{"type": "FeatureCollection", "features": [{"id": "10.1016/j.chemgeo.2021.120327", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:16:03Z", "type": "Journal Article", "created": "2021-05-18", "title": "Eruptive style controls the formation of silicon hexafluoride salts on volcanic ash: The case of the 2010 eruption of Eyjafjallaj\u00f6kull volcano, Iceland", "description": "Abstract The presence of fluoride (F\u2212)-bearing compounds in volcanic ash fallout is recognised to pose significant environmental and health hazards. Nevertheless, understanding of the formation and composition of these compounds remains limited, or even inconsistent. This hampers full comprehension of the risks and impacts elicited by fluorine-rich ash emissions after an explosive eruption. The 2010 activity of Eyjafjallajokull volcano in Iceland was characterised by contrasted eruptive styles - phreatomagmatic and magmatic - which produced ash deposits with distinct soluble F\u2212 contents. Based on X-ray photoelectron spectroscopy and leachate analyses of Eyjafjallajokull ash materials, we infer the existence of silicon hexafluoride salts, particularly Na2SiF6, dominantly if not exclusively on the magmatic ash, and suggest a reaction mechanism for their formation. The presence of Na2SiF6 explains the much greater F\u2212 concentration and higher acidity measured in leachates of the magmatic ash compared to those of the phreatomagmatic ash. River waters affected by ash deposition during the magmatic activity showed a temporary increase in F\u2212 and decrease in dissolved silicon isotope values (\u03b430Si). We contend that the formation of silicon hexafluoride salts on ash leads to a surface enrichment of the ash's silicate glass and mineral components in 28Si, with the release of this light Si from the magmatic ash during the early stage of weathering causing a depression in the riverine \u03b430Si. This supports existing evidence of silicate dissolution processes being influenced by the presence of fluorine. Our study also points to the likely important role of Na2SiF6 in modulating the environmental and health effects of ash emissions from fluorine-rich magmatic eruptions.", "keywords": ["Silicon hexafluoride salts", "13. Climate action", "Eyjafjallaj\u00f6kull volcano", "Silicon isotopes", "Ash", "Fluoride", "01 natural sciences", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.chemgeo.2021.120327"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Chemical%20Geology", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.chemgeo.2021.120327", "name": "item", "description": "10.1016/j.chemgeo.2021.120327", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.chemgeo.2021.120327"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2021-09-01T00:00:00Z"}}, {"id": "10.1016/j.gca.2016.06.008", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-28T16:16:29Z", "type": "Journal Article", "created": "2016-06-20", "title": "Silicon isotopes reveal recycled altered oceanic crust in the mantle sources of Ocean Island Basalts", "description": "Open Access23 pages, 5 figures, 2 tables", "keywords": ["Ocean Island Basalts", "Earth and Planetary Astrophysics (astro-ph.EP)", "GE", "550", "NDAS", "500", "Silicon isotopes", "FOS: Physical sciences", "7. Clean energy", "01 natural sciences", "12. Responsible consumption", "[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry", "13. Climate action", "[SDU.STU.GC] Sciences of the Universe [physics]/Earth Sciences/Geochemistry", "Recycling", "14. Life underwater", "BDC", "Mantle heterogeneity", "GE Environmental Sciences", "Astrophysics - Earth and Planetary Astrophysics", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.gca.2016.06.008"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Geochimica%20et%20Cosmochimica%20Acta", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.gca.2016.06.008", "name": "item", "description": "10.1016/j.gca.2016.06.008", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.gca.2016.06.008"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2016-09-01T00:00:00Z"}}, {"id": "10.1029/2021gc009904", "type": "Feature", "geometry": null, "properties": {"license": "Open Access", "updated": "2026-07-28T16:17:38Z", "type": "Journal Article", "created": "2021-10-26", "title": "Quantifying Non\u2010Thermal Silicate Weathering Using Ge/Si and Si Isotopes in Rivers Draining the Yellowstone Plateau Volcanic Field, USA", "description": "Abstract

In active volcanic regions, high\uffe2\uff80\uff90temperature chemical reactions in the hydrothermal system consume CO2 sourced from magma or from the deep crust, whereas reactions with silicates at shallow depths mainly consume atmospheric CO2. Numerous studies have quantified the load of dissolved solids in rivers that drain volcanic regions to determine chemical weathering rates and atmospheric CO2 consumption rates. However, the balance between thermal and non\uffe2\uff80\uff90thermal components to riverine fluxes in these areas remains poorly constrained, hindering accurate estimates of atmospheric CO2 consumption rates. Here we use the Ge/Si ratio and the stable silicon isotopes (\uffce\uffb430Si) as tracers for quantifying non\uffe2\uff80\uff90thermal silicon contributions in rivers draining the Yellowstone Plateau Volcanic Field, USA. The Ge/Si ratio (\uffc2\uffb5mol.mol\uffe2\uff88\uff921) was determined for seven thermal water samples (183\uffc2\uffa0\uffc2\uffb1\uffc2\uffa022), eight rivers (35\uffc2\uffa0\uffc2\uffb1\uffc2\uffa023) and six creeks flowing into Yellowstone Lake (5\uffc2\uffa0\uffc2\uffb1\uffc2\uffa03) during base flow and during peak water discharge following snowmelt. The \uffce\uffb430Si value (\uffe2\uff80\uffb0) was determined for thermal waters (\uffe2\uff88\uff920.09\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.04), Yellowstone River at Yellowstone Lake outlet (1.91\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.23) and creek samples (0.82\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.29). The calculated atmospheric CO2 consumption associated with non\uffe2\uff80\uff90thermal waters flowing through Yellowstone's rivers during peak discharge is \uffe2\uff88\uffbc3.03 ton.km\uffe2\uff88\uff922.yr\uffe2\uff88\uff921, which is \uffe2\uff88\uffbc2% of the annual mean atmospheric CO2 consumption in other volcanic regions. This study highlights the significance of quantifying seasonal variations in chemical weathering rates for improving estimates of atmospheric CO2 consumption rates in active volcanic regions. Glacial environments play an important role in high-latitude marine nutrient cycling, potentially contributing significant fluxes of silicon (Si) to the polar oceans, either as dissolved silicon (DSi) or as dissolvable amorphous silica (ASi). Silicon is a key nutrient in promoting marine primary productivity, contributing to atmospheric CO 2 removal. We present the current understanding of Si cycling in glacial systems, focusing on the Si isotope (\uffce\uffb4 30 Si) composition of glacial meltwaters. We combine existing glacial \uffce\uffb4 30 Si data with new measurements from 20 sub-Arctic glaciers, showing that glacial meltwaters consistently export isotopically light DSi compared with non-glacial rivers (+0.16\uffe2\uff80\uffb0 versus +1.38\uffe2\uff80\uffb0). Glacial \uffce\uffb4 30 Si ASi composition ranges from \uffe2\uff88\uff920.05\uffe2\uff80\uffb0 to \uffe2\uff88\uff920.86\uffe2\uff80\uffb0 but exhibits low seasonal variability. Silicon fluxes and \uffce\uffb4 30 Si composition from glacial systems are not commonly included in global Si budgets and isotopic mass balance calculations at present. We discuss outstanding questions, including the formation mechanism of ASi and the export of glacial nutrients from fjords. Finally, we provide a contextual framework for the recent advances in our understanding of subglacial Si cycling and highlight critical research avenues for assessing potential future changes in these environments. Glacial environments play an important role in high-latitude marine nutrient cycling, potentially contributing significant fluxes of silicon (Si) to the polar oceans, either as dissolved silicon (DSi) or as dissolvable amorphous silica (ASi). Silicon is a key nutrient in promoting marine primary productivity, contributing to atmospheric CO 2 removal. We present the current understanding of Si cycling in glacial systems, focusing on the Si isotope (\uffce\uffb4 30 Si) composition of glacial meltwaters. We combine existing glacial \uffce\uffb4 30 Si data with new measurements from 20 sub-Arctic glaciers, showing that glacial meltwaters consistently export isotopically light DSi compared with non-glacial rivers (+0.16\uffe2\uff80\uffb0 versus +1.38\uffe2\uff80\uffb0). Glacial \uffce\uffb4 30 Si ASi composition ranges from \uffe2\uff88\uff920.05\uffe2\uff80\uffb0 to \uffe2\uff88\uff920.86\uffe2\uff80\uffb0 but exhibits low seasonal variability. Silicon fluxes and \uffce\uffb4 30 Si composition from glacial systems are not commonly included in global Si budgets and isotopic mass balance calculations at present. We discuss outstanding questions, including the formation mechanism of ASi and the export of glacial nutrients from fjords. Finally, we provide a contextual framework for the recent advances in our understanding of subglacial Si cycling and highlight critical research avenues for assessing potential future changes in these environments. In active volcanic regions, high\uffe2\uff80\uff90temperature chemical reactions in the hydrothermal system consume CO2 sourced from magma or from the deep crust, whereas reactions with silicates at shallow depths mainly consume atmospheric CO2. Numerous studies have quantified the load of dissolved solids in rivers that drain volcanic regions to determine chemical weathering rates and atmospheric CO2 consumption rates. However, the balance between thermal and non\uffe2\uff80\uff90thermal components to riverine fluxes in these areas remains poorly constrained, hindering accurate estimates of atmospheric CO2 consumption rates. Here we use the Ge/Si ratio and the stable silicon isotopes (\uffce\uffb430Si) as tracers for quantifying non\uffe2\uff80\uff90thermal silicon contributions in rivers draining the Yellowstone Plateau Volcanic Field, USA. The Ge/Si ratio (\uffc2\uffb5mol.mol\uffe2\uff88\uff921) was determined for seven thermal water samples (183\uffc2\uffa0\uffc2\uffb1\uffc2\uffa022), eight rivers (35\uffc2\uffa0\uffc2\uffb1\uffc2\uffa023) and six creeks flowing into Yellowstone Lake (5\uffc2\uffa0\uffc2\uffb1\uffc2\uffa03) during base flow and during peak water discharge following snowmelt. The \uffce\uffb430Si value (\uffe2\uff80\uffb0) was determined for thermal waters (\uffe2\uff88\uff920.09\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.04), Yellowstone River at Yellowstone Lake outlet (1.91\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.23) and creek samples (0.82\uffc2\uffa0\uffc2\uffb1\uffc2\uffa00.29). The calculated atmospheric CO2 consumption associated with non\uffe2\uff80\uff90thermal waters flowing through Yellowstone's rivers during peak discharge is \uffe2\uff88\uffbc3.03 ton.km\uffe2\uff88\uff922.yr\uffe2\uff88\uff921, which is \uffe2\uff88\uffbc2% of the annual mean atmospheric CO2 consumption in other volcanic regions. This study highlights the significance of quantifying seasonal variations in chemical weathering rates for improving estimates of atmospheric CO2 consumption rates in active volcanic regions.