Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils ...

• Main Authors: Thomas Arrigo, Laurel K., Kretzschmar, Ruben
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2022
• Subjects: Iceland; Iron biogeochemistry; Organic carbon; Colloids; Wetlands
• Online Access: https://dx.doi.org/10.3929/ethz-b-000582238; http://hdl.handle.net/20.500.11850/582238

Soils of Iceland are characterized by an abundance of short-range order (SRO) iron (Fe) minerals and aluminosilicates. Interactions between these SRO mineral phases and soil organic carbon (OC) promote long-term stabilization of the latter through the formation of mineral-organic complexes and aggregates. However, Icelandic soils are also exposed to high rainfall events, which induce anoxic conditions, facilitate microbial reduction of ferric Fe, and may lead to the mobilization of mineral-associated OC. Here, we explored the fate of OC during Fe redox cycling by incubating six organic-rich soil horizons from three typical soil types across Iceland (Histosols, Histic and Gleyic Andosols) as soil slurries under anoxic conditions for up to 5 weeks and followed the effects of re-oxidation after 1, 2, and 5 weeks. Changes in solid-phase Fe speciation were assessed by combining Fe K-edge X-ray absorption spectroscopy with time-resolved parallel selective chemical extractions, and trends in aqueous element ... : Geoderma, 428 ...