 meq/kg during the flood peak but stabilized at around 1 meq/kg. Small amount of H2S (up to 1.5 µmol/kg) was detected. Concentrations of most of dissolved constituents including magmatic volatiles Cl-, F- and SO42- in flood water were comparable to the annual concentrations variation of these elements in considered rivers. Comparison of the flood water with Icelandic groundwaters and simple reaction path modelling of fluid chemical evolution suggest that the dissolved element composition of the flood waters developed due to long-time (at least two years) water-rock interaction in presence of limited amount of gases without direct contact of water with magma. This suggests that the origin of the heat source for glacier melting and causing these floods to emerge was geothermal rather than volcanic.
About Iwona: Iwona Galeczka was born 1984 in Tarnowskie Gory, Poland. She received a M.Sc. degree in Hydrogeology and Engineering Geology in 2008 from the University of Science and Technology, Krakow, Poland. Following graduation she worked for one year at the Polish Geological Institute as a junior geologist before moving to Iceland in 2009.
Snorri Guðbrandsson 2007 - 2013.
Experimental weathering rates of aluminium-silicates. Dissolution of crystalline basalt and plagioclase, and precipitation of aluminium rich secondary minerals. The supervisors were Dr. Sigurður Reynir Gíslason, at the University of Iceland‘s Institute of Earth Sciences, Eric Oelkers, CNRS Toulouse France Domenik Wolff-Boenisch, Curtin University, Australia.
Snorri Guðbrandsson defended his doctoral thesis for a joint degree in geochemistry from University of Iceland and Paul Sabatier University, Toulouse, France, on Wednesday, October 30th at 15:00 in Hátíðarsalur Háskóla Íslands, Main Building. Opponents were Dr. Marguerite Godard, Research director at Geosciences Montpellier, CNRS, Montpellier, France, Professor Per Aagaard, Department of Geosciences, University of Oslo, and Professor Kevin Burton from the Paul Sabatier University, Toulouse, France. The defence was chaired by Magnús Tumi Guðmundsson, Head of the Faculty of Earth Sciences.
Joint degree from: Faculty of Earth Science, School of Engineering and Natural Sciences, University of Iceland & Université de Toulouse, Universitée III Toulouse - Paul Sabatier, Géosciences Environment Toulouse, France, October 2013.
This work was funded by the Environmental Fund of Reykjavík Energy through the CarbFix Project, Delta-Min (Mechanism of Mineral Replacement Reactions: Grant PITN-GA-2008-215360) and the CarbFix (Collaborative Project-FP7-469 ENERGY-2011-1-283148), the Nordisk Mineralogical Network and the travel fund of the Earth Science Institute, University of Iceland.
Abstract: The chemical weathering of primary rocks and minerals in natural systems has a major impact on soil development and its composition. Chemical weathering is driven to a large extent by mineral dissolution. Through mineral dissolution, elements are released into groundwater and can readily react to precipitate secondary minerals such as clays, zeolites, and carbonates. Carbonates form from divalent cations (e.g. Ca, Fe and Mg) and CO2, and kaolin clay and gibbsite formation is attributed to the weathering of aluminium-rich minerals, most notably the feldspars. The CarbFix Project in Hellisheiði SW-Iceland aims to use natural weathering processes to form carbonate minerals by the re-injection of CO2 from a geothermal power plant back into surrounding basaltic rocks. This process is driven by the dissolution of basaltic rocks, rich in divalent cations, which can combine with injected CO2 to form and precipitate carbonates.
This thesis focuses on the dissolution behaviour of Stapafell crystalline basalt, which consists of three major phases (plagioclase, pyroxene, and olivine) and is rich in divalent cations. Steady-state element release rates from crystalline basalt at far-from-equilibrium conditions were measured at pH from 2 to 11 and temperatures from 5° to 75° C in mixedflow reactors. Steady-state Si and Ca release rates exhibit a U-shaped variation with pH, where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Silicon release rates from crystalline basalt are comparable to Si release rates from basaltic glass of the same chemical composition at low pH and temperatures ≥25°C but slower at alkaline pH and temperatures ≥50°C. In contrast, Mg and Fe release rates decrease continuously with increasing pH at all temperatures. This behaviour is interpreted to stem from the contrasting dissolution behaviours of the three major minerals comprising the basalt: plagioclase, pyroxene, and olivine. Element release rates estimated from the sum of the volume fraction normalized dissolution rates of plagioclase, pyroxene, and olivine are within one order of magnitude of those measured in this study. In addition, these experimental results show that during injection of CO2- charged waters with pH close to 3.6, crystalline basalt preferentially releases Mg and Fe relative to Ca to the fluid phase. The injection of acidic CO2-charged fluids into crystalline basaltic rocks may therefore favour the formation of Mg and Fe carbonates rather than calcite at acidic to neutral conditions. Plagioclase is the most abundant phase in crystalline basalts and thus influences strongly its reactivity. Plagioclase dissolution rates based on Si release show a common U-shaped behaviour as a function of pH where rates decrease with increasing pH at acid condition but increase with increasing pH at alkaline conditions. Constant pH plagioclase dissolution rates increase with increasing anorthite content at acid conditions, in agreement with literature findings. Interpretation and data fitting suggests that plagioclase dissolution rates are consistent with their control by the detachment of Si-rich activated complexes formed by the removal of Al from the mineral framework. Most notably, compared with previous assumptions, plagioclase dissolution rates are independent of plagioclase composition at alkaline conditions, e.g. anorthite-rich plagioclase dissolution rates increase with increasing pH at alkaline conditions. At such conditions rapid plagioclase dissolution rates likely dominate divalent metal release from crystalline basalts to the fluids phase dueto its high Ca content. Gibbsite is commonly the first mineral formed during low temperature dissolution of plagioclase. Gibbsite is an aluminium-hydroxide that is found in various soils as well as the dominant phase in many bauxite ores. Gibbsite precipitation rates were measured in closed system reactors at alkaline condition, both at 25 °C and 80 °C as a function of fluid saturation state. Analyses of the solids demonstrate that gibbsite precipitation occurred in all experiments. The comparison of gibbsite precipitation to the dissolution rates of plagioclase at pH 11 shows that the rates