Abstract
The groundwater tracers, deuterium (2H or D) and oxygen-18 (18O) are widely used to determine groundwater recharge origin, rate and temperature. Quantitative methods able to interpret δD and δ18O mobility in the subsurface, especially under high pressure and temperature conditions, remain the focus of ongoing research. Here we developed an isotope transport module as an add-on to the TOUGH2 simulator, which is able to describe the evolution of δD and δ18O in groundwater induced by advection, dispersion, water-rock interaction, and fractionation due to changes of water phase and density. The new model was tested by modelling the groundwater flow, temperature, fluid density and isotopic composition in a faulted, geothermal system in the Guide Basin, China. We found that the density-driven flow induced by temperature variations can lead to isotope fractionation between low- and high-density water. In addition, the density-driven flow creates multiple flow systems in the fault damage zone, increasing the complexity of the spatiotemporal isotope distribution. The results indicate that in scenarios where a density contrast occurs, such as in geothermal systems, the relationship between δD and δ18O in recharge water and discharging groundwater can only be fully understood if the coupled processes of fluid flow, heat transport and isotope fractionation in the subsurface are accounted for.
Accepted Version (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
