The influence of water-rock reactions and O isotope exchange with CO2 on water stable isotope composition of CO2 springs in SE Australia

Karolytė, Rūta and Johnson, Gareth and Serno, Sascha and Gilfillan, Stuart M. V. (2017) The influence of water-rock reactions and O isotope exchange with CO2 on water stable isotope composition of CO2 springs in SE Australia. Energy Procedia, 114. pp. 3832-3839. ISSN 1876-6102 (https://doi.org/10.1016/j.egypro.2017.03.1515)

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Abstract

Monitoring injected CO2 in CCS sites using oxygen isotopes of water has been demonstrated in field and laboratory experiments. Here, we examine natural CO2-rich springs in the Daylesford-Hepburn region, South East Australia, which show water 18O depletion compared to local precipitation. Geochemical modelling shows that water-rock reactions are unlikely to have a significant effect on the observed δ18O values, which can only be explained by isotopic exchange with CO2. The water δ18O shift can be used for monitoring CO2 impact on shallow groundwater aquifers, provided that there is sufficient CO2 and distinction between water and CO2 δ18O values exists.

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