Assessment of the amount of Cesium-137 released into the Pacific Ocean after the Fukushima accident and analysis of its dispersion in Japanese coastal waters

International audienceNumerical modeling was used to provide a new estimate of the amount of 137Cs released directly into the ocean from the Fukushima Daiichi nuclear power plant (NPP) after the accident in March 2011 and to gain insights into the physical processes that led to its dispersion in the marine environment during the months following the accident. An inverse method was used to determine the time-dependent 137Cs input responsible for the concentrations observed at the NPP's two liquid discharge outlets. The method was then validated through comparisons of the simulated concentrations with concentrations measured in seawater at different points in the neighborhood of the plant. An underestimation was noticed for stations located 30 km offshore. The resulting bias in the release inventory was estimated. Finally, the maximum 137Cs activity released directly to the ocean was estimated to lie between 5.1 and 5.5 PBq (Peta Becquerel = 1015 Bq) but uncertainties remain on the amount of radionuclides released during the first few days after the accident. This estimate was compared to previous ones and differences were analyzed further. The temporal and spatial variations of the 137Cs concentration present in the coastal waters were shown to be strongly related to the wind intensity and direction. During the first month after the accident, winds blowing toward the south confined the radionuclides directly released into the ocean to a narrow coastal band. Afterwards, frequent northward wind events increased the dispersion over the whole continental shelf, leading to strongly reduced concentrations

Les matériaux organiques dans les sépultures du Haut Moyen Âge en Alsace : état de la recherche et étude de cas provenant de la nécropole de Merxheim Obere Reben (Haut-Rhin)

L’intérêt de l’étude des matières organiques dans les sépultures du haut Moyen Âge n’est plus à démontrer au vu de l’apport indéniable qu’elle apporte aux connaissances du costume et des pratiques funéraires. Cette approche permet d’appréhender avec un nouveau regard les dépôts présents dans les tombes, les vêtements portés par les défunts, la position des éléments et accessoires vestimentaires, leur composition ainsi que les techniques de fabrication et d’assemblage mises en œuvre. Développée au sein d’un PCR spécialement dédié à ce thème sous la direction de Florence Carré, cette question fait également partie d’un axe de recherche du PCR « Espaces et pratiques funéraires en Alsace aux époques mérovingienne et carolingienne (Ve-Xe siècles) » initié par les études menées dans la région depuis plusieurs années (F. Médard/Anatex). Ce champ d’investigation, encore faiblement exploité sur le plan national, commence à connaître une nette progression depuis quelques années, nécessitant un partenariat étroit et interdisciplinaire entre spécialistes des archéomatériaux organiques, chimistes et conservateurs-restaurateurs.Cet article fait donc le point sur les données récemment acquises au niveau régional et présente quelques exemples rares et inédits provenant de la nécropole alto-médiévale de Merxheim (Haut-Rhin) étudiés par une équipe de recherche pluridisciplinaire.The interest of studying the organic remains in graves from the Early Middle Ages is fully demonstrated by its undeniable contribution to our knowledge of mortuary costumes and practices. This approach enables a new perspective of the deposits in tombs, the clothing worn by the deceased, the position of the clothing elements and accessories, their composition and manufacturing and assemblage techniques.This approach has been developed in the framework of a PCR (collective research project) entitled “Funerary spaces and practices in Alsace during the Merovingian and Carolingian periods (5th-10th centuries)”, initiated by the studies conducted in the region over several years (F. Médard/Anatex). The use of this investigative approach, still rare at the national level, has significantly increased in recent years, requiring close interdisciplinary partnerships between organic archeomaterials specialists, chemists, and curators-restorers.This article summarizes the data recently acquired at the regional scale and presents a few rare and unpublished examples from the early Medieval necropolis of Merxheim (Haut-Rhin), studied by an interdisciplinary research team.Die Bedeutung der Untersuchung der organischen Reste aus frühmittelalterlichen Gräbern ist angesichts ihres unleugbaren Beitrags zur Kenntnis der Tracht und der Bestattungssitten erwiesen. Der hier dargestellte Ansatz ermöglicht es die Grabbeigaben, die Kleidung der Toten, die Position der einzelnen Elemente und des Kleidungszubehörs, deren Komposition, Herstellungstechniken und Zusammenstellung unter einem neuen Gesichtspunkt zu betrachten.Diese Problematik wurde im Rahmen eines speziell diesem Thema gewidmeten und von Florence Carré geleiteten PCR entwickelt und bildet zudem eine der Hauptachsen des PCR „Bestattungsplätze und Grabriten der Merowinger- und Karolingerzeit im Elsass (5.–10. Jh.)“, das durch seit mehreren Jahren in der Region durchgeführte Studien initiiert wurde (F. Médard/Anatex). Dieser Forschungsbereich, mit dem man sich auf nationalem Niveau bisher noch wenig beschäftigt hat, trifft seit einigen Jahren zunehmend auf Interesse. Er erfordert eine enge und disziplinübergreifende Zusammenarbeit zwischen Spezialisten der organischen Archäomaterialien, Chemikern, Konservatoren und Restauratoren.Der vorliegende Artikel erläutert die neueren auf regionaler Ebene erhaltenen Daten und präsentiert einige seltene und noch unveröffentlichte Beispiele aus der frühmittelalterlichen Nekropole von Merxheim (Departement Haut-Rhin), die von einem interdisziplinären Team untersucht wurden

Mass spectral characterisation of a polar, esterified fraction of an organic extract of an oil sands process water.

