Snow cover impacts on hydrologic and biogeochemical cycling in alpine, sub-arctic environments

• Main Authors: Popp, A., Valiente, N., Aalstad, K., Trier Kjær, S., Yilmaz, Y., Pirk, N., Eiler, A., Dörsch, P., Hessen, D., Tallaksen, L., Larsen, L.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Arctic; Norway
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5020708

Headwater catchments release substantial amounts of greenhouse gases (GHGs) into the atmosphere. Despite extensive research on this topic, drivers of GHGs remain elusive, particularly in cold regions. Cryospheric changes, such as alterations in the snowpack, are strongly coupled with the hydrological cycle. However, we have limited insight into the nexus between snow cover changes, source water contributions (e.g., groundwater and glacial meltwater) to surface waters, and associated biogeochemical cycling. To better understand the drivers of hydrological and biogeochemical changes in cold regions, we obtained field- and satellite-derived data from two sub-arctic alpine catchments (one glaciated, one non-glaciated) in the north-western part of the Hardangervidda mountain plateau (South Central Norway) in 2020 and 2021. Fractional snow cover durations show that 2020 was exceptionally snow-rich, while 2021 was an average snow year. Our results indicate that gas saturations distinctively differ between snow-rich and normal snow conditions, with CO2 being enhanced in most water sources during the typical snow year compared to the snow-rich year. Depending on the water source (e.g., lake or stream water), we also found distinct differences between the glaciated and the non-glaciated catchments. Overall, waters in high-latitude, alpine systems seem to act as net GHG sources to the atmosphere. While groundwater is the most supersaturated water source, it only marginally contributes to most surface waters at our study sites and might thus not control GHG emissions. Our findings provide new insights into the linkage between snow cover changes and associated hydrologic and biogeochemical cycling in cold region headwater catchments.