EGU2020-5530
https://doi.org/10.5194/egusphere-egu2020-5530
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The origin and fate of organic matter in circum-Arctic subglacial ecosystems

Petra Vinsova1, Myrna J. Simpson2, Tiange Yuan2, Irka Hajdas3, Lukas Falteisek1, Tyler J. Kohler1,4, Jacob C. Yde5, Jakub D. Zarsky1, and Marek Stibal1
Petra Vinsova et al.
  • 1Charles University, Faculty of Science, Department of Ecology, Prague, Czechia (vinsovap@natur.cuni.cz)
  • 2Environmental NMR Centre and Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, Canada
  • 3Laboratory of Ion Beam Physics, Zurich, Switzerland
  • 4Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
  • 5Department of Environmental Sciences, Western Norway University of Applied Sciences, Sogndal, Norway

Glacier and ice sheet beds represent important yet underresearched cryospheric ecosystems. Life in the subglacial environment is mostly dependent on organic matter (OM) overridden by ice during times of glacier advance, and the nature of subglacial OM is, therefore, likely to drive the ecosystem functionality. Here we describe the origin, degradation stage and environmental context of OM present underneath glaciers in the circum-Arctic, and their effects on the resident microbial communities.

In total, 19 glaciers from Alaska, Greenland, Iceland, Svalbard, and Norway were sampled for subglacial sediments. Biomarker analysis of the sediment samples was conducted using total solvent extraction, and copper (II) oxide (CuO) oxidation techniques yielding lipids and lignin-derived phenols. The extracts were analyzed by GC-MS to characterize the molecular-level composition of OM present. The biomarker data were then placed in the context of other environmental data, such as radiocarbon age, nutrient contents, and microbial community composition. The majority of OM in the samples was plant-derived, suggested by the dominance of long-chain n-alkanols over the microbial-specific short-chain n-alkanols. The composition of long-chain n-alkanes (≥C20), used as biomarkers for vascular plant waxes, in the solvent extracts suggested grass sources for samples from most Greenland glaciers and conifer sources for some glaciers from Norway, Alaska, and Disko Island (Qeqertarsuaq) in West Greenland. The rest of the OM in the subglacial samples was identified to have more general tree sources. The carbon preference index (CPI) of long-chain n-alkanes suggested a high degradation stage in most samples and was correlated with the radiocarbon age of the sediments’ OC (r = -0.68). Sediments containing older and more degraded OM were found to host less diverse microbial communities compared to those of the younger sites.

In a rapidly warming climate, previously glacier-covered areas are being exposed as a consequence of glacier recession. This new land is standing at the onset of ecological succession and pedogenesis. Our results contribute to the understanding of the potential ecological function of subglacial OM as an important source of carbon and driver of microbial community development after deglaciation in the circum-Arctic region.

How to cite: Vinsova, P., Simpson, M. J., Yuan, T., Hajdas, I., Falteisek, L., Kohler, T. J., Yde, J. C., Zarsky, J. D., and Stibal, M.: The origin and fate of organic matter in circum-Arctic subglacial ecosystems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5530, https://doi.org/10.5194/egusphere-egu2020-5530, 2020

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