Detailed dissolved organic matter composition for different permafrost types across the western Canadian Arctic

Organic matter, upon dissolution into the aqueous state as dissolved organic matter (DOM), can undergo mineralization by microbes. There has been increasing effort to characterize DOM released from thawing permafrost because it may perpetuate a permafrost carbon feedback. Permafrost-derived DOM often has a composition that can be highly susceptible to mineralization by microbes, but most studies to date that characterize permafrost-derived DOM have been limited to select regions, and tend to focus on a single type of permafrost that reflects a particular deposit type. Importantly, diversity in permafrost history of formation and thaw modification processes have led to spatial and stratigraphic variability, but our understanding of variation in the composition of DOM derived from differing permafrost types (end-members) is poor. Here, we use Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterize DOM composition derived from a series of permafrost end-member types that are commonly found within the thaw-vulnerable western Canadian Arctic, including: tills (glacially-deposited), diamicton (thawed and processed mixed material), lacustrine (previously thawed lake basin sediments), peat (partially decomposed organic material), and Yedoma (syngenetic silty loess) deposits. We identified marked variation in DOM composition among permafrost end-member types. Tills were compositionally dissimilar to all other permafrost end-members. Compounds unique to Yedoma deposits were predominantly aliphatic, while compounds unique to peat, lacustrine, and diamicton deposits spanned saturation and oxygenation. All permafrost leachates were generally higher in aliphatics, lower in aromatics, and were less oxygenated than active layer leachates. Compositional differences appear to reflect not only variation in permafrost parent materials, but also a strong effect from thaw-driven modification processes. Constraining DOM composition and assessing its stratigraphic variability will become more pressing as the spatial and stratigraphic extent of thaw increases with future warming.

Metadata Access
Creator Tank, Suzanne; MacDonald, Erin; Froese, Duane; Hutchins, Ryan; Kokelj, Steve
Publisher Canadian Cryospheric Information Network
Contributor Polar Data Catalogue
Publication Year 2020
Rights Research programs, CCIN, or ArcticNet take no liability for the use or transmission of this data
OpenAccess true
Contact enmacdon(at); pdc(at)
Language English
Format Computer file
Discipline Biogeochemistry
Spatial Coverage (-133.770W, 68.540S, -132.934E, 69.270N)
Temporal Coverage Begin 2018-06-30T00:00:00Z
Temporal Coverage End 2018-07-08T00:00:00Z