Micro analyse quantitative des éléments traces dans la calcite de la coquille Saint Jacques (Pecten maximus) par Ablation Laser ICP-MS: une archive journalière de la biogéochimie des environnements côtiers tempérés

The development of Laser Ablation - Inductively Coupled Plasma - Mass spectrometry coupling (LA-ICP-MS) conduced to the quantitative micro analysis of trace elements (TE) in calcium carbonate (CaCO3) matrices by the use of CaCO3 standards (TE range of concentrations: 0-500 µg.g-1). Quantitative analyses of TE along the daily calcite striae of the Great Scallop shells (Pecten maximus) allowed the definition of chronological profiles at high temporal resolution. The significance of these profiles was then evaluated, particularly in the Bay of Brest (France). Background shell concentrations are directly related to TE dissolved concentration in the seawater surrounding the shell habitat and to the TE solubility constants within the carbonates, reflecting thus average environmental and hydroclimatic conditions. Recurrent transient or seasonal shell enrichments were observed for the molybdenum (Mo), the barium (Ba) and the manganese (Mn). Mo and Ba enrichments are identified as relevant tracers of phytoplankton dynamic in coastal temperate environments. Specific Mn enrichment, revealed for shells from the Bay of Seine, are related to continental inputs from the Seine river and to supplementary summer inputs induced by redox changes within the water column and at the sediment water/interface (SWI) in the estuary. The micro chemistry of trace elements in the shell can be thus considered as a relevant archive of environmental changes in coastal temperate ecosystems, and also allow to better constrain the biogeochemical cycle of trace elements at the sediment - water interface.Le couplage de l'Ablation Laser et de la Spectrométrie de Masse à Plasma Inductif Couplé (LA-ICP-MS) a été mis en œuvre pour la détermination quantitative des éléments traces dans des matrices de carbonate de calcium (CaCO3) grâce à l'utilisation de pastilles étalons de CaCO3 (concentrations en éléments traces: 0-500 µg.g-1). L'analyse quantitative des éléments traces le long des stries journalières de calcite des coquilles Saint Jacques Pecten maximus a conduit à la définition de profils chronologiques et à haute résolution temporelle. La signification de ces profils a ensuite été évaluée particulièrement pour la Rade de Brest (France). Les concentrations coquillières de fond sont directement liées aux concentrations de l'eau de mer en phase dissoute et aux constantes de solubilité dans les carbonates, traduisant ainsi les conditions environnementales et hydro climatiques moyennes. Des enrichissements récurrents, transitoires et/ou saisonniers ont été observés pour le molybdène (Mo), le baryum (Ba) et le manganèse (Mn). Les enrichissements du Mo et du Ba dans la coquille sont identifiés comme des indicateurs de la dynamique phytoplanctonique dans les environnements côtiers tempérés. Les enrichissements du Mn, observés spécifiquement pour les coquilles de la Baie de Seine, traduisent les apports fluviaux de la Seine et les oscillations des conditions rédox dans la colonne d'eau et à l'interface eau/sédiment. La micro chimie des éléments traces de la coquille est donc établie comme une archive à haute fréquence des changements des environnements côtiers tempérés, et permet aussi de mieux comprendre le cycle biogéochimique des éléments traces à l'interface eau - sédiment

Micro analyse quantitative des éléments traces dans la calcite de la coquille Saint Jacques (Pecten maximus) par Ablation Laser ICP-MS (une archive journalière de la biogéochimie des environnements côtiers tempérés.)

