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Determining sedimentary material sources in a Brazilian urban lake using Zn stable isotope compositions of bottom sediments: a preliminary study ArchiMer
Ferreira Araujo, Daniel; Boaventura, Geraldo; Mulholland, Daniel; Garnier, Jeremie; Machado, Wilson; Babinski, Marly; Dantas, Elton.
Zinc isotopes ratios provide qualitative and quantitative information about contributions from different Zn sources in the environment. Here we present the results of a preliminary study to identify the main sources controlling Zn isotope signatures of sediments from Lake Paranoá (Brazil), an urban water reservoir. The Zn isotope ratios were measured by MC-ICP-MS and expressed as δ66/64Zn notation relative to the JMC 3-0749-L solution. The studied sediments showed a narrow isotopic range (+0.00 to +0.13 ‰; n = 10) similar to that reported for intensely weathered soils worldwide (from -0.4 to +0.2‰). The geoaccumulation index (Igeo) also suggests low or negligible influence of Zn anthropogenic source. This research provides a baseline assessment of the Zn...
Tipo: Text Palavras-chave: Stable isotopes; MC-ICP-MS; Mass spectrometry; Environmental pollution; Metal contamination; Weathering; Zinc isotopes.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00666/77763/79899.pdf
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Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary ArchiMer
Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jerome; Van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine.
Rare earth element (REE) concentrations and neodymium isotopic composition (epsilon Nd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (< 0.45 mu m), colloidal and particulate REE and eNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while epsilon Nd values are shifted from the dissolved Nd river endmember (- 8.9) to values typical of...
Tipo: Text Palavras-chave: Earth sciences; Biogeochemistry; Oceanography.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00298/40952/40046.pdf
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