{"type": "FeatureCollection", "features": [{"id": "10.1021/acs.est.7b02944", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:17:30Z", "type": "Journal Article", "created": "2017-10-11", "title": "Novel Multi-isotope Tracer Approach To Test ZnO Nanoparticle and Soluble Zn Bioavailability in Joint Soil Exposures", "description": "Here we use two enriched stable isotopes, 68Znen and 64Znen (>99%), to prepare 68ZnO nanoparticles (NPs) and soluble 64ZnCl2. The standard LUFA 2.2 test soil was dosed with 68ZnO NPs and soluble 64ZnCl2 to 5 mg kg-1 each, plus between 0 and 95 mg kg-1 of soluble ZnCl2 with a natural isotope composition. After 0, 1, 3, 6, and 12 months of soil incubation, earthworms (Eisenia andrei) were introduced for 72 h exposures. Analyses of soils, pore waters, and earthworm tissues using multiple collector inductively coupled plasma mass spectrometry allowed the simultaneous measurement of the diagnostic 68Zn/66Zn, 64Zn/66Zn, and 68Zn/64Zn ratios, from which the three different isotopic forms of Zn were quantified. Eisenia andrei was able to regulate Zn body concentrations with no difference observed between the different total dosing concentrations. The accumulation of labeled Zn by the earthworms showed a direct relationship with the proportion of labeled to total Zn in the pore water, which increased with longer soil incubation times and decreasing soil pH. The 68Znen/64Znen ratios determined for earthworms (1.09 \u00b1 0.04), soils (1.09 \u00b1 0.02), and pore waters (1.08 \u00b1 0.02) indicate indistinguishable environmental distribution and uptake of the Zn forms, most likely due to rapid dissolution of the ZnO NPs.", "keywords": ["104002 Analytische Chemie", "550", "TRANSFORMATIONS", "FATE", "0211 other engineering and technologies", "Biological Availability", "02 engineering and technology", "01 natural sciences", "Soil", "104002 Analytical chemistry", "104023 Umweltchemie", "ENGINEERED NANOMATERIALS", "MD Multidisciplinary", "Animals", "Soil Pollutants", "105906 Environmental geosciences", "210004 Nanomaterials", "Oligochaeta", "EARTHWORM EISENIA-ANDREI", "0105 earth and related environmental sciences", "ENVIRONMENT", "104023 Environmental chemistry", "KNOWLEDGE GAPS", "[SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces", " environment", "6. Clean water", "Zinc", "Nanoparticles", "Zinc Isotopes", "Zinc Oxide", "210004 Nanomaterialien", "Environmental Sciences", "105906 Umweltgeowissenschaften"]}, "links": [{"href": "https://pubs.acs.org/doi/pdf/10.1021/acs.est.7b02944"}, {"href": "https://doi.org/10.1021/acs.est.7b02944"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Environmental%20Science%20%26amp%3B%20Technology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1021/acs.est.7b02944", "name": "item", "description": "10.1021/acs.est.7b02944", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1021/acs.est.7b02944"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-10-26T00:00:00Z"}}, {"id": "10.2307/2640985", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:20:34Z", "type": "Journal Article", "created": "2006-04-17", "description": "Elevated atmospheric CO2 has the potential to increase the production and alter the chemistry of organic substrates entering soil from plant production, the magnitude of which is constrained by soil-N availability. Because microbial growth in soil is limited by substrate inputs from plant production, we reasoned that changes in the amount and chemistry of these organic substrates could affect the composition of soil microbial com- munities and the cycling of N in soil. We studied microbial community composition and soil-N transformations beneath Populus tremuloides Michx. growing under experimental atmospheric CO2 (35.7 and 70.7 Pa) and soil-N-availability (low N 5 61 ng N\u00b7g 21 \u00b7d 21 and high N 5 319 ng N\u00b7g 21 \u00b7d 21 ) treatments. Atmospheric CO2 concentration was modified in large, open-top chambers, and we altered soil-N availability in open-bottom root boxes by mixing different proportions of A and C horizon material. We used phospholipid fatty-acid analysis to gain insight into microbial community composition and coupled this analysis to measurements of soil-N transformations using 15 N-pool dilution techniques. The infor- mation presented here is part of an integrated experiment designed to elucidate the phys- iological mechanisms controlling the flow of C and N in the plant-soil system. Our ob- jectives were (1) to determine whether changes in plant growth and tissue chemistry alter microbial community composition and soil-N cycling in response to increasing atmospheric CO2 and soil-N availability and (2) to integrate the results of our experiment into a synthesis of elevated atmospheric CO2 and the cycling of C and N in terrestrial ecosystems. After 2.5 growing seasons, microbial biomass, gross N mineralization, microbial im- mobilization, and nitrification (gross and net) were equivalent at ambient and elevated CO2, suggesting that increases in fine-root production and declines in fine-root N concentration were insufficient to alter the influence of native soil organic matter on