are close to equal. The precipitation rates of gibbsite, however, decrease faster with decreasing pH than plagioclase dissolution rates. As such it seem likely that plagioclase dissolution is faster than gibbsite precipitation at near to neutral pH, and the relatively slow rate of gibbsite precipitation influences plagioclase weathering in many Earth surface systems. Kaolinite is commonly the second secondary mineral formed during low temperature dissolution of plagioclase. Kaolinite precipitation rates were measured in mixed flow reactors as a function of fluid saturation state at pH=4 and 25 °C. In total eight long-term precipitation experiments were performed in fluids mildly supersaturated with respect to kaolinite, together with a known quantity of cleaned low defect Georgia Kaolinite as seeds. Measured kaolinite precipitation rates are relatively slow compared with plagioclase dissolution rates. This observation suggests that kaolinite formation during weathering is limited by its precipitation rates rather than by the availability of aqueous species sourced from plagioclase dissolution. Taken together the results of this study provide some of the fundamental scientific basic for predicting the rates and consequences of crystalline basalt and plagioclase dissolution at both the Earth’s surface and during the near surface injection of CO2 as part of carbon storage efforts. Results indicate that although gibbsite precipitation rates are relatively rapid, the relatively slow precipitation rates of kaolinite may be the process controlling the formation of this mineral at the Earth’s surface. This observation highlights the need to further quantify this secondary mineral precipitation rates at conditions typical at the Earth’s surface. Moreover, as the composition of divalent metals released from crystalline basalts varies significantly with pH, CO2 carbonation in basalt should yield a systematic variation in the identity of carbonate and zeolite minerals precipitated with distance from the injection site. This latter conclusion can be tested directly as part of the currently on-going CarbFix project in Hellisheiði, Iceland.
About Snorri: Snorri Guðbrandsson was born in 1976 in Reykjavík, Iceland. He started geology studies at the University of Iceland in 2003 and received a B.Sc. in 2007. During his undergraduate studies he worked at the Icelandic Institute of Natural History and later at the Iceland Geosurvey. The PhD research has been carried out at the Institute of Earth Sciences, University of Iceland and GET-CNRS, Midi-Pyrenees laboratory in Toulouse, France, along with a short stint at the NanoGeoScience Institute at the University of Copenhagen.
Jonas Olsson 2010 - 2014.
The formation of carbonate minerals and the mobility of heavy metals during water-CO2-mafic rock interactions. Instructors were Dr. Sigurður Reynir Gíslason, Research Professor, Institute of Earth Sciences, University of Iceland and Professor Susan Luise Svane Stipp, University of Copenhagen, Denmark.
On Monday May 26th 2014 Jonas Olsson introduced his Ph.D thesis in Geochemistry at University of Iceland in Askja. This is a double PhD degree from the University of Iceland and the University of Copenhagen. The main defence took place at University of Copenhagen Wednesday, 21 May 2014. The opponents were Prof. Bjørn Jamtveit, Department of Geosciences, University of Oslo, Konrad Herbst, Principal Research Chemist, Chemical Catalyst Department, Haldor Topsøe, Denmark and Hans Christian Bruun Hansen, Professor, Plant Science, University of Copenhagen, Denmark. Doctoral Committee; Professor Susan S. Stipp, University of Copenhagen, Dr. Sigurður Reynir Gíslason, University of Iceland Dr. Emil Makovicky, University of Copenhagen. Double degree in Geochemistry from the University of Iceland and the University of Copenhagen, May 2014
The project was funded by the Nordic Council of Ministers through the Nordic Volcanological Institute (NORDVULK), Institute of Earth Sciences, University of Iceland and the NanoGeoScience Group, Department of Chemistry, Copenhagen, Denmark.
Abstract: CarbFix is a pilot project in Iceland created to lock away CO2 through in-situ mineralization in the subsurface. The goal is to dissolve CO2 from the geothermal power plant, Hellisheiði, in water and inject it into basaltic rock formation for permanent storage. The carbonated water dissolves the basaltic host rock and liberates cations. Ideally, the cations react with the dissolved CO2 and form long time stable carbonate minerals. However, dissolution of the basaltic rock can lead to mobility of toxic metals, which is a potential threat to groundwater supplies and surface waters. Besides carbonate minerals, the reaction products are known to be manifold and reflect the complex composition of the basaltic materials and glass. Formation of secondary products, such as iron (hydr)oxides and clays, are considered undesirable, because (1) they consume the cations that could be used to sequester CO2, thus compete with the process of carbonation, and (2) they can form a passivating layer, which inhibit dissolution of the basaltic material and slow down the carbonation process. The purpose of this thesis was to identify formation products, relevant to CarbFix, and assess their ability to immobilize toxic metals released from basaltic material. The work was divided into four projects.
In the first project, basaltic material in form of fresh volcanic ash from the 2011 Grímsvötn eruption was classified as glassy tholeiitic basalt with <10 mass% of plagioclase and pyroxene. The ash was exposed water and the effluent analysed for 74 elements. The effluent was alkaline and high release rates of mainly S, Na, Ca, Mg, F and Cl were observed during the first 10 minutes. After 12 hours, the most abundant element released was Si. Secondary phases of Al and Fe precipitated on the ash surfaces and these were suspected of scavenging As, Ba, Cr, Co, Cu, Ga, Mn, Mo, Ni, P, Te, V and Zn. This study has also other implications: the small particle size of the ash means that they can travel long distances and this can impact air traffic and the chemical balance of surface waters close to and far away from the volcanic eruption.
In the second study, I investigated natural calcium carbonate precipitation in the Hvanná River, Iceland. A decrease of the concentrations of Cd, Co, Cu, Mg, Mn and Sr with distance downstream the river correlated with calcium. Partition coefficients derived from the precipitating calcite in the Hvanná River are consistent with values of controlled laboratory experiments from the literature for Ba, Cd, Co, Cu, Mg, Mn, Na, Ni, Sr and Zn. The calcium carbonates also scavenge other elements, including rare earth elements (REE) and the toxic metals As and Pb. This and the next study can be considered natural analogues to the carbonate precipitation in CarbFix project.
