Uranium and Multi-element Release from Orthogneiss and Granite (Austria): Experimental Approach Versus Groundwater Composition

Daniel Elster, Edith Haslinger, Martin Dietzel, Heinz Fröschl, Gerhard Schubert

Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

Abstract

In this study, the release of elements and in particular U from five Austrian orthogneiss and granite samples into a CO2-bearing solution was investigated to describe the initial phase (24 h) of leaching focusing on the impact of ferrous (hydro)oxide formation. Experiments were conducted at ambient temperature by flushing CO2:N2 gas through the reactive solution (pHinitial ~ 4.3) at a liquid:solid ratio of 10:1 with and without a reducing agent. The chemical evolution of the leaching solution was dominated by incongruent dissolution of silicates showing a parabolic kinetic behavior due to protective surface formation most likely caused by precipitation of amorphous FeIII/Al hydroxides. However, the relative distribution of Ca, Mg and Sr in the leaching solution excellently traced the individual bulk rock composition. The mobilization of U was highly prevented under oxidizing conditions by sorption onto ferrous (hydro)oxides, which were precipitating through ongoing silicate leaching. Therefore, the leaching behavior of individual U-bearing minerals was less relevant for U release. At reducing conditions, the above elements were accumulated in the solution, although an oversaturation regarding UIVO2 was calculated. This indicates its inhibited formation within the experimental run time. The composition of experimental leaching solutions did not reflect analyzed groundwater compositions from investigated local rock-type aquifers indicating that reaction rate constants of siliceous rocks significantly differ between values found in nature and in the laboratory. Change in active mineral surface areas with ongoing weathering, accumulation of secondary precipitates, leached layer formation and given reaction time are key factors for distinct elemental release.

Originalspracheenglisch
Seiten (von - bis)279-306
Seitenumfang28
FachzeitschriftAquatic Geochemistry
Jahrgang24
Ausgabenummer4
DOIs
PublikationsstatusVeröffentlicht - 1 Aug 2018

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Austria
orthogneiss
Uranium
granite
leaching
ground water
Leaching
uranium
Groundwater
groundwater
Bearings (structural)
Chemical analysis
Silicates
Rocks
rocks
Oxides
Minerals
silicates
silicate
Hydroxides

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    ASJC Scopus subject areas

    • Geophysik
    • !!Geochemistry and Petrology

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    Uranium and Multi-element Release from Orthogneiss and Granite (Austria) : Experimental Approach Versus Groundwater Composition. / Elster, Daniel; Haslinger, Edith; Dietzel, Martin; Fröschl, Heinz; Schubert, Gerhard.

    in: Aquatic Geochemistry, Jahrgang 24, Nr. 4, 01.08.2018, S. 279-306.

    Publikation: Beitrag in einer FachzeitschriftArtikelForschungBegutachtung

    Elster, Daniel ; Haslinger, Edith ; Dietzel, Martin ; Fröschl, Heinz ; Schubert, Gerhard. / Uranium and Multi-element Release from Orthogneiss and Granite (Austria) : Experimental Approach Versus Groundwater Composition. in: Aquatic Geochemistry. 2018 ; Jahrgang 24, Nr. 4. S. 279-306.
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