{"type": "FeatureCollection", "features": [{"id": "10.1016/j.scitotenv.2021.151567", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-27T16:17:14Z", "type": "Journal Article", "created": "2021-11-08", "title": "Mineral characterization and composition of Fe-rich flocs from wetlands of Iceland: Implications for Fe, C and trace element export", "description": "Open AccessIn freshwater wetlands, redox interfaces characterized by circumneutral pH, steep gradients in O2, and a continual supply of Fe(II) form ecological niches favorable to microaerophilic iron(II) oxidizing bacteria (FeOB) and the formation of flocs; associations of (a)biotic mineral phases, microorganisms, and (microbially-derived) organic matter. On the volcanic island of Iceland, wetlands are replenished with Fe-rich surface-, ground- and springwater. Combined with extensive drainage of lowland wetlands, which forms artificial redox gradients, accumulations of bright orange (a)biotically-derived Fe-rich flocs are common features of Icelandic wetlands. These loosely consolidated flocs are easily mobilized, and, considering the proximity of Iceland's lowland wetlands to the coast, are likely to contribute to the suspended sediment load transported to coastal waters. To date, however, little is known regarding (Fe) mineral and elemental composition of the flocs. In this study, flocs from wetlands (n = 16) across Iceland were analyzed using X-ray diffraction and spectroscopic techniques (X-ray absorption and 57Fe M\u00f6ssbauer) combined with chemical extractions and (electron) microscopy to comprehensively characterize floc mineral, elemental, and structural composition. All flocs were rich in Fe (229\u2013414 mg/g), and floc Fe minerals comprised primarily ferrihydrite and nano-crystalline lepidocrocite, with a single floc sample containing nano-crystalline goethite. Floc mineralogy also included Fe in clay minerals and appreciable poorly-crystalline aluminosilicates, most likely allophane and/or imogolite. Microscopy images revealed that floc (bio)organics largely comprised mineral encrusted microbially-derived components (i.e. sheaths, stalks, and EPS) indicative of common FeOB Leptothrix spp. and Gallionella spp. Trace element contents in the flocs were in the low \u03bcg/g range, however nearly all trace elements were extracted with hydroxylamine hydrochloride. This finding suggests that the (a)biotic reductive dissolution of floc Fe minerals, plausibly driven by exposure to the varied geochemical conditions of coastal waters following floc mobilization, could lead to the release of associated trace elements. Thus, the flocs should be considered vectors for transport of Fe, organic carbon, and trace elements from Icelandic wetlands to coastal waters.", "keywords": ["Minerals", "Iron", "Iceland", "Freshwater flocs", "04 agricultural and veterinary sciences", "15. Life on land", "Ferric Compounds", "01 natural sciences", "6. Clean water", "Trace Elements", "EXAFS", "13. Climate action", "Freshwater flocs; Fe(II)-oxidizing bacteria; Biominerals; Wetlands; EXAFS; 57Fe M\u00f6ssbauer", "Wetlands", "57Fe M\u00f6ssbauer", "Biominerals", "Fe(II)-oxidizing bacteria", "0401 agriculture", " forestry", " and fisheries", "14. 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The use of biochar as an amendment represents a tool to store organic carbon (C) in soil. The vulnerability of soil organic C (SOC) to the joint effects of climate change and biochar application needs to be better understood by investigating its main pools. Here, we evaluated the effects of partial rain exclusion (\u223c30%) and temperature increase (\u223c2\u00a0\u00b0C), combined with biochar amendment, on the distribution of soil organic matter (SOM) into particulate organic matter (POM) and the mineral-associated organic matter (MAOM). A set of indices suggested an increase in thermal stability in response to biochar addition in both POM and MAOM fractions. The MAOM fraction, compared to the POM, was particularly enriched in labile substances. Data from micro-Raman spectroscopy suggested that the POM fraction contained biochar particles with a more ordered structure, whereas the structural order decreased in the MAOM fraction, especially after climate manipulation. Crystalline Fe oxides (hematite) and a mix of ferrihydrite and hematite were detected in the POM and in the MAOM fraction, respectively, of the unamended plots under climate manipulation, but not under ambient conditions. Conversely, in the amended soil, climate manipulation did not induce changes in Fe speciation. Our work underlines the importance of discretely taking into account responses of both MAOM and POM to better understand the mechanistic drivers of SOC storage and dynamics.", "keywords": ["Particulate organic matter", " Mineral-associated organic matter", " Open top chambers", " Fe EXAFS", " Raman spectroscopy", " Thermal analysis", "Take urgent action to combat climate change and its impacts", "550", "Climate Change", "Fe EXAFS", "15. Life on land", "6. Clean water", "Carbon", "Soil", "Open top chamber", "13. Climate action", "Particulate organic matter", "Charcoal", "Raman spectroscopy", "Mineral-associated organic matter", "Particulate Matter", "Thermal analysis", "Open top chambers"]}, "links": [{"href": "https://iris.univr.it/bitstream/11562/1093186/2/JEMA%2c%202023%20-%20The%20effects%20of%20biochar%20on%20SOM%20pools%20are%20not.pdf"}, {"href": "https://doi.org/10.1016/j.jenvman.2023.118092"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Journal%20of%20Environmental%20Management", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.jenvman.2023.118092", "name": "item", "description": "10.1016/j.jenvman.2023.118092", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.jenvman.2023.118092"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-09-01T00:00:00Z"}}, {"id": "10.3390/soilsystems2040058", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-27T16:22:02Z", "type": "Journal Article", "created": "2018-10-29", "title": "Products of Hexavalent Chromium Reduction by Green Rust Sodium Sulfate and Associated Reaction Mechanisms", "description": "<p>The efficacy of in vitro Cr(VI) reduction by green rust sulfate suggests that this mineral is potentially useful for remediation of Cr-contaminated groundwater. Previous investigations studied this