Hydrothermal biotic and abiotic dissolution of basaltic glass: solubility and speciation of Fe by X-ray absorption spectroscopy (XAS)

While microbial activity might have a potentially dramatic impact towards silicate reactivity and CO2 sequestration in basalts, the magnitude of this impact remains unknown. Here we propose to investigate the impact of Pyrobaculum aerophilum, an Fe-reducing archeal strain recently identified from basaltic geothermal aquifers in Iceland, on the dissolution kinetics of basaltic glass, taken as a simplified model relevant for basaltic environments. This proposal will take advantage of the unique capability of the HP/HT autoclave available on the FAME beamline to monitor the release and speciation of Fe in the aqueous phase in situ, which we previously successfully used to investigate the dissolution kinetics of Fe-bearing minerals. We expect to get unprecedented data that will pave the way for quantifying the impact of deep biota on silicate reactivity in basaltic settings.