In the third study, water and solid samples from two hyper-alkaline springs in Oman were examined. The elements detected in the spring waters in order of abundance were Na, Cl, DIC, Ca, Mg, SO4, K, Br, Si, F, B, Sr, Al, Fe, Mo, Zn, Ni, Cu, Mn, V, Ba, Cr, Co, Ti, Hg and Pb. The carbonate samples were identified as aragonite needles and calcite rosettes with traces of serpentine and dypingite. The average concentration in μmol per gram CaCO3 of the carbonates were: Mg(430) > Na(81) > Si(46) > Sr(11) > K(1) > Al(0.95) > P(0.39) > Fe(0.26) > Ba(0.22) > Mn(0.13) > Zn(0.08) > Ni(0.07) > V(0.005) > Cr, Cu, Ti (0.003) > As, Ce(0.001) > Pb, Nd, La, Mo, Pr, Sm, Gd, Dy, Er, Cd, Yb, Eu, Th, Ho, Tb, Lu, Tm(<0.001). This suggests active scavenging of REE and toxic metals such as As, Ba, Cd and Pb by carbonate minerals but Hg was not removed from solution.
In the last project, the basaltic mineral, olivine ((Mg,Fe)2SiO4), was reacted with water and CO2 to form iron and magnesium carbonates both at aerobic and anaerobic conditions. Experiments were carried out in pure water equilibrated with CO2 at total pressures up to 80 bars, at temperatures 25 °C and 120 °C. Within days olivine crystals dissolved and secondary minerals formed when exposed to water only at room temperature. Within 4 days, a red precipitate formed when olivine was reacted at increased temperatures and CO2 partial pressures. The precipitate was identified as goethite, hematite, silica, and clay and carbonate minerals. My experiments suggest that supercritical CO2 is a key factor for the formation of magnesite. At 120 °C, iron did not precipitate as carbonate minerals but rather as iron oxides, independent of the oxygen level.
About Jonas: Jonas was born in 1983. He finished a MSc in Nanosciences from University of Copenhagen in 2009. After that he worked in the NanoGeoScience Group at the same university, and groundwater studies at University of Waterloo, Ontario, Canada. After that, he worked on his PhD at both Univerity of Copenhagen and University of Iceland, from 2010 to 2014.
Helgi Alfreðsson 2007 - 2015.
Water-rock interaction during mineral carbonation and volcanic ash weathering. The supervisors were Dr. Sigurður Reynir Gíslason, at the University of Iceland‘s Institute of Earth Sciences, Eric Oelkers, CNRS Toulouse France and the University College London, United Kingdom and Dr. Domenik Wolff-Boenisch Department of Applied Geology, Curtin University, Australia.
On Thursday September 17, 2015, Helgi Arnar Alfreðsson defended his PhD thesis in Geology (specialization: geochemistry). Opponents were Dr. Per Aagaard, Professor in geochemistry at the University of Oslo, and Dr. Pierre Delmelle, Professor in volcanology at the Université Catholique de Louvain, Belgium. The doctoral committee also included Dr. Stefán Arnórsson, Professor emeritus at the Faculty of Earth Sciences at the University of Iceland, Dr. Andri Stefánsson, Professor at the Faculty of Earth Sciences at the University of Iceland and Dr. Björn S. Harðarson, Specialist at Iceland GeoSurvey. The ceremony was chaired by Dr. Kristín Vala Ragnarsdóttir, Professor and substitute of the Head of the Faculty of Earth Sciences at the University of Iceland.
PhD degree was granted by the Faculty of Earth Science, School of Engineering and Natural Sciences, University of Iceland, September 2015.
This work was funded by the European Community through the MIN-GRO Research and Training Network (MRTN-CT-2006–035488) and the European R&D Project CARBFIX (FP7-ENERGY-2011-1-283148 CarbFix). Also by Reykjavík Energy and its Environmental and Energy Research Fund through the CarbFix project, the Icelandic Government through the Civil Protection during the Eyjafjallajökull eruption, and several travel grants from the Institute of Earth Sciences and the University of Iceland.
Abstract: Reduction of atmospheric carbon dioxide (CO2) is considered one of the biggest challenges of this century. Carbon capture and storage (CCS) is one of the solutions to lower the atmospheric CO2 content. The CarbFix project in Iceland was initiated to design and test a CO2 re-injection system, where CO2 from the Hellisheidi geothermal power plant was injected, fully dissolved in water, into basaltic rocks. The aim was to mineralize the carbon upon basalt dissolution via precipitation of carbonate minerals. Pre-injection study of the CarbFix site showed that the field consists of primitive basaltic rocks, both glassy and crystalline. The targeted aquifer was studied prior to the injection, showing high pH water, ranging in temperature from 15-35°C and isolated from the atmosphere. The dissolved chemistry showed formation of secondary minerals like calcite, Ca-rich zeolites, and clays. Geochemical modelling of the injection schemes predicted that 1-2 moles of basaltic rock were needed to lower the dissolved carbon back to pre-injection values through precipitation of Ca-Mg-Fe-carbonates. A syringe sampler for CO2 rich fluids and tracers was designed and tested in the laboratory and field. The sampler was designed as part of the monitoring of the carbonation process and the evolution of the CO2-rich fluid during the subsurface mineral carbonation.
The 2010 Eyjafjallajökull eruption provided a unique opportunity to study the impact of eruption mechanism; hydromagmatic versus magmatic, on the environmental chemistry. Plug-flow experiments were conducted on pristine volcanic ash, in order to evaluate the initial leaching from the ash surface. There was a dramatic difference between the pH evolutions of the effluent waters from the two ash types. Within minutes there was a “chemical divide” by several orders of magnitude in the proton concentration. The effluent from the hydromagmatic ash was alkaline but acid from the magmatic ash. This caused the effluent from the hydromagmatic ash to become highly supersaturated with common secondary minerals formed in volcanic terrain, but nearly all these minerals were undersaturated in the acid effluent from the magmatic ash.
