Groundwater flow and storage in aquifers on top of permafrost are very sensitive to climate conditions. These supra-permafrost aquifers (SPAs) exhibit high concentrations of dissolved organic carbon (DOC) due to rapid leaching from peat, the main material comprising SPAs. Thus, SPAs have an important role in carbon cycling. The biogeochemical transformation of the DOC into carbon dioxide and methane and DOC transport into aquatic water bodies depend on hydrologic conditions. How climate variability, such as variability in extreme weather events and freeze-thaw cycles, affects the coupled hydro-bio-geochemical processes within SPAs and the connectivity of SPAs with surface water bodies and the atmosphere are still unknown. This study addresses this gap through combining observations with modeling. First, we developed an ensemble of steady-state groundwater flow models which combined information on active layer hydro-stratigraphy, high resolution topography, and DOC concentrations from a first-order stream watershed, the Imnavait Creek in Alaska. The model ensemble showed that the range of groundwater discharge going into Imnavait Creek is the same as the range of summer streamflow. However, this approach does not explicitly represent SPA hydro-bio-geochemical dynamics. To address this, this study will be applying a multiphysics model, the Advanced Terrestrial Simulator (ATS), which integrates coupled surface and subsurface permafrost hydrology, energy transport, and biogeochemical reactions, to investigate the impact of different climate forcing. We will develop a 2D ATS model to first assess the impact of climate variability. The 2D domain is a 100 m-long and 40 m-thick transect beginning from the foot of a hillslope, through the riparian zone, and ending at Imnavait. Transect-specific observations determine the model geometry, flow and transport parameters, and boundary conditions. High-resolution hydro-stratigraphy and temperature observations (water table and ice table elevations) will be used for model assessment. The modeling will ultimately address how future climate, variable freeze-thaw cycles, and extreme weather affect lateral groundwater flow and overall biogeochemistry along the terrestrial-aquatic continuum.

Through the PolarTREC program that pairs US educators with field researchers in polar regions, our team has been collaborating on K-12 and undergraduate curriculum development and outreach activities on Arctic amplification of climate change. We have created new lesson plans and activities focused on how organic carbon from thawing permafrost in the Arctic is turned into carbon dioxide, a greenhouse gas that amplifies climate change. This presentation will cover our collaboration to bring this knowledge and experience to high school science students through classroom activities and projects. The focus will be laboratory activities designed for the chemistry classroom: use of spectrophotometry to assess degree of photobleaching in organic samples and evaluation of data from high resolution mass spectrometry to characterize complex organic mixtures. We will also review lessons learned from our efforts to promote enthusiasm for polar science within the general public and discuss the benefits of the PolarTREC program to researchers, educators, students, and the public.

Accounting for temporal changes in carbon dioxide (CO2) emissions from freshwaters remains a challenge for global and regional carbon budgets. Here, we synthesize 171 site-months of eddy covariance flux measurements of CO2 from 13 lakes and reservoirs in the Northern Hemisphere (NH) and quantify the magnitude and dynamics at multiple temporal scales. We found pronounced diel and sub-monthly oscillatory variations in CO2 flux at all sites. Diel variation converted sites to daily net sinks of CO2 in only 11% of site-months. Upscaled annual emissions had an average of 25% (range 3-58%) interannual variation. Given temporal variation remains under-represented in inventories of CO2 emissions from lakes and reservoirs, revisions in CO2 flux are needed using a better representation of sub-daily to interannual variability. Constraining short- and long-term variability is necessary to improve detection of temporal changes of CO2 fluxes in response to natural and anthropogenic drivers.

Accounting for temporal changes in carbon dioxide (CO2) emissions from freshwaters remains a challenge for global and regional carbon budgets. Here, we synthesize 171 site-months of eddy covariance flux measurements of CO2 from 13 lakes and reservoirs in the Northern Hemisphere (NH) and quantify dynamics at multiple temporal scales. We found pronounced sub-annual variability in CO2 flux at all sites. Accounting for diel variation, only 11% of site-months were net daily sinks of CO2. Annual CO2 emissions had an average of 25% (range 3-58%) interannual variation. Nighttime emissions regularly exceeded daytime emissions. Sources of CO2 flux variability were delineated through mutual information analysis. Sample analysis of CO2 fluxes indicate importance of continuous sampling. Constraining short- and long-term variability is necessary to improve detection of temporal changes of CO2 fluxes in response to natural and anthropogenic drivers.