Earthquake-triggered deposits in the subduction trench of the north Ecuador/south Colombia margin and their implication for paleoseismology
The north Ecuador/south Colombia convergent margin is affected by recurrent subduction earthquakes with magnitudes > 7.5, like the 1906, 1942, 1958, 1979 and 2016 events. The subduction trench is characterized by the construction of the Esmeraldas Turbidite System (ETS) fed by the large Esmeraldas Canyon that deeply incises the continental slope and that connects directly onshore with the Esmeraldas River. The detailed description of cores collected in the left-hand (western) proximal levee of the ETS and in two lobes allowed discriminating two types of coarse-grained deposits: (1) “classical” flood-generated turbidites are normally graded beds with structureless, laminated and cross-laminated intervals and high organic-matter content, while (2) earthquake-induced deposits consist of amalgamated normally-graded laminated/cross-laminated intervals separated by erosive surfaces. These latter are interpreted to be deposited by quasi-synchronous flows generated during a single earthquake. Organic matter is absent in such beds while ferromagnesian minerals and pumices are abundant, suggesting remobilization of the slope deposits. When two amalgamated beds are superimposed, the interbedded clayey interval is not bioturbated, suggesting a short time period between the beds deposition, and thus the impact of a major earthquake shock and following earthquakes on the triggering of landslides. Along the ETS, core-to-core correlation based on 210Pb excess revealed that 20th Century sedimentation occurred mainly in the proximal levee. There, a temporal relationship was established between the 1906, 1942, and 1979 earthquakes, and three coarse-grained beds showing features of earthquake-induced turbidites, suggesting the Esmeraldas Canyon was the main source for sediments to be remobilized during these earthquakes. The fining and thinning observed between the 1906, 1942 and 1979 turbidites correlate with the increasing distance of the rupture zone of each earthquake with the Esmeraldas Canyon. Earthquakes with magnitudes lower than 7 also affected the margin during the 20th Century but were not recorded in the trench sedimentation, suggesting that the turbidite levee acts as a natural filter so that potentially the highest the levee the strongest the earthquake magnitude recorded. At least ten earthquakes with the highest magnitudes were recorded on the turbidite levee within the last 800 years with a recurrence time ranging from about 268 years to 42–82 years, or less for the 20th Century earthquakes. The comparison of the main features of the 1906 turbidite with older earthquake-triggered turbidites identified in a core collected in the trench suggests that one or two earthquakes similar to the 1906 event might have occurred ~ 600 years ago.
(Marine Geology. vol. 384, n° 0025-3227, pp. 47 - 62, 01/02/2017)
GEOAZUR 6526, IRD, UPMC, UNS, INSU - CNRS, UniCA, CNRS, GEOAZUR 7329, INSU - CNRS, UniCA, CNRS, IRD [Occitanie], IRD, UniCA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UPMC
Occurrence of antibiotics in rural catchments
(Chemosphere. vol. 168, n° 0045-6535, pp. 483-490, 01/02/2017)
METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, HCMUT, VNU-HCM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Storm-induced marine flooding: Lessons from a multidisciplinary approach
There is a growing interest for marine flooding related to recent catastrophic events and their unintended consequences in terms of casualties and damages, and to the increasing population and issues along the coasts in a context of changing climate. Consequently, the knowledge on marine flooding has progressed significantly for the last years and this review, focused on storm-induced marine submersions, responds to the need for a synthesis. Three main components are presented in the review: (1) a state-of-the-art on marine submersions from the viewpoint of several scientific disciplines; (2) a selection of examples demonstrating the added value of interdisciplinary approaches to improve our knowledge of marine submersions; (3) a selection of examples showing how the management of future crises or the planning efforts to adapt to marine submersions can be supported by new results or techniques from the research community. From a disciplinary perspective, recent progress was achieved with respect to physical processes, numerical modeling, the knowledge of past marine floods and vulnerability assessment. At a global scale, the most vulnerable coastal areas to marine flooding with high population density are deltas and estuaries. Recent and well-documented floods allow analyzing the vulnerability parameters of different coastal zones. While storm surges can nowadays be reproduced accurately, the modeling of coastal flooding is more challenging, particularly when barrier breaches and wave overtopping have to be accounted for. The chronology of past marine floods can be reconstructed combining historical archives and sediment records. Sediment records of past marine floods localized in back barrier depressions are more adequate to reconstruct past flooding chronology. For the two last centuries, quantitative and descriptive historical data can be used to characterize past marine floods. Beyond providing a chronology of events, sediment records combined with geochronology, statistical analysis and climatology, can be used to reconstruct millennial-scale climate variability and enable a better understanding of the possible regional and local long-term trends in storm activity. Sediment records can also reveal forgotten flooding of exceptional intensity, much more intense than those of the last few decades. Sedimentological and historical archives, combined with high-resolution topographic data or numerical hindcast of storms can provide quantitative information and explanations for marine flooding processes. From these approaches, extreme past sea levels height can be determined and are very useful to complete time series provided by the instrumental measurements on shorter time scales. In particular, historical data can improve the determination of the return periods associated with extreme water levels, which are often inaccurate when computed based on instrumental data, due to the presence of gaps and too short time-series. Long-term numerical hindcast of tides and surges can also be used to provide the required time series for statistical analysis. Worst-case scenarios, used to define coastal management plans and strategies, can be obtained from realistic atmospheric settings with different tidal ranges and by shifting the trajectory of storms. Management of future crises and planning efforts to adapt to marine submersions are optimized by predictions of water levels from hydrodynamic models. Such predictions combined with in situ measurements and analysis of human stakes can be used to define a vulnerability index. Then, the efficiency of adaptation measures can be evaluated with respect to the number of lives that could be potentially saved. Numerical experiments also showed that the realignment of coastal defenses could result in water level reduction up to 1 m in the case where large marshes are flooded. Such managed realignment of coastal defenses may constitute a promising adaptation to storm-induced flooding and future sea level rise. From a legal perspective, only a few texts pay specific attention to the risk of marine flooding whether nationally or globally. Recent catastrophic events and their unintended consequences in terms of death and damages have triggered political decisions, like in USA after hurricane Katrina, and in France after catastrophic floods that occurred in 2010.