The pH of surface waters in the vicinity of the Eyjafjallajökull ranged from 4.8–8.2, with the low-range pH measured in the smaller Svadbaelisá-flood during the hydromagmatic phase, and ash-polluted rivers during the magmatic phase. Polluted water from the combined ash layers, showed neutral pH and high amounts of dissolved nutrients and pollutants. The glacial floods in the Markarfljót river were loaded with dissolved magmatic salts and acids, but also indicated neutralization by ash-dissolution with time. High amounts of dissolved elements and suspended ash were transported to the North–Atlantic Ocean. The flux of dissolved inorganic carbon (DIC) down the Markarfljót river, was 15 tonnes/sec during the hydromagmatic phase and 4 tonnes/sec during the magmatic phase, estimated to be total of 10,000 tonnes. These contrasting environmental impacts of magmatic versus hydromagmatic eruption phases, showed that significant iron fertilization of the ocean was only possible from the magmatic ash. And furthermore, the hydro-magmatic ash protected the environment on land by neutralizing the acidic and polluted waters that had been in contact with the magmatic ash.
About Helgi: Helgi Arnar Alfreðsson was born 9th of July, 1984 in Sauðárkrókur, N-Iceland. His parents are Helga Kristín Sigurðardóttir and Alfreð Guðmundsson. Helgi started his undergraduate studies in geology at the University of Iceland in 2004 and graduated with a BSc degree in geology from the Department of Earth Sciences in 2007. He worked part-time during these years, as an assistant driller at Iceland Drilling, working in the re-injection area at the Hellisheidi power plant, and later as a borehole geologist at Iceland GeoSurvey, studying the same area. In the autumn of 2007, Helgi started his graduate studies at the Department of Earth Sciences, University of Iceland. He has worked on his project at the Institute of Earth Sciences, University of Iceland, University of Edinburgh in Scotland, and Oxford University in England. Helgi’s wife is Júlía Katrín Björke and they have two children, Halldór b. 2007, and Alfreð Vilhelm, b. 2014.
Eydís Salome Eiríksdóttir, 2012 - 2016.
Weathering and riverine fluxes in pristine and controlled river catchments in Iceland. The supervisors were Dr. Sigurður Reynir Gíslason, Research Professor at the University of Iceland‘s Institute of Earth Sciences and Dr. Eric H. Oelkers, Professor at the University College in London and CNRS, Toulouse France.
On Friday March 4, 2016, Eydís Salome Eiríksdóttir defended her Ph.D. thesis in Geology, at University of Iceland, Askja room 132 at 14:00. Opponents were Dr. Jérôme Gaillardet, Professor at the Institut de Physique du Globe de Paris, France, and Dr. Suzanne Anderson, Associate Professor at the University of Colorado in Boulder, USA. The doctoral committee included the supervisors, Dr. Hákon Aðalsteinsson, Project Manager at Landsvirkjun, National Power Company of Iceland and Dr. Sophie Opfergelt, Associate Professor at the Université Catholique de Louvain, Belgium. The ceremony was chaired by Dr. Áslaug Geirsdóttir, Professor and the Deputy Head of the Faculty of Earth Sciences, University of Iceland.
PhD degree was granted by the Faculty of Earth Science, School of Engineering and Natural Sciences, University of Iceland March 2016.
This work was funded by the Landsvirkjun, the National Power Company of Iceland, the Ministry for the Environment and Natural Resources in Iceland, the University of Iceland Research Fund in 2013 and 2014, and the Icelandic Road and Coastal Administration.
Abstract: Anthropogenic water management has extensively altered the worlds’ river systems through impoundments and channel diversions to meet mankind’s increasing demand for water, energy, and transportation. One of these altered river systems is the, now dammed, glacial river Jökulsá á Dal in Eastern Iceland. Construction of the dam (Kárahnjúkar) in the highlands North-East of Vatnajökull ice cap was from 2004 to 2007. An initial baseline study of Jökulsá á Dal, prior to dam construction, was conducted from 1998 to 2003 in order to constrain the natural discharge regime and fluxes of suspended- and dissolved material. This river monitoring resumed in 2007 in order to assess the impact of damming Jökulsá á Dal and the construction of Hálslón reservoir and Kárahnjúkar power plant on these riverine fluxes. Monitoring lasted until 2013.
The dataset collected before dam construction was used to demonstrate natural changes within the river catchments and to assess the effect of climate on chemical weathering rates within the catchment. There is a positive correlation between riverine discharge and suspended load but the correlation is negative between discharge and the concentrations of most dissolved elements (e.g. SiO2, Na, Ca, Mg, DIC, SO4, Cl, F, Sr, Mo). However, some elements are controlled by other factors, such as sunlight (e.g. NO3) and the redox potential of the water (e.g. Fe and Mn). The results showed a positive correlation between the climate parameters (water temperature and river discharge) and riverine fluxes of suspended- and dissolved material, and thus on the flux of many essential nutrients to coastal waters. This potentially adds to the negative feedback between chemical weathering of silicates and atmospheric CO2 through photosynthesis in the oceans. Before damming, the glacial river Jökulsá á Dal carried a large suspended sediment load, the majority of which is now deposited in Hálslón reservoir. However, the finest grains remain suspended and are transported with the diverted water from Hálslón reservoir, through headrace tunnels to the power plant, and into the Lagarfljót river. The result of these anthropogenic interventions is increased discharge and concentration of suspended matter in Lagarfljót. The concentrations of the riverine dissolved elements have changed less than the particle concentration. However, since damming, there has been an overall increase in the flux of dissolved constituents. Other anthropogenic alterations can have an impact on river regimes and the environment in more general terms. Precipitation in South Iceland has been monitored for decades, providing the opportunity to study long term changes. This precipitation dataset has enabled the direct measurement of acid rain, widespread in the 1970’s. This acid rain caused environmental damage on the continents but, after new regulations limiting industrial emissions of anthropogenic sulphur from Europe and North America, pH in the precipitation from South Iceland increased between 1980 and 1998. However, since 1998 the pH has once again started to decrease. The timing of this acidification of precipitation is concurrent with increased riverine sulphur fluxes in the region. A proposed cause of these changes is the development of the Nesjavellir geothermal power plant in the vicinity, which started producing electricity in 1998, and the construction and operation of the Hellisheidi geothermal power plant since 2006.