microbial physiology; this was the case in both low- and high-N soil. Similarly, elevated CO2 did not alter the proportion of bacterial, actinomycetal, or fungal phospholipid fatty acids in low-N or high-N soil, indicating that changes in substrate input from greater plant growth under elevated CO2 did not alter microbial community composition. Our results differ from a substantial number of studies reporting increases and decreases in soil-N cycling under elevated CO 2. From our analysis, it appears that soil-N cycling responds to elevated atmospheric CO 2 in experimental situations where plant roots have fully colonized the soil and root-associated C inputs are sufficient to modify the influence of native soil organic matter on microbial physiology. In young developing ecosystems where plant roots have not fully exploited the soil, microbial metabolism appears to be regulated by relatively large pools of soil organic matter, rather than by the additional input of organic substrates under elevated CO 2.", "keywords": ["measurement-", "soil microorganisms", "Ecology and Evolutionary Biology", "nitrogen-: cycling-", "feedback", "microbial community composition", "techniques-", "Environmental-Sciences)", "01 natural sciences", "litter-plant", "biomass-", "gross and net", "124-38-9: CARBON DIOXIDE", "Spermatophytes-", "cycling-", "soil-organic-matter", "mineralization", "Spermatophyta-", "responses-", "phospholipid-fatty-acids", "2. Zero hunger", "Climatology- (Environmental-Sciences)", "Angiosperms-", "Angiospermae-", "Plants-", "global climate change", "microbial immobilization", "nutrient-", "Soil-Science", "6. Clean water", "metabolism-", "soil-N transformations", "transformation-", "substrates-", "7727-37-9: NITROGEN", "atmosphere-", "elevated atmospheric", "570", "nitrification-", "nitrogen immobilization", "Science", "Vascular-Plants", "poplars-", "phospholipid fatty acids (PFLAs)", "carbon-dioxide", "growth-", "soil-microbial-community-composition", "Salicaceae-: Dicotyledones-", "microbial-flora", "Populus tremuloides", "Plantae-", "organic-matter", "consortia-", "0105 earth and related environmental sciences", "communities-", "ecosystem", "analysis-", "atmospheric CO2 and soil-N availability", "soil-availability", "mineralization-", "carbon dioxide", "fatty-acids", "15. Life on land", "substrate-input", "Populus-tremuloides (Salicaceae-)", "13. Climate action", "roots-", "Terrestrial-Ecology (Ecology-", "composition-", "Dicots-", "immobilization-", "seasons-", "ecosystems-"], "contacts": [{"organization": "Zak, Donald R., Pregitzer, Kurt S., Curtis, Peter S., Holmes, William E.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.2307/2640985"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Ecological%20Applications", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.2307/2640985", "name": "item", "description": "10.2307/2640985", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.2307/2640985"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2000-02-01T00:00:00Z"}}, {"id": "10.3929/ethz-b-000640921", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-25T16:21:20Z", "type": "Journal Article", "title": "Mineral transformations of ferrihydrite and lepidocrocite in suspension and in paddy soil: A closer look at the effects of silicate, phosphate, and the soil matrix", "description": "unspecifiedIron (Fe) (oxyhydr)oxides, such as ferrihydrite and lepidocrocite, are ubiquitous in soils. Due to their high surface area, Fe (oxyhydr)oxides constitute important sorbents for nutrients and contaminants in the soil, including silicate and phosphate. Under sub- or anoxic conditions in water-saturated or submerged soils, Fe(III) acts as an alternative electron acceptor during the microbial metabolization of organic matter. This leads to the reductive dissolution of Fe (oxyhydr)oxides, the formation of Fe(II) and the potential release of adsorbed components. The presence of Fe(II) accelerates the transformation of ferrihydrite and lepidocrocite to more crystalline Fe minerals, such as goethite or magnetite. Silicate and phosphate can interfere with these mineral transformations. However, how silicate and phosphate impact the trajectory and mineral products of ferrihydrite and lepidocrocite transformation has not been fully resolved yet. Up to now, Fe mineral transformations have mainly been studied in simplified model systems, such as mineral suspensions, but rarely in soil. Further, transformations of ferrihydrite and lepidocrocite in soils during redox cycles, including the recurring reduction and oxidation of Fe, remain obscure. Redox active soils include paddy soils which are crucial for the global production of rice as a staple food. This thesis investigated factors that govern Fe (oxyhydr)oxide transformations in redox active paddy soils. The doctoral project was designed to move consecutively from controlled laboratory to in-situ field experiments. In all experiments, the stable isotope 57Fe was used as a tracer in combination with isotope analysis of dissolved and solid phases and/or 57Fe M\u00f6ssbauer spectroscopy.  