RATIONALE: Characterising complex mixtures of organic compounds in polar fractions of heavy petroleum is challenging, but is important for pollution studies and for exploration and production geochemistry. Oil sands process-affected water (OSPW) stored in large tailings ponds by Canadian oil sands industries contains such mixtures. METHODS: A polar OSPW fraction was obtained by silver ion solid-phase extraction with methanol elution. This was examined by numerous methods, including electrospray ionisation (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) and ultra-high-pressure liquid chromatography (uHPLC)/Orbitrap MS, in multiple ionisation and MS/MS modes. Compounds were also synthesised for comparison. RESULTS: The major ESI ionisable compounds detected (+ion mode) were C15-28 SO3 species with 3-7 double bond equivalents (DBE) and C27-28 SO5 species with 5 DBE. ESI-MS/MS collision-induced losses were due to water, methanol, water plus methanol and water plus methyl formate, typical of methyl esters of hydroxy acids. Once the fraction was re-saponified, species originally detected by positive ion MS, could be detected only by negative ion MS, consistent with their assignment as sulphur-containing hydroxy carboxylic acids. The free acid of a keto dibenzothiophene alkanoic acid was added to an unesterified acid extract of OSPW in known concentrations as a putative internal standard, but attempted quantification in this way proved unreliable. CONCLUSIONS: The results suggest the more polar acidic organic SO3 constituents of OSPW include C15-28  S-containing, alicyclic and aromatic hydroxy carboxylic acids. SO5 species are possibly sulphone analogues of these. The origin of such compounds is probably via further biotransformation (hydroxylation) of the related S-containing carboxylic acids identified previously in a less polar OSPW fraction. The environmental risks, corrosivity and oil flow assurance effects should be easier to assess, given that partial structures are now known, although further identification is still needed

Impact of synoptic atmospheric forcing on the mean ocean circulation

The impact of synoptic atmospheric forcing on the mean ocean circulation is investigated by comparing simulations of a global eddy-permitting ocean-sea ice model forced with and without synoptic atmospheric phenomena. Consistent with previous studies, transient atmospheric motions such as weather systems are found to contribute significantly to the time-mean wind stress and surface heat loss at mid and high latitudes owing to the nonlinear nature of air-sea turbulent fluxes. Including synoptic atmospheric forcing in the model has led to a number of significant changes. For example, wind power input to the ocean increases by about 50%, which subsequently leads to a similar percentage increase in global eddy kinetic energy. The wind-driven subtropical gyre circulations are strengthened by about 10-15%, whereas even greater increases in gyre strength are found in the subpolar oceans. Deep convection in the northern North Atlantic becomes significantly more vigorous, which in turn leads to an increase in the Atlantic Meridional Overturning Circulation (AMOC) by as much as 55%. As a result of the strengthened horizontal gyre circulations and the AMOC, the maximum global northward heat transport increases by almost 50%. Results from this study show that synoptic atmospheric phenomena such as weather systems play a vital role in driving the global ocean circulation and heat transport, and therefore should be properly accounted for in paleo and future climate studies

Apical Transport of Influenza A Virus Ribonucleoprotein Requires Rab11-positive Recycling Endosome

Influenza A virus RNA genome exists as eight-segmented ribonucleoprotein complexes containing viral RNA polymerase and nucleoprotein (vRNPs). Packaging of vRNPs and virus budding take place at the apical plasma membrane (APM). However, little is known about the molecular mechanisms of apical transport of newly synthesized vRNP. Transfection of fluorescent-labeled antibody and subsequent live cell imaging revealed that punctate vRNP signals moved along microtubules rapidly but intermittently in both directions, suggestive of vesicle trafficking. Using a series of Rab family protein, we demonstrated that progeny vRNP localized to recycling endosome (RE) in an active/GTP-bound Rab11-dependent manner. The vRNP interacted with Rab11 through viral RNA polymerase. The localization of vRNP to RE and subsequent accumulation to the APM were impaired by overexpression of Rab binding domains (RBD) of Rab11 family interacting proteins (Rab11-FIPs). Similarly, no APM accumulation was observed by overexpression of class II Rab11-FIP mutants lacking RBD. These results suggest that the progeny vRNP makes use of Rab11-dependent RE machinery for APM trafficking

High-resolution modelling of ocean circulation can reveal retention spots important for biodiversity conservation

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Alternatives to the Robert–Asselin filter

International audienceThe Leap Frog time stepping scheme (hereafter LF) partly loses its conservation properties when a Robert-Asselin filter (hereafter RA) is used to damp the computational mode. The LF + RA scheme actually leads to a well-known long term attenuation of the physical mode. Besides, the stability of the LF, e.g. the maximum permitted time step, is lowered by the use of the RA. Several methods, derived from the Laplacian approach of Marsaleix et al. (2008), are presented as an alternative to the RA. It appears that the physical mode is eventually much less impacted by higher order time filters. However, in some cases, the stability of the time stepping scheme becomes worse than that of the LF + RA. A five points scheme finally appears to preserve both the amplitude of the physical mode and the stability of the time stepping scheme. The analysis of these filters is based on a triple approach: the kinetic energy balance, the amplification factors of the oscillation equation, numerical experiments performed with a 3D circulation ocean model

Les matériaux organiques dans les sépultures du haut moyen âge : état de la recherche et cas d’études provenant de la nécropole de Merxheim « Obere Reben » (Haut-Rhin)

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Sur la piste des matériaux organiques grâce à la spectrométrie de masse

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