About Eydís: Eydís Salome Eiríksdóttir was born on 27th of April 1972. Her parents are Vilborg Gunnlaugsdóttir and Eiríkur Sigurðsson. Eydís started her undergraduate studies in geology at the University of Iceland in 1993 and graduated with a BSc degree in geology from the Department of Earth Sciences in 1996. In 1998 Eydís started working as an associate scientist at the Science Institute, later Institute of Earth Sciences, at the University of Iceland, monitoring the environmental impact of the glacier river damming in Jökulsá á Dal in Eastern Iceland, among other work. In 2005 Eydís started her graduate studies at the Department of Earth Sciences, University of Iceland and finished a MSc in 2007 and continued her work at the Institute of Earth Sciences. In 2012 she started her PhD studies that she has worked at concurrent to other duties at the Institute. Her partner is Daði Þorbjörnsson and they have two sons, Baldur born 2001 and Arnaldur born 2004.
Sandra Ósk Snæbjörnsdóttir 2012-2017.
On Wednsday the 19th of April, Sandra Ósk Snæbjörnsdóttir defend her Ph.D. thesis in Geology.
The title of the thesis is: Mineral storage of carbon in basaltic rocks. Opponents were Dr. Jordi Cama, Researcher at the Institute of Environmental Assessment and Water Research, Barcelona, Spain and Professor Stuart Haszeldine, Professor of carbon capture and storage at the University of Edinburgh. Advisers were Dr. Sigurður Reynir Gíslason, Research professor, University of Iceland and Professor Eric Oelkers, Professor at the University College London, Director of Research at CNRS, Toulouse, France and Visiting Adjunct Professor at the University of Iceland. The assessment committee included Professor Martin Stute, professor at Barnard College and Adjunct Senior Research Scientist at Columbia University, New York and Dr. Hjalti Franzson, senior geologist at Iceland GeoSurvey.
Abstract: In-situ carbonation of basaltic rocks could provide a carbon storage solution for the long term. Permanence is essential for the success and public acceptance of carbon storage. The aim of this study was twofold, to evaluate and make a first estimate of the theoretical mineral storage potential of CO2 in basaltic rocks, and to characterise the mineralisation process using geochemical data from the CarbFix test site in Hellisheidi, SW-Iceland, which comprises both injection and monitoring wells.
Studies on mineral storage of CO2 in basaltic rocks are still at an early stage. Therefore, natural analogues are important for gaining a better understanding of the carbon mineralisation process in basaltic rocks at elevated pCO2. The amount and spatial distribution of CO2 stored as calcite in the bedrock of geothermal systems in Iceland indicate a large storage potential for CO2 in basaltic rocks. These natural analogues were used as a guideline for evaluating the theoretical potential of CO2 storage in basaltic formations. The largest storage potential lies offshore, where CO2 may be stored in minerals for the long term in mid-ocean ridges. The theoretical mineral CO2 storage capacity of the mid-ocean ridges exceeds, by orders of magnitude, the amount of CO2 that would be released by the burning of all fossil fuel on Earth. Iceland is the largest landmass found above sea level on the mid-ocean ridges, about 103,000 km2. It is mostly made of basaltic rocks (~90%), which makes it ideal for demonstration of the viability of this carbon storage method.
Two injection experiments were carried out at the CarbFix site where 175tonnes of pure CO2 and 73 tonnes of a CO2-H2S-gas mixture were injected in to basaltic rocks at 500-800 m depth with temperatures ranging from 20-50°C.All gases were dissolved in water during their injection. Extensive geochemical monitoring was carried out prior to, during, and after these injections. Sampled fluids from the first monitoring well, HN-04, showed a rapid increase in Ca, Mg, and Fe concentrations during the injections. Pyrite was identified in water samples from the injection well, which indicates that the H2S was mineralised before it reached the first monitoring well. In July 2013, the fluid sampling pump in the well broke down due to calcite precipitation, confirming the mineralisation of the injected CO2. Calculations indicate that the sampled fluids were saturated with respect to siderite about four weeks after the injections began, and with respect to calcite about three months after each injection. Pyrite was supersaturated prior to and during the mixed gas injection and in the following months. Mass balance calculations, based on the recovery of non-reactive tracers co-injected into the subsurface together with the acid gases, confirm that more than 95% of the CO2 injected into the subsurface was mineralised within two years. Essentially all of the injected H2S was mineralised within four months of its injection.
Data collected prior to, during, and after the CO2 injection was used in an attempt to model the CO2-water-rock interaction during and after the injection. The results suggest that the mineralisation of the second and main breakthrough of the injected carbon is mainly driven by basaltic glass dissolution. The results also point towards dissolution of crystalline basalts during the first breakthrough of the injected solution.
This breakthrough path is dominated by fracture flow, indicating that the fracture transects the more crystalline interiors of the lavas. No carbonates are saturated in the injection fluid, but iron rich carbonates, such as siderite, are predicted to form if the pH exceeds ~4.6. With progressive dissolution of basaltic rock, and a subsequent rise of pH along with a decrease in the dissolved CO2 concentration, more Ca-rich carbonates, such as calcite, are calculated to become saturated. At this stage, carbonates become more abundant, forming along with chalcedony, and later, both zeolites and smectites appear. The efficiency of the carbon injection is limited by the porosity and the availability of cations, both of which are restricted by the formation of zeolites and smectites at pH above ~6.5.
