Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/36932
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: Ferrihydrite transformations in flooded paddy soils: rates, pathways, and product spatial distributions
Author(s): Grigg, Andrew R. C.
ThomasArrigo, Laurel K.
Schulz, Katrin
Rothwell, Katherine A.
Kaegi, Ralf
Kretzschmar, Ruben
Contact Email: katherine.rothwell@stir.ac.uk
Issue Date: 2022
Date Deposited: 21-Mar-2025
Citation: Grigg ARC, ThomasArrigo LK, Schulz K, Rothwell KA, Kaegi R & Kretzschmar R (2022) Ferrihydrite transformations in flooded paddy soils: rates, pathways, and product spatial distributions. <i>Environmental Science: Processes & Impacts</i>, 24 (10), pp. 1867-1882. https://doi.org/10.1039/d2em00290f
Abstract: Complex interactions between redox-driven element cycles in soils influence iron mineral transformation processes. The rates and pathways of iron mineral transformation processes have been studied intensely in model systems such as mixed suspensions, but transformation in complex heterogeneous porous media is not well understood. Here, mesh bags containing 0.5 g of ferrihydrite were incubated in five water-saturated paddy soils with contrasting microbial iron-reduction potential for up to twelve weeks. Using X-ray diffraction analysis, we show near-complete transformation of the ferrihydrite to lepidocrocite and goethite within six weeks in the soil with the highest iron(II) release, and slower transformation with higher ratios of goethite to lepidocrocite in soils with lower iron(II) release. In the least reduced soil, no mineral transformations were observed. In soils where ferrihydrite transformation occurred, the transformation rate was one to three orders of magnitude slower than transformation in comparable mixed-suspension studies. To interpret the spatial distribution of ferrihydrite and its transformation products, we developed a novel application of confocal micro-Raman spectroscopy in which we identified and mapped minerals on selected cross sections of mesh bag contents. After two weeks of flooded incubation, ferrihydrite was still abundant in the core of some mesh bags, and as a rim at the mineral-soil interface. The reacted outer core contained unevenly mixed ferrihydrite, goethite and lepidocrocite on the micrometre scale. The slower rate of transformation and uneven distribution of product minerals highlight the influence of biogeochemically complex matrices and diffusion processes on the transformation of minerals, and the importance of studying iron mineral transformation in environmental media.
DOI Link: 10.1039/d2em00290f
Licence URL(s): http://creativecommons.org/licenses/by-nc/3.0/

Files in This Item:
File Description SizeFormat 
Ferrihydrite transformations in flooded paddy soils_ rates_ pathways_ and product spatial distributions.pdfFulltext - Published Version2.71 MBAdobe PDFView/Open



This item is protected by original copyright



A file in this item is licensed under a Creative Commons License Creative Commons

Items in the Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

The metadata of the records in the Repository are available under the CC0 public domain dedication: No Rights Reserved https://creativecommons.org/publicdomain/zero/1.0/

If you believe that any material held in STORRE infringes copyright, please contact library@stir.ac.uk providing details and we will remove the Work from public display in STORRE and investigate your claim.