Arctic Permafrost Thawing Enhances Sulfide Oxidation

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dc.citation.articleNumbere2022GB007644en_US
dc.citation.issueNumber11en_US
dc.citation.journalTitleGlobal Biogeochemical Cyclesen_US
dc.citation.volumeNumber37en_US
dc.contributor.authorKemeny, Preston Cossletten_US
dc.contributor.authorLi, Gen K.en_US
dc.contributor.authorDouglas, Madisonen_US
dc.contributor.authorBerelson, Williamen_US
dc.contributor.authorChadwick, Austin J.en_US
dc.contributor.authorDalleska, Nathan F.en_US
dc.contributor.authorLamb, Michael P.en_US
dc.contributor.authorLarsen, Williamen_US
dc.contributor.authorMagyar, John S.en_US
dc.contributor.authorRollins, Nick E.en_US
dc.contributor.authorRowland, Joelen_US
dc.contributor.authorSmith, M. Isabelen_US
dc.contributor.authorTorres, Mark A.en_US
dc.contributor.authorWebb, Samuel M.en_US
dc.contributor.authorFischer, Woodward W.en_US
dc.contributor.authorWest, A. Joshuaen_US
dc.date.accessioned2024-05-08T18:56:10Zen_US
dc.date.available2024-05-08T18:56:10Zen_US
dc.date.issued2023en_US
dc.description.abstractPermafrost degradation is altering biogeochemical processes throughout the Arctic. Thaw-induced changes in organic matter transformations and mineral weathering reactions are impacting fluxes of inorganic carbon (IC) and alkalinity (ALK) in Arctic rivers. However, the net impact of these changing fluxes on the concentration of carbon dioxide in the atmosphere (pCO2) is relatively unconstrained. Resolving this uncertainty is important as thaw-driven changes in the fluxes of IC and ALK could produce feedbacks in the global carbon cycle. Enhanced production of sulfuric acid through sulfide oxidation is particularly poorly quantified despite its potential to remove ALK from the ocean-atmosphere system and increase pCO2, producing a positive feedback leading to more warming and permafrost degradation. In this work, we quantified weathering in the Koyukuk River, a major tributary of the Yukon River draining discontinuous permafrost in central Alaska, based on water and sediment samples collected near the village of Huslia in summer 2018. Using measurements of major ion abundances and sulfate (SO42− {\textSO_4^2-\) sulfur (34S/32S) and oxygen (18O/16O) isotope ratios, we employed the MEANDIR inversion model to quantify the relative importance of a suite of weathering processes and their net impact on pCO2. Calculations found that approximately 80% of SO42− {\textSO_4^2-\ in mainstem samples derived from sulfide oxidation with the remainder from evaporite dissolution. Moreover, 34S/32S ratios, 13C/12C ratios of dissolved IC, and sulfur X-ray absorption spectra of mainstem, secondary channel, and floodplain pore fluid and sediment samples revealed modest degrees of microbial sulfate reduction within the floodplain. Weathering fluxes of ALK and IC result in lower values of pCO2 over timescales shorter than carbonate compensation (∼104 yr) and, for mainstem samples, higher values of pCO2 over timescales longer than carbonate compensation but shorter than the residence time of marine SO42− {\textSO_4^2-\ (∼107 yr). Furthermore, the absolute concentrations of SO42− {\textSO_4^2-\ and Mg2+ in the Koyukuk River, as well as the ratios of SO42− {\textSO_4^2-\ and Mg2+ to other dissolved weathering products, have increased over the past 50 years. Through analogy to similar trends in the Yukon River, we interpret these changes as reflecting enhanced sulfide oxidation due to ongoing exposure of previously frozen sediment and changes in the contributions of shallow and deep flow paths to the active channel. Overall, these findings confirm that sulfide oxidation is a substantial outcome of permafrost degradation and that the sulfur cycle responds to permafrost thaw with a timescale-dependent feedback on warming.en_US
dc.identifier.citationKemeny, P. C., Li, G. K., Douglas, M., Berelson, W., Chadwick, A. J., Dalleska, N. F., Lamb, M. P., Larsen, W., Magyar, J. S., Rollins, N. E., Rowland, J., Smith, M. I., Torres, M. A., Webb, S. M., Fischer, W. W., & West, A. J. (2023). Arctic Permafrost Thawing Enhances Sulfide Oxidation. Global Biogeochemical Cycles, 37(11), e2022GB007644. https://doi.org/10.1029/2022GB007644en_US
dc.identifier.digitalArcticPermafrostThawingen_US
dc.identifier.doihttps://doi.org/10.1029/2022GB007644en_US
dc.identifier.urihttps://hdl.handle.net/1911/115675en_US
dc.language.isoengen_US
dc.publisherWileyen_US
dc.rightsExcept where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND) license. Permission to reuse, publish, or reproduce the work beyond the terms of the license or beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/en_US
dc.titleArctic Permafrost Thawing Enhances Sulfide Oxidationen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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