Iron mineral dissolution releases iron and associated organic carbon during permafrost thaw

This is a Preprint and has not been peer reviewed.

Downloads

Download Preprint

Authors

Monique S Patzner, Carsten W. Mueller, Miroslava Malusova, Moritz Baur, Verena Nikeleit, Thomas Scholten, Carmen Hoeschen, James Byrne, Thomas Borch, Andreas Kappler

Abstract

It has been shown that reactive soil minerals, specifically iron(III) (oxyhydr)oxides, can trap organic carbon in soils overlying intact permafrost, and may limit carbon mobilization and degradation as it is observed in other environments. However, the use of iron(III)-bearing minerals as terminal electron acceptors in permafrost environments and thus their stability and capacity to prevent carbon mobilization during permafrost thaw is poorly understood. We have followed the dynamic interactions between iron and carbon, using a “space for time” approach, across a thaw gradient in Abisko (Sweden), where wetlands are expanding rapidly due to permafrost thaw. We show through bulk (selective extractions, EXAFS) and nanoscale analysis (correlative SEM and nanoSIMS) that organic carbon is bound to reactive Fe primarily in the transition between organic and mineral horizons in palsa underlain by intact permafrost. During thaw, water-logging and O2 limitation lead to reducing conditions and an increase in abundance of Fe(III)-reducing bacteria which favor mineral dissolution and drive mobilization of both iron and carbon along the thaw gradient. By providing a terminal electron acceptor, the “rusty carbon sink” is effectively destroyed along the thaw gradient and cannot prevent carbon release with thaw.

DOI

https://doi.org/10.31223/osf.io/52w47

Subjects

Environmental Microbiology and Microbial Ecology Life Sciences, Environmental Sciences, Life Sciences, Microbiology, Physical Sciences and Mathematics

Keywords

Iron reduction, Permafrost, Abisko, Arctic, EXAFS, iron carbon associations, iron cycling, nanoSIMS, peatlands

Dates

Published: 2020-02-07 19:04

Last Updated: 2020-05-04 10:20

Older Versions
License

CC BY Attribution 4.0 International

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.