About Sandra Ósk: Born in Reykjavik 29th of December 1983. Started geology studies at the University of Gothenburg in 2006 after one year of studying music at the Academy of Music and Drama. Finished bachelor degree from the University of Iceland in February 2009 and was employed as a geologist by Iceland GeoSurvey by graduation. Finished a MSc degree from the University of Iceland in November 2011 with emphasis on geothermal alteration and clay minerals. Started PhD studies in June 2012. Her research was carried out at the University of Iceland with three months on secondment at Lamont Doherty Earth Observatory in New York, USA early 2016.
Rebecca Anna Neely 2012-2017.
On Wednesday the 9th of August 2017, Rebecca Anna Neely defended her Ph.D. thesis in geology. The thesis title is “Molybdenum isotope behaviour in aqueous systems”
Opponents were Dr Thomas F. Nägler, Associate Professor of Isotope Geology at the Institute of Geology at the University of Bern, Switzerland and Dr Caroline L. Peacock, Associate Professor of Biogeochemistry at the School of Earth & Environment at the University of Leeds, United Kingdom. Adviser were Dr Sigurður Reynir Gíslason, Research Professor of Geochemistry at the Institute of Earth Sciences at the University of Iceland and Dr Kevin Burton, Professor of Geochemistry Durham University UK and Professor of Paleoceanography at Université Paul Sabatier in Toulouse, France. The assessment committee also included Dr Eric H. Oelkers, Professor of Aqueous Geochemistry at the University College London, Director of Research CNRS, Université Paul Sabatier, Toulouse, France and Visiting Adjunct Professor at the Institute of Earth Sciences, University of Iceland. Dr Magnús Tumi Guðmundsson, professor and head of Faculty of Earth Sciences at the University of Iceland, chaired the ceremony.
Abstract: Molybdenum isotopes are used to quantify changes in Earth’s surface paleoredox conditions but their application relies upon a simplified model in which rivers dominate the ocean input with minor contributions from hydrothermal fluids. The effect of groundwater discharge is rarely considered. This study finds that cold groundwaters (δ98MoGROUNDWATER -0.1‰) are compositionally similar to their host rocks (δ98MoBASALT -0.15‰) whilst hydrothermal waters are enriched in heavy isotopes (δ98MoHYDROTHERMAL +0.2‰ to +1.8‰). Using flux estimates from the literature, the inclusion of these data results in the revaluation of the Mo ocean input from +0.5‰ (just rivers) to +0.35‰ (combined), in the modern day.
As a bio-essential element, Mo is important in many biogeochemical cycles: especially, as a cofactor in nitrogenase, the most common nitrogen fixing enzyme. Biological fractionations of some 1.5‰ are observed, with light Mo removed from Lake Mývatn by cyanobacterial uptake during an algal bloom. If preserved, these biological fractionations may need to be considered in the interpretation of the sedimentary record.
Despite the growing evidence that the vapour-phase - formed through magma degassing and fluid boiling - can selectively concentrate and transport metals, the effects on metal stable isotopes remain poorly understood. For example, Mo isotopes show great variability in ore deposits, some of which is attributed to vapour-phase transport. Here we examine the vapour-phase in four geothermal systems in Iceland; the vapour-phase is always lighter than the brine with enrichment factors of some εV-L -2.9‰. This is an important first step towards understanding the mechanisms behind vapour transport and isotopic effects.
About Rebecca: Rebecca started her Earth Science studies at the University of Oxford, UK which culminated in a Masters of Earth Science in 2011. She then went on to work as a laboratory- and field- assistant in geochemistry and volcanology before moving and starting a PhD at the University of Iceland in August 2012. Much of the research was carried out in collaboration with Durham University, including more than two years spent there as a visiting student.
Deirdre Elizabeth Clark 2014-2019.
Thesis title: Mineral storage of carbon in basaltic rocks at elevated temperatures. A field and experimental study. PhD Committee: Sigurður Reynir Gíslason University of Iceland, Eric H. Oelkers, CNRS Toulouse France. Iwona Galeczka ÍSOR -the Icelandic GeoSurvey, Domenik Wolff-Boenisch, Curtin University, Perth, Australia. Opponents: Bjørn Jamtveit University of Oslo, Norway. Gregory M. Dipple University of British Columbia, Vancouver, Canada.
Thesis Abstract: The reduction of carbon dioxide (CO2) emissions in the atmosphere is currently one of the main challenges facing humanity. One solution is carbon capture from concentrated sources and directly from the atmosphere, and long term storage in rocks. Basaltic rocks are rich in divalent cations, Ca2+, Mg2+ and Fe2+, which react with the dissolved CO2 to form stable carbonate minerals. Mineralization of water-dissolved CO2 injected into basaltic rocks at 20–50 °C occurs within two years in field-scale settings.
In this study, a high-pressure column flow-through experiment was run to simulate CO2 injection into glassy basaltic rocks at 50 °C. The aim of this experiment was to investigate the proportions of injected dissolved CO2 and high-pH groundwater needed to reach a “sweet spot” in the reacted fluid composition that favors the saturation of carbonates rather than zeolites and clays at pH 5.2–6.5 at 50 °C, as all compete for divalent cations and pore space. Results highlighted the importance of initial pCO2 and pH values to obtain a balance between the formation of carbonates versus clays and zeolites. Moreover, modelling indicates that pauses in CO2 injection while still injecting water can result in enhanced large molar volume Ca-Na-zeolite and Mg-Fe-clay formation that consumes pore space within the rocks.
Parallel to the laboratory experiment, industrial-scale testing of a CO2-H2S gas mixture injection commenced in 2014 at the Hellisheiði geothermal power plant in Iceland. By the end of 2017, 23,200 metric tons of CO2 and 11,800 metric tons of hydrogen sulfide (H2S) had been injected to a depth of 750 m into fractured, hydrothermally altered basalts at > 250 °C. We collected over 80 water and gas samples from monitoring and injection wells, before and during injection. Major, minor, and trace element geochemical data were compiled to assess the magnitude of carbon and sulfur mineralization in the subsurface in relation to relevant primary and secondary minerals in the geothermal reservoir and to evaluate the potential scavenging and mobility of trace metals.
