{"type": "FeatureCollection", "features": [{"id": "10.1016/j.epsl.2017.04.022", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-24T16:16:07Z", "type": "Journal Article", "created": "2017-04-29", "title": "Testing the chondrule-rich accretion model for planetary embryos using calcium isotopes", "description": "Open AccessUnderstanding the composition of raw materials that formed the Earth is a crucial step towards understanding the formation of terrestrial planets and their bulk composition. Calcium is the fifth most abundant element in terrestrial planets and, therefore, is a key element with which to trace planetary composition. However, in order to use Ca isotopes as a tracer of Earth's accretion history, it is first necessary to understand the isotopic behavior of Ca during the earliest stages of planetary formation. Chondrites are some of the oldest materials of the Solar System, and the study of their isotopic composition enables understanding of how and in what conditions the Solar System formed. Here we present Ca isotope data for a suite of bulk chondrites as well as Allende (CV) chondrules. We show that most groups of carbonaceous chondrites (CV, CI, CR and CM) are significantly enriched in the lighter Ca isotopes ($\ufffd\ufffd^{44/40}Ca$ = +0.1 to +0.93 permill) compared with bulk silicate Earth ($\ufffd\ufffd^{44/40}Ca$ = +1.05 $ pm$ 0.04 permill, Huang et al., 2010) or Mars, while enstatite chondrites are indistinguishable from Earth in Ca isotope composition ($\ufffd\ufffd^{44/40}Ca$ = +0.91 to +1.06 permill). Chondrules from Allende are enriched in the heavier isotopes of Ca compared to the bulk and the matrix of the meteorite ($\ufffd\ufffd^{44/40}Ca$ = +1.00 to +1.21 permill). This implies that Earth and Mars have Ca isotope compositions that are distinct from most carbonaceous chondrites but that may be like chondrules. This Ca isotopic similarity between Earth, Mars, and chondrules is permissive of recent dynamical models of planetary formation that propose a chondrule-rich accretion model for planetary embryos.", "keywords": ["Earth and Planetary Astrophysics (astro-ph.EP)", "chondrules", "parent bodies", "calcium isotopes", "FOS: Physical sciences", "Earth", "01 natural sciences", "chondrites", "[SDU] Sciences of the Universe [physics]", "accretion", "13. Climate action", "10. No inequality", "Astrophysics - Earth and Planetary Astrophysics", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.epsl.2017.04.022"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Earth%20and%20Planetary%20Science%20Letters", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.epsl.2017.04.022", "name": "item", "description": "10.1016/j.epsl.2017.04.022", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.epsl.2017.04.022"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-07-01T00:00:00Z"}}, {"id": "10.1038/srep44255", "type": "Feature", "geometry": null, "properties": {"updated": "2026-05-24T16:17:39Z", "type": "Journal Article", "created": "2017-03-09", "title": "Calcium isotope fractionation between aqueous compounds relevant to low-temperature geochemistry, biology and medicine", "description": "Abstract<p>Stable Ca isotopes are fractionated between bones, urine and blood of animals and between soils, roots and leaves of plants by &gt;1000\uffe2\uff80\uff89ppm for the 44Ca/40Ca ratio. These isotopic variations have important implications to understand Ca transport and fluxes in living organisms; however, the mechanisms of isotopic fractionation are unclear. Here we present ab initio calculations for the isotopic fractionation between various aqueous species of Ca and show that this fractionation can be up to 3000\uffe2\uff80\uff89ppm. We show that the Ca isotopic fractionation between soil solutions and plant roots can be explained by the difference of isotopic fractionation between the different first shell hydration degree of Ca2+ and that the isotopic fractionation between roots and leaves is controlled by the precipitation of Ca-oxalates. The isotopic fractionation between blood and urine is due to the complexation of heavy Ca with citrate and oxalates in urine. Calculations are presented for additional Ca species that may be useful to interpret future Ca isotopic measurements.</p>", "keywords": ["Calcium Isotopes", "Chemical Fractionation", "[SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]", "FE", "Plant Roots", "01 natural sciences", "Article", "Bone and Bones", "[SDU] Sciences of the Universe [physics]", "Soil", "PHOSPHATE", "Animals", "Humans", "ION", "MONITOR", "0105 earth and related environmental sciences", "ENVIRONMENT", "CA", "PLASMA", "Temperature", "Plants", "6. Clean water", "3. Good health", "Plant Leaves", "MAGNESIUM", "13. Climate action", "OXALATE", "[SDU.STU] Sciences of the Universe [physics]/Earth Sciences", "BONE"], "contacts": [{"organization": "Moynier, Fr\u00e9d\u00e9ric, Fujii, Toshiyuki,", "roles": ["creator"]}]}, "links": [{"href": "https://www.nature.com/articles/srep44255.pdf"}, {"href": "https://doi.org/10.1038/srep44255"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Scientific%20Reports", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1038/srep44255", "name": "item", "description": "10.1038/srep44255", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1038/srep44255"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2017-03-09T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=calcium+isotopes&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=calcium+isotopes&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=calcium+isotopes&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=calcium+isotopes&offset=2", "hreflang": "en-US"}], "numberMatched": 2, "numberReturned": 2, "distributedFeatures": [], "timeStamp": "2026-05-25T02:12:54.332031Z"}