reaction but did not sufficiently characterize the intermediates and end products at chromate (CrO42\uffe2\uff88\uff92) concentrations typical of contaminant plumes, hindering identification of the dominant reaction mechanisms under these conditions. In this study, batch reactions at varying chromate concentrations and suspension densities were performed and the intermediate and final products of this reaction were analyzed using X-ray absorption spectroscopy and electron microscopy. This reaction produces particles that maintain the initial hexagonal morphology of green rust but have been topotactically transformed into a poorly crystalline Fe(III) oxyhydroxysulfate and are coated by a Cr (oxy) hydroxide layer that results from chromate reduction at the surface. Recent studies of the behavior of Cr(III) (oxy) hydroxides in soils have revealed that reductive transformation of CrO42\uffe2\uff88\uff92 is reversible in the presence of Mn(IV) oxides, limiting the applicability of green rust for Cr remediation in some soils. The linkage of Cr redox speciation to existing Fe and Mn biogeochemical cycles in soils implies that modification of green rust particles to produce an insoluble, Cr(III)-bearing Fe oxide product may increase the efficacy of this technique.</p>", "keywords": ["Geography & travel", "910", "green rust sulfate", " chromium", " EXAFS", " metal redox cycles", "540", "ddc:910", "metal redox cycles", "01 natural sciences", "6. Clean water", "620", "EXAFS", "13. Climate action", "ddc:540", "ddc:550", "green rust sulfate", "info:eu-repo/classification/ddc/910", "chromium", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://eprints.whiterose.ac.uk/140695/1/Thomas%20et%20al%202018.pdf"}, {"href": "http://www.mdpi.com/2571-8789/2/4/58/pdf"}, {"href": "https://doi.org/10.3390/soilsystems2040058"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Soil%20Systems", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.3390/soilsystems2040058", "name": "item", "description": "10.3390/soilsystems2040058", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.3390/soilsystems2040058"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2018-10-29T00:00:00Z"}}, {"id": "11369/445129", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-27T16:26:13Z", "type": "Journal Article", "created": "2023-05-09", "title": "The effects of biochar on soil organic matter pools are not influenced by climate change", "description": "The sustainability of Mediterranean croplands is threatened by climate warming and rainfall reduction. The use of biochar as an amendment represents a tool to store organic carbon (C) in soil. The vulnerability of soil organic C (SOC) to the joint effects of climate change and biochar application needs to be better understood by investigating its main pools. Here, we evaluated the effects of partial rain exclusion (\u223c30%) and temperature increase (\u223c2\u00a0\u00b0C), combined with biochar amendment, on the distribution of soil organic matter (SOM) into particulate organic matter (POM) and the mineral-associated organic matter (MAOM). A set of indices suggested an increase in thermal stability in response to biochar addition in both POM and MAOM fractions. The MAOM fraction, compared to the POM, was particularly enriched in labile substances. Data from micro-Raman spectroscopy suggested that the POM fraction contained biochar particles with a more ordered structure, whereas the structural order decreased in the MAOM fraction, especially after climate manipulation. Crystalline Fe oxides (hematite) and a mix of ferrihydrite and hematite were detected in the POM and in the MAOM fraction, respectively, of the unamended plots under climate manipulation, but not under ambient conditions. Conversely, in the amended soil, climate manipulation did not induce changes in Fe speciation. Our work underlines the importance of discretely taking into account responses of both MAOM and POM to better understand the mechanistic drivers of SOC storage and dynamics.", "keywords": ["Particulate organic matter", " Mineral-associated organic matter", " Open top chambers", " Fe EXAFS", " Raman spectroscopy", " Thermal analysis", "Take urgent action to combat climate change and its impacts", "550", "Climate Change", "Fe EXAFS", "15. Life on land", "6. Clean water", "Carbon", "Soil", "Open top chamber", "13. 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On the volcanic island of Iceland, wetlands are replenished with Fe-rich surface-, ground- and springwater. Combined with extensive drainage of lowland wetlands, which forms artificial redox gradients, accumulations of bright orange (a)biotically-derived Fe-rich flocs are common features of Icelandic wetlands. These loosely consolidated flocs are easily mobilized, and, considering the proximity of Iceland's lowland wetlands to the coast, are likely to contribute to the suspended sediment load transported to coastal waters. To date, however, little is known regarding (Fe) mineral and elemental composition of the flocs. In this study, flocs from wetlands (n = 16) across Iceland were analyzed using X-ray diffraction and spectroscopic techniques (X-ray absorption and 57Fe M\u00f6ssbauer) combined with chemical extractions and (electron) microscopy to comprehensively characterize floc mineral, elemental, and structural composition. All flocs were rich in Fe (229\u2013414 mg/g), and floc Fe minerals comprised primarily ferrihydrite and nano-crystalline lepidocrocite, with a single floc sample containing nano-crystalline goethite. Floc mineralogy also included Fe in clay minerals and appreciable poorly-crystalline aluminosilicates, most likely allophane and/or imogolite. Microscopy images revealed that floc (bio)organics largely comprised mineral encrusted microbially-derived components (i.e. sheaths, stalks, and EPS) indicative of common FeOB Leptothrix spp. and Gallionella spp. Trace element contents in the flocs were in the low \u03bcg/g range, however nearly all trace elements were extracted with hydroxylamine hydrochloride. This finding suggests that the (a)biotic reductive dissolution of floc Fe minerals, plausibly driven by exposure to the varied geochemical conditions of coastal waters following floc mobilization, could lead to the release of associated trace elements. 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