Analytical Work for Rock-Water Interaction at LOT/ABM Meeting
Proposed analytical work for the next ABM parcel focuses on trace minerals, soluble salts, and dissolved organic acids in the context of rock-water interactions. The investigation includes qualitative measurements, new separation techniques, and analysis of iron-bentonite interactions. The aim is to understand the rapid redistribution of trace mineral components and their impact on pore water composition. Long-term effects and experimental artifacts are also considered for a comprehensive study.
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LOT / ABM Meeting Malm , May 9-10, 2012 Proposed analytical work for next ABM parcel Urs M der, Paul Wersin, Andreas Jenni Rock-Water Interaction Institute of Geological Sciences, University of Bern
Proposed work for new ABM parcel Trace minerals Focus on soluble salts (sulphates, carbonates) Clay context: WC, Xi(minimize sample mass) Dissolved organic acids Performed qualitative measurements with IC. New separation columns: attempt to quantify LMWOA in aqueous extracts (possibly in combination with core infiltration experiments). Iron-bentonite interaction Analysis of interaction zone (SEM, XRD, XRF, XAS ) Collaboration with other labs (ABM and others)
Trace mineral components Trace mineral components control pore water composition and exchanger composition (Ca-sulfate, silica, calcite, dolomite, pyrite, solid organic material). Some trace components react rapidly relative to experimental timescales or even times for analytical procedures. LOT experience shows that re-distribution of trace minerals may be efficient and relatively rapid (Ca-sulfate). cristobalite/amorphous The distribution components conjunction with mass transfer processes observed in the ABM experiment. and re-distribution therefore of be trace investigated mineral should also in
Dissolve organic acids in MX-80 pore water F O1 Cl O2 system O3 MX-80 core infiltration experiment (LOT core); Metrosep ASUPP1_250 Standards on upper horizontal axis; bentonite samples #10-#15 Decreasing oa concentration from #10 to #15;
Why look at Fe-bentonite interaction? Fe(0) + 2H2O Fe2+ + H2 + 2OH- Mont. dissolution Prec. of corrosion products Fe-clay interactions Fe3O4, GR, FeCO3, FeS >Fe(II)-clay, Fe-smectite, berthierine .
A lot has already been done ... Destabilisation of structure by Fe(III) reduction (Lantenois et al. 2005) > Transformation to berthierine / chlorite at higher T (Cathelineau et al..) > Dissolution via corrosion induced pH increase (Kumpulainen et al. 2010) > Reaction of hydrogen with Fe(III) in clay (Didier et al. 2012) > but process details are still not understood.
What about long-term? Experimental artefacts from O2 ingress > Transient effects may mask slow, long-term processes > Long-term simulations based on simplistic models > Birgersson & Wersin 2011
Fe-bentonite in ABM (1) Possibility to study longer term processes at realistic accelerated conditions > Valuabe experience gained from prev. field studies should allow adequate sampling/storage and analysis > Study interaction skin zone: SEM, -XRD, -XRF, XAS... >
Fe-bentonite in ABM (2) Different clay materials: interlayer cation, Fe content, accessories > Supported by modelling > Possibility to design new test with iron avoid galvanic bridging to study corrosion (ABM-2) > Last bu not least: ABM team qualified to do the job >
