Hydrogeological characteristics of groundwater and surface water associated with two small lake systems on King George Island, Antarctica

Although groundwater is an important component of the water cycle in the polar regions, groundwater in Antarctica has rarely been studied. This study evaluated the physical and chemical characteristics of groundwater, surface water, and snow in two lakes on the Barton Peninsula, King George Island, Antarctica, with a particular focus on groundwater. Influxes/outfluxes of groundwater were measured using seepage meters, and hydraulic conductivities were calculated based on grain size analysis for the sediments. A total of 41 water samples were used to determine the chemical compositions and isotopic ratios of oxygen and hydrogen. The groundwater fluxes measured in one lake (referred to as “Lake A”) were −9.9 × 10⁻¹⁰ ~ 2.7 × 10⁻⁹ m/s (average of −9.1 × 10⁻¹⁰ ± 3.6 × 10⁻⁹ m/s) and in a second lake (referred to as “Lake B”) were 2.2 × 10⁻⁹ ~ 3.0 × 10⁻⁹ m/s (average of 2.6 × 10⁻⁹ ± 4.0 × 10⁻¹⁰ m/s). This indicates that groundwater flux is highly dynamic in Lake A, whereas groundwater influx in Lake B is relatively stable. Hydraulic conductivity for the lake sediments ranged between 1.7 × 10⁻⁶ m/s and 2.1 × 10⁻⁴ m/s. Oxygen and hydrogen isotopic compositions followed the global meteoric water line (GMWL) and local meteoric water line (LMWL), indicating that groundwater and surface water in the study area originate from the atmosphere. Evaporation may not be an influential factor probably due to the relatively humid climate during the summer season in the study area. Groundwater and surface water might partially experience isotopic exchange fractionation during and after the snow melting process. The chemical composition of groundwater was distinguished from that of surface water and snow by higher concentrations of major anions (Cl, SO₄, and alkalinity), major cations (Ca, Mg, K, and Na), and trace elements (Si, Li, Sr, Mn, Zn, and Cu), resulting from water-rock interactions. To the best of our knowledge, this is the first study to directly measure groundwater fluxes in lake systems in Antarctica, and to evaluate the characteristics of groundwater in the Barton Peninsula. It may therefore serve as a basis for studying the role of groundwater in the water cycle of Antarctica.