The French Atlantic margin and deep-sea submarine systems
The sedimentary infill of the Bay of Biscay off Ireland, UK, France and Spain took place in four phases. The last one (35 Ma to present) is characterised by gravitational, pelagic, contouritic and glacigenic processes leading to the setup of three deep sea systems. To the North, the Celtic and Armorican fans are fed by a "canyon-dominated" margin and its connection with the "Manche" palaeoriver, which drained a large area of western Europe. To the South, the Cap-Ferret fan results from the evolution of a "tectonic-dominated" margin and the erosion of the Pyrenee mountains.
(Geo-Marine Letters. vol. 26, n° 0276-0460, pp. 311-315, 28/10/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Introduction to “Turbidite systems off France and the Lesser Antilles”
Without Abstract
(Geo-Marine Letters. vol. 26, n° 0276-0460, pp. 305-310, 28/10/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Evidence of an altered protective effect of metallothioneins after cadmium exposure in the digenean parasite-infected cockle (Cerastoderma edule)
The aim of the present study was to analyse the relation between parasitism and subsequent metallothioneins (MT) in the case of metal contamination. Experimental exposure of parasitized and unparasitized cockles (Cerastoderma edule) to cadmium (Cd) was performed, with the cockle as first or second intermediate host of 2 digenean species. After 7 days of Cd exposure in microcosms, cockles infected as first intermediate host byLabratrema minimusexhibited metal concentrations in tissues double that in uninfected cockles. Jointly, MT concentrations of parasitized cockles were not modified in comparison with uninfected individuals in which concentrations were increased 4·3-fold compared with controls. In cockles experimentally infected as the second intermediate host byHimasthla elongata, cadmium concentrations significantly increased again in parasitized cockles compared with uninfected individuals in contaminated conditions. Simultaneously, MT concentrations in healthy cockles increased, whereas they significantly decreased in parasitized individuals. Therefore, the presence of digenean parasites in Cd-exposed cockles leads to a maintenance or a decrease in MT concentrations compared with healthy individuals, whereas Cd accumulation in tissues is significantly increased. These experiments indicate a significant alteration of the protective effect of metallothioneins towards metals which could consequently enhance cockle vulnerability. Moreover, these results highlight the limit of the use of MT as a biomarker of metal pollution in field monitoring if parasitism is not taken into account.
(Parasitology. vol. 134, n° 0031-1820, pp. 237, 11/10/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Empirical Estimation of Nearshore Waves From a Global Deep-Water Wave Model
Global wind-wave models such as the National Oceanic and Atmospheric Administration WaveWatch 3 (NWW3) play an important role in monitoring the world's oceans. However, untransformed data at grid points in deep water provide a poor estimate of swell characteristics at nearshore locations, which are often of significant scientific, engineering, and public interest. Explicit wave modeling, such as the Simulating Waves Nearshore (SWAN), is one method for resolving the complex wave transformations affected by bathymetry, winds, and other local factors. However, obtaining accurate bathymetry and determining parameters for such models is often difficult. When target data is available (i.e., from in situ buoys or human observers), empirical alternatives such as artificial neural networks (ANNs) and linear regression may be considered for inferring nearshore conditions from offshore model output. Using a sixfold cross-validation scheme, significant wave height Hs and period were estimated at one onshore and two nearshore locations. In estimating Hs at the shoreline, the validation performance of the best ANN was r=0.91, as compared to those of linear regression (0.82), SWAN (0.78), and the NWW3 Hs baseline (0.54)
(IEEE Geoscience and Remote Sensing Letters. vol. 3, n° 1545-598X, pp. 462-466, 01/10/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Report on the 2nd international meeting of the IUGS lower Cretaceous ammonite working group, the “Kilian Group” (Neuchâtel, Switzerland, 8 September 2005)
(Cretaceous Research. vol. 27 (5), n° 0195-6671, pp. 712-715, 01/10/2006)
LGL-TPE, ENS de Lyon, UCBL, INSU - CNRS, UJM, CNRS, UNSA, PEPS, UCBL, INSU - CNRS, CNRS, LGCA, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, CNRS, LDO, INSU - CNRS, UBO EPE, CNRS
Eastern Australia: A possible source of dust in East Antarctica interglacial ice
The Australian continent is characterised by an extremely variable surficial geochemistry, reflecting the varied lithology of Australian basement rocks. Samples representative of Australian aeolian dust have been collected in (1) regions where meteorological records, satellite observation and wind erosion modelling systems have indicated frequent dust activity today (mainly the Lake Eyre Basin), and (2) from deposits of mixed dust materials. The 87Sr/86Sr and 143Nd/144Nd isotopic composition of the fine (< 5 μm) fraction of Australian dust samples was measured for comparison with the Sr and Nd isotopic composition of fine aeolian dust that reached the interior of the East Antarctic Plateau. The isotopic field for Australian dust is characterised by 87Sr/86Sr ratios ranging from 0.709 to 0.732 and εNd(0) between − 3 and − 15. The low Sr radiogenic values and εNd(0) of − 3 obtained for Lake Eyre samples are explained by the lithology of the Lake Eyre catchment showing a dominance of Tertiary intraplate volcanic material. These new data show that the dust contribution from Australia could have been dominant during interglacial periods (Holocene and Marine Isotopic Stage 5.5) to Antarctica. During glacial times, studies have shown that the South American dust isotopic signature overlaps the glacial Antarctic dust field suggesting this region as dominant aeolian dust source. However, the Australian Lake Eyre dust isotopic signature partially overlaps with the Antarctic glacial dust signature. We propose that the relatively greater contribution of Australian dust inferred for Antarctic interglacial ice compared with glacial ice is not directly reflective of changes in dust transport pathway, but instead is related to a differential weakening of the South American sources during interglacial time with respect to the Australia sources. Our findings have implications for interglacial versus glacial atmospheric circulation, at least in the Southern Hemisphere.
