The steady uptick in global temperature may bring significant perturbations to the cycling and transfer of carbon (C) in the coastal Arctic. Given the high C content of Arctic soils, the region may become an increasingly important source of methane (CH₄) and carbon dioxide (CO₂) in coming decades. We present targeted observations along a lake to bay system during the spring thaw in the coastal Canadian high Arctic, which has been shown to deliver a pulse of greenhouse gases from the freshwater system to the bay, where they are rapidly ventilated to the atmosphere. As warming impacts the timing and dynamics of the ice retreat, C sources may shift and the magnitude of outgassing may change. We investigate the sources and pathways of the dissolved CO₂ and CH₄ via stable carbon isotope analyses, and augment our spatial survey by employing a profiling autonomous kayak (ChemYak) outfitted with a suite of biogeochemical sensors. Observed CH₄ ranged from 1-5900 ppm, with δ¹³C values ranging from -70 to -47‰ (mean: -61.1±10.5‰); CO₂ ranged from 100-3350 ppm, with δ¹³C values of  -12 to 38‰ (mean: 6.1±13.1‰). Isotopic depletion was correlated with lower CH₄, and enrichment consistent with a primary productivity signal was seen in lower concentrations of CO₂. Isotopic signatures clustered with habitat type, revealing spatial variability in the processes controlling the production and transformation of CH₄. Through this work, we aim to improve our understanding of the interannual variability present at this site and evaluate the system’s response to a changing climate.

Primary Presenter: Shawnee Traylor, MIT-WHOI Joint Program (straylor@whoi.edu)

Authors:

Sarah Youngs, Woods Hole Oceanographic Institution   (syoungs@whoi.edu)

John Pohlman, United States Geological Survey  (jpohlman@usgs.gov)

Anna Michel, Woods Hole Oceanographic Institution  (amichel@whoi.edu)

David Nicholson, Woods Hole Oceanographic Institution   (dnicholson@whoi.edu)