Evaporation and water sourcing dominate lake and stream isotopic
variability across time and space in a High Arctic periglacial landscape
Abstract
Rapidly changing climate is disrupting the High Arctic’s natural water
systems. This disruption demands high quality monitoring of Arctic
hydrology to better reconstruct past changes, track ongoing
transformations, and assess future environmental threats. Water isotopes
are valuable tracers of hydrological processes, but logistical
challenges limit the length and scope of isotopic monitoring in High
Arctic landscapes. Here, we present a comprehensive isotopic survey of
535 water samples taken in 2018–2019 of the lakes, streams, and other
surface waters of the periglacial Pituffik Peninsula in far northwest
Greenland. The δ18O, δ2H, and deuterium-excess values of these samples,
representing 196 unique sites, grant us unprecedented insight into the
environmental drivers of the region’s hydrology and water isotopic
variability. We find that the spatial and temporal variability of lake
isotopes is dominated by evaporation and connectivity to summer
meltwater sources, while evaporation determines interannual isotopic
changes. Stream isotopic compositions vary in both space and time based
on the relative source balance of tundra snowpack meltwater versus
surface melt from the nearby Greenland Ice Sheet. Overall, our survey
highlights the diversity of isotopic composition and evolution in
Pituffik surface waters, and our complete isotopic and geospatial
database provides a strong foundation for future researchers to study
hydrological changes at Pituffik and across the Arctic. Water isotope
samples taken at individual times or sites in similar periglacial
landscapes likely have limited regional representativeness, and
increasing the spatiotemporal extent of isotopic sampling is critical to
producing accurate and informative High Arctic paleoclimate
reconstructions.