A fast, single column extraction chromatography method for the isolation of neodymium from iron-rich materials prior to radiogenic isotope ratio measurements

International audienceA novel separation method is described for the separation of Nd from Fe-rich, silicate samples in view of isotopic analyses. The procedure is based on the synergistic enhancement of the extraction of the REE from HCl media by the diglycolamide ligand in the presence of large amounts of Fe(III). Following sample decomposition with a mixture of HF and HCl, the resulting, ca. 4 M HCl solution is immediately loaded on a column of DGA resin, without evaporation of HF and volatilization of silicon. Both Fe(III) and the REE are extracted by the resin while most other elements pass through the column. Then, iron is stripped from the column with 3 M HNO3. Finally, the LREE are eluted sequentially by means of HCl of decreasing strength, thereby providing a Nd fraction suitable for isotope ratio measurements by MC-ICP-MS. Because it does not require evaporation steps, this method offers a robust, straightforward alternative to more complicated schemes when samples unusually rich in iron are to be analysed. The potential of this protocol is demonstrated by several replicate analyses of two Fe-rich international SRMs, namely the banded iron IF-G (56 wt% Fe2O3) and the bauxite BX-N (23% Fe203

A Minoan and a Neolithic tsunami recorded in coastal sediments of Ios Island, Aegean Sea, Greece

co-auteur étrangerInternational audienceIn this work, we document two distinct tsunami deposits on the coasts of Ios Island, Aegean Sea, Greece. The younger tsunami deposit, dated 1831–1368 cal. BCE, includes both marine sediments and pumices from the ~1600 BCE Minoan eruption of Santorini volcano. This is the first evidence of the Minoan tsunami in the Cycladic Islands North of Santorini. Tsunami waves inundated the Manganari coastal plain, southern coast of Ios, over a distance >200 m (>2 m a.s.l.). The second tsunami deposit reworks pumice from the 22 ka Cape Riva eruption mixed with marine sediment. We assume a Neolithic age for this major tsunami, with a wave runup >13 m a.s.l. on the southern and eastern coasts of Ios. The source of this tsunami - volcanic eruption, landslide, or earthquake - remains unknown. Additionally, we provide the first on-land evidence of Cape Riva deposits outside Santorini, thus questioning previous estimates on the magnitude of this eruption

The La-Ce Isotope Systematics in Gough Island Lavas: New Constraints on the Origin of the EM1 Component

International audienc

The high field strength element budget of atmospheric aerosols (puy de Dôme, France)

International audienceHigh field strength elements (HFSE), including Zr, Hf, Nb, Ta and Ti have low solubility in aqueous fluids and partition into dense and resistant minerals. HFSE proved useful in studying terrestrial weathering and sediment transport, but little is known about their behavior during atmospheric processes, which play an important role in global sedimentary cycles. The atmospheric budget of HFSE is evaluated from the sequential dissolution of aerosol samples collected between 2011 and 2014 at puy de Dôme (1465 m elevation, French Massif Central). Aerosols were sampled during nighttime, while the site is generally located above the planetary boundary layer.Systematic, partial recovery of HFSE during gentle dissolution of aerosols indicates that resistant minerals are ubiquitous in air samples. Total dissolution of aerosols in pressure vessels reveals that Zr and Hf occur on average in sub-crustal abundance, which is consistent with the sampling site being dominantly influenced by oceanic air masses depleted in zircons. Conversely, zircon excess occasionally occurs in continental air masses, in particular those originating from northern Africa. Overall, the Hf/Nd ratio, a proxy for zircon fractionation, varies from 0.26 to 3.94 times the Upper Continental Crust (UCC) value, encompassing the range of worldwide loess. This wide compositional range is consistent with (1) the occurrence of coarse zircons (10–30 μm) in dust source, with possible local enrichments relative to bulk UCC in residual wind-winnowed soils, and (2) gravitational settling of coarse zircons during long-distance (>ca. 1000 km) transport.Niobium and Ta are systematically more abundant (by a mean factor of ∼3) in puy de Dôme aerosols than expected from average crustal or soil concentrations. The volume-weighted average Nb/Ta ratio of 15.5 ± 2.6 (1σ) is also higher than in bulk UCC (11.4–13.3). The positive Nb–Ta anomaly of free troposphere aerosols unlikely reflects a net Nb–Ta enrichment but might result from loss of more water-soluble elements during weathering of aerosols in clouds.Depletion in Zr–Hf (coarse zircons settling) and Nb–Ta enrichment (cloud processing) might occur during large-scale transport of mineral dust over ocean basins, which could explain the peculiar HFSE distribution in some Hawaiian soils showing inputs of Asian dust

The trace metal signature of atmospheric aerosols sampled at a European regional background site (puy de Dôme, France)

International audienceTrace metal composition of atmospheric aerosols provides clues as to emission sources and history of air masses. Atmospheric trace metal concentrations measured between 2011 and 2013 at puy de Dôme (1,465 m elevation, central France) are, on average, intermediate between low-altitude urban sites and Atlantic remote environment (115 ng/m3 Al, 0.55 ng/m3 Sr, 0.136 ng/m3 Ce, 1.34 ng/m3 Pb). Three main factors control trace metal variability: (1) the concentrations markedly decrease at night while the site is generally located in the free troposphere/nocturnal residual layer (average of 43 ng/m3 Al, 0.27 ng/m3 Sr, 0.052 ng/m3 Ce, 0.25 ng/m3 Pb during 2012 summer nights). The nocturnal depletion is greater for refractory crustal elements (Al, Fe, Ti and rare earth elements) than for B, Na and chalcophile/siderophile elements (e.g., Tl, In, Sb, Zn, Cd, Cu, Bi, Mo, Re, Pt and Pd), which probably partition into the gas phase and/or a fine mode fraction. (2) Cr, Ni, Mo, Ag, Pb and Pt record a greater influence of anthropogenic sources (combustion, iron/steel industry, and automobile exhaust catalysts) in winter, and/or in the continental air mass that most frequently influences the site during the cold season. (3) Air masses reaching the site have distinct trace element fingerprints depending on their origin. The African air has crustal like signatures (Al/Ti, La/Sm). The Atlantic air is enriched in B, Cu, Bi, Co, W, Re and Ag and depleted in Tl, Sb and Se relatively to Al. Continental air is enriched in Cr and Ni and depleted in Na. Local air (France) is enriched in chalcophile elements (Zn, Pb, Se, As, Sb, Tl) and to a lesser extent in alkalis and rare earth elements, likely due to limited activation and scavenging of primary particles during a short-history of transport

A New Interlaboratory Characterisation of Silicon, Rare Earth Elements and Twenty‐Two other Trace Element Mass Fractions in the Natural River Water Certified Reference Material SLRS ‐6 ( NRC ‐ CNRC )

International audienceThe natural river water reference material SLRS‐6 (NRC‐CNRC) is the newest batch of a quality control material routinely used in many international environmental laboratories. This work presents a nine‐laboratory compilation of measurements of major and trace element mass fractions and their related uncertainties, unavailable in the NRC‐CNRC certificate (B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Y, Zr and REEs). Measurements were mostly made using inductively coupled plasma‐mass spectrometry. The results are compared with equivalent data for the last batch of the material, SLRS‐5, measured simultaneously with SLRS‐6 in this study. In general, very low mass fractions, close to the quantification limits, were found in the new batch. The Sr isotopic ratio is also reported