1. LOT / ABM Meeting Malmö, May 9-10, 2012 Proposed analytical work for next ABM parcel Urs Mäder, Paul Wersin, Andreas Jenni Rock-Water Interaction Institute of Geological Sciences, University of Bern

2. Proposed work for new ABM parcel Trace minerals Focus on soluble salts (sulphates, carbonates) Clay context: WC, X i (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)

3. Trace mineral components Trace mineral components control pore water composition and exchanger composition (Ca-sulfate, cristobalite/amorphous 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). The distribution and re-distribution of trace mineral components should therefore also be investigated in conjunction with mass transfer processes observed in the ABM experiment.

4. 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; Dissolve organic acids in MX-80 pore water Cl F system O1 O2 O3

5. Why look at Fe-bentonite interaction? Fe(0) + 2H 2 O  Fe 2+ + H 2 + 2OH - Prec. of corrosion products Fe-clay interactions Fe 3 O 4, GR, FeCO 3, FeS… >Fe(II)-clay, Fe-smectite, berthierine…. Mont. dissolution

6. 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.

7. What about long-term?  Experimental artefacts from O 2 ingress  Transient effects may mask slow, long-term processes  Long-term simulations based on simplistic models Birgersson & Wersin 2011

8. 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...

9. 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