Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils
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 aggre...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/582238 2023-05-15T16:47:42+02:00 Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils Thomas Arrigo, Laurel K. Kretzschmar, Ruben 2022-12-15 application/application/pdf https://hdl.handle.net/20.500.11850/582238 https://doi.org/10.3929/ethz-b-000582238 en eng Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.geoderma.2022.116217 info:eu-repo/semantics/altIdentifier/wos/000919522500003 info:eu-repo/grantAgreement/EC/H2020/788009 http://hdl.handle.net/20.500.11850/582238 doi:10.3929/ethz-b-000582238 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Geoderma, 428 Iceland Iron biogeochemistry Organic carbon Colloids Wetlands info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2022 ftethz https://doi.org/20.500.11850/582238 https://doi.org/10.3929/ethz-b-000582238 https://doi.org/10.1016/j.geoderma.2022.116217 2023-02-27T00:41:11Z 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 contents were measured in both the dissolved (<3 kDa) and fine colloidal fractions (3 kDa to 0.45 µm). In all soils, anoxic incubation resulted in microbial reduction of Fe(III) and concomitant increases in soil solution pH. However, soils containing SRO Fe minerals underwent more extensive Fe reduction. Rapid (<1 wk) increases in aqueous element contents (including Fe, Al, and OC) were recorded in all soil slurries, and mobilization of colloids occurred in soil horizons which reached the highest pH values (>4.6). Mobilized colloids persisted during re-oxidation of the soil slurries, which also resulted in the formation of new Fe mineral phases, the composition of which was influenced by initial soil Fe mineralogy. Collectively, our results suggest that increases in the frequency of redox cycles in Icelandic soils are likely to result in shifts in Fe mineralogy and may contribute to the increased mobilization of soil OC as organic-Fe-/Al-colloids. ISSN:0016-7061 ISSN:1872-6259 Article in Journal/Newspaper Iceland ETH Zürich Research Collection |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
Iceland Iron biogeochemistry Organic carbon Colloids Wetlands |
spellingShingle |
Iceland Iron biogeochemistry Organic carbon Colloids Wetlands Thomas Arrigo, Laurel K. Kretzschmar, Ruben Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils |
topic_facet |
Iceland Iron biogeochemistry Organic carbon Colloids Wetlands |
description |
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 contents were measured in both the dissolved (<3 kDa) and fine colloidal fractions (3 kDa to 0.45 µm). In all soils, anoxic incubation resulted in microbial reduction of Fe(III) and concomitant increases in soil solution pH. However, soils containing SRO Fe minerals underwent more extensive Fe reduction. Rapid (<1 wk) increases in aqueous element contents (including Fe, Al, and OC) were recorded in all soil slurries, and mobilization of colloids occurred in soil horizons which reached the highest pH values (>4.6). Mobilized colloids persisted during re-oxidation of the soil slurries, which also resulted in the formation of new Fe mineral phases, the composition of which was influenced by initial soil Fe mineralogy. Collectively, our results suggest that increases in the frequency of redox cycles in Icelandic soils are likely to result in shifts in Fe mineralogy and may contribute to the increased mobilization of soil OC as organic-Fe-/Al-colloids. ISSN:0016-7061 ISSN:1872-6259 |
format |
Article in Journal/Newspaper |
author |
Thomas Arrigo, Laurel K. Kretzschmar, Ruben |
author_facet |
Thomas Arrigo, Laurel K. Kretzschmar, Ruben |
author_sort |
Thomas Arrigo, Laurel K. |
title |
Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils |
title_short |
Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils |
title_full |
Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils |
title_fullStr |
Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils |
title_full_unstemmed |
Iron speciation changes and mobilization of colloids during redox cycling in Fe-rich, Icelandic peat soils |
title_sort |
iron speciation changes and mobilization of colloids during redox cycling in fe-rich, icelandic peat soils |
publisher |
Elsevier |
publishDate |
2022 |
url |
https://hdl.handle.net/20.500.11850/582238 https://doi.org/10.3929/ethz-b-000582238 |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Geoderma, 428 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.geoderma.2022.116217 info:eu-repo/semantics/altIdentifier/wos/000919522500003 info:eu-repo/grantAgreement/EC/H2020/788009 http://hdl.handle.net/20.500.11850/582238 doi:10.3929/ethz-b-000582238 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/582238 https://doi.org/10.3929/ethz-b-000582238 https://doi.org/10.1016/j.geoderma.2022.116217 |
_version_ |
1766037789533536256 |