(Earth-Science Reviews. vol. 165, n° 0012-8252, pp. 151 - 184, 01/02/2017)
LIENSs, INSU - CNRS, ULR, CNRS, LNEC, ISMAR, ISMAR, CNR, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INSU - CNRS, UM, CNRS, UA, CEJEP, ULR, LETG - Nantes, UNICAEN, NU, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, LETG - Brest, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, CRIHAM [Limoges, Poitiers], UP, IR SHS UNILIM, UNILIM, MSHS de Poitiers [Maison des sciences de l'homme et de la société de Poitiers], UP, CNRS, SHOM, BRGM
The open sea as the main source of methylmercury in the water column of the Gulf of Lions (Northwestern Mediterranean margin)
Despite the ecologic and economical importance of coastal areas, the neurotoxic bioaccumulable monomethylmercury (MMHg) fluxes within the ocean margins and exchanges with the open sea remain unassessed. The aim of this paper is to address the questions of the abundance, distribution, production and exchanges of methylated mercury species (MeHgT), including MMHg and dimethylmercury (DMHg), in the waters, atmosphere and sediments of the Northwestern Mediterranean margin including the Rhône River delta, the continental shelf and its slope (Gulf of Lions) and the adjacent open sea (North Gyre).
(Geochimica et Cosmochimica Acta, n° 0016-7037, 01/02/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, OOB, UPMC, CNRS
Gas- and particle-phase products from the photooxidation of acenaphthene and acenaphthylene by OH radicals
This work is focused on the gas-phase oxidation of acenaphthylene and acenaphthene by OH radicals and associated secondary organic aerosol (SOA) formation under low and high-NOx conditions. Experiments were carried out in an atmospheric simulation chamber using a proton transfer reaction time-of-flight-mass spectrometer (PTR-TOF-MS) and an aerosol time-of-flight-mass spectrometer (ATOFMS) to chemically characterize the gas- and particle-phase products, respectively. Due to the structures of these two aromatic compounds, the proposed chemical mechanisms exhibit some differences. In the case of acenaphthene, H-atom abstraction from the saturated cyclopenta-fused ring was found to be competitive with the OH-addition to the aromatic rings. During the photooxidation of acenaphthene using nitrous acid (HONO), aromatic ring-opening products such as indanone and indanone carbaldehyde, generated through OH addition to the aromatic ring, were formed in higher yields compared to low-NOx conditions. In the case of acenaphthylene, OH addition to the unsaturated cyclopenta-fused ring was strongly favored. Hence, ring-retaining species such as acenaphthenone and acenaphthenequinone, were identified as the main reaction products in both gas- and particle-phases, especially under high-NOx conditions. Subsequent SOA formation was observed in all experiments and SOA yields were determined under low/high-NOx conditions to be 0.61/0.46 and 0.68/0.55 from the OH-initiated oxidation of acenaphthylene and acenaphthene, respectively.
