ORCID
- Manners, Hayley: 0000-0001-8545-4463
Abstract
Dissimilatory iron reduction (DIR) is suggested to be one of the earliest forms of microbial respiration. It plays an important role in the biogeochemical cycling of iron in modern and ancient sediments. Since microbial iron cycling is typically accompanied by iron isotope fractionation, stable iron isotopes are used as tracer for biological activity. Here we present iron isotope data for dissolved and sequentially extracted sedimentary iron pools from deep and hot subseafloor sediments retrieved in the Nankai Trough off Japan. Dissolved iron (Fe(II)aq) is isotopically light throughout the ferruginous sediment interval but some samples have exceptionally light isotope values. Such light values have never been reported in natural marine environments and cannot be solely attributed to DIR. We show that the light isotope values are best explained by a Rayleigh distillation model where Fe(II)aq is continuously removed from the pore water by adsorption onto iron (oxyhydr)oxide surfaces. While the microbially mediated Fe(II)aq release has ceased due to an increase in temperature beyond the threshold of mesophilic microorganisms, the abiotic adsorptive Fe(II)aq removal continued, leading to uniquely light isotope values. These findings have important implications for the interpretation of dissolved iron isotope data especially in deep subseafloor sediments.
DOI
10.1038/s41598-023-37254-2
Publication Date
2023-06-24
Publication Title
Scientific Reports
Volume
13
Issue
1
ISSN
2045-2322
Embargo Period
2023-06-30
Organisational Unit
School of Geography, Earth and Environmental Sciences
Recommended Citation
Köster, M., Staubwasser, M., Meixner, A., Kasemann, S., Manners, H., Morono, Y., Inagaki, F., Heuer, V., Kasten, S., & Henkel, S. (2023) 'Uniquely low stable iron isotopic signatures in deep marine sediments caused by Rayleigh distillation', Scientific Reports, 13(1). Available at: https://doi.org/10.1038/s41598-023-37254-2