During the first phase of the CarbFix2 injection (June 2014 to July 2016), over 50% of injected carbon and 76% of sulfur mineralized within four to nine months. Four months after the doubling of gas injection rates in July 2016, the decrease in injected fluid pH led to increased mineralization during the second phase (July 2016 to December 2017), resulting in over 60% of the injected carbon and over 85% of the sulfur mineralizing. Doubling the gas injection rate brought the gas-charged fluids closer to the “sweet spot” of mineralization. The Ca release from the reservoir rocks to the fluid phase is a potential limiting factor for calcite (CaCO3) precipitation, although dolomite (Ca,Mg(CO3)2) and thus aqueous Mg may also play a role in the mineralization of the injected carbon. The mineralization rates are accelerated by the high temperatures (> 250 °C) of the formation rocks, but this is the upper temperature limit for carbon storage via the mineral carbonation of basalts due to decarbonation reactions. However, the injectivity of the injection well has remained stable throughout the study period confirming that the host rock permeability has been essentially unaffected by 3.5 years of mineral carbon and sulfur reactions.
Basalt rock dissolution is also known to release trace elements, having been extensively studied in Icelandic geothermal systems. Yet, little is known with regards to their mobility as a consequence of gas injection into basaltic rocks. The results here reveal the mobilization and uptake of several trace elements, particularly Ba, Sr, As, and Mo. Carbonates, sulfides, and secondary minerals such as epidote and actinolite likely incorporated these elements, among others. Notably, although these geothermal fluids are not meant for consumption, the trace elements were generally not above the drinking water standards set by the World Health Organization, the European Union, and Iceland, with the main exception of As. However, while As was significantly elevated before and during the first year of gas injection, concentrations have since been greatly reduced over time to levels at or below drinking water standards.
Funding: This work was financially supported from the European Commission through the projects CarbFix (EC Project 283148), CO2-React (EC Project 317235), CarbFix2 (EC Project 764760), and S4CE (EC Project 764810) in addition to Reykjavík Energy and the first CarbFix team, who without their interest and investment in the original CarbFix project, none of the subsequent research would have been possible.
About Deirdre: Deirdre Elizabeth Clark was born on 8 April 1988. Her parents are Deanna Borchers and Paul Chudleigh Clark. She grew up in Calgary, AB, Canada and Scotch Plains, NJ, USA. In 2010 she obtained her BSc in geology and BA in environmental studies from the George Washington University in Washington, D.C., USA. She then completed an MSc degree in geochemistry and hydrology from Utrecht University in the Netherlands in 2013. She began her doctoral studies at the University of Iceland in 2014.
Current PhD Students
Tobias Linke, 1. November 2016.
Tobias did his MSc in Martin-Luther-University in Halle-Wittenberg Germany where studied the structure and composition of Layered Double Hydroxides he synthesised in the laboratory.
His PhD project will focus on the sequestration of metals, nutrients and carbon into and on the surfaces of iron -oxides, -hydroxides and -carbonates in volcanic sols and their desorption when exposed to pH, oxygen and salinity gradients.
This project is funded by the European Union, Grant 675219 – METAL-AID – ITN-2015 and is part of the Horizon 2020 Marie Sklowdowska Initial Training Network: Metal-Aid (http://nanogeoscience.dk/metalaid )
Description of MSc students (from 1996 -)
Andri Stefánsson 1996 - 1998.
Andri's field and theoretical study focussed on the chemical weathering of basalts in western Iceland and the thermodynamic properties and stability of primary minerals of basalts in surface and crustal waters.
The study was supported by the Icelandic Research Council; RANNÍS and Icelandic Alloys ltd. (see publication list SRG).
Matthildur Bára Stefánsdóttir 1997 - 1999.
The 1996 outburst flood from the Grímsvötn subglacial caldera, Iceland: Composition of the caldera lake water, origin of the suspended flood solids and the flux of readily dissolved nutrients and metals to the sea.
This was a field and experimental study of the erosion and suspended matter/seawater interaction during and after the 1996 outburst flood from the Vatnajökull Glacier, Iceland. The work was supported by the Science Institute, the Icelandic Road Administration, and the Icelandic Glaciological Society (see publication list SRG).
Ingunn María Þorbergsdóttir 1999 - 2002.
This was an in situ benthic flux chamber study of benthic oxygen flux and internal loading of nutrients and certain metals in the shallow eutrophic Lake Mývatn, Iceland. This study was supported by Grant 0005200 from the Icelandic Research Fund for Graduate Education and Grant 996230099 from the Icelandic Research Council; RANNÍS, the Mývatn Research Station, the National Energy Authority, the Science Institute and the University of Akureyri, Iceland (see publication list SRG).
Bergur Sigfússon 2002 - 2003.
Assessment of in situ weathering of an Histic Andosol – microcosm to field scale study
The work was funded by the Icelandic Governmental Fund for Graduate Education, Nordic Aluminium Ltd., Icelandic Alloys Ltd. and the Science Institute, University of Iceland and University of Aberdeen, Scotland (see publication list SRG).
Eydís Salome Eiríksdóttir 2005 - 2007.
Temporal variation of chemical and mechanical weathering in NE Iceland: Evaluation of a steady-state model of erosion. Co-advised by Dr. Pascale Louvat, the Institut de Physique du Globe de Paris, France.
This study was funded by Landsvirkjun, the National Power Company of Iceland, the Icelandic Ministry for the Environment, the Energy Resources Department of the National Energy Authority in Iceland, RANNÍS, the Icelandic Science Foundation (grant 051510005), and the Science Fund of the University of Iceland.