(Earth and Planetary Science Letters. vol. 249, n° 0012-821X, pp. 1-13, 15/09/2006)
GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], UniCA, LGCA, OSUG, UJF, Grenoble INP, INSU - CNRS, IRSTEA, USMB [Université de Savoie] [Université de Chambéry], CNRS, CNRS, ANU, UNIMIB, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Tectonophysique, UM2, INSU - CNRS, CNRS
Massive sand beds attributed to deposition by dense water cascades in the Bourcart canyon head, Gulf of Lions (northwestern Mediterranean Sea)
Nowadays, the Gulf of Lions continental shelf and slope are under the influence of dense water cascading, wind-induced bottom currents and the geostrophic Northern Current. In order to characterize sedimentary activity at the shelf break, several interface and piston cores were taken in the Bourcart canyon head and a current meter equipped with temperature, conductivity, pressure and turbidity sensors was moored during the 2003–2004 winter season. Even if the canyon is not connected directly to continental sources since Last Glacial Maximum, detailed grain size, X-ray and sediment facies analysis of interface cores show that down to 350 m water depth, the canyon head is blanketed by up to 1.5 m of structureless muddy medium-grained sand. 210Pbexc activity measurements demonstrate present day sedimentary activity of the canyon head. Time series of currents with peak velocity reaching 0.37 m/s, suspended sediment concentration and temperature indicate that dense water cascading is the main process allowing the reworking, transport and accumulation of sand within the canyon head, even though winter 2003–2004 was characterized by low cascading events compared to other years. These sand beds, called “cascadite” constitute a new type of deposit that differs from other typical slope deposits (turbidites, hyperpycnites, contourites) in terms of flow duration and sedimentological characteristics. They are similar to shallow water contourites. They might be time-equivalent to the recent turbidites described throughout the deep western Gulf of Lions basin.
(Marine Geology. vol. 234, n° 0025-3227, pp. 111-128, 05/09/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, ICM, CSIC, LDO, INSU - CNRS, UBO EPE, CNRS
Mercury distribution in fish organs and food regimes: significant relationships from twelve species collected in French Guiana (Amazonian basin)
(Science of the Total Environment. vol. 368, n° 0048-9697, pp. 262-270, 01/09/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMBA, UBS, UBO EPE, CNRS
Metallothionein response to cadmium and zinc exposures compared in two freshwater bivalves, Dreissena polymorpha and Corbicula fluminea
Metallothionein (MT) response to cadmium (Cd) and zinc (Zn) bioaccumulation after single or combined direct exposure was compared in two freshwater bivalves, Dreissena polymorpha (zebra mussel) and Corbicula fluminea (Asiatic clam). Bivalves were exposed to 0.133 microM Cd and/or 15.3 microM Zn, with metal and MT concentrations analysed in the whole soft body after 1, 3, 10 and 24 days of exposure and compared with controls. Results showed significant increase in MT concentrations in both species exposed to Cd and Cd+Zn with a higher accumulation of the protein compared to the control in D. polymorpha for nevertheless similar Cd levels accumulated with time. Exposure to Zn alone led to a significant increase in MT concentrations only in C. fluminea, whereas there was a lack of MT gene induction in the zebra mussels which was confirmed by MT mRNA quantification in gills (RT-PCR). Mussel mortality after 10 days of exposure to Zn and Cd + Zn is discussed with regard to detoxification mechanisms, which include metallothioneins.
(BioMetals. vol. 19, n° 0966-0844, pp. 399-407, 01/08/2006)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
$^{234}$Th sorption and export models in the water column: A review
Over the past few decades, the radioisotope pair of $^{238}$U/$^{234}$Th has been widely and increasingly used to describe particle dynamics and particle export fluxes in a variety of aquatic systems. The present paper is one of five review articles dedicated to $^{234}$Th. It is focused on the models associated with $^{234}$Th whereas the companion papers (same issue) are focused on present and future methodologies and techniques (Rutgers van der Loeff et al.), C/$^{234}$Th ratios (Buesseler et al.), $^{234}$Th speciation (Santschi et al.) and present and future applications of $^{234}$Th (Waples et al.). In this paper, we review current $^{234}$Th scavenging models and discuss the relative importance of the non steady state and physical terms associated with the most commonly used model to estimate $^{234}$Th flux. Based on this discussion we recommend that for future work the use of models should be accompanied by a discussion of the effect that model and data uncertainty have on the model results. We also suggest that future field work incorporate repeat occupations of sample sites on time scales of 1-4 weeks in order to evaluate steady state versus non steady state estimates of $^{234}$Th export, especially during high flux events (> ca. 800 dpm m$^{-2}$ d$^{-1}$). Finally, knowledge of the physical oceanography of the study area is essential, particularly in ocean margins and in areas of established upwelling (e.g. Equatorial Pacific). These suggestions will greatly enhance the application of $^{234}$Th as a tracer of particle dynamics and flux in more complicated regimes.
(Marine Chemistry. vol. 100, n° 0304-4203, pp. 234-249, 01/08/2006)
VUB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, SBU, SUNY, WHOI, WHOI, WHOI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, GEDI, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, VUB