Fe and C in northern soils: Understanding coupled biogeochemical cycles
Funding: ETH Career Seed Grant (1.1.2019 – 1.4.2020), Polar Access Fund (1.5.2020 – 1.10.2021)
Project Team: Laurel ThomasArrigo, Ruben Kretzschmar, Kurt Barmettler
Collaborators: Olafur Arnalds (The Agricultural University of Iceland)
Poorly-crystalline, short-range order (SRO) iron minerals with high surface areas constitute one of the most reactive components in soils and sediments and influence the biogeochemical cycling of carbon. This is particularly true for redox dynamic environments where, in the absence of oxygen, microbial or abiotic reduction of Fe(III) leads to SRO iron mineral recrystallization or transformations and, potentially, the release of associated carbon. However, SRO iron mineral transformations may be likewise influenced or inhibited by association with organic matter. Thus, the nature of coupled Fe and C biogeochemical cycles is dynamic, and is likely to change during redox fluctuations. Because changing climate patterns are expected to disproportionately impact hydrologic regimes of high-latitude soils and thereby alter the frequency and duration of redox cycles, this project aims to identify the factors which control SRO iron mineral recrystallization and transformations in arctic soils during biogeochemical redox processes, with special focus on the consequent changes in the storage, mobilization, and quality of SRO-associated organic carbon.
Key Publications:
ThomasArrigo, L. K., Notini, L., Shuster, J., Nydegger, T., Vontobel, S., Fischer, S., Kappler, A. and Kretzschmar, R. (2021) Mineral characterization and composition of Fe-rich flocs from wetlands of Iceland: Implications for Fe, C and trace element export. Sci. Total Environ. 816: 151567. external pageLink
ThomasArrigo, L. K.; Byrne, J.; Kappeler, A.; Kretzschmar, R. (2018): Impact of organic matter on iron(II)-catalyzed mineral transformation in ferrihydrite-OM coprecipitates. Environ. Sci. Technol. 52: 12316-12326. external pageLink
ThomasArrigo, L. K., Mikutta, C., Byrne, J., Kappler, A., and Kretzschmar, R. (2017): Iron(II)-catalyzed iron atom exchange and mineralogical changes in iron-rich organic freshwater flocs: an iron isotope tracer study. Environ. Sci. Technol. 51: 6897-6907. external pageLink