This study critically assesses the temporal sensitivity of the steady-state model of erosion that has been applied to chemical and mechanical weathering studies of volcanic islands and the continents, using only one sample from each catchment. The model assumes a geochemical mass balance between the initially unweathered rock of a drainage basin and the dissolved and solid loads of the river. Chemical composition of 178 samples of suspended and dissolved inorganic river constituents, collected in 1998–2002, were studied from five basaltic river catchments in NE Iceland. The Hydrological Service in Iceland has monitored the discharge and the total suspended inorganic matter concentration (SIM) of the glacial rivers for ~four decades, making it possible to compare modelled and measured SIM fluxes. Concentration of SIM and grain size increased with discharge. As proportion of clay size particles in the SIM samples increased, concentrations of insoluble elements increased and of soluble decreased. The highest proportion of altered basaltic glass was in the clay size particles. The concentration ratio of insoluble elements in the SIM was used along with data on chemical composition of unweathered rocks (high-Mg basalts, tholeiites, rhyolites) to calculate the pristine composition of the original catchment rocks. The calculated rhyolite proportions compare nicely with area weighted average proportions, from geological maps of these catchments. The calculated composition of the unweathered bedrock was used in the steady-state model, together with the chemical composition of the suspended and dissolved constituents of the river. Seasonal changes in dissolved constituent concentrations resulted in too low modelled concentrations of SIMmod at high discharge (and too high SIMmod at low discharge). Samples collected at annual average river dissolved load yielded SIMmod concentrations close to the measured ones. According to the model, the studied rivers had specific mechanical denudation rates of 1.3–3.0 kg/m2/yr whereas the average measured rates were 0.8– 3.5 kg/m2/yr which are among the highest on Earth. This study validates the use of a steady-state model of erosion to estimate mechanical weathering rates at the scale of a river catchment when the collected riverine dissolved load represents the average chemical composition over a mean hydrological year (see publication list SRG).
Sigríður Magnea Óskarsdóttir 2006 - 2007.
Spatial distribution of dissolved constituents in Icelandic river waters
This study was funded by the Energy Resources Department of the National Energy Authority, the Hydrological Service of the National Energy Authority, and RANNÍS, the Icelandic Science Foundation.
In this study we map the spatial distribution of selected dissolved constituents in Icelandic river waters using GIS methods to study and interpret the connection between river chemistry, bedrock, hydrology, vegetation and aquatic ecology. Five parameters were selected: alkalinity, SiO2, Mo, F and the dissolved inorganic nitrogen and dissolved inorganic phosphorus mole ratio (DIN/DIP). The highest concentrations were found in rivers draining young rocks within the volcanic rift zone and especially those draining active central volcanoes. However, several catchments on the margins of the rift zone also had high values for these parameters, due to geothermal influence or wetlands within their catchment area. The DIN/DIP mole ratio was higher than 16 in rivers draining old rocks, but lowest in rivers within the volcanic rift zone. Thus primary production in the rivers is limited by fixed dissolved nitrogen within the rift zone, but dissolved phosphorus in the old Tertiary catchments. Nitrogen fixation within the rift zone can be enhanced by high dissolved molybdenum concentrations in the vicinity of volcanoes. The river catchments in this study were subdivided into several hydrological categories. Importantly, the variation in the hydrology of the catchments cannot alone explain the variation in dissolved constituents. The presence or absence of central volcanoes, young reactive rocks, geothermal systems and wetlands is important for the chemistry of the river waters. We used too many categories within several of the river catchments to be able to determine a statistically significant connection between the chemistry of the river waters and the hydrological categories. More data are needed from rivers draining one single hydrological category. The spatial dissolved constituent distribution clearly revealed the difference between the two extremes, the young rocks of the volcanic rift zone and the old Tertiary terrain (see publication list SRG). Mahnaz Rezvani Khalilabad 2007 - 2008. Born and raised in Iran.
Characterization of the Hellisheidi-Threngsli CO2 sequestration target aquifer by tracer testing
This study was sponsored by the Government of Iceland, through the United Nations University Geothermal Training Programme. The associated field research operation was funded by Reykjavik Energy through the CarbFix program. Mineral sequestration is among several promising methods of CO2 emission reduction. It involves incorporation of CO2 into a solid phase via precipitation of carbonate minerals. A prerequisite to carbonate precipitation is the availability of aqueous metal cations and a network of porous media for fluid flow and water rock interactions. The Hellisheidi-Threngsli lava field in SW Iceland comprises ideal conditions for studying the feasibility of permanent CO2 storage as minerals in basaltic rocks. Prior to the injection, detailed information needs to be gathered to delineate the CO2 injection strategy and reservoir potential to store CO2. In heterogeneous porous aquifers, simulations and predictions of groundwater flow and solute transport require detailed knowledge of aquifer parameters and their spatial distribution. Tracer testing offers the possibility to efficiently investigate the aquifer between the injection and sampling wells and to characterize the relevant aquifer properties based on effective parameter values. Tracer tests can be performed at laboratory and field-scales with depth integrated (two-dimensional) or multilevel (three-dimensional) set-ups, and under natural or forced hydraulic gradient conditions. Both non-reactive and reactive tracer compounds can be used. This contribution reviews depth integrated and natural and forced gradient tracer test methods, their fields of application at different transport scales, the SF6 and Na-Fluorescein tracers and their applications, high resolution multi-level/multi-tracer methods, as well as approaches to evaluate tracer experiments and to quantify tracer transport. Finally this study reports on a forced gradient dipole tracer test conducted between wells HN-02 and HN-04 at the Hellisheidi-Threngsli site to characterize the physical properties of the main aquifers to answer whether tortuosity and porosity will provide enough reactive surface area for CO2-water interaction with basaltic rocks in target zone or not. Simulation and interpretation of initial tracer test results suggest that most of the water flows through a homogenous thick layer of low porosity, fine-medium grained basaltic lava, with high tortuosity along the flow paths, which will provide a large reactive surface area for water rock interactions (see publication list SRG).
Sylviane L. G. Lebon 2008-2009.
Volcanic activity and environment: impacts on agriculture and use of geological data to improve recovery processes. Co-advised with Dr. Freysteinn Sigmundsson University of Iceland. Master’s degree granted by the Department of Environmental Sciences and Natural Resources Management, University of Iceland.
Anja Leth 2010-2012.
Characterisation of suspended material from rivers draining meltwater of Eyjafjallajökull during the explosive eruption in 2010. Co-advised with Dr. Susan Stipp University of Copenhagen. Master’s degree granted by the Faculty of Science, University of Copenhagen.