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Registros recuperados: 7
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A First Look at Dissolved Ge Isotopes in Marine Sediments ArchiMer
Baronas, J. Jotautas; Hammond, Douglas E.; Rouxel, Olivier; Monteverde, Danielle R..
The removal of chemical species from seawater during the precipitation of authigenic minerals is difficult to constrain but may play a major role in the global biogeochemical cycles of some elements, including silicon (Si) and germanium (Ge). Here, we present Ge/Si, δ74Ge, and supporting chemical data of pore waters and core incubations at three continental margin sites in California and the Gulf of Mexico. We used these data to partition Ge release and uptake by the various allogenic (delivered via sedimentation) and authigenic (formed in situ) phases in these sediments. About half of the pore water Ge (δ74Gepw = 1.3–2.4‰) is supplied by biogenic silica dissolution (δ74Ge ~ 3‰), with the other half contributed by lithogenic particulates (δ74Ge ~ 0.6‰)....
Tipo: Text Palavras-chave: Germanium; Biogenic silica; Authigenesis; Fe oxides; Isotope fractionation; Continental margin.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00504/61556/65466.pdf
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Determination of the copper isotope composition of seawater revisited: A case study from the Mediterranean Sea ArchiMer
Baconnais, Isabelle; Rouxel, Olivier; Dulaquais, Gabriel; Boye, Marie.
A new technique for the determination of dissolved copper isotope composition (δ65Cu) of seawater was applied to examine copper sources and internal cycling in the Mediterranean Sea. A succession of chelating resin with nitrilotriacetic acid functional groups and strong base anion exchange resin, together with optimization of the multi-collector inductively coupled plasma mass spectrometry set-up allowed to isolate copper from seawater matrix and to measure the 65Cu/63Cu ratios in seawater with an external precision of 0.06‰ (2 s.d.). This method was first applied for inter-comparison measurements to surface and deep waters sampled at station BATS in the North Atlantic Ocean. Disparities in δ65Cu reported here and in the literature over these samples...
Tipo: Text Palavras-chave: Copper isotope; Seawater; Mediterranean Sea; Geotraces; Isotope fractionation.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00457/56880/58742.pdf
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Ge/Si and Ge Isotope Fractionation During Glacial and Non-glacial Weathering: Field and Experimental Data From West Greenland ArchiMer
Baronas, J. Jotautas; Hammond, Douglas E.; Bennett, Mia M.; Rouxel, Olivier; Pitcher, Lincoln H.; Smith, Laurence C..
Glacial environments offer the opportunity to study the incipient stages of chemical weathering due to the high availability of finely ground sediments, low water temperatures, and typically short rock-water interaction times. In this study we focused on the geochemical behavior of germanium (Ge) in west Greenland, both during subglacial weathering by investigating glacier-fed streams, as well as during a batch reactor experiment by allowing water-sediment interaction for up to 2 years in the laboratory. Sampled in late August 2014, glacial stream Ge and Si concentrations were low, ranging between 12–55 pmol/L and 7–33 µmol/L, respectively (Ge/Si = 0.9–2.2 µmol/mol, similar to parent rock). As reported previously, the dissolved stable Ge isotope ratio...
Tipo: Text Palavras-chave: Glacial weathering; Germanium; Isotope fractionation; Amorphous silica; Experimental dissolution.
Ano: 2021 URL: https://archimer.ifremer.fr/doc/00684/79577/82249.pdf
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Iron isotope fractionation in iron-organic matter associations: Experimental evidence using filtration and ultrafiltration ArchiMer
Lotfi-kalahroodi, Elaheh; Pierson-wickmann, Anne-catherine; Guénet, Hélène; Rouxel, Olivier; Ponzevera, Emmanuel; Bouhnik-lecoz, Martine; Vantelon, Delphine; Dia, Aliou; Davranche, Mélanie.
