Use of Long-lived Radionuclides for Dating Very Old Groundwaters

This CRP addresses the use of new tools for the estimation of very old groundwater ages (> 50000 years), which is one of the most elusive hydrological parameter to assess in the case of groundwater resources. With an increasing population and potential impact of climate change, groundwater extracted from deeper horizons is becoming the most important fresh water resource in many areas. Despite significance of age information for water resources, waste management, subsurface reactive transport, and paleoclimate, this parameter is always very difficult to assess. Additionally,  comprehensive dating tools are not often available to many Member States.The main focus of this new CRP will be the implementation of several isotope hydrology assessments of deep/large aquifer systems using long-lived radionuclides, isotope age tracers and noble gases (carbon-14, krypton-81, chlorine-36, helium-4, etc…). These techniques are either hard to access or to implement in many member states.       Following the recent increase in the analytical capacity of the IAEA’s noble gas facility, this CRP will provide the possibility to improve Member States’ capabilities in the assessment of deep groundwater systems by offering the combined use of the paleo-temperature estimates from isotopes of neon, argon, krypton and xenon and the age dating by helium-4 cross calibrated with other isotope techniques. Other noble gas isotopes, such as krypton-81, will also be analysed in selected samples. The case studies to be conducted as part of this CRP will provide a unique data set and excellent information for expanding the use of these age dating tracers to TC projects aiming at assessing deep aquifer systems in Member States.