(Atmospheric Environment. vol. 151, n° 1352-2310, pp. 34-44, 01/02/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UCC
Novel histone deacetylase 6 (HDAC6) selective inhibitors: a patent evaluation (WO2014181137)
(Expert Opinion on Therapeutic Patents. vol. 27, n° 1354-3776, pp. 229-236, 31/01/2017)
UNIL, UNIGE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IC2MP [Poitiers], UP, INC-CNRS, CNRS
Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach
While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR model to assess the performance of several surface nudging techniques in reconstructing the variability of the AMOC. Special attention is given to the reproducibility of an extreme positive AMOC peak from a preindustrial control simulation. Nudging includes standard relaxation techniques towards the sea surface temperature and salinity anomalies of this target control simulation, and/or the prescription of the wind-stress fields. Surface nudging approaches using standard fixed restoring terms succeed in reproducing most of the target AMOC variability, including the timing of the extreme event, but systematically underestimate its amplitude. A detailed analysis of the AMOC variability mechanisms reveals that the underestimation of the extreme AMOC maximum comes from a deficit in the formation of the dense water masses in the main convection region, located south of Iceland in the model. This issue is largely corrected after introducing a novel surface nudging approach, which uses a varying restoring coefficient that is proportional to the simulated mixed layer depth, which, in essence, keeps the restoring time scale constant. This new technique substantially improves water mass transformation in the regions of convection, and in particular, the formation of the densest waters, which are key for the representation of the AMOC extreme. It is therefore a promising strategy that may help to better constrain the AMOC variability and other ocean features in the models. As this restoring technique only uses surface data, for which better and longer observations are available, it opens up opportunities for improved reconstructions of the AMOC over the last few decades.
(Climate Dynamics, n° 0930-7575, pp. 1-17, 25/01/2017)
LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, UOR, PARVATI, 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, OCCR, UNIBE
Effects of PVP/PEI coated and uncoated silver NPs and PVP/PEI coating agent on three species of marine microalgae
In the last years, applications for silver nanoparticles (Ag NPs) continue to increase together with the concerns about their potential input and hazards in aquatic ecosystems, where microalgae are key organisms. The aim of the present study was to assess the relative sensitivity of three marine microalgae species with differences in cell wall composition/structure exposed to Poly N-vinyl-2-pirrolidone/Polyethyleneimine (PVP/PEI) coated 5 nm Ag NPs and uncoated 47 nm Ag NP. As limited attention has been paid to the role of coating agents in NP toxicity, the effect of PVP/PEI alone was also evaluated. After 72 h in artificial seawater, 47 nm Ag NPs formed around 1400 nm size aggregates while PVP/PEI coated 5 nm Ag NPs reached around 90 nm. Ag+ release in seawater was around 3% for 47 nm Ag NPs and 30% for PVP/PEI coated 5 nm Ag NPs. PVP/PEI coated 5 nm Ag NP aggregates entrapped the algal cells in a network of heteroaggregates, while uncoated 47 nm Ag NPs interacted to a lesser extent with algae. The concentration of PVP/PEI coated 5 nm Ag NPs that exerted the median effect (EC50) on algae growth pointed out differences in algae sensitivity: T. suecica was about 10 times more sensitive than I. galbana and P. tricornutum. Further, the coating agent alone was as toxic to algae as PVP/PEI coated 5 nm Ag NPs, suggesting that presence of the coating agent was the main driver of toxicity of coated NPs. Uncoated 47 nm Ag NPs instead, showed similar toxicity towards algae although P. tricornutum was slightly less sensitive than T. suecica and I. galbana, which agrees with the presence of a resistant silicified cell wall in the diatom. The present work demonstrates differences in sensitivity of three marine microalgae, possibly related to their cell surface and size characteristics.
(Science of the Total Environment. vol. 577, n° 0048-9697, pp. 45-53, 15/01/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Identification of the Molecular Clockwork of the Oyster Crassostrea gigas
Molecular clock system constitutes the origin of biological rhythms that allow organisms to anticipate cyclic environmental changes and adapt their behavior and physiology. Components of the molecular clock are largely conserved across a broad range of species but appreciable diversity in clock structure and function is also present especially in invertebrates. The present work aimed at identify and characterize molecular clockwork components in relationship with the monitoring of valve activity behavior in the oyster Crassostrea gigas. Results provided the characterization of most of canonical clock gene including clock, bmal/cycle, period, timeless, vertebrate-type cry, rev-erb, ror as well as other members of the cryptochrome/photolyase family (plant-like cry, 6–4 photolyase). Analyses of transcriptional variations of clock candidates in oysters exposed to light / dark regime and to constant darkness led to the generation of a putative and original clockwork model in C. gigas, intermediate of described systems in vertebrates and insects. This study is the first characterization of a mollusk clockwork. It constitutes essential bases to understand interactions of the different components of the molecular clock in C. gigas as well as the global mechanisms associated to the generation and the synchronization of biological rhythms in oysters.
(PLoS ONE. vol. 12, n° 1932-6203, pp. e0169790, 10/01/2017)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Lacustrine record of last millennia eruptions in Northern Chilean Patagonia (45–47°S)
(The Holocene. vol. 27, n° 0959-6836, pp. 1227 - 1251, 10/01/2017)
ULiège, ULiège, LMV, UBP, INSU - CNRS, UJM, UJM EPE, CNRS, GEOTOP, UQAM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UdeC, ULiège, UdeC