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Dive into the research topics where Runar Blomqvist is active.

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Featured researches published by Runar Blomqvist.


Journal of Contaminant Hydrology | 2001

U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes

Juhani Suksi; Kari Rasilainen; J. Casanova; Timo Ruskeeniemi; Runar Blomqvist; J.A.T. Smellie

U-series data relating to groundwater, fracture coatings and the adjoining rock matrix in a groundwater flow system at the Palmottu natural analogue site was examined. The aim was to obtain an experimental reference for migration modelling in a transport section defined within the flow system. The U-series reference obtained turned out to be a very useful tool for fine tuning the flow route and for migration mechanism considerations. The U-series data are well in line with other interpretations of the migration system.


Applied Geochemistry | 2004

207Pb/206Pb and 238U/230Th dating of uranium migration in carbonate fractures from the Palmottu uranium ore (southern Finland)

C Pomiès; B Hamelin; J Lancelot; Runar Blomqvist

Precambrian U ore deposits, such as Oklo, Cigar-Lake or Palmottu, constitute invaluable analogues of nuclear waste repositories that provide direct evidence of U mobility or sequestration, over very large time intervals in geological formations. In this study, pervasive millimeter thick calcite veins filling microfractures in gneiss and granite surrounding the Palmottu U ore (Finland) were analysed, as fingerprints of past fluid circulation through the site. Stable Pb isotopes and short halflife 234U-230Th isotopes, all products of the U decay chain, have been chosen to investigate long term (over a Ga) and recent (within the last 500 ka) U migrations, respectively. Lead, U and Th isotopes have been analysed by thermo-ionisation mass spectrometry on mg-size bulk carbonate samples, and ion probe analyses of Pb isotopes performed on microinclusions of pyrite, monazite and coffinite. A striking contrast was found between the preservation of a well defined Pb–Pb isochron (1925±70 Ma, MSDW=2.47, N=17) on the one hand, and fractionated 230Th/238U ratios (230Th/238U<1) on the other hand. This shows that although the veins were formed simultaneously to the ore itself, during the Fennoscandian orogeny, and behaved mainly as a closed system for several billion years, U migrations did occur in the last 0.5 Ma. The recent U mobility is probably related to changes in the groundwater circulation through the bedrock. Nowadays, the dispersion of the U is, however, restricted to within a few meters around the U ore. It is shown that complex processes of dissolution and re-adsorption (or re-crystallisation) took place within these tiny carbonate fracture fillings. Relatively unradiogenic 206Pb/204Pb ratios measured by SIMS in coffinite micro-inclusions demonstrate recent precipitation of this mineral. Coffinite being the main U-bearing phase in the carbonate fracture fillings, its crystallization probably played a major role in U redistribution within the fractures, and in the relatively restricted dispersion of U through the bedrock.


Radiochimica Acta | 1994

Redox Chemistry in Uranium-rich Groundwater of Palmottu Uranium Deposit, Finland

Lasse Ahonen; Heini Ervanne; Timo Jaakkola; Runar Blomqvist

Groundwater redox conditions and oxidation states of dissolved uranium were studied in natural water samples from a uranium deposit. Consistently good correlations were observed between the dissolved U(IV)/U(VI) ratio and the measured redox potential value. Dissolved redox pairs in a uranium-rich groundwater sample were studied by monitoring the Eh-change caused by acid/base addition. The results have been compared with the theoretical redox behaviour of uranium.


MRS Proceedings | 1992

Uranium mineral - groundwater equilibration at the Palmottu natural analogue study site, Finland

Lasse Ahonen; Heini Ervanne; Timo Ruskeeniemi; Timo Jaakkola; Runar Blomqvist

The redox-potential, pH, chemical composition of fracture waters, and uraninite alteration associated with the Palmottu uranium mineralization, have been studied. The data have been interpreted by means of thermodynamic calculations. The results indicate equilibrium between uraninite, ferric hydroxide and groundwater in the bedrock of the study site. Partially oxidized uraninite (UO{sub 2.33}) and ferric hydroxide are in equilibrium with the fresh, slightly acidic and oxidized water type, while primary uraninite is stable with deeper waters that have a higher pH and lower Eh. Measured Eh-pH values of groundwater cluster within a relatively narrow range indicating buffering by heterogeneous redox-processes. A good consistency between measured Eh and analyzed uranium oxidation states was observed.


Applied Geochemistry | 2000

Assessing the past thermal and chemical history of fluids in crystalline rock by combining fluid inclusion and isotopic investigations of fracture calcite

Alexander Blyth; Shaun K. Frape; Runar Blomqvist; Pasi Nissinen


Water Research | 2005

Boron isotope fractionation in groundwaters as an indicator of past permafrost conditions in the fractured crystalline bedrock of the fennoscandian shield.

Joël Casanova; Philippe Négrel; Runar Blomqvist


Geofluids | 2003

Strontium isotopic characterization of the Palmottu hydrosystem (Finland): water–rock interaction and geochemistry of groundwaters

Philippe Négrel; Joël Casanova; Runar Blomqvist; Juha Kaija; Shaun K. Frape


Canadian Journal of Earth Sciences | 2005

87Sr/86Sr of brines from the Fennoscandian Shield: a synthesis of groundwater isotopic data from the Baltic Sea region

Philippe Négrel; Joël Casanova; Runar Blomqvist


Ground Water Monitoring and Remediation | 1995

Handheld Double Packer Equipment for Water Sampling and Hydraulic Measurements in Deep Boreholes

Marcus Laaksoharju; Lasse Ahonen; Runar Blomqvist


Geochimica et Cosmochimica Acta | 2006

Methane–halide reactions in shield waters, inferred from δ13C and δ2H of methane and δ81Br and δ37Cl of dissolved ions

Randy L. Stotler; S.K. Frape; Orfan Shouakar-Stash; Timo Ruskeeniemi; Runar Blomqvist

Collaboration


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Timo Ruskeeniemi

Geological Survey of Finland

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Philippe Négrel

Institut de Physique du Globe de Paris

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Joël Casanova

Centre national de la recherche scientifique

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Kari Rasilainen

VTT Technical Research Centre of Finland

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Lasse Ahonen

Geological Survey of Finland

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S.K. Frape

University of Waterloo

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