Applications of Isotopes (Including Noble Gases) in Hydrological and Geothermal Studies
Orfan Shouakar-Stash and Daniele L. Pinti
The aim of this course is to present the latest advancement in using environmental isotopic techniques (CSIA, noble gases, etc.) for characterizing (e.g., tracing sources, estimating ages etc.) crustal fluids at large – from shallow aquifers to high-enthlapy fluids – and the fate of their contaminant load. The potential audience includes environmental professionals, government scientists, regulators, environmental consultants, researchers, students and community stakeholders engaged in the management and remediation of contaminated sites or exploiting fluids for greener energies (e.g., geothermal resources).
Groundwater quality studies focus on understanding where contaminants come from and the transformations that they may experience in the subsurface geochemical environments. Environmental isotopes including compound-specific isotope analysis (CSIA) are one of the most growing tools applied in contaminant studies. The course will include an introduction about theory and background, followed by an extended presentation of several field case studies. The course will cover the application of environmental isotopes, 13C, 2H, 18O, 87Sr/86Sr, 37Cl, 81Br and 3H, to trace the origin of contaminants and the attenuation processes that take place in the aquifer. The topics comprise groundwater pollution from various sources (e.g. LNAPLs, DNAPLs) as well as urban activities. Furthermore, the course is designed to present the latest advancement in 13C-CSIA, 37Cl-CSIA, 81Br-CSIA, and 2H-CSIA and the potential applications of CSIA, to better understand contaminated sites. Groundwater is also a source of cleaner energy, such as hydroelectricity or low- and high-enthalpy geothermics and tracing sources and determining residence times are important issues for estimating the sustainability of the resources. However, if short-lived nuclides (3H and 14C) are well established for determining young groundwater ages, geological fluids used in geothermal energy production are often well beyond the limit of the method, requiring the use of other isotopic system such as noble gases, actinides or radiogenic isotopes. Through theoretical explanations and case histories worldwide we will show how those isotopes can add constraints in both sources and ages of fluids involved in energy ressources.
Advanced Geochemical Modeling
Chen Zhu is a Professor of Earth and Atmospheric Sciences at Indiana University, USA. Chen is the first author of the book with Greg Anderson, Environmental Applications of Geochemical Modeling published by Cambridge University Press, which is used as a textbook at universities around the world. Chen has worked on all three aspects of geochemical modeling: fundamental geochemistry underlying modeling, computer codes and databases, and applications to geological carbon sequestration, nuclear waste disposal, diagenesis, and groundwater contamination and remediation. Zhu holds a Ph.D. from Johns Hopkins University, an MSc from the University of Toronto, a BS from the Chengdu University of Technology (formerly Chengdu College of Geology), and a postdoctoral fellowship at the Woods Hole Oceanographic Institution.
At the end of the short course, students will be able to:
- Become familiar with the concepts, tools, and range of geochemical modeling applications;
- Use geochemical modeling as a tool to interpret natural and engineered systems; and
- Use popular geochemical modeling software packages such as PHREEQC and ToughReact.
Students will enhance their problem-solving skills and quantitative skills through problem sets and modeling exercises.
Geochemical modeling is a powerful tool, which has wide applications such as geothermal energy, CO2 storage in saline aquifers and basalts, and groundwater contamination and remediation. Recently, new databases, code enhancements, and utilities associated with computer programs have expanded the applicable ranges of these modeling tools. This short course will introduce these new tools and use examples to demonstrate these expanded geochemical modeling capabilities with examples.
Parkhurst, D. L., & Appelo, C. A. J. (2013). Description of input and examples for PHREEQC version 3: a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations (No. 6-A43). US Geological Survey.
Zhu C and Anderson GM (2002) Environmental Applications of Geochemical Modeling. Cambridge University Press, London, 304 pp. weblink
Zhu, C. & Nordstrom, D. K. Flying Blind: Geochemical Modeling and Thermodynamic Data Files. Groundwater n/a (2022). https://doi.org/10.1111/gwat.13223
Zimmer, K., Zhang, Y., Lu, P., Chen, Y., Zhang, G., Dalkilic, M., & Zhu, C. (2016). SUPCRTBL: a revised and extended thermodynamic dataset and software package of SUPCRT92. Computers & Geosciences, 90, 97-11