Modeling Climate Sensitivity of Biogeochemistry at Two Ponds in the Yukon-Kuskokwim Delta, AK

In high-latitude tundra ecosystems, small ponds significantly influence hydrological and permafrost dynamics, serving as key nodes for biogeochemical activities. However, the extent of their contribution to the carbon balance, especially in the context of climate change, remains under-researched. We employed in-situ measurements to calibrate a numerical model, focusing on two distinct ponds in Alaska's Yukon-Kuskokwim Delta. These ponds differ in size, depth, and proximity to recent wildfires. We utilized the LAKE model, a one-dimensional tool adept at simulating thermodynamics, hydrodynamics, and biogeochemical processes, informed by meteorological data from nearby eddy covariance towers. Model evaluations, benchmarked against data from June to August 2022, revealed a high degree of accuracy, especially in predicting water temperatures. Our numerical simulation shows variations in dissolved CO2 levels between the ponds, while CH4 concentrations remained similar. We developed a sensitivity analysis tool to help refine our understanding of the biogeochemical parameters and their influence on CO2 and CH4 fluxes. Simulations under warming scenarios provided insights into the ponds' responses to climatic changes. The results of this modeling experiment will improve the understanding of the drivers and trajectory of biogeochemical cycling in disturbed and undisturbed high-latitude ponds. Future research will explore the relationship between pond methane concentrations and methylmercury, with implications for aquatic ecosystem health.