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Carbon Fate, Iron Dissolution, and Molecular Characterization of Dissolved Organic Matter in Thawed Yedoma Permafrost under Varying Redox Conditions
Citation:
Barreto, M., R. Wani, A. Goranov, T. Sowers, M. Fischel, T. Douglas, P. Hatcher, AND D. Sparks. Carbon Fate, Iron Dissolution, and Molecular Characterization of Dissolved Organic Matter in Thawed Yedoma Permafrost under Varying Redox Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 58(9):4155-4166, (2024). https://doi.org/10.1021/acs.est.3c08219
Impact/Purpose:
Permafrost carbon represent 50% of all terrestrial carbon, Destabilization of this carbon pool may have significant impacts on climate change, sea level rise, ocean acidification, and other environmental factors. Here, the stability of permafrost carbon is assessed using advanced techniques and with changing redox conditions, simulating fluctuating environmental conditions. The results presented may inform the degree and process of carbon destabilization in this critical pool, facilitating future climate change modeling efforts.
Description:
Permafrost soils store ∼50% of terrestrial C, with Yedoma permafrost containing ∼25% of the total C. Permafrost is undergoing degradation due to thawing, with potentially hazardous effects on landscape stability and water resources. Complicating ongoing efforts to project the ultimate fate of deep permafrost C is the poorly constrained role of the redox environment, Fe-minerals, and its redox-active phases, which may modulate organic C-abundance, composition, and reactivity through complexation and catalytic processes. We characterized C fate, Fe fractions, and dissolved organic matter (DOM) isolates from permafrost-thaw under varying redox conditions. Under anoxic incubation conditions, 33% of the initial C was lost as gaseous species within 21 days, while under oxic conditions, 58% of C was lost. Under anoxic incubation, 42% of the total initial C was preserved in a dissolved fraction. Lignin-like compounds dominated permafrost-thaw, followed by lipid- and protein-like compounds. However, under anoxic incubation conditions, there was accumulation of lipid-like compounds and reduction in the nominal oxidation state of C over time, regardless of the compound classes. DOM dynamics may be affected by microbial activity and abiotic processes mediated by Fe-minerals related to selective DOM fractionation and/or its oxidation. Chemodiversity DOM signatures could serve as valuable proxies to track redox conditions with permafrost-thaw.
URLs/Downloads:
DOI: Carbon Fate, Iron Dissolution, and Molecular Characterization of Dissolved Organic Matter in Thawed Yedoma Permafrost under Varying Redox Conditions
https://pubmed.ncbi.nlm.nih.gov/38385246/