Holocene glacial discharge fluctuations and recent instability in East Antarctica
Antarctica holds the largest ice sheet in the world, the East Antarctic Ice Sheet (EAIS), and plays a significant role in both local and global climate through the interactions between ice sheets, ocean, sea ice, and atmosphere. Our understanding of East Antarctica Holocene climate variability relies mainly on ice cores that however do not document glacial discharge history. Here, we present the first high resolution δ 18 O diatom record derived from two marine sediment cores retrieved on the East Antarctic continental shelf to reconstruct glacial discharge off Adélie Land and George V Land (AL-GVL) over the last 11,000 years from decadal to centennial resolution. Our results suggest multi-centennial glacier advances and retreats until 2000 cal yr BP, followed by a period of relative instability marked by two major glacial retreats centered at ∼1700 cal yr BP and ∼1980 CE. We suggest that the multi-centennial oscillations during the Early/Mid-Holocene reflect glacier fluctuations in response to long-term local seasonal insolation and short-term solar variability. We also propose that δ 18 O diatom variability over the last 2000 years was the result of a recent change in the AL-GVL region to increasing atmospheric influence, linked to ENSO intensification and teleconnections strengthening between low and high latitudes.
(Earth and Planetary Science Letters. vol. 394, n° 0012-821X, pp. 38-47, 01/05/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS
Quantification of MTE in surface sediments of Morbihan Coast (South Brittany, France): A preliminary approach for determination of sources and dynamics
(27/04/2014)
GEOARCHI, UBS, UBO EPE, IBSHS, UBO EPE, LGO, UBS, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS
Caractérisation de la contamination des systèmes aquatiques par les psychotropes : développement d'une méthode de référence incluant une démarche multifactorielle de hiérarchisation
Les résidus de médicaments font partie des polluants dits « émergents » pour lesquels il n’existe actuellement pas de réglementation quant à leur présence dans l’environnement. Afin d’anticiper un risque éventuel pour l’Homme et les milieux aquatiques il est, entre autres, nécessaire de réaliser un état des lieux de la contamination des systèmes aquatiques par ce type de micropolluants. Dans ce contexte, disposer de données de mesures de qualité (traçables et comparables) constitue un prérequis indispensable pour décider au mieux des politiques à conduire dans ce domaine. L’étude des psychotropes présente un enjeu important d’autant plus qu’il s’agit de molécules abondamment consommées.Les travaux conduits lors de cette thèse avaient deux objectifs principaux. Le premier était de caractériser l’occurrence environnementale de composés psychotropes. Le second objectif était de proposer des outils métrologiques permettant d’assurer l’exactitude, la traçabilité, la comparabilité mais également la représentativité des résultats de mesure.Dans un premier temps, une méthode multi-résidus par SPE-LC-MS² a été développée pour une sélection de composés psychotropes et d’autres médicaments de consommation courante. Les limites de quantification de la méthode étaient de l’ordre du ng.L-1. Cela a permis de caractériser leur occurrence dans différents cours d’eau et rejets de station d’épuration en France. En parallèle, une approche par échantillonnage intégratif a été développée et déployée dans différents sites. Cette stratégie complémentaire a permis d’établir les niveaux d’occurrence des 68 psychotropes et traceurs sélectionnés et de conduire une démarche de hiérarchisation dans le but d’établir une liste restreinte de composés d’intérêt. Enfin, une méthode de référence associant la dilution isotopique à la spectrométrie de masse (DI-MS) a été développée pour l’analyse de 24 psychotropes dans les eaux de surface. Elle se caractérise par des incertitudes élargies (k=2) inférieures à 10%. La mise en oeuvre de cette méthode dans des études environnementales a permis de mettre en évidence l’importance de la contribution de l’incertitude liée à l’échantillonnage par rapport à l’incertitude totale de mesure.
(18/04/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
ECHIBIOTEB : Outils innovants d’échantillonnage, d’analyses chimiques et biologiques pour le suivi des traitements avancés des eaux usées et des boues
(pp. 1, 02/04/2014)
UR MALY, IRSTEA, INERIS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Trematode communities in cockles (Cerastoderma edule) of the Ria de Aveiro (Portugal): Influence of inorganic contamination
This work aims to assess the trematode parasites infecting the edible cockle Cerastoderma edule, collected in the Ria de Aveiro lagoon, one of the most relevant biodiversity hotspots of the Western Iberia, and evaluate the relationship between the observed patterns and environmental descriptors. A total of 11 of the 16 trematode species known to infect C. edule were identified, including Himasthla continua and Psilostomum brevicolle as new occurrences in this lagoon. Parvatrema minutum was the most abundant and dominant species. Species richness and prevalence were high. The relationship between trematode species abundance, intensity and prevalence, and also environmental variables, showed that most parasites preferred muddy sand areas with euhaline conditions in opposition to areas with contamination and/or distant from the lagoon entrance. This study highlighted the good ecological status of the ecosystem and the transitional biogeographic characteristics of the western Portuguese coast where northern and subtropical faunas can coexist.