Le couplage de l'Ablation Laser et de la Spectrométrie de Masse à Plasma Inductif Couplé (LA-ICP-MS) a été mis en œuvre pour la détermination quantitative des éléments traces dans des matrices de carbonate de calcium (CaCO3) grâce à l'utilisation de pastilles étalons de CaCO3 (concentrations en éléments traces: 0-500 g.g-1). L'analyse quantitative des éléments traces le long des stries journalières de calcite des coquilles Saint Jacques Pecten maximus a conduit à la définition de profils chronologiques et à haute résolution temporelle. La signification de ces profils a ensuite été évaluée particulièrement pour la Rade de Brest (France). Les concentrations coquillières de fond sont directement liées aux concentrations de l'eau de mer en phase dissoute et aux constantes de solubilité dans les carbonates, traduisant ainsi les conditions environnementales et hydro climatiques moyennes. Des enrichissements récurrents, transitoires et/ou saisonniers ont été observés pour le molybdène (Mo), le baryum (Ba) et le manganèse (Mn). Les enrichissements du Mo et du Ba dans la coquille sont identifiés comme des indicateurs de la dynamique phytoplanctonique dans les environnements côtiers tempérés. Les enrichissements du Mn, observés spécifiquement pour les coquilles de la Baie de Seine, traduisent les apports fluviaux de la Seine et les oscillations des conditions rédox dans la colonne d'eau et à l'interface eau/sédiment. La micro chimie des éléments traces de la coquille est donc établie comme une archive à haute fréquence des changements des environnements côtiers tempérés, et permet aussi de mieux comprendre le cycle biogéochimique des éléments traces à l'interface eau - sédiment.The development of Laser Ablation - Inductively Coupled Plasma - Mass spectrometry coupling (LA-ICP-MS) conduced to the quantitative micro analysis of trace elements (TE) in calcium carbonate (CaCO3) matrices by the use of CaCO3 standards (TE range of concentrations: 0-500 g.g-1). Quantitative analyses of TE along the daily calcite striae of the Great Scallop shells (Pecten maximus) allowed the definition of chronological profiles at high temporal resolution. The significance of these profiles was then evaluated, particularly in the Bay of Brest (France). Background shell concentrations are directly related to TE dissolved concentration in the seawater surrounding the shell habitat and to the TE solubility constants within the carbonates, reflecting thus average environmental and hydroclimatic conditions. Recurrent transient or seasonal shell enrichments were observed for the molybdenum (Mo), the barium (Ba) and the manganese (Mn). Mo and Ba enrichments are identified as relevant tracers of phytoplankton dynamic in coastal temperate environments. Specific Mn enrichment, revealed for shells from the Bay of Seine, are related to continental inputs from the Seine river and to supplementary summer inputs induced by redox changes within the water column and at the sediment water/interface (SWI) in the estuary. The micro chemistry of trace elements in the shell can be thus considered as a relevant archive of environmental changes in coastal temperate ecosystems, and also allow to better constrain the biogeochemical cycle of trace elements at the sediment - water interface.PAU-BU Sciences (644452103) / SudocSudocFranceF

Development of an on-line UV decomposition system for direct coupling of liquid chromatography to atomic-fluorescence spectrometry for selenium speciation analysis

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Nickel and vanadium contamination of benthic invertebrates following the "Erika" wreck

International audienceLevels of nickel and vanadium, trace metals found in high concentration in the oil spilled from the "Erika" tanker off Brittany (France) in December 1999 (41 ± 1 and 87 ± 3 mg kg −1 respectively), have been monitored over a one-year period following this accidental event in several benthic invertebrates. Ni and V in mussels (Mytilus edulis) and oysters (Crassostrea gigas) soft tissues were analysed twice a month by graphite furnace atomic absorption spec-trometry and a scallop (Pecten maximus) shell daily growth bands were sampled every three bands by laser ablation and analysed by ICP-MS for these two contaminants. Survey data for mollusc tissues were compared with reference data arising from the national monitoring database. Ni concentrations in dried tissues, comparable with reference data (1.8 ± 0.9 µg g −1 in mussels and 1.2 ± 0.5 µg g −1 in oysters) do not show any additional input during the whole period. Conversely, a sharp increase in vanadium concentrations (up to 4.6 and 3.2 µg g −1 for mussels and oysters respectively) is observed around May 2000, i.e. 5 months after the wreck, compared with the monitoring data (1.4 ± 0.6 µg g −1 in mussels and 1.3 ± 0.6 µg g −1 in oysters). Furthermore, no Ni peak is detectable in the time profiles of scallop shell growth bands where a V peak is observed also in May 2000. This study shows that although a "mussel-watch-type" network, based on the monitoring of vanadium concentration in mollusc tissues, is able to identify contamination due to oil spills, similar information might be obtained a posteriori by analysing daily growth bands of scallop shells. Key words: Oil spill / Nickel / Vanadium / Mussel / Oyster / Scallop shell / Monitoring Résumé-Résumé. Contamination des invertébrés benthiques par le nickel et le vanadium suite au naufrage de l'« Erika ». Les concentrations en nickel et en vanadium, métaux traces présents en quantité importante dans le fioul échappé du pétrolier « Erika » au large de la Bretagne (France) en décembre 1999 (41 ± 1 et 87 ± 3 mg kg −1 respectivement) ont fait l'objet d'un suivi d'un an après le naufrage chez quelques invertébrés benthiques. Ni et V ont été analysés deux fois par mois dans les tissus mous de moules (Mytilus edulis) et d'huîtres (Crassostrea gigas) par absorption atomique à four graphite et tous les trois jours dans les stries journalières de croissance des valves d'une coquille Saint-Jacques (Pecten maximus) par ICP-MS après ablation laser. Les données obtenues pour les tissus de mollusques ont été comparées avec les valeurs de références fournies par le programme national de surveillance. Durant toute la période d'étude, on n'observe pas d'apport occasionnel en nickel, dont les concentrations dans la chair séchée sont comparables aux valeurs de référence (1,8 ± 0,9 µg g −1 chez les moules et 1,2 ± 0,5 µg g −1 chez les huîtres). En revanche, une élévation importante des concentrations en vanadium (jusqu'à 4,6 et 3,2 µg g −1 chez les moules et les huîtres respectivement) comparées aux donnés de la surveillance (1,4 ± 0,6 µg g −1 chez les moules et 1,3 ± 0,6 µg g −1 chez les huîtres), est observée en mai 2000, soit 5 mois après le naufrage. De la même manière, aucun pic de nickel n'a été détecté dans les profils temporels de stries journalières de coquille de pectinidé alors qu'un pic de vanadium est observable en mai 2000. Cette étude montre qu'un réseau d'observation de type « mussel-watch » basé sur la surveillance des concentrations en vanadium dans les tissus de mollusques est apte à identifier une contamination due à une marée noire, et une information du même type pourrait être obtenue a posteriori en analysant les stries journalières des valves de coquilles Saint-Jacques. a Correspondin

