Isotope ecohydrological studies in an Arctic Finland watershed

Understanding Arctic water cycle processes and catchment hydrology is essential to quantifying ecohydrological changes in seasonally snow-covered systems in the North. We have implemented a new research program in the Pallas region of Arctic Finland to systematically monitor coupled atmospheric, ecosystem and ecohydrological processes. We capture northern ecohydrological changes through a comprehensive stable water isotope (δ²H, δ¹⁸O, d-excess) monitoring program. Our mission is to obtain a detailed picture of the Arctic water cycle from oceans to atmosphere and precipitation, to the subsequent partitioning between vegetation, groundwater and headwater streams. Specifically, our program at the Pallas watershed consists of: 1) continuous high-frequency in-situ stable water isotope monitoring of atmospheric water vapor and stream water, 2) extensive precipitation and snow stable isotope monitoring program to measure spatial and temporal variability in the isotopic composition of the snowpack and snowmelt, 3) soil water flux isotope measurements using lysimeters, soil coring, and experimental tracer approaches to characterize water movement in the shallow subsurface, and 4) water isotope sampling from plants to better understand the role of vegetation in the short growing season of the northern water cycle. This integrated approach allows us to better understand and quantify how these complex systems interact and function today, and how they may alter in the future under shifting seasonal patterns of synoptic climate, weather, snow and sea ice at the wider Boreal and Arctic basin-scale.