An international team, including Spain's Geological and Mining Institute of the CSIC (IGME-CSIC), has described for the first time how the groundwater system that feeds several freshwater lakes on Deception Island in Antarctica works. The system is formed by highly permeable volcanic deposits. The study, conducted during the 2024 and 2025 Antarctic campaigns, reveals that a significant portion of meltwater and rain infiltrates the ground, generating an annual recharge equivalent to 41% of precipitation. The researchers show that despite being in closed craters, the lakes are connected to the sea through the subsurface and even react to tides. This unusual behavior for polar and volcanic environments allowed for the proposal of a new hydrogeological model for the island and helps to anticipate how it might change with warming and the degradation of permanently frozen soil (permafrost). Led by IGME researcher Jorge Jódar, the study has been published in the Journal of Hydrology: Regional Studies. The research includes the first estimation of the altitudinal isotopic gradient, an analysis that identifies the origin of the recharge water—snow and rain—based on altitude. This 'signature' allows for reconstructing the origin of the water that recharges the aquifers and feeds the lakes, better interpreting the climate records preserved in the ice, and improving climate and hydrological models in polar regions. This study is an advance in understanding the functioning of water systems in polar-volcanic environments, while also offering a method that can be applied in other regions of Antarctica, where the behavior of groundwater remains largely unknown.
