Genomic Science Program
U.S. Department of Energy | Office of Science | Biological and Environmental Research Program

The Complex System of Organic Carbon Remineralization in Rapidly Thawing Svalbard Permafrost and Active Layer Soils

Authors:

Karen G. Lloyd1* (klloyd@utk.edu), Tatiana A. Vishnivetskaya1, Andrew D. Steen1, Robert Hettich2, Renxing Liang3, John Cliff, Tullis C. Onstott3, Andrey Abramov4, Fumnanya Abuah1, Julia Boike5, James Bradley6, Joy Buongiorno1, Margaret Cramm6, Richard J. Giannone2, Donato Giovannelli7, Zhou Lyu6, Francesco Montemagno7, Sayali Mulay1,2, Iyanu Oduwole1, Raegan Paul1, Jacob T. Perez1, Samantha Peters2, Mircea Podar3, Igor Shokodko4, Katie Sipes1, Artemii Sukhanov4, Xiaofen Wu1

Institutions:

1University of Tennessee–Knoxville; 2Oak Ridge National Laboratory; 3Princeton University–Princeton; 4Institute of Physicochemical and Biological Problems of Soil Science–Russia; 5Alfred Wegener Institute–Germany; 6Queen Mary University–United Kingdom; 7University of Naples–Italy

Goals

Researchers will determine the factors within a complex natural microbial community that dictate how much carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are released in thawing permafrost, including the precise mechanisms of soil organic carbon (C) degradation by specific microbial community members in permafrost from Svalbard. This research focuses on a critical area of the Arctic, with high rates of storm intensification, temperature increase, and permafrost thaw. The results from this study will therefore be predictors for the future of permafrost thaw in the rest of the Arctic.

Abstract

Arctic soil communities are on the frontline of the global response to climate change. This multi-institutional and multi-international collaboration has tackled the complexity of microbial organic matter remineralization across permafrost and active layers, as well as sediments from both of these locations that have been redeposited onto the fjord floor by seasonal glacial melt. Researchers completed two field seasons in Svalbard, Norway, in spite of the COVID-19 pandemic, a new war affecting the participation of some of the collaborators, and the passing of a member of the leadership team who was also a dear friend. Researchers have leveraged this project with international collaborators who have greatly expanded the breadth of the original project to mutually enhance this work. This projected is reporting: (1) multiomics approach for examining in situ microbial communities combining metagenomics, metabolomics, metatranscriptomics, and metaproteomics with geochemical measurements to recreate depth gradients across the soils and fjord sediments; (2) incubation studies examining gas fluxes and uptake of labeled substrates into the active fraction of microbial biomass; (3) development of molecular dynamics models to understand the interactions of C-degrading enzymes with mineral surfaces; (4) multiseasonal metabolic flux measurements to yield system-wide net process rates. Across all these different metrics, researchers find that the activity and diversity of microbial communities, as well as their ability to breakdown different sources of organic matter and the amount of gases that result from that, changes with depth in unexpected ways. Most notably, the well-established steep drop-in microbial activity with depth that is present in most temperate ecosystems does not occur in the Svalbard active layer soils or in fjord sediments. By partnering with a long-term monitoring station in Bayelva, researchers have seasonal variation measurements of temperature and liquid water content from over 20 years, showing that soils buried tens of centimeters have higher volumetric water content due to insulation from surficial soils (Sipes et al. 2024). Fjord sediments, in turn, have access to deep reach of oxidized sulfur and C compounds, stimulating a burst of transcriptional activity in a range of fermentative and respiratory microorganisms. The pathways and activities for C degradation differ greatly by depth in both systems, as well as by location across the permafrost and fjord system. This implies that the organic matter in freshly thawed permafrost may be immediately available to microbial degradation, since the work demonstrates that the deeply buried communities are already active due to the higher liquid water availability. The presence of a new set of degradational capabilities in the fjord sediments suggests that even if organic matter from freshly thawed permafrost is not degraded in situ, it has a secondary chance to be degraded after being swept into the fjords from glacial run off. In total, a picture is emerging of the permafrost and fjord system as being a larger scale “factory” for processing thawing permafrost, with the subsurface playing a key role, possibly amplifying the rate of CO2 production beyond what occurs in surficial terrestrial soils alone.

References

Lloyd, K.G., et al. Submitted 2024. “Depth-specific distribution of acidobacterial classes in permafrost active layer in Ny Ålesund, Svalbard (79°N).”

Funding Information

This work is funded by the DOE, Office of Science, BER program, Genomic Science Program (DE-SC0020369). Supplemental funding came from the Alfred Wegener Polar Institute AWIPEV, the British Antarctic Survey, the Dirigible Italia Research Station, as well as Italy MUR PRA2021 program MeltingICE project to DG, National Genomics Infrastructure in Stockholm funded by Science for Life Laboratory, the Knut and Alice Wallenberg Foundation and the Swedish Research Council, and SNIC/Uppsala Multidisciplinary Center for Advanced Computational Science for assistance with massively parallel sequencing and access to the UPPMAX computational infrastructure.