Stable isotope hydrology of surface and ground waters in King George Island, Antarctica.

The region around the tip of the Antarctic Peninsula is warming fast, a situation that will lead to widespread changes in local hydrological cycles. King George Island (KGI) hosts a complex network of lakes and rivers, fed by glaciers, snow and rain, and underlain by thick permafrost. We present here the first study of the stable isotope composition of the surface waters in the ice-free southern peninsulas of KGI. Permafrost samples had the highest δ¹⁸O and δ²H values (-6.7 and -50 ‰, respectively), and river waters the lowest (-9.1 and -70 ‰, respectively), with groundwater (-8.2 and -62.7 ‰, respectively), lakes (-8.6 and -66.8 ‰, respectively) and (summer) meltwater (-9 and -69.5 ‰, respectively) having intermediary values. Our results suggest that a clear separation of the various water bodies (permafrost, snow, meltwater, lakes) based on the δ¹⁸O_water and δ²H_water is possible. Further, water in lakes on a W-E transect (i.e. with increased distance from the Bellingshausen Sea) have a general tendency towards lower δ¹⁸O (and δ²H) values. The results allow for the establishment of a baseline against which ongoing and future changes of the hydrological cycle could be analysed, and past climate changes be reconstructed.