Colloids have been recognized as key vectors of pollutants in aqueous environment. Amongst them, those formed by iron (Fe) and organic matter (OM) are of major importance due to their ubiquity in the surface environment and strong affinity for metals. In the recent years, Fe stable isotopes have been increasingly used to elucidate the sources and biogeochemical cycling of Fe in Earth's surface environments. In this study, we aim to elucidate (i) the possible Fe isotopic signature resulting from the Fe/OM colloid formation and (ii) the mechanisms involved in the development of such isotopic signature. For this purpose, Fe-OM associations were synthesized through binding and titration experiments. Various pH levels were used in order to study the isotope...
Tipo: Text Palavras-chave: Filtration; Size fractionation; Isotope fractionation; Colloidal; Dissolved; Fe isotopes.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00480/59174/61811.pdf
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Nuclear field shift effect in isotope fractionation of thallium ArchiMer
Fujii, Toshiyuki; Moynier, Frederic; Agranier, Arnaud; Ponzevera, Emmanuel; Abe, Minori; Uehara, Akihiro; Yamana, Hajimu.
Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (Tl-203 and Tl-205) in a chemical exchange system. Tl isotopes were fractionated in a liquid-liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ion-exchange chemistry, the isotope ratio of Tl-205/Tl-203 in equilibrated aqueous phase was measured precisely by multiple-collector-inductively-coupled-plasma-mass-spectrometry. A large isotope fractionation > 1 aEuro degrees was found. Electronic structures of...
Tipo: Text Palavras-chave: Thallium; Isotope fractionation; Redox; Ligand exchange; Nuclear field shift; Ab initio calculation.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00135/24624/22691.pdf
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Zinc isotopic variations in ureilites ArchiMer
Brugier, Yann-aurélien; Barrat, Jean-alix; Gueguen, Bleuenn; Agranier, Arnaud; Yamaguchi, Akira; Bischoff, Addi.
The Ureilite Parent Body (UPB) was a C-rich planetary embryo disrupted by impact. Ureilites are fragments of the UPB mantle and among the most numerous achondrites. Zinc isotopic data are presented for 26 unbrecciated ureilites and a trachyandesite (ALM-A) from the same parent body. The δ66Zn values of ureilites range from 0.40 to 2.71 ‰ including literature results. Zinc isotopic compositions do not correlate with the compositions of olivine cores, with C and O isotopic compositions, with Zn abundances, nor with shock grades. The wide range of δ66Zn displayed by the ureilites is chiefly explained by evaporation processes that took place during the catastrophic breakup of the UPB. During breakup, the high temperatures of the UPB mantle allowed Zn to...
Tipo: Text Palavras-chave: Ureilite; Zinc isotopic composition; Isotope fractionation; Shock.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00472/58335/60889.pdf
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穩定同位素在農業及生態環境上之應用 Taiwan Agricultural Research Institute
彭宗仁; 劉滄棽; 林幸助; Tsung-Ren Peng; Tsang-Sen Liu; Hsing-Juh Lin.
[[abstract]]近20年由於「氣相同位素比值質譜儀」的改良和氫、氧、碳、氮和硫等穩定同位素的廣泛研究,穩定同位素的研究技術已實質增加我們對於這些元素在自然生態系中生地化循環的瞭解。雖然物質具相同之化學組成,但如果來源不同或經不同物理/化學過程所產生,其同位素比值會因同位素的分化作用而有差異。穩定同位素的研究主要是建立在此同位素分化作用所造成的同位素比值差異,而此同位素比值差異可被質譜儀測知。在了解造成此差異之原因後,進而幫助我們解釋環境變遷的訊息及意涵。為讓國內更多相關研究人員了解穩定同位素技術的可利用性,本文描述氣相同位素比值質譜儀之分析原理,及整理氫、氧、碳、氮和硫等同位素在農業及相關生態環境研究上應用的文獻。
Palavras-chave: 穩定同位素 同位素分化作用 氣相同位素比值質譜儀 Stable isotope; Isotope fractionation; Gas isotope ratio mass spectrometer [[classification]]4.
Ano: 2006
Registros recuperados: 7
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