Guohui Gao, Christophe Colin, Giuseppe Siani, Sophie Sepulcre, Rosella Pinna-Jamme, Frederic Haurine, Arnaud Dapoigny
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We analyzed <i>ε</i>Nd in planktonic foraminifera samples and in non-decarbonated sediment leachates obtained with three solutions commonly used in the context of the Mediterranean Sea: (a) 0.02 M hydroxylamine hydrochloride (HH) solution, (b) 1N HCl, and (b) a 25% (v/v) acetic acid (AA). Our results show that (a) the foraminiferal <i>ε</i>Nd remains unaffected by the diagenesis of tephra content; (b) all three methods indicate significantly more radiogenic <i>ε</i>Nd values in tephra levels (up to 1.5 <i>ε</i>Nd unit), which is attributed to tephra dissolution accounting for 2.7% of extracted Nd; (c) of the three leaching methods applied to samples with low tephra content, hydroxylamine hydrochloride (HH) yields <i>ε</i>Nd values that are more consistent with those obtained on planktonic foraminifera; (d) the <i>ε</i>Nd values of planktonic foraminifera in core MD90-917 remained constant indicating that the Adriatic deep water primarily reflects the local Nd isotope composition over the last 20 kyr.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 4","pages":""},"PeriodicalIF":2.9000,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011992","citationCount":"0","resultStr":"{\"title\":\"Assessment of Seawater Nd Isotope Signatures Extracted From Foraminiferal Shells and Authigenic Phases From Volcanogenic Sediments of the Adriatic Sea\",\"authors\":\"Guohui Gao, Christophe Colin, Giuseppe Siani, Sophie Sepulcre, Rosella Pinna-Jamme, Frederic Haurine, Arnaud Dapoigny\",\"doi\":\"10.1029/2024GC011992\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The neodymium isotope signatures (<i>ε</i>Nd) of the authigenic fraction have been extensively used to reconstruct past seawater <i>ε</i>Nd and hydrological circulation. Among the various methods, sequential extraction of hydrogenic ferromanganese oxyhydroxides from bulk sediments represents a rapid and straightforward approach that may potentially induce artifacts due to the potential release of non-seawater-derived Nd during the extraction procedure. Here we investigated different methods for extracting past seawater Nd isotope compositions from a core collected in the Adriatic Sea whose tephra layers have been previously well documented. We analyzed <i>ε</i>Nd in planktonic foraminifera samples and in non-decarbonated sediment leachates obtained with three solutions commonly used in the context of the Mediterranean Sea: (a) 0.02 M hydroxylamine hydrochloride (HH) solution, (b) 1N HCl, and (b) a 25% (v/v) acetic acid (AA). 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Assessment of Seawater Nd Isotope Signatures Extracted From Foraminiferal Shells and Authigenic Phases From Volcanogenic Sediments of the Adriatic Sea
The neodymium isotope signatures (εNd) of the authigenic fraction have been extensively used to reconstruct past seawater εNd and hydrological circulation. Among the various methods, sequential extraction of hydrogenic ferromanganese oxyhydroxides from bulk sediments represents a rapid and straightforward approach that may potentially induce artifacts due to the potential release of non-seawater-derived Nd during the extraction procedure. Here we investigated different methods for extracting past seawater Nd isotope compositions from a core collected in the Adriatic Sea whose tephra layers have been previously well documented. We analyzed εNd in planktonic foraminifera samples and in non-decarbonated sediment leachates obtained with three solutions commonly used in the context of the Mediterranean Sea: (a) 0.02 M hydroxylamine hydrochloride (HH) solution, (b) 1N HCl, and (b) a 25% (v/v) acetic acid (AA). Our results show that (a) the foraminiferal εNd remains unaffected by the diagenesis of tephra content; (b) all three methods indicate significantly more radiogenic εNd values in tephra levels (up to 1.5 εNd unit), which is attributed to tephra dissolution accounting for 2.7% of extracted Nd; (c) of the three leaching methods applied to samples with low tephra content, hydroxylamine hydrochloride (HH) yields εNd values that are more consistent with those obtained on planktonic foraminifera; (d) the εNd values of planktonic foraminifera in core MD90-917 remained constant indicating that the Adriatic deep water primarily reflects the local Nd isotope composition over the last 20 kyr.
期刊介绍:
Geochemistry, Geophysics, Geosystems (G3) publishes research papers on Earth and planetary processes with a focus on understanding the Earth as a system. Observational, experimental, and theoretical investigations of the solid Earth, hydrosphere, atmosphere, biosphere, and solar system at all spatial and temporal scales are welcome. Articles should be of broad interest, and interdisciplinary approaches are encouraged.
Areas of interest for this peer-reviewed journal include, but are not limited to:
The physics and chemistry of the Earth, including its structure, composition, physical properties, dynamics, and evolution
Principles and applications of geochemical proxies to studies of Earth history
The physical properties, composition, and temporal evolution of the Earth''s major reservoirs and the coupling between them
The dynamics of geochemical and biogeochemical cycles at all spatial and temporal scales
Physical and cosmochemical constraints on the composition, origin, and evolution of the Earth and other terrestrial planets
The chemistry and physics of solar system materials that are relevant to the formation, evolution, and current state of the Earth and the planets
Advances in modeling, observation, and experimentation that are of widespread interest in the geosciences.