Marine sponges as a powerful tool for trace elements biomonitoring studies in coastal environment

International audienceIn this work, we performed a comparative study on six marine sponge species collected along the French Mediterranean and Irish coasts for their TEs accumulation. Intra and inter-species variabilities were examined. Among the Mediterranean species, Cymbaxinella damicornis accumulates significantly more As and Cu than others sponge species; Chondrilla nucula more Ni and Mo and Acanthella acuta more Ag. Among Irish samples, Hymeniacidon perlevis showed higher accumulation properties for most of TEs in comparison to Halichondria panicea. Bioconcentration Factors were > 1 in all species for most of TEs. This study suggests that TEs bioaccumulation is most likely associated to differences in morphological features and/or to specific bacterial communities associated to different species. The determination of Pb isotope ratios revealed mainly natural Pb sources for Mediterranean and Kilkieran Bay's samples, and rather anthropogenic influence for Belfast samples. This study confirms that sponges represent a powerful tool for biomonitoring studies

Comparative study on the bioaccumulation and biotransformation of arsenic by some northeastern Atlantic and northwestern Mediterranean sponges

International audienceThe bioaccumulation and biotransformation of arsenic (As) were studied in six representative marine sponges from the French Mediterranean and Irish Atlantic coasts. Methodologies were carefully optimized in one of the species on Haliclona fulva sponges for two critical steps: the sample mineralization for total As analysis by ICP-MS and the extraction of As species for HPLC-ICP-MS analysis. During the optimization, extractions performed with 0.6 mol L−1 H3PO4 were shown to be the most efficient. Extraction recovery of 81% was obtained which represents the best results obtained until now in sponge samples. Total As analyses and As speciation were performed on certified reference materials and allow confirming the measurement quality both during the sample preparation and analysis. Additionally, this study represents an environmental survey demonstrating a high variability of total As concentrations among the different species, probably related to different physiological or microbial features. As speciation results showed the predominance of arsenobetaine (AsB) regardless of the sponge species, as well as the occurrence of low amounts of dimethylarsinic acid (DMA), arsenate (As(+V)), and unknown As species in some samples. The process responsible for As transformation in sponges is most likely related to sponges metabolism itself or the action of symbiont organisms. AsB is supposed to be implied in the protection against osmolytic stress. This study demonstrates the ability of sponges to accumulate and bio-transform As, proving that sponges are relevant bio-monitors for As contamination in the marine environment, and potential tools in environmental bio-remediation

Oxic and post-oxic chemical changes related to eogenesis and mesogenesis in a Miocene paleolake

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Barium and molybdenum records in bivalve shells: Geochemical proxies for phytoplankton dynamics in coastal environments?

International audienceBarium:calcium and molybdenum:calcium ratios were investigated in shells of the tropical scallop Comptopallium radula. Three juvenile specimens were harvested alive in the southwest lagoon of New Caledonia after a 1-year hydrological survey. Calcite samples representing a few hours of biomineralization were laser-ablated along the maximal growth axis and analyzed for Ba and Mo content using an inductively coupled plasma mass spectrometer. Absolute dates of shell precipitation assigned on the basis of periodic formation of shell growth patterns led to the accurate reconstruction of ontogenetic variations of elemental ratios with subweekly resolution. Inter-individual variability of Ba:Ca and Mo:Ca time series was low, indicating an environmental control on the incorporation of these elements within shells. Both profiles were characterized by a background level punctuated by sharp peaks. The ingestion of diatoms enriched in Ba (adsorbed on iron oxyhydroxides associated with the frustules) is the most likely cause of the formation of Ba:Ca peaks. Some contribution of diatom-associated barite is also possible. In every instance, Ba:Ca would possibly be a proxy for the timing and magnitude of diatom blooms. Among all the theories that could be advanced to explain the occurrence of Mo:Ca peaks, the most plausible appears to be the ingestion of phytoplankton cells grown upon NO3- and therefore containing high levels of Mo required for the activity of nitrate reductase. If this is so, then Mo:Ca could be a new proxy for nitrate uptake by phytoplankton in coastal ecosystems, helping to reconstruct the balance between new and regenerated production in paleoenvironments