In the first part of this thesis, the effect of silicate on Fe(II)-catalyzed transformation of ferrihydrite and lepidocrocite was examined in mineral suspensions spiked with 57Fe(II) at two Fe(II):Fe(III) molar ratios. The reactivity of ferrihydrite towards 57Fe(II) adsorption and Fe atom exchange with dissolved 57Fe(II) was only marginally impacted by coprecipitated silicate. Silicate hindered ferrihydrite transformation to goethite and magnetite as compared to silicate-free ferrihydrite. During mineral transformation, coprecipitated silicate led to the formation of thicker lepidocrocite crystallites from ferrihydrite and silicate was redistributed in the solid phase. For lepidocrocite, magnetite formed at the higher Fe(II):Fe(III) molar ratio. This contrasts the decreased Fe atom exchange and inhibited mineral transformation in the presence of surface-adsorbed silicate on lepidocrocite surfaces. The results demonstrate that silicate strongly interferes with Fe mineral transformations whereas the mineral reactivity towards Fe(II) adsorption and Fe atom exchange can remain high.  In a following experiment, the transformation of ferrihydrite and lepidocrocite during three redox cycles was studied in laboratory mesocosms filled with paddy soil. To understand the effect of the soil matrix on mineral transformations, minerals were incubated either as minerals without the addition of soil or as 57Fe-labeled mineral-soil mixes in mesh bags. The results showed that ferrihydrite and lepidocrocite transformed to goethite and/or magnetite when incubated as mineral mesh bags without soil. When ferrihydrite and lepidocrocite were mixed with soil, a mixed valent and highly disordered Fe phase formed. Goethite additionally formed in lepidocrocite-soil mixes. Throughout repeated redox cycles, solid-associated Fe(II) fractions in mineral-soil mixes during anoxic periods increased, suggesting an increasing extent of Fe mineral reduction. The outcomes of this study showed that Fe mineral transformations are strongly impacted when minerals are exposed to the soil matrix, which can lead to highly disordered instead of crystalline Fe mineral transformation products.  In a final experiment, the in-situ transformation of Fe oxyhydroxides and the effect of phosphate were investigated in a field-incubation of minerals in a flooded rice paddy soil in Thailand. Ferrihydrite, lepidocrocite and phosphate-adsorbed ferrihydrite were incubated using mesh bags, containing the minerals without soil or 57Fe-labeled mineral-soil mixes. The field-incubation of ferrihydrite and lepidocrocite in mineral mesh bags without soil resulted in goethite formation with a much larger transformation extent in ferrihydrite. With pre-adsorbed phosphate, the transformation of ferrihydrite was strongly hindered. In mineral-soil mixes ferrihydrite and lepidocrocite transformed to goethite to a similar extent. Pre-adsorbed phosphate on ferrihydrite surfaces strongly hindered mineral transformation in the mineral-soil mixes but enhanced Fe reduction compared to phosphate-free ferrihydrite. These findings demonstrate the dual role of phosphate during mineral transformations when minerals are closely associated or in direct contact with the soil matrix.  The outcomes of this thesis highlight the importance of considering silicate and phosphate interactions with Fe (oxyhydr)oxides, by demonstrating their strong impact on the trajectory of mineral transformations. Mineral transformations in soil have been shown in this thesis to be much slower compared to mineral suspension experiments. Further, when minerals are closely associated or in direct contact with the soil matrix, highly disordered Fe phases can form instead of crystalline Fe minerals. Such disordered Fe phases can be highly reactive, as this work demonstrated for the exposure to redox cycles. Collectively, the gained insights contribute to a better assessment of Fe cycling in redox-active soils which can control nutrient and contaminant mobility in the environment.", "keywords": ["Transformations", "Field study", "iron reduction", "15. Life on land", "laboratory study", "6. Clean water", "Lepidocrocite", "Natural sciences", "Ferrihydrite", "Rice paddy", "Redox reactions", "iron minerals", "FOS: Natural sciences", "info:eu-repo/classification/ddc/500"], "contacts": [{"organization": "Schulz, Katrin", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.3929/ethz-b-000640921"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Thesis/Dissertation", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.3929/ethz-b-000640921", "name": "item", "description": "10.3929/ethz-b-000640921", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.3929/ethz-b-000640921"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2023-01-01T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=TRANSFORMATIONS&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=TRANSFORMATIONS&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=TRANSFORMATIONS&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=TRANSFORMATIONS&offset=3", "hreflang": "en-US"}], "numberMatched": 3, "numberReturned": 3, "distributedFeatures": [], "timeStamp": "2026-07-26T03:10:06.292208Z"}