Name
Isotopic Characterization of Spatio-Temporal Water and Carbon Cycle Evolution in Lake Basins Across a Permafrost Thaw Trajectory, Mackenzie Delta Uplands Region, Canada
Description
Widespread permafrost degradation in Canada's western Arctic has led to the formation of shoreline retrogressive thaw slumps (SRTS), a process influential in modifying hydrological dynamics and environmental processes in tundra lakes by modifying the movement and transfer water, sediments, inorganic and organic matter, and dissolved chemical constituents from the surrounding basin to the lake. To investigate hydro-ecological effects of SRTS, water sampling campaigns were conducted in 2004, 2005, and 2008 for paired lakes (undisturbed vs SRTS) in the upland region adjacent to the Mackenzie Delta, Canada.
A prior isotope mass balance (IMB) of 18O/2H study revealed key hydrological characteristics: i) higher evaporation/inflow and precipitation/inflow for lakes with active SRTS compared to undisturbed lakes, and typically higher ratios for lakes with stabilized versus active SRTS; ii) water yields higher for active SRTS sites compared to undisturbed/stabilized SRTS sites, suggesting that slumping is an initial but not a sustained source of water delivery to lakes; iii) basins with wildfire history had lower water yields, attributed to reduced permafrost influence on runoff generation.
The objectives of this presentation are: 1) expand the IMB (18O and 2H) derived hydrological indicators (e.g., water yield, evaporation/inflow ratio) developed by Wan et al. (2020) to include carbon indicators of 13C DIC and DIC/DOC; 2) explore the influences of permafrost disturbance and substrate mobilization into lakes on carbon signatures and processes; and 3) advance our understanding of tundra lake isotopic characterization of spatiotemporal water and carbon cycling evolution in lakes and basins across a permafrost thaw trajectory.
A prior isotope mass balance (IMB) of 18O/2H study revealed key hydrological characteristics: i) higher evaporation/inflow and precipitation/inflow for lakes with active SRTS compared to undisturbed lakes, and typically higher ratios for lakes with stabilized versus active SRTS; ii) water yields higher for active SRTS sites compared to undisturbed/stabilized SRTS sites, suggesting that slumping is an initial but not a sustained source of water delivery to lakes; iii) basins with wildfire history had lower water yields, attributed to reduced permafrost influence on runoff generation.
The objectives of this presentation are: 1) expand the IMB (18O and 2H) derived hydrological indicators (e.g., water yield, evaporation/inflow ratio) developed by Wan et al. (2020) to include carbon indicators of 13C DIC and DIC/DOC; 2) explore the influences of permafrost disturbance and substrate mobilization into lakes on carbon signatures and processes; and 3) advance our understanding of tundra lake isotopic characterization of spatiotemporal water and carbon cycling evolution in lakes and basins across a permafrost thaw trajectory.