Naturally dissolved arsenic concentrations in the Alpine/Mediterranean Var River watershed (France)

International audience• Variations of dissolved arsenic concentration according to water/rock interactions • As in river water originates from Perm-ian and Hercynian metamorphic rocks • 4.2 tons⋅year − 1 of dissolved As is transferred to the Mediterranean Sea. • The use of a mixing model supports the non-conservative nature of arsenic. A detailed study on arsenic (As) in rocks and water from the Var River watershed was undertaken aiming at identifying (i) the origin and the distribution of As in this typical Alpine/Mediterranean basin, and (ii) As input into the Mediterranean Sea. Dissolved As concentrations in the Var River range from 0.1 to 4.5 μg⋅L −1 , due to high hydrological variability and the draining through different geological formations. In the upper part of the Var drainage basin, in the Tinée and the Vésubie valleys, high levels of dissolved As concentrations occur (up to 263 μg ⋅ L −1). The two main sources of As in rocks are the Hercynian metamorphic rocks and the Permian argilites. Highly heterogeneous distribution of As in waters draining through metamorphic rocks is probably related to ore deposits containing arsenopyrite. As, U, W and Mo concentrations in water and rocks correspond to the formation of As-rich ore deposits around Argentera granite by hydrothermal fluids deposited at the end of the Hercynian chain formation, which occurred about 300 My ago. In 2009, weekly monitoring was performed on the Var River (15 km upstream of the mouth), highlighting an average dissolved As concentration (b0.45 μm) of 2.7 ± 0.9 μg⋅L −1 , which is significantly higher than the world-average baseline for river water (0.83 μg ⋅ L −1). Taking the average annual discharge (49.4 m 3 ⋅ s −1) into account and the As levels in the dissolved phase and in deposits of the Var River, dissolved As input into the Mediterranean Sea would be 4.2 ± 1.4 tons⋅year −1 which represents 59% of the total As flux. This study also reveals a probable non-conservative As behaviour, i.e., possible transfer between aqueous and solid phases, during the mixing of the Var River with a tributary

Mineral assemblages and temperature associated with Cu enrichment in the Seival area (Neoproterozoic Camaquã Basin of Southern Brazil)

International audienceThe Neoproterozoic sequence of volcanic rocks in the Camaquã Basin included in the Lavras do Sul Shoshonitic Association hosts disseminated Cu deposits. The volcanic sequence in the Seival Mine area includes andesitic lava flows, lapilli tuff, volcanic agglomerate and andesitic dikes with pervasive alteration. The hydrothermal alteration is interpreted to be a product of late–magmatic fluids or the mixing of magmatic with meteoric fluids or basinal brines. The late–magmatic hydrothermal system started after volatile oversaturation and degassing in a magmatic system, which was partially segregated into vesicles. The similar REE contents in the andesine–labradorite and albite indicate that the fluid temperatures ranged from 600 to 250 °C. The crystallization of titanite and Fe–clinochlore to Mg–chamosite followed the albitization process. The temperature range associated with the chloritization process was estimated using a chlorite geothermometer and varied from 251 ± 56 to 183 ± 39 °C. The precipitation of Mg–saponite and smectite–rich chlorite/smectite mixed–layers in some andesitic lava flows and the precipitation of quartz, calcite, barite and hematite in fractures suggest fluid circulation with temperatures lower than the chloritization process. The alteration minerals are represented by chlorite and albite associated with pyrite–chalcopyrite, while chlorite/smectite mixed–layers and barite or hematite are associated with bornite–chalcocite–covellite. Thermodynamic calculations confirm the potential coprecipitation of pyrite–chalcopyrite with chlorite and albite. The occurrence of bornite–chalcocite–covellite and barite seems to be favored by low–temperature chlorite/smectite with neutral to mildly acidic water influx. Consequently, albitization and the process of chloritization at high temperatures (>ca. 251 ± 56 °C) can be used as an exploration guide for primary pyrite–chalcopyrite enrichment, and chlorite/smectite at low temperatures (ca. 250 to 50 °C) can be related to bornite–chalcocite–covellite or the process of Cu enrichment