(Marine Pollution Bulletin. vol. 82, n° 0025-326X, pp. 117-126, 27/03/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Sandra E. Shumway (Ed.) : Shellfish aquaculture and the environment
(Environmental Science and Pollution Research, n° 0944-1344, 26/03/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
PCB Integration of a Vivaldi Antenna on IPD Technology for 60-GHz Communications
The integration of a Vivaldi antenna on a printed circuit board (PCB) targeting 60-GHz WiGig applications is presented in this letter. The integrated passive device (IPD)technology from STMicroelectronics based on a glass substrate is used for the antenna manufacturing. In free space, the radiation pattern measurements show a realized gain higher than 4 dBi in the endfire direction from 56 to 65 GHz. The impact of the integration of the antenna on the PCB is investigated in details showing reasonable disturbance of the reflection coefficient, but strong modifications of the radiation pattern, especially the pointing direction of the main beam. From the analysis of the surface waves propagating along the PCB when the Vivaldi is integrated, a novel topology is proposed to preserve the main radiation in the endfire direction with enhanced realized gain.
(IEEE Antennas and Wireless Propagation Letters. vol. 13, n° 1536-1225, pp. 678-681, 16/03/2014)
ST-CROLLES, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEAT, UNS, CNRS, UniCA
What are the outcomes of an industrial remediation on a metal-impacted hydrosystem? A 2-year field biomonitoring of the filter-feeding bivalve Corbicula fluminea
The Riou-Mort watershed (southwest France) exhibits high metal contaminations (Cd and Zn) related to an important mining past. In this context, a remediation process has been implemented in 2007 to reduce the watershed contamination. The aim of this study was to assess the early effectiveness of the remediation process on the hydrosystem contamination state. A biomonitoring was realized over two years (2008-2010) with the filter-feeding bivalve Corbicula fluminea, exposed along a contamination gradient. Several biological parameters were monitored: (1) Cd and Zn bioaccumulation, (2) Metallothionein (MT) production as detoxification mechanism, (3) differential gene expression (cat, sod, gst, 12S, cox1, mt). The physicochemical data highlighted strong metal contamination persistence in the river water and failed to demonstrate a significant decrease of metal contamination during the 2-year monitoring. The bioaccumulation results confirmed the persistence of a water contamination despite remediation works, with maximum values measured downstream from the industrial site (Joany). The bioaccumulation increased in 2010, reaching 69.3±5.3μgCdg(-1) DW at Joany in July 2010, whereas it did not exceed 1.4±0.2μgCdg(-1) DW at the reference site throughout the biomonitoring. MT concentrations were closely related to the contamination gradient, especially at Joany, demonstrating their strong involvement in the detoxification processes. The mt gene induction was strongly correlated to the MT and metal concentrations. The gene inductions of cat, sod, gst and 12S were correlated to both the metal concentrations and the seasonal variations, especially temperatures. This suggests that environmental factors require serious consideration for the interpretation of bioaccumulation kinetics and thus for the assessment of the remediation effectiveness. Consequently, the whole results did not yet highlight strong beneficial effects of remediation work on the hydrosystem contamination state. First benefits of that process should be progressively felt, once the remediation achieved, and should grandly accelerate the decontamination process of the contaminated area.
(Chemosphere. vol. 108, n° 0045-6535, pp. 214-224, 01/03/2014)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Expansion of pelagic denitrification during early Pleistocene cooling
Bioavailable nitrogen is removed from the oceans in oxygen-deficient benthic and pelagic environments by denitrification. Future warming is predicted to reduce ocean oxygenation and to cause hypoxic regions to expand, potentially accelerating denitrification. A compilation of high-resolution sedimentary nitrogen isotope (δN15) records from the eastern tropical Pacific, North Pacific, and the Arabian Sea, and a global multi-site survey are presented as evidence for weak pelagic denitrification at the end of the Pliocene warm period. Mean δN15 values increased in the major oxygen minimum zones (OMZs) between 2.1 and 1.5 Ma. Pelagic denitrification strengthened during a period of long term global cooling, despite solubility driven increases in initial oxygen contents of Antarctic intermediate and Subantarctic mode waters ventilating the OMZs. This trend is opposite to the predicted mean trend for a cooling ocean as well as to the observed glacial-interglacial variation. Several alternatives to explain the shift are proposed, including a rise in net respiration, a progressive increase in the ventilation age of the deep ocean associated with million year scale, secular cooling, and a shoaling of the remotely ventilated thermocline to shallow depths corresponding to the zone of peak subsurface respiration. Given no evidence for a net increase in production, we assert that large-scale, climate-driven changes in ocean circulation regulate long timescale variations in the extent of pelagic denitrification. Additional data and modeling are required to fully explain the observations.
(Earth and Planetary Science Letters. vol. 389, n° 0012-821X, pp. 52-61, 01/03/2014)
BTP, LOCEAN, IPSL, ENS-PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Simultaneous 2D Imaging of Dissolved Iron and Reactive Phosphorus in Sediment Porewaters by Thin-Film and Hyperspectral Methods
(Environmental Science and Technology. vol. 48, n° 0013-936X, pp. 2816-2826, 21/02/2014)
BIAF, UA, LPG-ANGERS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, LPG, UA, UN UFR ST, UN, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPGP, INSU - CNRS, UPD7, UR, IPG Paris, CNRS