Primary Productivity in Permafrost-Influenced Aquatic Ecosystems of the Arctic (PROPERAQUA)

• Applicant: Professorin Dr. Kirsten Küsel, since 12/2022
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management ; Oceanography
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 396657413

This project aims to investigate the primary productivity in the Kolyma River (Siberian tundra, Russia) influenced by organic material from thawing permafrost (perennially frozen soil). Permafrost in the Arctic is thawing due to climate change, exposing to the environment large amounts of organic material that contain highly labile carbon. The Kolyma River region is an ideal location to study climate change-driven processes at the land-river-sea interfaces. Each year during the snow melt period, organic material from degrading permafrost is washed out into the Kolyma River, becoming an additional source of carbon for bacterial consumption and photodegradation that in turn will increase the production of CO2 in this aquatic ecosystem. The rates of CO2 utilization (CO2-sink) by photoautotrophic organisms for the production of biomass (biological primary production) are still a gap in the knowledge of the Arctic carbon cycle. In this project, two key metrics of the biological carbon cycle will be measured: (i) gross oxygen production (GOP) and (ii) net community production (NCP). GOP is the rate of oxygen that has been produced by photosynthesis and is used as a proxy of the total rate of carbon fixation and storage as biomass (Gross Primary Production). NCP is the net amount of carbon uptake reduced by GOP and the loss of organic carbon through community respiration. Seasonal changes of GOP and NCP along with their spatial distribution will be measured from spring to autumn. To accomplish this goal, a state-of-the-art method established for marine systems will be applied to Arctic inland waters for the first time. This method relies on measurements of Oxygen-to-Argon ratios (O2/Ar) as well as the isotope ratios of dissolved oxygen (17O/16O and 18O/16O) to dissect the physical and biological sources of oxygen and the distinct isotopic signatures of atmospheric and photosynthetic oxygen in the waters of the Kolyma River. Finally, the novel data of primary productivity along with measurements of p(CO2), dissolved organic carbon and the content of nutrients will be integrated into a hydrology-biogeochemistry numerical model to link in a one-dimensional carbon budget the major constituents of the carbon cycle and associated hydrological processes of the Kolyma River. PROPERAQUA will unravel the turnover and fate of organic matter and nutrients from thawing permafrost in Arctic aquatic ecosystems and will reconcile the contribution of aquatic primary production to the Arctic carbon budget. These results serve as a baseline for larger-scale studies aiming to better identify the current and future environmental impact of climate change in the Arctic aquatic carbon cycle.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Cooperation Partners: Dr. Mathias Göckede; Professor Dr. Jan Kaiser
• Ehemalige Antragstellerin: Karel Castro Morales, Ph.D., until 11/2022